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Equipment Discussions >> Cats & Casses

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hottr6
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Reged: 06/28/09

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"But Maks have a narrow FOV" - WTH???
      #5663577 - 02/05/13 01:18 PM

I am always reading the most abused and over-used byline in astronomy.... Maks have a narrow FOV. I'll suggest that such statements are made be people who came down in the last rainstorm.

Anyone ever heard slow 'fracs have a narrow field of view repeated multiple times in the same thread? No? Try saying that in the Refractor forum and be prepared to be stoned with chipped flint glass.

Anyone whoever grew up with 'scopes before the optics revolution in the late 80s grew up with long 'fracs and Kellners (if they were lucky). Magnifications greater than 70x would clip the Moon.

Today, any noob can plop a 70 degree AFOV eyepiece in their long-focus 'scope and enjoy WIIIIDE views.

I'm plenty happy with today's WIIIIDE views offered by long-focus Maks and 'fracs.


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Binojunky
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: hottr6]
      #5663588 - 02/05/13 01:26 PM

Having a bad day?DA.

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KerryR
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Binojunky]
      #5663606 - 02/05/13 01:42 PM

Doesn't the long, narrow central baffle in most Maks impose a limit to the TFOV attainable, a limit that's not present in other designs to the same extent?

I think most peoples' perception is not that Maks have an implicitly narrow FOV (even though the size of the visual back does make this implicit to a certain degree), but rather that it's difficult to get wide TFOV's that are easier to get with other designs, which may make them limiting for certain aplications. Same would apply, it'd seem, to long focus refractors, though to a lesser degree because 2" and low power ep's can be used more effectively-- potentially much larger full field illumination and no central obstruction in the exit pupil. Perhaps this point gets over-simplified by the "Maks have a narrow FOV".

I could have all that wrong, but I don't think so. Hopefully, someone with a better grasp of the numbers than me (who has none) will post some information that should clarify (or correct) things further.


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watcher
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: hottr6]
      #5663692 - 02/05/13 02:40 PM

Ya mean to tell me that my IM715 isn't a Milky way scanner, and I'm not going to fit Andromeda in the eyepiece!? Well, I can live with that. That's why they make 6" F/5 refractors!

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spencerj
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: watcher]
      #5663815 - 02/05/13 03:51 PM

I see where the OP is coming from. Any post with the term Maksutov Cassegrain generates a barrage of posts with the term narrow field of view. The focal length of the scope never seems to come up.

For a surprising number of posters, an MCT with a focal length of 1800mm has a narrow FOV, but an SCT with a 2000mm focal length is a versatile telescope that provides great DSO views. I am not saying it doesn't, just questioning why (at times) the MCT is considered almost useless for this purpose.


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Eddgie
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: hottr6]
      #5663932 - 02/05/13 04:47 PM

When I say that MCTs have narrow fields, it is relative to other telescopes of the same aperture.

A 5" SCT will generally have a wider true field capability than a 5" MCT.

An 11" SCT can have about the same true field as a 7" MCT.

Relative to other designs, MCTs often do have much narrower true fields.

When made at f/10, they loose the advantage of having a smaller central obstruction than an f/10 SCT. They get the same true field capability, but loose the contrast advantage. And of course they are very expensive.

The truth may hurt, but it is the truth. Compared to similar aperture reflectors, MCTs generally do have a much narrower true field capability.

But this only matters if one needs a bigger field. The contrast advantage tha an f/15 MCT offers over an SCT of the same aperture makes them better (for inch of aperture) planetary scopes.

All scope have compromises. The compromise of the MCT is that unless you take special steps (which makes them very expensive to make) you wind up with a longer focal lenght scope than you get with SCTs or with Reflectors.

Or, you can take those steps and get it f/10, but then you limit the contrast potential to the same as the f/10 SCT.

Pick your poison. Higher contrast but at the expense of being limited


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Eddgie
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Eddgie]
      #5663952 - 02/05/13 05:03 PM

Regarding my last post, let me do the math on it for anyone that is interested.

The 180mm MCT has a focal lenght of 2700mm.

If you put a 2" diagonal on it to be able to use an eyepiece with a bigger field stop, the focal lenght goes up about 170mm, so 2870mm.

The baffle in the MCT is about 41mm. Assuming you want a well illuminated field, you would match this with an eyepecie with a 41mm field stop to avoid vignetting.

The C11 has a focal lenght of 2800mm, but with a 2" diagonal, the focal lenght goes up to 2970mm. The C11 though can utilize an eyepeice with a 46mm field stop and have better off axis illumination than the 180mm MCT with a 2" diagonal.

So while a 7" MCT has a slighly shorter focal lenght than an 11" MCT, the smaller baffle means that (if you want to really compare apples to apples) you have to use an eyepeice with a smaller field stop (again, assuming you wanted to be fair and limit the field stop to the size of the baffle).

The SCTs ability to use a 46mm field stop eyepeices balances out the slightly longer focal length.

So, a C11 can get about the same size true field as a 7" MCT.

That is why people say that MCTs have narrow fields. When compared to SCTs and reflectors of the same aperture, the fields are indeed usually narrower. Again the Intes MCTs can be f/10, but now you have a secondary obstruction that is about the same size, so loose the contrast advantage of a small obstruction.


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Mark Costello
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Eddgie]
      #5663975 - 02/05/13 05:16 PM

When I "window shop" for a "complementary" telescope to my 5"F6.5 achromat refractor, I keep a 7"F15 MCT on the list. Maybe it would be on an dual alt-az mount with the achro riding shotgun, finding things for the MCT and dishing out the "big picture" view before the MCT gets used for the details. The big compromise for me would be the cap on aperture. Other scopes under consideration include a 8", 9.25" or 10" SCT, or a 8-10" Dob. As you say, there're compromises all around, making this a tough pick. Oh well, between my tight budget and the good performance of my refractor, I will be taking my time on this.


Best Regards,


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Lee Jay
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: hottr6]
      #5664028 - 02/05/13 05:36 PM

I have my 5" Mak, with it's narrow field of view of around 1 degree. It's such an easy thing to fix that I don't consider it a problem. When I want a wide field, I just use my little refractor with its 5 degree field of view. What's the problem?

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Goodchild
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Lee Jay]
      #5664079 - 02/05/13 06:01 PM

Different kinds of scopes have their individual specialty. Mak's are probably best used for planetary viewing. I like mine. BTW, mine is an Ioptron with an f/12 focal ratio.

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Jon Isaacs
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Eddgie]
      #5664135 - 02/05/13 06:34 PM

Quote:


When I say that MCTs have narrow fields, it is relative to other telescopes of the same aperture.






I say something like: "a relatively narrow maximum possible true field of view." I will make a similar comment about a long focal length refractor.

This most often comes up with smaller Maks, long focal lengths, 1.25 inch focusers. It is a valid concern. The most glaring example is the ETX-125 with it's 1900mm focal length and a 1.25 inch focuser... The maximum possible field of view is right about 0.83 degrees..., the same TFOV that is possible with a 25 inch F/5 Newtonian.

Jon


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iluxo
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re: 7"F15 Mak... new [Re: Goodchild]
      #5664137 - 02/05/13 06:36 PM

Mark, I have a dual-scope setup with a 7" f/15 Mak exactly as you describe. While I have a choice for the second scope - either a 4" f/7 APO, or a 7" f/10 Mak - these days I tend to leave both of them behind and its only the 7" f/15 that goes to the mountain with me.

The reason is that as alluded to above, my 7" f/15 has a 2" back and a useful field of view about 40+ minutes of arc, enough to comfortably fit the full moon in my LV50 eyepiece at 54X, and frankly I've never found it desirable to go for a lower magnification than this. I can find things in the sky to this accuracy, so I really don't need the refractor as a super-finder, and the other Mak doesn't offer a useful advantage.

Where the dual-scope setup really DOES come into its own is on public star parties as I can handle two queues with the eyepieces at different heights, one for smaller kids and the other to suit taller people.

Edited by iluxo (02/05/13 06:42 PM)


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azure1961p
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Re: re: 7"F15 Mak... new [Re: iluxo]
      #5664314 - 02/05/13 08:59 PM

I totally agree and add the other nonsense line: "maks aren't suitable for deepsky" as if everything up there is the size of M31, the veil and the seven Sisters.

It is peculiar how it attracts these things. I like Jon's phrasing.

Pete

Edited by azure1961p (02/05/13 09:04 PM)


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cheapersleeper
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Re: re: 7"F15 Mak... new [Re: azure1961p]
      #5664993 - 02/06/13 11:03 AM

Did I miss "International Protest a Fact Day?"

If someone said, "You know, your 12" f5 homemade dob works pretty well, but doesn't it break your back carrying it around," I would tell them, "yeah, it does."

Regards,
B


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KerryR
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Re: re: 7"F15 Mak... new [Re: azure1961p]
      #5665020 - 02/06/13 11:18 AM

Quote:

I totally agree and add the other nonsense line: "maks aren't suitable for deepsky" as if everything up there is the size of M31, the veil and the seven Sisters.

It is peculiar how it attracts these things. I like Jon's phrasing.

Pete




Who ever said that? Double stars ARE deep sky...

(joke)


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hottr6
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Reged: 06/28/09

Loc: 7,500', Magdalena Mtns, NM
Re: "But Maks have a narrow FOV" - WTH??? new [Re: spencerj]
      #5665046 - 02/06/13 11:35 AM

Quote:

I see where the OP is coming from. Any post with the term Maksutov Cassegrain generates a barrage of posts with the term narrow field of view. The focal length of the scope never seems to come up.

For a surprising number of posters, an MCT with a focal length of 1800mm has a narrow FOV, but an SCT with a 2000mm focal length is a versatile telescope that provides great DSO views. I am not saying it doesn't, just questioning why (at times) the MCT is considered almost useless for this purpose.



At least one person understood my post.


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hottr6
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Eddgie]
      #5665061 - 02/06/13 11:46 AM

Quote:

When I say that MCTs have narrow fields, it is relative to other telescopes of the same aperture.



But Eddgie, even that statement is misleading. What you mean to say is MCTs have narrow fields relative to other telescopes with shorter focal lengths.

I keep coming back to slow refractors. No one has ever accused a Unitron or Zeiss Telementor of having a narrow field of view, even though it is more true than almost all MCTs of similar aperture.

Yeah, I'm grousing, but it is because maybe well-meaning people who parrot misleading or incomplete statements.


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fuzzystuff4ever
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: hottr6]
      #5665097 - 02/06/13 12:05 PM

I just think of my C90 as a nice F15 refractor that's been magically shrunken down to the size of a propane cylinder. I use my AstroTelescopes 152/F5.9 for wide field views if desired.

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Jon Isaacs
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: hottr6]
      #5665199 - 02/06/13 12:53 PM

Quote:

Quote:

When I say that MCTs have narrow fields, it is relative to other telescopes of the same aperture.



But Eddgie, even that statement is misleading. What you mean to say is MCTs have narrow fields relative to other telescopes with shorter focal lengths.

I keep coming back to slow refractors. No one has ever accused a Unitron or Zeiss Telementor of having a narrow field of view, even though it is more true than almost all MCTs of similar aperture.

Yeah, I'm grousing, but it is because maybe well-meaning people who parrot misleading or incomplete statements.




The maximum possible True Field of View is a function of both focal length and the focuser size, both are important. There are other scopes with similar apertures with similar narrow maximum possible TFoVs but in general, they are quite uncommon. Anyone buying Unitron should know what they are getting. Telementors have a 840mm focal length and from what I have read can be fitted with 1.25 inch and even 2 inch accessories so field of view is not an issue with them.

The fact that the ETX-125 has the same 0.83 degree maximum TFoV as a 25 inch F/5 Newtonian should be something of a wake up call. Five time the aperture, 25 times the light but the same TFoV. Making a comparison in the 5 inch size, a 130 mm F/5 Newtonian fitted with a 2 inch focuser is capable of a 3.7 degree TFoV. There was a time when I owned both an ETX-125 and a 130mm F/5, it only took one night under dark skies to determine which one stayed and which one moved on. An issue not mentioned so far but important is the maximum possible exit pupil size/image brightness.

For someone choosing a scope, the maximum TFoV is an important issue. It can be a big surprise to buy a 90mm Mak and discover that the Pleiades wont't fit or that big bright images are not going to happen.

Slow scopes, particularly slow scopes fitted with 1.25 inch focusers provide significantly narrower maximum True Fields of View than fast telescopes, particularly those fitted with a 2 inch focuser, of the same aperture. This is just the way it is, something to accept the same way one accepts chromatic aberration in a refractor or coma in a Newtonian...

My 8 inch F/5 Newtonian is capable of a 2.4 degree TFoV. I know of no Mak-Cassegrain of any aperture than can provide anything close to that... It's just the way the world works.

Jon


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KerryR
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Jon Isaacs]
      #5665239 - 02/06/13 01:15 PM

Even for same aperture and same focal length:
Take an 4" f12.72 refractor and an Orion 102mm Mak. Doesn't the refractor inherently permit a wider TFOV because the light cone is (usually) less restricted than the Mak, the Mak having it's necessarily narrow baffle and visual back?

It's easy (and common) to put a 2" diagonal on a 4" refractor, long focus or otherwise, and impossible to do so on the Mak (without cutting the light cone, owing to the width of the baffle and visual back), so there's also the issue of full field illumination, too, as well as the area occluded by the secondary in the exit pupil, which inherently puts a cap on the widest (usefull) TFOV in the Mak.

I'm not implying Maks are useless for DSO's or anything. Just saying the design as it's normally executed does inherently offer a narrower FOV than a refractor of the same focal length and aperture, unless I've got it wrong (a distinct possibility).


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coopman
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Jon Isaacs]
      #5665247 - 02/06/13 01:18 PM

Many observers today have no firsthand experience of what looking thru an f/15 refractor is like, so Maks DO indeed have a narrow FOV by the standards that they are used to. I've been observing since I was a teenager (45+ years ago now)and I've never looked thru a long focal length refractor.

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hottr6
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: KerryR]
      #5665279 - 02/06/13 01:35 PM

Quote:

Even for same aperture and same focal length:
Take an 4" f12.72 refractor and an Orion 102mm Mak. Doesn't the refractor inherently permit a wider TFOV because the light cone is (usually) less restricted than the Mak, the Mak having it's necessarily narrow baffle and visual back?




Jon has alluded to this, and I do agree that vignetting will occur in the Mak, but if a Mak and a 'frac have the same focal length, they will still have the same FOV when using the same eyepiece, regardless of the size of the eyepiece's field stop (but the Mak will be vignetted). Is this a correct statement?

I don't have much experience with many Maks, but I have been working under the assumption that the Synta Maks have narrow baffle tubes that will contribute to vignetting. Do Questars, Russian Rumak-Maks and the 7" Meade have "undersized" baffle tubes that contribute to vignetting?


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orion61

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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Eddgie]
      #5665310 - 02/06/13 01:49 PM

Quote:

When I say that MCTs have narrow fields, it is relative to other telescopes of the same aperture.

A 5" SCT will generally have a wider true field capability than a 5" MCT.

An 11" SCT can have about the same true field as a 7" MCT.

Relative to other designs, MCTs often do have much narrower true fields.

When made at f/10, they loose the advantage of having a smaller central obstruction than an f/10 SCT. They get the same true field capability, but loose the contrast advantage. And of course they are very expensive.

The truth may hurt, but it is the truth. Compared to similar aperture reflectors, MCTs generally do have a much narrower true field capability.

But this only matters if one needs a bigger field. The contrast advantage tha an f/15 MCT offers over an SCT of the same aperture makes them better (for inch of aperture) planetary scopes.

All scope have compromises. The compromise of the MCT is that unless you take special steps (which makes them very expensive to make) you wind up with a longer focal lenght scope than you get with SCTs or with Reflectors.

Or, you can take those steps and get it f/10, but then you limit the contrast potential to the same as the f/10 SCT.

Pick your poison. Higher contrast but at the expense of being limited



Wouldn't that then call for the comment that a Mak should be far superior than the same size SCT for Planetary viewing useing the same eyepieces?
but we never hear the Positive aspects of Maks..
WE NEED A MAK FORUM..
Heck, we can have one for audio equipment and pets??
this way us true Maksutov fans can have a safe haven for
a Big Mak chat..LOL


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Eddgie
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: hottr6]
      #5665335 - 02/06/13 02:00 PM

The baffle tube is not "Undersized." It is the right size for the secondary mirror in the scope.

The contrast of f/15 MCTs can approach that of a refractor because the central obstruction is very small.

The Baffle doesn't need to be any wider (and in fact can be smaller) than the diameter of the secondary baffle, though usually they are made a bit narrower than this.

If you make it fatter, you have to make it shorter so that light leaving the inside edge of the primary can make it to the center of the secondary.

In other words, the size of the baffle is a function of the diameter of the secondary and the spacing between the primary and secondary.

It would not make sense to use a bigger baffle because light could squeek past the secondary mirror and fall directly into the baffle.

This means that the price you pay for having contrast that approaches that of a refractor with the same aperture is that you have to have a small baffle, and this is what limits your true field.

Again, this is why MCTs generally have narrower fields than similar or even much larger SCTs (as my earlier example of the 180MCT vs a C11 clearly shows). To keep the contrast high, you have to use a small secondary, and then you get stuck with a soda straw baffle, which limits the field.

This is what made the MCT popular when refractors were achromats. You could get better contrast from a 7" f/15 MCT than you could get from a 7" f/18 achromat!

But you can get even better contrast peformance out of a C11, and get about the same true field as the MCT and a bigger field than a 7" f/18 achromat.

Again, you can get f/10 out of the MCT, but only with a SCT sized secondary. The only advantage of an f/10 MCT over a similar aperture SCT is that the MCT is better corrected for coma.

The 10" MCT though will be expensive because in the MCT design, you have to take special steps to eliminate higher order spherical abberation, or the scope will not perform well. You can aspherise, or you can use different curves on the front and rear of the meniscus, and on the secondary, but this makes for an expensive scope.

Otherwise, your MCT will usually be limited to about f/12.5 (and even then will have some HSA), and that means that it will usually be limited to a narrower true field than similar aperture refractors, reflectors, or SCTs.

And hence, for a given aperture, the MCTs usually have the narrowest true field capabilites.


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moynihan
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: orion61]
      #5665337 - 02/06/13 02:02 PM

Quote:

WE NEED A MAK FORUM..






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watcher
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: orion61]
      #5665365 - 02/06/13 02:13 PM

Quote:


Wouldn't that then call for the comment that a Mak should be far superior than the same size SCT for Planetary viewing useing the same eyepieces?
but we never hear the Positive aspects of Maks..
WE NEED A MAK FORUM..
Heck, we can have one for audio equipment and pets??
this way us true Maksutov fans can have a safe haven for
a Big Mak chat..LOL




Sorry,. There is no safe haven. Jon Isaacs will always be there to tell you that newts are better!


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spencerj
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: moynihan]
      #5665437 - 02/06/13 02:49 PM

A lot of this discussion (small baffle, only 1.25" diagonal) is assuming a Gregory MCT. The MCT also comes in the Rumak flavor. I am a fan of the Russian made Rumak Maksutov Cassegrains--MK66, MK67, M603, M703, among others. Those are still Maksutov Cassegrains. I would confidently take any one of them over a similar sized standard SCT for a number of reasons: less field curvature and less variation in optical quality being at the top of the list.

In my Intes MK66-DX, I use a 26mm Nagler T5. That combination gives me almost 1.2* TFOV at about 70x with an exit pupil of about 2mm. The field is flat and sharp to the edge. For me, this is a fine scope for DSO's and the planetary views . . . they are rather OK as well.

I guess I will just have to thank my lucky stars that I can't afford to own an F20 Dall-Kirkham scope. I can't imagine the ridicule those folks put up with . . . "Don't you know you can't see the whole Pleiades cluster in that fancy new scope?"


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Jon Isaacs
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: watcher]
      #5665492 - 02/06/13 03:20 PM

Quote:

Sorry,. There is no safe haven. Jon Isaacs will always be there to tell you that newts are better!




I won't tell you they are "better" but I will tell you they are different and how they are different.

It's really choosing equipment that is good at what you like to do. If you are a widefield junky, a Mak-Cass is a poor choice. If a compact, portable scope that does a good job on the planets, double stars and smaller DSOs is in the cards, a Mak-Cass is one to seriously consider.

Jon


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Eddgie
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Jon Isaacs]
      #5665613 - 02/06/13 04:32 PM

Yes, I don't get it..

Why do people get so defensive about this or that design.

All telescopes have some kind of compromise.

Sure a 6" APO can be as perfect as a 6" Aperture can be, but it costs a lot and it is pretty easy to match the performance 100" by using an 8" reflector and a Paracorr, and it will cost 4 to 5 times as much for the 6" APO.

The MCTs that someone else mentioned do indeed have better coma correction than a standard SCT, and have consistently excellent optical quality, but they cost two to three times what a similar sized SCT costs.

Reflectors get very akward to use as they get larger, and pressure the eyepiece performance and the viewers threshold of coma tolerance as they get fast enough to keep one off of a ladder.

Absolutely everything in optics is compromised in some way or other.

No scope is perfect for everyone because everyones needs are different, and most people simply don't have the money to buy 14" APOs or 14" Rumaks.

People like you and me just relate the news. We don't make the news.

I don't really have any interest in what anyone owns, but if they ask a question about "Why is this?" I try to answer.

If it makes me sound biased, I take that as someone just not liking the news.

Having owned refractors, reflectors, and compound scopes in all different shapes and sizes, I like them all, but they all have their compromises.

Why can't people just accept that and move on?


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Cepheus Elf
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: hottr6]
      #5665626 - 02/06/13 04:38 PM

Quote:

I am always reading the most abused and over-used byline in astronomy.... Maks have a narrow FOV. I'll suggest that such statements are made be people who came down in the last rainstorm.

Anyone ever heard slow 'fracs have a narrow field of view repeated multiple times in the same thread? No? Try saying that in the Refractor forum and be prepared to be stoned with chipped flint glass.

Anyone whoever grew up with 'scopes before the optics revolution in the late 80s grew up with long 'fracs and Kellners (if they were lucky). Magnifications greater than 70x would clip the Moon.

Today, any noob can plop a 70 degree AFOV eyepiece in their long-focus 'scope and enjoy WIIIIDE views.

I'm plenty happy with today's WIIIIDE views offered by long-focus Maks and 'fracs.







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Mary
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Loc: Highlands Ranch, CO
Re: "But Maks have a narrow FOV" - WTH??? new [Re: Jon Isaacs]
      #5665652 - 02/06/13 04:56 PM

Quote:



If a compact, portable scope that does a good job on the planets, double stars and smaller DSOs is in the cards, a Mak-Cass is one to seriously consider.





Absolutely right. My little 127 really won me over.

Mary


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Mary
sage


Reged: 01/29/08

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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Eddgie]
      #5665654 - 02/06/13 04:58 PM

Quote:



All telescopes have some kind of compromise.






And this is correct as well!

Mary


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Mark Costello
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Mary]
      #5665701 - 02/06/13 05:25 PM

Quote:

Quote:



All telescopes have some kind of compromise.






And this is correct as well!

Mary





... and I consider it to be my task as an amateur astronomer and potential telescope purchaser to understand the compromises and pick out which features on which I want versus on which I'm willing to compromise.

On my first acquisition in coming back into this hobby in 2003-2004, I wanted ruggedness, portability, ease of setup and teardown, ergonomics of use, relative low cost, and my intrinsic - or insane idea as to what was a telescope, but was willing to compromise a bit on image quality in favor of price, so I settled on a not too large achromatic refractor (first 4" and now 5").

