Return to the Cloudy Nights Telescope Reviews home pageAstronomics discounts for Cloudy Nights members
· Get a Cloudy Nights T-Shirt · Submit a Review / Article

Click here if you are having trouble logging into the forums

Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User

Equipment Discussions >> Cats & Casses

Pages: 1 | 2 | 3 | 4 | 5 | 6 | 7 | (show all)
bierbelly
Postmaster
*****

Reged: 01/23/04

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

The solution


<----------


Post Extras: Print Post   Remind Me!   Notify Moderator  
Classic8
professor emeritus


Reged: 04/12/06

Loc: Naperville, IL, USA
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.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Eddgie
Postmaster
*****

Reged: 02/01/06

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?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Ed Holland
Pooh-Bah


Reged: 06/16/10

Loc: San Jose, CA and Oxford, UK
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

Post Extras: Print Post   Remind Me!   Notify Moderator  
Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
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


Post Extras: Print Post   Remind Me!   Notify Moderator  
hottr6
Carpal Tunnel
*****

Reged: 06/28/09

Loc: 7,500', Magdalena Mtns, NM
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?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
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


Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
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.


Post Extras: Print Post   Remind Me!   Notify Moderator  
hottr6
Carpal Tunnel
*****

Reged: 06/28/09

Loc: 7,500', Magdalena Mtns, NM
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.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Eddgie
Postmaster
*****

Reged: 02/01/06

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?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Classic8
professor emeritus


Reged: 04/12/06

Loc: Naperville, IL, USA
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.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
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


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
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


Post Extras: Print Post   Remind Me!   Notify Moderator  
hottr6
Carpal Tunnel
*****

Reged: 06/28/09

Loc: 7,500', Magdalena Mtns, NM
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.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1 | 2 | 3 | 4 | 5 | 6 | 7 | (show all)


Extra information
4 registered and 10 anonymous users are browsing this forum.

Moderator:  Cotts, Starman27, kkokkolis 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 5609

Jump to

CN Forums Home


Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics