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Equipment Discussions >> Cats & Casses

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BYoesle
Post Laureate
*****

Reged: 06/12/04

Loc: Goldendale, Washington USA
Re: Why do people even buy SCTs??? new [Re: ATM57]
      #6224455 - 11/30/13 12:34 AM

Great, just what we need: another petty and ridiculous sectarian divide.

First, let me say I’ve owned all kinds of telescopes. I don’t think it appropriate to disparage a particular type of telescope, as they all have their pluses and minuses. SCTs offer a large aperture in a compact size, among other advantages. However, they can also have their limitations and issues, and indeed often can be made to perform even better by modifying them – both optically and mechanically. Where does the concept of “believing in their SCTs” (or any telescope for that matter) come into play? Perhaps I’m just an atheist when it comes to material objects, or at least telescopes

That said, I’m having a little trouble understanding your post Ed.

Quote:

I have just been so thrilled with my SCTs in the past. Most of them were really able telescopes that presented me with hundereds of hours of wonderful observing. And none of the mods I tried seemed to make any meaningful difference for my own observing needs that I stopped chasing the "Mod of the day" a long time ago. And the bigger I went, the more I enjoyed them. The more I could see. More deep sky, more planetary detail, more stars in clusters. No mods or anything. I just went bigger and bigger and saw more and more... At least one person loves them just the way they are...




If you were so thrilled with the SCT’s you had in the past and loved them just the way they are, why did you get an Edge HD as listed in the signature? Could it have been OTA/mirror venting, a new secondary mirror and corrective optics to eliminate coma and flatten the field, and a primary mirror clutch/lock to eliminate mirror shift?

It seems you have “voted with your feet” and abandoned the very scopes you love “just the way they are.” So if someone with an older version SCT attempts via modification to gain some of the same advantages you have obtained by buying an newer version of the SCT, doesn’t that mean you have simply paid to have the mods done for you rather than attempting them yourself? Hasn’t your very action demonstrated that which you are concerned with -- enhancing the perception that there is “so much wrong” with SCTs? If you have chosen a “better mouse trap” via a manufacturer, why shouldn’t someone try some of the same via modification of their existing scope -- without being subjected to the claim that they are denigrating the SCT?

Lastly, let me just say some of us like to tinker and experiment to see what improvements we can make on our own, and how the incremental improvements can add up...

Best wishes to one and all,


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EFT
Vendor - Deep Space Products
*****

Reged: 05/07/07

Loc: Phoenix, AZ
Re: Why do people even buy SCTs??? new [Re: BYoesle]
      #6224477 - 11/30/13 12:52 AM

My first real scope was an SCT and I doubt that I will ever be without one. They may not be perfect, but that cannot be beat for size, performance AND price. I have yet to feel the desire to haul around a 6-foot plus tube or a hugely heavy collapsible newt that must be completely disassembled for transport. Someday maybe, but I still won't give up my SCT. Nothing wrong with modding them to improve the performance, but even that may not be necessary depending on where you use the scope.

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azure1961p
Postmaster
*****

Reged: 01/17/09

Loc: USA
Re: Why do people even buy SCTs??? new [Re: BYoesle]
      #6224504 - 11/30/13 01:36 AM

Quote:

Great, just what we need: another petty and ridiculous sectarian divide.

First, let me say I’ve owned all kinds of telescopes. I don’t think it appropriate to disparage a particular type of telescope, as they all have their pluses and minuses. SCTs offer a large aperture in a compact size, among other advantages. However, they can also have their limitations and issues, and indeed often can be made to perform even better by modifying them – both optically and mechanically. Where does the concept of “believing in their SCTs” (or any telescope for that matter) come into play? Perhaps I’m just an atheist when it comes to material objects, or at least telescopes

That said, I’m having a little trouble understanding your post Ed.

Quote:

I have just been so thrilled with my SCTs in the past. Most of them were really able telescopes that presented me with hundereds of hours of wonderful observing. And none of the mods I tried seemed to make any meaningful difference for my own observing needs that I stopped chasing the "Mod of the day" a long time ago. And the bigger I went, the more I enjoyed them. The more I could see. More deep sky, more planetary detail, more stars in clusters. No mods or anything. I just went bigger and bigger and saw more and more... At least one person loves them just the way they are...




If you were so thrilled with the SCT’s you had in the past and loved them just the way they are, why did you get an Edge HD as listed in the signature? Could it have been OTA/mirror venting, a new secondary mirror and corrective optics to eliminate coma and flatten the field, and a primary mirror clutch/lock to eliminate mirror shift?

It seems you have “voted with your feet” and abandoned the very scopes you love “just the way they are.” So if someone with an older version SCT attempts via modification to gain some of the same advantages you have obtained by buying an newer version of the SCT, doesn’t that mean you have simply paid to have the mods done for you rather than attempting them yourself? Hasn’t your very action demonstrated that which you are concerned with -- enhancing the perception that there is “so much wrong” with SCTs? If you have chosen a “better mouse trap” via a manufacturer, why shouldn’t someone try some of the same via modification of their existing scope -- without being subjected to the claim that they are denigrating the SCT?

Lastly, let me just say some of us like to tinker and experiment to see what improvements we can make on our own, and how the incremental improvements can add up...

Best wishes to one and all,




I think you mis took his intent.

Pete


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JJK
Carpal Tunnel


Reged: 04/28/08

Re: Why do people even buy SCTs??? new [Re: ATM57]
      #6224509 - 11/30/13 01:46 AM

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I have had all ... refractors, apo's, reflectors, SCT's and sorry, aperture rules! A really sweet scope like my Meade 14"ACF is awesome. Imagine having a 14" refractor, oh my goodness, I'd need a crane to haul THAT around!