In looking at a possible second and larger telescope, I know I still want some portability and ease of setup and teardown although am willing to compromise some on this (15 minutes versus 5 minutes for my current rig). That mainly limits the scope to some kind of reflector and its size to maybe 10" give or take a bit.

If I want to put a premium on image quality and maybe cost and compromise on everything else, it'll probably be a Newtonian reflector. If it's this, it'll definitely be a dob. And I'll see if I can find a longer focal length Newtonian (about 60" give or take a little).

If I want to insist mainly on ergonomics of use and hold down the cost a little, and a longer focal length (so as not to "compete" with my refractor), it's likely to be the Schmidt Cassegrain telescope (SCT).

If I want to insist somewhat on a combination of high image quality and portability (a bit of compromising in this) and am willing to settle for an even longer focal length and the extra cap on aperture due to availability, it may be a 7"F15 type Maksutov Cassegrain telescope (MCT).


That's a lot of things to consider. Good thing that between my achro's performance and my wallet's, I have a lot of time.

Edited by Mark Costello (02/07/13 01:50 PM)


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GeneT
Ely Kid
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: spencerj]
      #5665804 - 02/06/13 06:29 PM

Quote:

Any post with the term Maksutov Cassegrain generates a barrage of posts with the term narrow field of view.




I wonder how many of these people had ever done serious viewing with a Mak or SCT. I viewed with a C8 for about 10 years. I never commented or complained about the narrow FOVs. I did comment that I found slower optical systems to be more forgiving of more inexpensive eyepieces. All I could afford in those days were Celestron eyepieces. I was very pleased with the views provided by both the telescope and my eyepieces.


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Scott BeithAdministrator
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: GeneT]
      #5665859 - 02/06/13 07:09 PM

I used to own a very nice Orion Starmax 127 and I called it an "apo in a can"

Great little scope that never needed collimation and in 2003 it provided stunning views of Mars.

From my perspective it did have a narrow FOV but on my intended targets (planets and the Moon) it didn't matter a bit. The fact that my next scope purchase was a SV 80mm f/6 refractor may have an impact on my perception of the Mak's FOV.

I use middle focal ratio (f/7 - f/7.8) refractors now but I still have fond memories of the 5" Mak.


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Mark Costello
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Scott Beith]
      #5665942 - 02/06/13 08:04 PM

Quote:

I used to own a very nice Orion Starmax 127 and I called it an "apo in a can"

Great little scope that never needed collimation and in 2003 it provided stunning views of Mars.

From my perspective it did have a narrow FOV but on my intended targets (planets and the Moon) it didn't matter a bit. The fact that my next scope purchase was a SV 80mm f/6 refractor may have an impact on my perception of the Mak's FOV.

I use middle focal ratio (f/7 - f/7.8) refractors now but I still have fond memories of the 5" Mak.






Scott, if all you had were that SV80mmF6 refractor (was it the old Night Hawk) and the 127mm MCT, I'd say you had two nicely complementary telescopes. I may do that on a larger scale, my 5" achro and maybe a 7"F15 Mak. I'm not sure....

Edited by Mark Costello (02/07/13 01:50 PM)


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Eric63
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Loc: Ottawa, Ontario
Re: "But Maks have a narrow FOV" - WTH??? new [Re: Mark Costello]
      #5665961 - 02/06/13 08:21 PM

Mark, I'm also using complementary scopes as you described. I have a 127mm Mak that I was using with an 102mmF5 Achro, but I have now acquired my son's 150mm F5 Newt. So I think the Achro may go soon. Anyway, I now have the Mak for med to high power and the Newt for wide field and DSO's. They are both very portable, with quick set up and take down, and complement each other nicely. And they both ride nicely on the AZ4

BTW, I use a 2inch 32mm 70 degree EP in my Mak and I find the field of view more than acceptable. In fact the Mak is the scope I use the most right now.

Eric


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orion61

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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Eric63]
      #5665982 - 02/06/13 08:43 PM

I have a Meade 7" F15 Mak, my second. It is better than the first optically, I love the field of view but I am not into wide field scanning, I put a 6.3 FF/FR on my C8 for that.
The 7" is my favorite scope, I love it, There are so many details on Jupiter my Brain goes into shock! So much to take in, A Bino viewer adds to that,
I have a 127 SLT that is my Grab & Go, that replaced my ETX 90, The ETX is now my Travel scope, and Solar scope.
Along with a 12" SCT and 4" APO and 6" F8 RV6 I have most bases covered. except the 16" Dob.... Don't you love to hear a grown man whine?
Lets all PM the Admin for a Mak Forum?? HAPPY PM's


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Eric63
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: orion61]
      #5665995 - 02/06/13 08:56 PM

Orion61

I am also sold on Maks and I am considering upgrading to the 6" in the future. I think 7" would be too much since I would like to stay with the AZ4 mount. But that is down the road since the 127mm is providing me with an amazing view right now. As you said in another thread, it's a classic in the making BTW, last year I read many of your comments on the 127 Mak and your views help me a great deal in choosing this telescope.

Eric


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*skyguy*
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Reged: 12/31/08

Loc: Western New York
Re: "But Maks have a narrow FOV" - WTH??? new [Re: Eric63]
      #5666064 - 02/06/13 09:33 PM

So what if a Mak has a slightly narrower view than a general purpose scope like a SCT. Its optical design provides a comparable view with an APO refractor (or a f/15 achromat) in a lighter, more compact and more portable OTA ... and at a far lower cost. My long focal length 5" f/15 Mak will reach 257X using only a 7.4mm eyepiece and shows absolutely stunning views of the planets and the moon ... no need to use a barlow that will only "muddle" up the view. Try that with a f/10 SCT or a fast APO refractor.

When I want to go wide-view, I pull out my grab-n-go 5" f/3.64 SNT Comet Catcher that has the finest wide field views I've ever experienced using any telescope.

No one telescope will provide the perfect view for all types of observing ... from low power wide field to high power planetary viewing. I'd rather have ... which I do ... the perfect low power scope and the perfect high power scope ... than a single "middle-of-the-road" general purpose scope, that from necessity has to be a compromise between the two types of "specialty" scopes.

I have been and always will be a big fan of the Maksutov .... however, I'm also a big fan of the SCT, refractor and newtonian scopes. It all depends on the type of viewing I want to do ... and how much money I have to spend!


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Jeff B
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Reged: 12/30/06

Re: "But Maks have a narrow FOV" - WTH??? new [Re: hottr6]
      #5666073 - 02/06/13 09:41 PM

Of course, there is the Mak-Newt....I'm just say'n.

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azure1961p
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Reged: 01/17/09

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Re: "But Maks have a narrow FOV" - WTH??? new [Re: hottr6]
      #5666118 - 02/06/13 10:03 PM

Quote:


At least one person understood my post.




Well that's an irony isn't it. Your exhibiting a narrow field of view in making that statement.

Pete


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Scott BeithAdministrator
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Mark Costello]
      #5666179 - 02/06/13 10:39 PM

Quote:


Scott, if all you had were that SV80mmF6 refractor (was it the old Night Hawk) and the 127mm apo, I'd say you had two nicely complementary telescopes. I may do that on a larger scale, my 5" achro and maybe a 7"F15 Mak. I'm not sure....




It was a SV Nighthawk (excellent little achromat).
The 5" Mak gave way to an Orion ED80 which was sold for my current SV 102V.

I am a refractor guy with a strong appreciation for Maks.


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pogobbler
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Scott Beith]
      #5666407 - 02/07/13 02:37 AM

My response to the "But Maks have a narrow FOV" comment is... "Yeah... so?". Though I have a couple scopes that can give fields in excess of 2 degrees, I've never had a problem with the capabilities of a scope that'll only give a (relatively) narrow field of view, like a Mak. I like a wide field view, but a narrow field of view only eliminates a small minority of potential targets, so if I can't get all of the Pleiades in the eyepiece or can only view part of M31 at one time, or can't scan the Milky Way 2-4 degrees at a time, I can live with that.

I do think it gets said rather too often... I mean, sure, a beginner might not realize that, but most people on here do realize that the potential field of view is limited on a Mak. I mean, come on... yes, we know it, and there's a lot more to astronomy than just wide field viewing and the capability is more important to some than others... and may very well not be important at all to many of us who have scopes or binoculars that give fields of view measured in degrees rather than arc-minutes.


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cheapersleeper
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: pogobbler]
      #5666423 - 02/07/13 03:02 AM

Gents, I think you may be missing the fact that our hobby has been blitzed with Ad hype and new products for several decades that either infer or actually claim outright that the wider the field, theh happier you will be. It's part of astro culture by now. As such, people are going to constantly reinforce it.

The Mak is an attack on orthodoxy!!

B


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Jeff B
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: hottr6]
      #5666546 - 02/07/13 07:06 AM

Of course, the other sour grapes story is that inch-for-inch, the image in the Mak is dimmer.

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azure1961p
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Reged: 01/17/09

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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Jeff B]
      #5666566 - 02/07/13 07:19 AM

I think that's true in any cassegrain system - though Celestrons XLT coatings have me rethinking that. I'm a guy whose happy as pie with an 1800mm fl x 8" aperture used for deepsky. When I had deepsky sky's I was fearless with it - Abell planetaries, galaxies through the summer Milky Way, it was a true performer. I swear I've seen more detail in m51 than in sketches others have on the Internet with substantially larger aperture. The real unsung upside to maks and long focus instruments with smaller CO's is the star fields are stunning. No you don't get the wider angle views compared to an f/4 but the generous fields you do get have beautiful star images and if you need to bring the power up to view a difficult clusters fainter members all the better. I love the deepsky capability of larger aperture on faint objects like galaxies but the stars are too often comparitively hideous.

Pete


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moynihan
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: pogobbler]
      #5666606 - 02/07/13 08:09 AM

Quote:

scopes or binoculars that give fields of view measured in degrees rather than arc-minutes.




A blanket or lawn chair
Summer night
Nikon 12x50 SE
5 degrees of sharp and flat field
Sigh, It is February


Edited by moynihan (02/07/13 08:11 AM)


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Jon Isaacs
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: *skyguy*]
      #5666693 - 02/07/13 09:26 AM

Quote:

No one telescope will provide the perfect view for all types of observing ... from low power wide field to high power planetary viewing.




Some scopes are better than others at providing the best possible views over a wide range of magnifications.

A Mak-Cassegrain with a 30% central obstruction is not an apo refractor of equal aperture... In the smaller sizes, 3, 4, 5 inch, there are apo refractors that provide essentially perfect widefield views and high power planetary views. A Newtonian with premium quality mirrors, a reasonably small secondary and a coma corrector (if needed) can provide excellent views over a wide range of magnifications. Similarly, a Mak-Newt can provide both high quality, low power views and excellent views of the planets and double stars, typically Mak-Newts have small central obstructions, below 20%.

Some observers such as myself, believe there is more to viewing the night sky than zooming in on particular objects, that of importance are the relationships between objects, large scale features as well as objects that are just big. Most of these are best seen with relative fast telescopes of both large and small apertures that can provide big, bright fields of view. The views of the Cygnus with a 6mm exit pupil at 17x and 4 degree Field of view as are not hype, they are real, it's a different way to experience the night sky...

One should not deny the differences between the various scope designs nor should one dismiss the importance of the capabilities of one design over another. A fast telescope with high quality optics can provide both high quality low power views and high quality high power views. A slow telescope has a more limited range.

Jon


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maknewtnut
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: hottr6]
      #5666697 - 02/07/13 09:27 AM

Quote:

I am always reading the most abused and over-used byline in astronomy.... Maks have a narrow FOV. I'll suggest that such statements are made be people who came down in the last rainstorm.

Anyone ever heard slow 'fracs have a narrow field of view repeated multiple times in the same thread? No? Try saying that in the Refractor forum and be prepared to be stoned with chipped flint glass.

Anyone whoever grew up with 'scopes before the optics revolution in the late 80s grew up with long 'fracs and Kellners (if they were lucky). Magnifications greater than 70x would clip the Moon.

Today, any noob can plop a 70 degree AFOV eyepiece in their long-focus 'scope and enjoy WIIIIDE views.

I'm plenty happy with today's WIIIIDE views offered by long-focus Maks and 'fracs.





Shane, you're absolutely right.

The reality is that when it comes to design types, the SCT and MCT are closely related. Both can be produced at identical focal ratios. If both also utilize an identical primary focal ratio (which they often do), the same parameters for secondary size and baffle diameter apply to both.

Those who continually refer to FOV limitations for the Mak only might be more accurate if they followed such comments with something like, "Or at least that's what I believe after reading this month's catalog from Orion".


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*skyguy*
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Jon Isaacs]
      #5666800 - 02/07/13 10:31 AM

Quote:

Quote:

No one telescope will provide the perfect view for all types of observing ... from low power wide field to high power planetary viewing.




Some scopes are better than others at providing the best possible views over a wide range of magnifications.

In the smaller sizes, 3, 4, 5 inch, there are apo refractors that provide essentially perfect widefield views and high power planetary views.





Yes, they can provide high power planetary views ... however you have failed to consider the compromise that a fast APO refractor has to deal with to achieve high power. Mainly, you have to use extremely short focal length eyepieces ... which are literally a pain in the neck to use ... or using a longer FL eyepiece with a barlow ... which will always "muck-up" the view.

The Mak is a specialized instrument for high power observing that has its own advantages and disadvantages over other types of scopes ... and that includes APO and Achromatic refractors.

So, who cares if the Mak has a narrow FOV ... it doesn't need or was designed to have it!


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Jon Isaacs
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: *skyguy*]
      #5666823 - 02/07/13 10:48 AM

Quote:

Quote:

Quote:

No one telescope will provide the perfect view for all types of observing ... from low power wide field to high power planetary viewing.




Some scopes are better than others at providing the best possible views over a wide range of magnifications.

In the smaller sizes, 3, 4, 5 inch, there are apo refractors that provide essentially perfect widefield views and high power planetary views.





Yes, they can provide high power planetary views ... however you have failed to consider the compromise that a fast APO refractor has to deal with to achieve high power. Mainly, you have to use extremely short focal length eyepieces ... which are literally a pain in the neck to use ... or using a longer FL eyepiece with a barlow ... which will always "muck-up" the view.

The Mak is a specialized instrument for high power observing that has its own advantages and disadvantages over other types of scopes ... and that includes APO and Achromatic refractors.

So, who cares if the Mak has a narrow FOV ... it doesn't need or was designed to have it!




Well...

Simply put: Barlows do not "always muck up the view." Barlows are simple and a decent Barlow has negligible effect on the quality of the image, certainly far less than hanging a 30% or larger obstruction in the middle of the optical path.

It is worth keeping in mind that a 6 inch F/15 Mak is actually a 6 inch F/3 telescope with full aperture corrector and a magnifying secondary mirror that performs the same task as a Barlow.

As far as who cares? Folks who choose other designs. So... yeah, a Mak-cassegrain has advantages and disadvantages, one of disadvantage is that the maximum possible true field of view is smaller than most other popular designs of similar aperture.

That's just how it is. It's worth noting when choosing a scope.

Jon


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hottr6
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Reged: 06/28/09

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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Eddgie]
      #5666875 - 02/07/13 11:08 AM

Quote:

All telescopes have some kind of compromise.

Why can't people just accept that and move on?



Eddgie,

You are of course 110% correct. Why cannot people accept this and move on?

The reason for my rant is that many folk qualify statements about Maks with "Maks and their narrow FOV". Other 'scope designs never seem to receive as many qualifying statements, otherwise we would be forever reading statements such as:

"Extremely expensive APOs....."
"Neck-breaking Newts...."
"Violet-colored achros......"
"Mirror-shifting SCTs....."

We do see these and similar comments being made infrequently, but my beef is that we don't see them multiple times in every single thread about those designs.

I'd like to suggest that Maks are the Rodney Dangerfield of 'scopes, but they are way too pretty.


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JJK
Carpal Tunnel


Reged: 04/28/08

Re: "But Maks have a narrow FOV" - WTH??? new [Re: hottr6]
      #5666889 - 02/07/13 11:17 AM

Quote:


I keep coming back to slow refractors. No one has ever accused a Unitron or Zeiss Telementor of having a narrow field of view, even though it is more true than almost all MCTs of similar aperture.

Yeah, I'm grousing, but it is because maybe well-meaning people who parrot misleading or incomplete statements.




I can fit in virtually all of the M42 complex in my AP 10" f/14.6 Mak-Cass using a Leitz 30 mm 88* AFOV eyepiece. The view is absolutely stunning. I don't care that I can't completely visualize the relatively rare number of very wide DSOs (e.g. M31) in the FOV of this OTA, as I have other instruments to do that.

BTW, parrots aren't just mimics. They are actually intelligent creatures with personalities of their own.


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moynihan
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: JJK]
      #5666908 - 02/07/13 11:31 AM

Quote:

BTW, parrots aren't just mimics. They are actually intelligent creatures with personalities of their own.


Like Alex

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Jon Isaacs
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: hottr6]
      #5666929 - 02/07/13 11:42 AM Attachment (33 downloads)

Quote:

The reason for my rant is that many folk qualify statements about Maks with "Maks and their narrow FOV". Other 'scope designs never seem to receive as many qualifying statements, otherwise we would be forever reading statements such as:

"Extremely expensive APOs....."
"Neck-breaking Newts...."
"Violet-colored achros......"
"Mirror-shifting SCTs....."

We do see these and similar comments being made infrequently, but my beef is that we don't see them multiple times in every single thread about those designs.




You must be reading different forums that I do.

To my eye, coma, chromatic aberration, awkward viewing positions, off-axis eyepiece astigmatism in fast scopes, cost, mounting requirements, difficulties in transport, thermal equilibrium, dewing, collimation, field curvature, are among the many issues that are discussed with similar frequency as the field of view of a Mak.

I can tell you that anytime someone brings up the topic of mounting a Newtonian on a GEM, I will be right there pointing out all the fun and games that entails and just why it was that the Dobsonian became so popular. And I will include a photo just to emphasize the point.

Jon Isaacs

Edited by Jon Isaacs (02/07/13 01:48 PM)


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spencerj
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Jon Isaacs]
      #5667042 - 02/07/13 12:53 PM

What is the difference between an observer from the Northeast and an observer from California? We wear shoes in the winter

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George Methvin
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: spencerj]
      #5667161 - 02/07/13 02:06 PM

But Sct don't give refractor like views and have narrow FOV..hear that way to much. Why because SCT or not refractor..LOl and Maks are not F/5 to F/7 refractors. Apple and oranges. Its not really that big of a deal. Buy one of each type of telescope and try to be happy. I have two scope one 10 SCT I use for those really close up views and one 120mm ed refractor for those wide field views..there you go the best of both worlds...Iam happy.. .

Edited by George Methvin (02/07/13 02:07 PM)


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Robo-bob
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Jon Isaacs]
      #5667218 - 02/07/13 02:42 PM

Quote:

Quote:

The reason for my rant is that many folk qualify statements about Maks with "Maks and their narrow FOV". Other 'scope designs never seem to receive as many qualifying statements, otherwise we would be forever reading statements such as:

"Extremely expensive APOs....."
"Neck-breaking Newts...."
"Violet-colored achros......"
"Mirror-shifting SCTs....."

We do see these and similar comments being made infrequently, but my beef is that we don't see them multiple times in every single thread about those designs.




You must be reading different forums that I do.

To my eye, coma, chromatic aberration, awkward viewing positions, off-axis eyepiece astigmatism in fast scopes, cost, mounting requirements, difficulties in transport, thermal equilibrium, dewing, collimation, field curvature, are among the many issues that are discussed with similar frequency as the field of view of a Mak.

I can tell you that anytime someone brings up the topic of mounting a Newtonian on a GEM, I will be right there pointing out all the fun and games that entails and just why it was that the Dobsonian became so popular. And I will include a photo just to emphasize the point.

Jon Isaacs




Man Jon, every time I see that pic of you standing on that ladder in bare feet, my feet go into spasms. Kind of like watching another guy get kicked in the....well, you know.


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Jon Isaacs
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Robo-bob]
      #5667236 - 02/07/13 02:53 PM

Quote:


Man Jon, every time I see that pic of you standing on that ladder in bare feet, my feet go into spasms. Kind of like watching another guy get kicked in the....well, you know.




I keep that photo just to post in the winter. When I first posted it, I did not know that I was barefoot, someone had to point it out to me.

It does get cold up in the mountains east of San Diego... thermal socks and thick soled boots are definitely on the menu.

Jon


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JJK
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: moynihan]
      #5667255 - 02/07/13 03:03 PM

Quote:

Quote:

BTW, parrots aren't just mimics. They are actually intelligent creatures with personalities of their own.


Like Alex




Alex had an exceptional (and trained) way to communicate. I don't have the time to train my parrots that way, but it's clear a lot of processing is going on in their heads.


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JJK
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: spencerj]
      #5667266 - 02/07/13 03:07 PM

Quote:

What is the difference between an observer from the Northeast and an observer from California? We wear shoes in the winter




Actually, make that thick-soled shoes or boots, several layers of socks, long underwear, normal clothes, Carhartt one-piece coverall, balaclava, and gloves!


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Scott BeithAdministrator
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Jon Isaacs]
      #5667690 - 02/07/13 07:14 PM

Quote:



To my eye, coma, chromatic aberration, awkward viewing positions, off-axis eyepiece astigmatism in fast scopes, cost, mounting requirements, difficulties in transport, thermal equilibrium, dewing, collimation, field curvature, are among the many issues that are discussed with similar frequency as the field of view of a Mak.


Jon Isaacs




Yep - just hang out in the refractor forum a bit and you will see the "CA is horrible - only apos are worth owning" vs. "Who would spend that kind of money when an achromat is just as good" battle surface on a repeated basis.

EVERY scope is a compromise. Just the way it is...


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Jon Isaacs
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Scott Beith]
      #5667831 - 02/07/13 08:44 PM

Quote:



EVERY scope is a compromise. Just the way it is...




No, No, No....

Your scopes are compromises, my scopes are perfect...

Now if I can just find an eyepiece that is free from astigmatism at F/1.4...



Jon


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Robo-bob
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Jon Isaacs]
      #5667889 - 02/07/13 09:24 PM

Quote:

Quote:



EVERY scope is a compromise. Just the way it is...




No, No, No....

Your scopes are compromises, my scopes are perfect...

Now if I can just find an eyepiece that is free from astigmatism at F/1.4...



Jon




Seriously Jon, men who stand on ladders in their bare feet don't exactly have a whole lot of credibility


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aa6ww
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Robo-bob]
      #5667989 - 02/07/13 10:32 PM

Quote:

Quote:

Quote:

The reason for my rant is that many folk qualify statements about Maks with "Maks and their narrow FOV". Other 'scope designs never seem to receive as many qualifying statements, otherwise we would be forever reading statements such as:

"Extremely expensive APOs....."
"Neck-breaking Newts...."
"Violet-colored achros......"
"Mirror-shifting SCTs....."

We do see these and similar comments being made infrequently, but my beef is that we don't see them multiple times in every single thread about those designs.




You must be reading different forums that I do.

To my eye, coma, chromatic aberration, awkward viewing positions, off-axis eyepiece astigmatism in fast scopes, cost, mounting requirements, difficulties in transport, thermal equilibrium, dewing, collimation, field curvature, are among the many issues that are discussed with similar frequency as the field of view of a Mak.

I can tell you that anytime someone brings up the topic of mounting a Newtonian on a GEM, I will be right there pointing out all the fun and games that entails and just why it was that the Dobsonian became so popular. And I will include a photo just to emphasize the point.

Jon Isaacs




Man Jon, every time I see that pic of you standing on that ladder in bare feet, my feet go into spasms. Kind of like watching another guy get kicked in the....well, you know.







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BPO
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: hottr6]
      #5668000 - 02/07/13 10:37 PM

Like a lot of people, as a kid I started out on small refractors. After that I moved up to increasingly larger aperture SCTs. Eventually I graduated to big reflectors, and learned that anything less, especially small refractors - any refractors, in fact - were only for amateurs. Then a few years later I rediscovered the joys of small refractors. Finally, I tried and loved every one of the Maks made by Synta, including the wonderful 190mm Mak-Newt.

Any telescope is better than no telescope.


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Scott BeithAdministrator
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Jon Isaacs]
      #5668136 - 02/07/13 11:48 PM

Quote:

Quote:



EVERY scope is a compromise. Just the way it is...




No, No, No....

Your scopes are compromises, my scopes are perfect...

Now if I can just find an eyepiece that is free from astigmatism at F/1.4...



Jon






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Jon Isaacs
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: BPO]
      #5668421 - 02/08/13 07:42 AM

Quote:

Eventually I graduated to big reflectors, and learned that anything less, especially small refractors - any refractors, in fact - were only for amateurs.




This is a hobby, we are amateur astronomers...

Jon


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azure1961p
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Jon Isaacs]
      #5668439 - 02/08/13 08:05 AM

Sadly, the wages some of the pros make at observatories might seem like an extension of that term. Ill never forget the poor guy who had to ride his bike to work (and a junky one one) to Keck.

Pete


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hottr6
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: azure1961p]
      #5668830 - 02/08/13 11:52 AM

Quote:

Sadly, the wages some of the pros make at observatories might seem like an extension of that term. Ill never forget the poor guy who had to ride his bike to work (and a junky one one) to Keck.

Pete



There are very few jobs in the world that have a better commute to work than Keck. Besides, the guy on a bike was prolly a tri-athlete in training. I'll bet he could afford shoes, too.

Shane in grey-zone New Mexico


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Jon Isaacs
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: hottr6]
      #5668874 - 02/08/13 12:14 PM

Quote:

Quote:

Sadly, the wages some of the pros make at observatories might seem like an extension of that term. Ill never forget the poor guy who had to ride his bike to work (and a junky one one) to Keck.

Pete



There are very few jobs in the world that have a better commute to work than Keck. Besides, the guy on a bike was prolly a tri-athlete in training. I'll bet he could afford shoes, too.

Shane in grey-zone New Mexico




I am guy that commuted to work via bicycle for more than 20 years. I consider it a luxury. Unfortunately age has caught up with me and those 125 mile/weeks are not possible any more.

But the Kecks, I believe the observatory is at about 14,000 feet. An ex-coworker is a operator and he says just being there are 14,000 feet is no fun.

Jon


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Mark Costello
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Jon Isaacs]
      #5669096 - 02/08/13 01:45 PM

Back on subject, MCTs have characteristics that at least to me present bigger challenges than the field of view. If I had a 7" F15 MCT, I can work around that by putting it on a goto mount or putting it on a dual saddle mount and have my 5" achro ride shotgun. Other challenges associated with MCTS from my perspective include:

1) Availability of MCTs: It appears that Orion 7" MCTs are quite available, and so are Questars (if you can afford them). Those appear to be the only choice for 7" MCTs. There are offerings from Meade, Celestron, and Ioptron, but only for smaller apertures. There used to be MCTs available from Intes-Micro and Santel, but the dealers offering them either have stopped or closed their doors. My workaround is to buy what's available and not worry about what's not available. Factoring in cost, if I were to get a MCT, it'd be the Orion 180mmF15 MCT.

2) Weight: As MCTs get larger, their weight goes up notably and with it, the difficulties in setting up the rig and putting it away. For me, that would limit me to 8" at most, based on specs for MCTs that once were offered here in the US. At 16 lbm, the Orion 7"F15 would not pose a problem here.

3) Heat transfer lag or cooldown. From here in North Carolina, this could be a problem. Picking on the Orion, I just don't see aby provisions for active or passive speedup of cooling. My workaround would either to set up very early or to store the optical tube assembly in un-airconditioned storage room (in a case or bag, of course).


None of this means that I've ruled out a MCT as a companion scope for my refractor. It only means that there may be problems with MCTs other than field of view of which I should be aware and ready to resolve.

Best,


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NHRob
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Mark Costello]
      #5669214 - 02/08/13 02:49 PM

You can still order Intes-Micro maks through APM. There may be others but, I'm not sure.

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moynihan
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Mark Costello]
      #5669275 - 02/08/13 03:26 PM

Stellar Optical?

Intes Micro among others....


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Robo-bob
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: moynihan]
      #5670029 - 02/09/13 01:04 AM

Quote:

Stellar Optical?

Intes Micro among others....




I've tried to contact Stellar numerous times with no response. Odd as they advertise on the side liner here on CN.


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Asbytec
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Robo-bob]
      #5670182 - 02/09/13 05:55 AM

Unless you want wide field vistas, I am not sure what the narrow field hoopla is all about. The MCT FOV is actually perfect for lunar, planetary, double stars, and even most deep sky.

The MCT also seems plagued with the cool down myth. Its really not a myth, but its overblown. Their reputation may have stemmed from the earlier, heavy models. No doubt the Meade took a while with its massive internal weight. Other than that, their cool down appears to be similar to the similarly designed SCT.

I find neither to be a problem at all, and I star hop to every target including 10th mag doubles. Properly executed, the MCT is an impressive design. My Orion is simply jaw dropping. So much so, the FOV just is not a concern with the high power work I enjoy.


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Jon Isaacs
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Asbytec]
      #5670195 - 02/09/13 06:36 AM

Quote:

Unless you want wide field vistas, I am not sure what the narrow field hoopla is all about. The MCT FOV is actually perfect for lunar, planetary, double stars, and even most deep sky.

The MCT also seems plagued with the cool down myth. Its really not a myth, but its overblown. Their reputation may have stemmed from the earlier, heavy models. No doubt the Meade took a while with its massive internal weight. Other than that, their cool down appears to be similar to the similarly designed SCT.

I find neither to be a problem at all, and I star hop to every target including 10th mag doubles. Properly executed, the MCT is an impressive design. My Orion is simply jaw dropping. So much so, the FOV just is not a concern with the high power work I enjoy.




I am not sure what all the hoopla is about either. One needs to merely accept that in comparison other designs, Maksutov-Cassegrains have a narrow maximum possible true field of view, have difficulty achieving large exit pupils and low magnifications and move on.

If any of those things are important to you as an observer, if you do want a scope that is capable of "widefield vistas" and is "perfect for lunar, planetary, double stars, and deep sky", such telescopes exist, they just have their own sets of disadvantages and issues.

Jon


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Eddgie
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Jon Isaacs]
      #5670475 - 02/09/13 10:39 AM

Quote:

Maksutov-Cassegrains have a narrow maximum possible true field of view, have difficulty achieving large exit pupils and low magnifications and move on.




Ah, but it is all relative, isn't it? And that is what telescope design is about.

The origins of the Mak position it as an "Alternative" to its contemporary designs.

And what where the contemporary designs for amateurs? When it was introduced, what was the MCT competing with?

Well, it was competing with another scope that had narrow fields of view, that also had trouble with generating wider exit pupils, and that was very expensive to make in 5" to 8" apertures.

What was that other scope? It was the large observatory achromat.

And for this competitor, the MCT was in fact a superior design in just about every way.

It offered the same contrast and a long focus achromat of the same aperture, it offerd in some cases a wider true field of view and potentially a bigger exit pupil, it was far easier to mount, and it costs less to make.

In every way, it was simply a better telecope than a large long focus achromat.

And that remains the case today. I don't know why anyone in their right mind would buy a 7" f/18 achromat when they could buy a 180mm MCT and get esentially the same performance for a fraction of the price.

So, it is all realtive, and relative to the 6" and 7" long focus achromat, the 180mm MCT is a total winner.

But I would rather have a C11. You get a bigger true field with a bigger exit pupil, coupled to a much bigger aperture with better resolution and contrast.

And this answers why there are so few larger MCTs on the market. The market has spoken, and said that it prefers other options, and that other option is almost always these days, a larger, less expensive, SCT.

It is always about the market and what people are buying, and they buy SCTs because the packaging is better, and the price is cheaper.

I would rather have a 5" SCT than a 4" MCT.

I would rather have a 6" SCT than a 5" MCT.

I would rather have an 8" SCT than a 7" MCT.

I would rahter have an 11" SCT than an 8" MCT.

And so it would seem, would a lot of other people.

Aperture is aperture, and the advanteages of more aperture for the same money in a package that is essentially about the same size and weight is what the MCT competes with today.

When it was long focus acrhomats, it was oh, so easy. The MCT was a better scope in just about every way.

It's a jungle out there.. LOL>


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ColoHank
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Eddgie]
      #5670517 - 02/09/13 11:09 AM

Which explains why there are more Chevrolets than Rolls Royces, but we all know which is the better automobile.

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RogerRZ
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: ColoHank]
      #5670867 - 02/09/13 02:44 PM

Quote:

Which explains why there are more Chevrolets than Rolls Royces, but we all know which is the better automobile.




If you could get a RR for Chevy money, I doubt there would be many bowties on the road.


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Jon Isaacs
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Eddgie]
      #5671944 - 02/10/13 08:07 AM

Quote:


Maksutov-Cassegrains have a narrow maximum possible true field of view, have difficulty achieving large exit pupils and low magnifications and move on.

Quote:


Ah, but it is all relative, isn't it? And that is what telescope design is about.







Relative or not, it just is... Design is about accepting the restrictions and limitations as engineers do, as another parameter. You recognize it, accept it and consider it when making choices.

If you want to look at history, there always were large Newtonians and there still are. If one wants the best possible planetary views and the seeing is sufficient to support a large aperture...

Just to note:

"And that remains the case today. I don't know why anyone in their right mind would buy a 7" f/18 achromat when they could buy a 180mm MCT and get esentially the same performance for a fraction of the price."

Once it's cooled down, maybe...

Jon


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Eddgie
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Jon Isaacs]
      #5672198 - 02/10/13 11:43 AM

I'd rather carry a 7" MCT, mount, and cooling fan than carry out a 7" f/18 refractor and the mount for it.

For what I would pay for the mount for the refractor, I could have a custom made cooling fan for the MCT.

It is of course my own opinion, but I am sure that for every 7" f/18 achromat sold today, there are a couple of hundered 7" MCTs that get sold.

There really isn't anything a 7" f/15 MCT can't do as well or better than a 7" f/18 achomat. Saying cooling is some kind of obstacle seems to me to be less than solid logic when it is a problem that is easily delt with.


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RichD
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Eddgie]
      #5672834 - 02/10/13 06:36 PM

I love my little 5" mak. I got it originally as a grab and go scope for looks at the moon and planets as I was getting tired of lugging out the 12" dob all the time. I wasn't expecting much in the way of deepsky from it but I was very pleasantly surprised, after all it has a max true field of 1 degree so will fit about 95 of the messier catalogue objects.

I think the saying that Maks have narrow fields of view has come about maybe from advertising and advice given to new astronomers in part. You could imagine a noob being slightly disappointed with a Mak if they pointed it at the pleiades or M31. More experienced observers know that it is horses for courses and that MCTs are better suited to those objects that fit a 1 degree field or thereabouts, but how are beginners supposed to know this? they don't so sayings like these get thrown around and after a while they become believed by people.


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Jon Isaacs
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: RichD]
      #5672922 - 02/10/13 07:35 PM

Quote:


I think the saying that Maks have narrow fields of view has come about maybe from advertising and advice given to new astronomers in part. You could imagine a noob being slightly disappointed with a Mak if they pointed it at the pleiades or M31. More experienced observers know that it is horses for courses and that MCTs are better suited to those objects that fit a 1 degree field or thereabouts, but how are beginners supposed to know this? they don't so sayings like these get thrown around and after a while they become believed by people.




And you are saying that the maximum possible field of view of a Mak-Cassegrain is not narrow in comparison other telescopes of the same aperture? Saying that more experienced astronomers know that a 5 inch Mak-Cass is limited to a 1 degree TFoV seems to me to be saying that a 5 inch Mak-Cass has a Narrow Maximum Possible Field of View in comparison to other 5 inch scopes.

"Believed by some people", it's just how it is, there is nothing to believe or disbelieve, it's a matter of understanding...

Jon Isaacs


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Jon Isaacs
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Eddgie]
      #5672936 - 02/10/13 07:40 PM

Quote:

There really isn't anything a 7" f/15 MCT can't do as well or better than a 7" f/18 achomat. Saying cooling is some kind of obstacle seems to me to be less than solid logic when it is a problem that is easily delt with.




If you want to play games... a 7 inch F/12 or F/15 or whatever focal ratio achromat does provide a substantially brighter image than an 7 inch F/15 Mak.

Disassembling the scope, cutting holes in the tube, installing fans, how many really do that???

The proper scope to compare to a 7 inch Mak is a longer focal length Newtonian, the achromat is red herring.



Jon


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Asbytec
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Jon Isaacs]
      #5672954 - 02/10/13 07:53 PM

Jon, Rich may have a point. Seems, per the OP, they have a rep for a narrow FOV and for some reason thats a bad thing.

As you correctly say, without understanding, such a rep - no doubt promoted by the 'fracter crowd through fear of Mak 'fracter like performance - gives MCT FOV a bad name. It might turn some folks off, those who prefer wide fields and those who do not understand.

Same with cool down.


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RichD
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Asbytec]
      #5673476 - 02/11/13 04:16 AM

I didn't explain my point very well. I was trying to say that the term "narrow field of view" is often mentioned of MCTs and that the uninitiated may think that this really limits their use drastically to a small range of objects.

It is true that a 5" MCT has a narrower TFOV than an similar sized reflector or even an SCT, but the above saying though it is true also, gives the MCT a reputation which is not fully deserved IMO.

Of course I take your point John and indeed this is the way I think about the matter, but when I am out with my Mak and looking at M41 or M50 say with a 24mm Panoptic giving a hair over a 1 deg field, I sometimes find myself thinking of all the comments I have heard or read over the years that a small mak is no good for deepsky and smiling to myself.


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ColoHank
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: RogerRZ]
      #5673746 - 02/11/13 10:10 AM

Quote:

If you could get a RR for Chevy money, I doubt there would be many bowties on the road.




If you could get a Rolls Royce for Chevy money, it wouldn't be a Rolls Royce; it would just be another Chevy.


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Re: "But Maks have a narrow FOV" - WTH??? new [Re: RichD]
      #5673757 - 02/11/13 10:14 AM

Quote:

Of course I take your point John and indeed this is the way I think about the matter, but when I am out with my Mak and looking at M41 or M50 say with a 24mm Panoptic giving a hair over a 1 deg field, I sometimes find myself thinking of all the comments I have heard or read over the years that a small mak is no good for deepsky and smiling to myself.




There is no doubt there are plenty of wonderful DSOs to be seen with a 5 inch Mak..

I am an admitted Widefield/Richest field Junky, I spend a good amount of time looking more than small, named objects This is the way I look at it:

There are many objects with in the range of a 5 inch Mak with a 1 degree maximum True Field of View. Granted, this is is significantly narrower than the 1.35 degree TFoV possible with a 16 inch F/4.4 and M7 in the big scope will show details just not visible in any small scope. But still, there are a great number of objects, visible in a 5 inch with a 1 degree TFoV.

However, if one looks at the things that a small aperture scope does better optically than a large scope, that is, "What can a small scope show me that a large scope cannot?" Resolution, contrast, light gathering, these are all on the side of the larger scope. And certainly the portability factor of a small scope is important. But at the eyepiece, the right small scope can offer wider fields of view than a large scope, otherwise that's about it.

Widefields of view may or may not matter... They do to me. If I am out where the skies are dark and clear, I have some sort of glass and plywood and aluminum contraption setup and I am checking out the Veil Nebula, it's pretty sweet with a 6mm exit pupil at 70x with an O-III filter but I can only see part of it at one time. A 5 inch Mak-Cass is not going to show me anything new but a 4 or 5 inch F/5 or F/6, it'll show me a view of the Veil that is not possible with the larger scope.

The "limited" possible field of view of the Mak-Cass just is. It's not something to argue about, it's not something to deny, it's something to understand, to be aware of and to accept. It just is, the same way a 25 inch F/5 Newtonian is about 10 feet tall. It's not something to deny, to argue about, it's something to understand, to be aware of and to accept.

Jon

Edited by Jon Isaacs (02/11/13 02:07 PM)


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KerryR
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Jon Isaacs]
      #5673801 - 02/11/13 10:38 AM

It's worth noting the the narrow FOV reputation IS a worthwhile consideration for neophytes, for whom ANY long focus scope, and it's inherent narrower FOV, can impose difficulties in target acquisition when learning to star hop. I believe it is with beginners in mind that the narrow FOV thing is promoted, for good reason. This doesn't have to be a hard and fast 'rule', especially in consideration of other important factors such as cost, size, weight, and ease of mounting, not to mention (accurate) go to, but certainly worth consideration.

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Jon Isaacs
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: KerryR]
      #5673817 - 02/11/13 10:52 AM

Quote:

It's worth noting the the narrow FOV reputation IS a worthwhile consideration for neophytes, for whom ANY long focus scope, and it's inherent narrower FOV, can impose difficulties in target acquisition when learning to star hop. I believe it is with beginners in mind that the narrow FOV thing is promoted, for good reason. This doesn't have to be a hard and fast 'rule', especially in consideration of other important factors such as cost, size, weight, and ease of mounting, not to mention (accurate) go to, but certainly worth consideration.






It is certainly more difficult to starhop with a 90mm F/14 Mak than a 80mm F/5 ST-80...

Jon


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Asbytec
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Jon Isaacs]
      #5673969 - 02/11/13 12:28 PM

Quote:

The "limited" possible field of view of the Mak-Cass just is. It's not something to argue about, it's not something to deny, it's something to understand, to be aware of and to accept.




Again, that is a most excellent point, Jon. Seems, though, too often the FOV is portrayed as a bad thing to be avoided. Along with cool down, these two aspects are driven home giving the MCT an undeserved bad reputation. Those two conditions are almost synonymous with MCTs. Mention a Mak, and someone will bring either or both into the discussion almost as if a Mak has a form of cancer. It simply perpetuates the myth and does nothing for understanding the design.


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spencerj
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Jon Isaacs]
      #5674011 - 02/11/13 12:52 PM

Quote:

If I am out where the skies are dark and clear, I have some sort of glass and plywood and aluminum contraption setup and I am checking out the Veil Nebula, it's pretty sweet with a 6mm exit pupil at 700x with an O-III filter but I can only see part of it at one time.





That must be a really small part of the veil. Or is that 70x with a 31mm Nagler in the 16" scope? Or do you have a scope with a 21000mm focal length and 4200mm aperture to get to 700x and a 6mm exit pupil? Or a 310mm Nagler? I know that Newtonians are fantastic scopes, but . . . maybe I am misplacing a decimal point somewhere?


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spencerj
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: spencerj]
      #5674024 - 02/11/13 01:01 PM

I think as a general rule, people who buy a 2 door coup understand that the vehicle does not have seatbelts for 9 passengers. Maybe it just doesn't need to be pointed out repeatedly in the the 2-door-coup forum. Maybe we could just all assume that we understand the personal choice and "compromise" that was made when the car was bought.

In the Beginner's forum . . . fair enough, but here . . . it should not be necessary.


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KerryR
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: spencerj]
      #5674088 - 02/11/13 01:41 PM

I wouldn't expect folks new to the hobby to limit themselves exclusively to the beginners forum. They can and should investigate and partake in any forum of interest. Otherwise, when would one 'graduate', specifically, from the beginners forum?

I'm unaware of a forum where any scope's short comings are not a constant source of discussion. For example, it's rare for someone to post a question on a short focus achromat in the refractor forum and not have someone point out, obvious though it is to many of us, that the poster may find chromatic aberration limiting. If the poster was already aware, no harm done. If not, they learned something, even less harm done. And, let us not forget the many folks who read but don't post who may have learned something.

Point is, we're ALL here to discuss scopes, even though we have varying expertise and experience, so why wouldn't we discuss the most relevant attributes (comparatively narrow FOV in this case), and even the less relevant attributes (does narrow FOV matter and to whom)? It's certainly what I see going on in the other forums.

I think the source of the sore spot may be that limited FOV is less frequently mentioned with other Cats, particularly the SCT. It should be. But that's a different argument to one that suggests discussion or mention of certain inherent design limitations should be taboo in a given forum.


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Jon Isaacs
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: spencerj]
      #5674141 - 02/11/13 02:14 PM

Quote:

I think as a general rule, people who buy a 2 door coup understand that the vehicle does not have seatbelts for 9 passengers. Maybe it just doesn't need to be pointed out repeatedly in the the 2-door-coup forum. Maybe we could just all assume that we understand the personal choice and "compromise" that was made when the car was bought.

In the Beginner's forum . . . fair enough, but here . . . it should not be necessary.




I would say this: Why then the complaining... Everyone knows a Mak has a narrow FOVin comparison to other designs of equal aperture, so are we even bothering with this thread?

Jon


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Asbytec
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: KerryR]
      #5674143 - 02/11/13 02:16 PM

Good comment, Kerry.

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Ed Holland
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Asbytec]
      #5674183 - 02/11/13 02:53 PM

On the flip side, one nice thing is that one can reach the higher useful magnifications for planetary with longer focal length eyepieces. That is a helpful feature (to me) for Lunar & planetery work & the occasional double star viewing.

My 127mm (118 ) f/12 Mak has served very well as a planetary scope, giving views that complement those I can obtain from a 5" refractor of f/9.3. The refractor has a little more to offer on feignt targets, but I'm pretty limited by haze & light pollution most of the time. The refractor is not immune to cool down issues in the form of tube currents. On the flip side, these issues are easily avoided in either scope by planning equiment setup ahead of viewing.

A telescope collection is like a socket set - pick the right one for the job. I'm dead lucky to have a few modest but fun instruments to enjoy. Each has a character of its own which adds variety to viewing the heavens


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spencerj
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Asbytec]
      #5674188 - 02/11/13 02:55 PM

It is just that sometimes, certain things get repeated so often that they become disconnected from their original purpose--as pure and chivalrous as that may have been.

There is currently a post in this very forum where an experienced observer is truly baffled with the performance of a 41mm Panoptic and 26mm Nagler in a C6. He expected disastrous results based on the math and ray traces and the factual drop in edge of field illumination (and probably posts from members of this community). Yet when he actually tried it . . . the combination worked fine. He was pleased with the view.


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orion61

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Re: "But Maks have a narrow FOV" - WTH??? new [Re: spencerj]
      #5674461 - 02/11/13 05:05 PM

For photography the FL of a Mak is not nearly the issue than it used to be. I remember guiding until my head felt like it was going to fall off.
Now we can do it in a small fraction of the time.
Both SCT'S AND MAKS HAVE ADVANTAGES over the other.
I am mainly a Lunar/Planetary/Double Star viewer.
for photography the SCT gets the nod.
You guys remember photography through a Newtonian?
6-10 mph winds had my Cave bouncing all over.


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Asbytec
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Ed Holland]
      #5674624 - 02/11/13 06:59 PM

LOL, Ed. A few of us know that 'wink.' My 'eye' is wide open and performing beautifully, NFOV and all.

Edited by Asbytec (02/11/13 07:03 PM)


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BigC
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: hottr6]
      #5675653 - 02/12/13 11:35 AM

Does a 7" f"X" Mak have a narrower FOV than a 7" f"X" refractor ?

Comparing scopes of the same focal length would seem to be more "fair";and really they should have the same clear aperture in order to compare two optical systems that begin with the same amount of light.So maybe I would discover that my 5" f13?(just a guess,it is a Bushnell)Mak would equal a 4" f13 APO.

And the Mak is easier to mount and store.

It SEEMS obvious to me one needs at least two scopes:one widefield and one long focus!

A universal tool is one that does all jobs equally poorly.


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KerryR
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: BigC]
      #5675784 - 02/12/13 12:48 PM

Quote:

Does a 7" f"X" Mak have a narrower FOV than a 7" f"X" refractor ?

Comparing scopes of the same focal length would seem to be more "fair";and really they should have the same clear aperture in order to compare two optical systems that begin with the same amount of light.So maybe I would discover that my 5" f13?(just a guess,it is a Bushnell)Mak would equal a 4" f13 APO.

And the Mak is easier to mount and store.

It SEEMS obvious to me one needs at least two scopes:one widefield and one long focus!

A universal tool is one that does all jobs equally poorly.




Depends on the baffles, focuser diameter, and diagonal diameter, I think, in the refractor, all of which affect TFOV. In most cases, I believe the refrator will have a wider available light cone, and so should be capable of a wider field, even at the same focal length.

Then there's also the issue that the refractor can be used at larger exit pupils, exceeding 7mm, without a secondary shadow dimming the center of the FOV (effective aperture reduced in both cases)

As you point out, the big advantage to the Mak is not it's performance characteristics relative to the refractor, but it's cost, weight, shortness, ease of mounting, and, arguably, it's fairly refractor-like performance, which sums up the whole reason the design ever came about in the first place. Same arguments would apply to an SCT.

But really, how many f12-15 refractors, not to mention Newts, do we see anyway?


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Asbytec
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: KerryR]
      #5676000 - 02/12/13 02:52 PM

Id need to look up the specifics, but the CAT design - not only the Mak - will vignette the field. However, there is also the usable field to consider. If a CAT vignettes some of the usable field, that may rub wide field folks the wrong way. I cant pull figures from memory, but I believe spot Maks have smaller usable fields than Rumaks. Those in turn differ from refractor and other CAT designs, including classical Cassegrains, etc. All designs have some level of usable fields and vignetting.

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Ed Holland
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Asbytec]
      #5676037 - 02/12/13 03:08 PM

There are some odd artifacts, IIRC with all Cassegrain variants. These can lead to edge vignetting due to the presence of a baffle, and (I think) central FOV dimming at very low magnifications due to the CO.

Someone may want to comment on the validity of my second comment.

Ed

P.S. I like my f/10 and longer scopes, but I'll consider a wide field instrument if you can get me nearer to Jupiter or Saturn


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Asbytec
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Ed Holland]
      #5676044 - 02/12/13 03:11 PM

Yea, Ed, same here.

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Jon Isaacs
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: BigC]
      #5676131 - 02/12/13 03:50 PM

Quote:

Comparing scopes of the same focal length would seem to be more "fair";and really they should have the same clear aperture in order to compare two optical systems that begin with the same amount of light.So maybe I would discover that my 5" f13?(just a guess,it is a Bushnell)Mak would equal a 4" f13 APO.




Such comparisons are not about being fair, rather they are about being realistic. 4 inch F/5 refractors with 2 inch focusers exist. 5 inch F/5 Mak-Cass' don't. On the other hand, 5 inch Maks that are 15 inches long exist and 5 inch Newtonians that are 15 inches long don't.

It's not about being "fair", it about what is and what is possible.

Jon


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maknewtnut
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Jon Isaacs]
      #5676809 - 02/12/13 11:30 PM

After reading more input to this thread over the past few days, I have to say something to Jon. I believe the thread was about folks in this forum comparing MakCass telescopes to SchmidtCass telescopes (or other Cassegrain variants). In reading many of your replies, I get the impression your take was MakCass compared to Newt.

To expand on a few points that were made, one has to first consider the strengths and weaknesses of any telescope design type when making comparisons. When it comes to the 80mm refractor v 90mm f/14 MCT comparo, of course the refractor will be the better choice for most...because it is at smaller apertures that the refractor provides the most pros vs cons. At apertures of ~10" and larger, the Newtonian reflector provides the most pros vs cons compared to other designs. It is at mid-apertures where the MCT (and other Cassegrain variants for that matter) provide more pros than cons.

To lump all MCT's into the f/12 and slower 'basket' supports the OP's point more than it supports supposed arguments against it.

(and FWIW, to list only Chinese f/12-f/15 MCT and Questars as the only available options is just plain wrong...or once again, claiming what one 'knows' is what they read from the latest Orion catalog...those were shipped across an ocean to the N America for those who might be under the impression that ordering from a vendor on another continent won't lead to the same method of arrival)


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Eric63
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: maknewtnut]
      #5677224 - 02/13/13 08:50 AM

My two cents here. I saw the OPs post as a jab with a touch of sarcasm at those who complain about the narrow FOV of Maks but then go and recommend F10 SCT or F10 to F15 refractor. I have only been in the hobby less than a year but it did not take me long to figure out the difference between scopes, and which ones I like best. In the end the view is not the only thing that counts. Ergonomics, economics and storage are other factors that to me are very important. I got a 127Mak because I did not want to spend a fortune on an apochromat, nor did I want a long tube or a large cumbersome tube. My Mak is very portable, stores easily, I have no vibration issues at all and I can sit comfortably behind it in an area where I have limited space. Oh yes, and the views are fabulous. For my viewing habits, smaller instruments are best and coming onto my 1 year anniversary in the hobby I have found that the combination of a 6 inch F5 newt and a 5 inch Mak best suit my needs. So yes, I knew about the Narrow FOV and I welcomed it since My Mak is my solar system scope for around the house and my Newt is my wide field and DSO scope when I travel to a darker site. And I have to add, that when I do use the Mak for brighter DSOs, I love the views. Yes they are not wide field, but when I have to come in closer the contrast and sharpness is much appreciated.

Eric


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KerryR
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: maknewtnut]
      #5677330 - 02/13/13 09:59 AM

Quote:


...
To lump all MCT's into the f/12 and slower 'basket' supports the OP's point more than it supports supposed arguments against it.
...





There are commercially produced MCT's that are faster than f12? Who and how fast? Obviously, some MCT's can accept a focal reducer, but I don't think that's what you're talking about.


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Jon Isaacs
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: maknewtnut]
      #5677390 - 02/13/13 10:42 AM

Quote:

After reading more input to this thread over the past few days, I have to say something to Jon. I believe the thread was about folks in this forum comparing MakCass telescopes to SchmidtCass telescopes (or other Cassegrain variants). In reading many of your replies, I get the impression your take was MakCass compared to Newt.




That might have been the case but I just went back and read the original post and the no mention SCT or other Cassegrain varient. This is what I did find however:

"Today, any noob can plop a 70 degree AFOV eyepiece in their long-focus 'scope and enjoy WIIIIDE views.

I'm plenty happy with today's WIIIIDE views offered by long-focus Maks and 'fracs."

In any event, the field of view knock referred to is generally in comparison to Newtonians and fast refractors...

Jon


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RichD
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: KerryR]
      #5677412 - 02/13/13 10:49 AM






There are commercially produced MCT's that are faster than f12? Who and how fast? Obviously, some MCT's can accept a focal reducer, but I don't think that's what you're talking about.




Most Intes Micro MCTs and other high end russian/Euro designs are f/10. Some are slower but most are f/10.


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ColoHank
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: KerryR]
      #5677555 - 02/13/13 11:58 AM

Quote:

As you point out, the big advantage to the Mak is not it's performance characteristics relative to the refractor, but it's cost, weight, shortness, ease of mounting, and, arguably, it's fairly refractor-like performance, which sums up the whole reason the design ever came about in the first place. Same arguments would apply to an SCT.






I've read somewhere that the design came about because Dmitri Maksutov wanted to create a relatively low-priced, easy-to-manufacture scope (originally all spherical surfaces) to equip Soviet classrooms. His intent, while laudible, wasn't to rival refractor performance or stimulate discussion, though it appears he's done both.


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Asbytec
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Eric63]
      #5677603 - 02/13/13 12:32 PM

Nice comment, Eric. Id simply add the Mak is a little narrow for some folk's preferences, but its certainly not a debilitating handicap relative to the design strengths. I star hop with mine and love the lunar and planetary views, to some extent thanks to the focal length and narrow FOV.

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Mark Costello
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: maknewtnut]
      #5678146 - 02/13/13 06:35 PM

Quote:



...........

(and FWIW, to list only Chinese f/12-f/15 MCT and Questars as the only available options is just plain wrong...or once again, claiming what one 'knows' is what they read from the latest Orion catalog...those were shipped across an ocean to the N America for those who might be under the impression that ordering from a vendor on another continent won't lead to the same method of arrival)







I was one of those, if not the only one who wrote that. Yes, I know I "can" buy an Intes-Micro MCT from a vendor on another continent and it'll get here in a boat as the MCTs come to Orion. But as a practical matter, I stand by what I said. From where I sit I see at least two differences between buying a foreign MCT from an American vendor (Orion) and buying one from a foreign vendor. They are VERY material in any decision I might make on brand IF I decide to buy an MCT.

1) Orion can place an order for several (5, 10, 50 etc.) MCTs on some periodic or occasional basis and probably get a break on shipping. Sometimes they pass that break by offering free shipping (they are doing that right now for bulkier Dobs.) A European vendor will ship one MCT and they have to charge me shipping for that one scope to make a fair profit and so I have to pay the full shipping costs for the one MCT. I see that as a big difference.

2) If there are any problems with a MCT sold in America, Orion, I can get some kind of satisfaction from the vendor within a reasonable time frame. My impression is that that I may be out on a limb if there is a problem of any kind with the particular MCT that gets shipped to me. That makes me pause and stop even though the I-T MCTs evidently have high build quality, it's just the idea that one unit might have a defect and I get it and the vendor is an ocean and a continent away.


NOTE TO ANY FOREIGN VENDOR: In writing what I wrote, I mean no disrespect at all and am only conveying my honest concerns. If I'm in the wrong, I'm willing to learn better from YOU.


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Eric63
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Asbytec]
      #5678269 - 02/13/13 08:02 PM

Hi Norme

I had a new experience in star hopping with my Mak. In addition to my Telrad, I added a 9X50 RACI finder. I was at a dark site last weekend and the finder became a nice little wide field scope that allowed me to scan the sky for something interesting and then zoom in for a closer look with the Mak. It was a new way of using the Mak and I loved it. And all from the comfort of my observing chair

Eric


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Asbytec
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Eric63]
      #5678361 - 02/13/13 09:09 PM



You know, Eric, I grind trough it the old fashioned way. Jupiter and the moon are not tough, but a 10th mag double can be. Still, its very doable and sometimes enjoyable. The ~1 degree field is plenty, really, once you get close. But, I like that you found a nice method.


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BPO
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Jon Isaacs]
      #5842553 - 05/05/13 09:59 PM

Yes, that was my point.

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Eddgie
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: ColoHank]
      #5843111 - 05/06/13 08:59 AM

Quote:

I've read somewhere that the design came about because Dmitri Maksutov wanted to create a relatively low-priced, easy-to-manufacture scope (originally all spherical surfaces) to equip Soviet classrooms. His intent, while laudible, wasn't to rival refractor performance or stimulate discussion, though it appears he's done both.





In fact, his attempt was indeed to rival refractors, and he no doubt succeeded.

But you have to remeber that the refractors he was attempting to rival were the refractors that existed at the time, which were long focus achromats.

And with long focus achromats, once you get bigger than about 4", you are limited by chromatic abberation.

Now the funny thing is that with MCTs, once you get bigger than about 4", you are limited by higher order spherical abberation.

If you keep the focal lenght long though (f/15 to f/18) you get three big benefits.

The first is the very small obstruction, and while this slighly lowers contrast, it would be no worst then the chromatic abberarion caused by using a similarly fast large achromat.

The second is that that the system is somewhat easier to make, though this is in fact not a major benefit becuse there are three spherical surfaces vs four for a refractor.

THe last is the mounting, where you can easily mount a 6" f/17 MCT vs a 6" f/17 achromat.

There is another issue as well. When this design was first created, there were no modern coatings. This meant the MCT acutally enjoyed a slight advantage in light transmission. Silvered optics required recoating, but were very high tranmsission. Large refractors had much more light loss than can be achieved today.

So in fact, the MCT design was superior in many ways.

As for the field of view, at f/17 each instrument would have esentiall the same field.

Once again, one must remember the state of the art during that time. Eyepicees were mostly Orthos or Kellners, and these eyepecies were rarely allowed to an apparent field of more than about 40 degrees. This means that if you had a 1" eyepeice, you were limited to a field stop size of about 20mm.

The MCT baffle and secondary was allowed to be very small because once again, eyepeices of the day simply did not need a big baffle.

Bottom, line... Back when the design was introduced, it was in fact a better telescope than the long focus achroamt that it very quickly replaced.

Edited by Eddgie (05/06/13 02:52 PM)


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bierbelly
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Eddgie]
      #5843386 - 05/06/13 11:59 AM

The solution


<----------


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Classic8
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Eddgie]
      #5843695 - 05/06/13 02:15 PM

I suppose if you're used to Newts, the typical FOV in a Mak seems constricting. If you're used to an SCT or long f/l refractor, the difference probably doesn't seem nearly as noticeable. Most of the objects I've looked at fit into a Mak's FOV at low power. It isn't THAT narrow.

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Eddgie
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Classic8]
      #5843782 - 05/06/13 03:05 PM

It's all relative of course.

I find that even with the C14, the great majority of deep sky objects easily fit into the field.

In fact, I have been using Binoviewers for the last year and a half, and even limited to 1.25" format, most things I like to look at still fit into the field.

But then there is the really big stuff. Large open clusters, and even larger star clouds.

Even a 2 degree field will not allow you to frame many of these objects.

There are always tradeoffs. Even the finest APO made is limited by the diffraction of its own aperture and to break that limit (by going progressively larger) starts to impose other limits (cost and the increasing concern of chromatic aberration).

The tradeoff of the MCT is an excellent one. If well designed with a very small central obstruction, if offers contrast performance with no meaning full difference to a similar sized APO.

The tradeoff is that it will not be able to show as wide a field.

Is that bad? I don't think so.

It just is what it is.... A design that has to made to a long focal length to maintain contrast to a similar sized refractor. The penalty is a narrower field.What is wrong with that?


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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Eddgie]
      #5844391 - 05/06/13 08:34 PM

^Nothing, and one benefit, usually, is lower cost

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Jon Isaacs
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Eddgie]
      #5847250 - 05/08/13 07:34 AM

Quote:

I find that even with the C14, the great majority of deep sky objects easily fit into the field.




This has something to do with the fact that historically, telescopes that were used to discover DSOs had a narrow field of view. If one has dark skies, there is a whole big world out there beyond what can be seen with a focal length approaching 13 feet.

Jon


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hottr6
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Jon Isaacs]
      #5848464 - 05/08/13 06:51 PM

Quote:

Quote:

I find that even with the C14, the great majority of deep sky objects easily fit into the field.




This has something to do with the fact that historically, telescopes that were used to discover DSOs had a narrow field of view. If one has dark skies, there is a whole big world out there beyond what can be seen with a focal length approaching 13 feet.

Jon



I live at a dark-sky site, and most of my work (super-nova search, no AP, no filters) is with magnifications providing at most 0.6 degree FOVs.

Other than outreach with the usual suspects of "big" targets and aimless Milky Way sweeping, what am I missing with small FOVs?


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Jon Isaacs
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: hottr6]
      #5849005 - 05/08/13 10:56 PM

Quote:


I live at a dark-sky site, and most of my work (super-nova search, no AP, no filters) is with magnifications providing at most 0.6 degree FOVs.

Other than outreach with the usual suspects of "big" targets and aimless Milky Way sweeping, what am I missing with small FOVs?





Shane:

Obviously you are satisfied with what you see and your approach to this hobby. A scope with a narrow field of view seems to do the job for you.

But there are other paradigms than inpecting/observing specific, already known and cataloged objects. The celestial sphere is a large place, about 41,253 square degrees or about 146,000 different 0.6degree circles.

Glenn Ledrew calls it the Holistic viewing of the universe, observing the multi-scale nature of the universe. One can back away and see relationships and large scale features in the rich nebulosity of the our own galaxy. Filters are good for this...

A relative of mine is a well known geologist whose expertize is in understanding the oil bearing rocks of the California oil fields. Before she retires, every year she would give tours of the region to oil company geologists, usually she had a couple of buses full.

She once told me that if you had 100 geologists and showed them a shear cliff of rock with a single gleaming, red rock embedded in the surface, 97 of them would rush to the red rock and try to understand it. Only three would look at the structure of the rock cliff and try to understand that. Both are worthy but in this particular situation, it was the formation that held the key, not the red rock.

I personally find viewing the night sky in a variety of possible ways most rewarding. Narrow, high magnification viewing with a large telescope, wider lower power views with a large telescope, even wider, even lower power views with a small telescope. Of course, I am not "working", I spend my days in a laboratory "working." I am enjoying the universe, I am enjoying the night sky.

Jon


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GlennLeDrew
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Jon Isaacs]
      #5849093 - 05/08/13 11:36 PM

Most amateurs overlook big, subtle objects, and moreover tend to focus only on the light emitters. If dark clouds are of interest, a very wide field is mandatory. While there are a goodly number of tiny cloudlets, the full band of the Milky Way is rife with structures of up to 10 degrees.

And there are the big, nearby clusters, most stellar associations, and no small number of large nebulae. And as Jon reminded us, appreciating the forest as well as the trees facilitates a fuller picture of the geography of the sky.

These are some reasons to not restrict to sub-degree FOVs.


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hottr6
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Jon Isaacs]
      #5849138 - 05/09/13 12:17 AM

Jon and Glenn,

Thanks for your thoughts. I guess I sound presumptious when I use the word "work". I'm just a volunteer citizen scientist who wants to contribute data to the people who have wider and deeper thoughts about the origins of our universe.

I also have to state that of the 3 hours my GEM may track the sky each clear evening, I would spend at most 30 minutes looking into the eyepiece. I need to rest my eye after capturing photons, and what better way than to look upwards into the dark sky and enjoy all that my naked eyes can absorb. It is during those times that I can (I think) appreciate the shape and size of our own galaxy, and it's place relative to our equally large, but distant neighbors. For this, no telescope is needed, and I long for 180-degree FOV eyeballs.

I like your story about your geologist friend. I do have training in geology, but abandoned it in favor of mathematics and physics to understand the origin of our planet and solar system. I would be one of the 97, because for me, that gleaming red rock is older than the surrounding matrix, and by definition, it's story is all the more interesting because it has been to more places, and witnessed more events.

As an aside, as a young scientist I was told that as we become increasingly specialized, we learn more and more about smaller and smaller things, so that one day, we will know everything about nothing! I was chided for my response that the speaker knew nothing of calculus.


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Re: "But Maks have a narrow FOV" - WTH??? new [Re: hottr6]
      #5849545 - 05/09/13 09:12 AM

Quote:

Other than outreach with the usual suspects of "big" targets and aimless Milky Way sweeping, what am I missing with small FOVs?





There is no reason at all that someone must have a wide field of view but there is no reason at all to suggest that there is no point in having a wide field of view either.

There are a great many large objects that will not fit into a .6 degree field.

There are numerous large nebula for example that will not come close to fitting into a .6 degree field.

There are numerous star clusters that will not fit into a .6 degree field.

For example, most amateurs maybe have never looked for the Cluster Melotte 20 (CI 442).

This cluster is so large that most people panning across it would not realize that it is a cluster.

To see it takes very wide (5 degree) field to really see it well.

Because the cluster is not condensed, if you looked at it in a narrow field, you would only see a tiny fraction of the entire cluster.

And this is not a "Bright" cluster.

It only stands out from the background when seen in a field that is much larger than the cluster itself.

There are a great many, large, faint clusters that cannot really be easily identified as a cluster because they lay against the Milky Way, and it is hard to tell the cluster is there unless you frame a large enough area around it to see it.

Don't get me wrong. I agree that even with .5 degree in my C14, I far far more fits into the field than doesn't fit into the field.

But a lot of stuff doesn't.

And for the things that won't fit, I have smaller, faster telescopes.

I use my 6" APO for big stuff.

Compare the 2.1 degree true field of my 6" APO to 1 degree (well illuminated) field of a 6" f/14 MCT, and tell me which would be better suited to these kinds of targets?


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Classic8
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: GlennLeDrew]
      #5850452 - 05/09/13 04:53 PM

Quote:

Most amateurs overlook big, subtle objects, and moreover tend to focus only on the light emitters. If dark clouds are of interest, a very wide field is mandatory. While there are a goodly number of tiny cloudlets, the full band of the Milky Way is rife with structures of up to 10 degrees.

And there are the big, nearby clusters, most stellar associations, and no small number of large nebulae. And as Jon reminded us, appreciating the forest as well as the trees facilitates a fuller picture of the geography of the sky.

These are some reasons to not restrict to sub-degree FOVs.




Just as there are some reasons not to restrict yourself to a dob or other wide-field instrument. Narrowness of field is only one of many aspects of observing, or should I say, enjoying the act of observing.


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Re: "But Maks have a narrow FOV" - WTH??? new [Re: hottr6]
      #5850978 - 05/09/13 09:40 PM

Quote:

I would be one of the 97, because for me, that gleaming red rock is older than the surrounding matrix, and by definition, it's story is all the more interesting because it has been to more places, and witnessed more events.




I suspect it is possible the red rock could have been deposited or crystallized in place.


Quote:

As an aside, as a young scientist I was told that as we become increasingly specialized, we learn more and more about smaller and smaller things, so that one day, we will know everything about nothing!




My father was a well known oceanographer who was involved in many aspects of not only the ocean but the world in general. At his memorial service, Roger Revelle finished your story.

"Most scientists learn more and more about less and less until they know everything about nothing. John Isaacs learned however learned less and less about more and more until he nothing about everything." The reality was that he knew quite a bit about most everything...

Jon


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Jon Isaacs
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Classic8]
      #5850989 - 05/09/13 09:50 PM

Quote:


Just as there are some reasons not to restrict yourself to a dob or other wide-field instrument. Narrowness of field is only one of many aspects of observing, or should I say, enjoying the act of observing.




The catch is that a wide field instrument is able to also provide those narrow fields of view... It can do both.

I can admit to owning a telescope that is limited to 0.75 degree TFoV but it also operates as a "Richest Field Telescope" because while it has a 125 inch focal length, it F/5 so that I can view at 102X with a 6.2 mm exit pupil. A 1mm exit pupil is 635x.

Jon


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hottr6
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Re: "But Maks have a narrow FOV" - WTH??? new [Re: Jon Isaacs]
      #5851282 - 05/10/13 02:22 AM

Quote:

At his memorial service, Roger Revelle finished your story.



I knew Roger, and was at his service. Now you know who chided me. I worked at IGPP. My office was next to Walter Munk's and had the best view on the planet.

Good to know you, Jon, but your Dad was before my time.


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