Yeah, a 14" refractor would be a monster to be sure even if it was an APO. My C-9 is currently satisfying my large planetary scope needs. A 9" refractor could not be afforded even if I built my own hence my "modded" C-9. We all satisfy our needs in different ways.

Scopejunkie




While SCTs have their virtues, it would take much less than a 9" refractor to outperform a 9" SCT.




Not mine.

Scopejunkie




Which 9" refractors did you test your 9" SCT against, and on which targets?




I have built 3 8" refractors. Two at F/12 and 1 at F/9. I know how 8" refractors perform and would compare to my modified C-9.

Scopejunkie




Did you grind the lenses, what style (achro, apo) where they, and what were the specifications of the objectives (smoothness, zones, coatings)?


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ATM57
super member


Reged: 01/01/10

Loc: Tehachapi, CA
Re: Why do people even buy SCTs??? new [Re: JJK]
      #6224519 - 11/30/13 02:03 AM

Quote:

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I have had all ... refractors, apo's, reflectors, SCT's and sorry, aperture rules! A really sweet scope like my Meade 14"ACF is awesome. Imagine having a 14" refractor, oh my goodness, I'd need a crane to haul THAT around!




Yeah, a 14" refractor would be a monster to be sure even if it was an APO. My C-9 is currently satisfying my large planetary scope needs. A 9" refractor could not be afforded even if I built my own hence my "modded" C-9. We all satisfy our needs in different ways.

Scopejunkie




While SCTs have their virtues, it would take much less than a 9" refractor to outperform a 9" SCT.




Not mine.

Scopejunkie




Which 9" refractors did you test your 9" SCT against, and on which targets?




I have built 3 8" refractors. Two at F/12 and 1 at F/9. I know how 8" refractors perform and would compare to my modified C-9.

Scopejunkie




Did you grind the lenses, what style (achro, apo) where they, and what were the specifications of the objectives (smoothness, zones, coatings)?




I won't go into the details concerning the three 8" refractors I have built. That's not the reason for this thread. I will say that the lenses were tested before I built scopes around them though.

Scopejunkie


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doug mc
super member
*****

Reged: 03/21/09

Loc: Tamborine Mountain Australia
Re: Why do people even buy SCTs??? new [Re: jrbarnett]
      #6224520 - 11/30/13 02:04 AM

I thought , what would be better than my c6---- you got it , a c8. So i went and got one. Happy camper. Versatile, comfortable viewing on a stool, no need for hyper expensive eyepieces, yada yada, the list goes on.

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drago
sage


Reged: 01/11/08

Loc: Latvia
Re: Why do people even buy SCTs??? new [Re: Footbag]
      #6224537 - 11/30/13 02:25 AM

Quote:

Quote:

built quality?

SCT have no chances to good newtonian, imho.




So... What is a good Newtonian?

Strehl doesn't matter if your focuser cannot hold your CCD camera.




i there talking about visual instrument. if we talking about a photographic, then statements is another. large central obstruction and mediocre optics quality there are no problem...


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kkokkolisModerator
Carpal Tunnel
*****

Reged: 09/23/09

Loc: Piraeus, Greece
Re: Why do people even buy SCTs??? new [Re: azure1961p]
      #6224542 - 11/30/13 02:38 AM

Quote:

Whose angry? I thought its been fairly good thread. Differing opinions here and there but nothing Id call anger. And the spirit of the OP was tongue n cheek anyway.

Pete




I wish, hope and consider that you are right. I'm happy as long as I am wrong!


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AlaskaWolf
member


Reged: 11/09/13

Loc: Meridian, ID
Re: Why do people even buy SCTs??? new [Re: jimbo728]
      #6224573 - 11/30/13 03:46 AM

10-in. F/12.0 Alpha Draconis Apochromatic OTA: $91,280 (used to be a naval gun)
OR
Celestron CGE PRO 1100 EdgeHD : $6,999

Yeah...I think I can deal with the SCT's faults, buy a new F-350, take that vacation to Bora Bora, and get change back

I love refractors...but if I want to see something that big, I'll just head on down to Mobile with Uncle Rod and visit the USS Alabama....


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Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Why do people even buy SCTs??? new [Re: ur7x]
      #6224576 - 11/30/13 03:47 AM

Quote:

My 9.25 SCT kicks my F/5 6" Newts backside.




I imagine it does when it comes to working at high magnifications, it ought to. However there are places a 6 inch F/5 will go that a 9.25 inch F/10 cannot and that's the reason to own both these scopes. One of them is capable of a 3 degree field of view, one of them is capable of a 1 degree field of view..

The right scope for the job at hand is what it all about. There are objects that are best suited for an 80mm F/5 with a 2 inch focuser, there are objects that are best suited for a 635mm aperture.. The California nebula is not much to look at in a 0.7 degree TFoV.

Jon


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Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Why do people even buy SCTs??? new [Re: EFT]
      #6224584 - 11/30/13 03:58 AM

Quote:

My first real scope was an SCT and I doubt that I will ever be without one. They may not be perfect, but that cannot be beat for size, performance AND price. I have yet to feel the desire to haul around a 6-foot plus tube or a hugely heavy collapsible newt that must be completely disassembled for transport




A data point:

I used to setup my 12.5 inch Tube Dob alongside a variety of guys with 12 inch LX-200s. I could do it in less than a minute, the tube was about 51 inches long... I never did see someone setup a 12 inch LX-200 in less than a minute...

Jon


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David Knisely
Postmaster
*****

Reged: 04/19/04

Loc: southeastern Nebraska
Re: Why do people even buy SCTs??? new [Re: Jon Isaacs]
      #6224586 - 11/30/13 04:02 AM

Quote:

Quote:

My 9.25 SCT kicks my F/5 6" Newts backside.




I imagine it does when it comes to working at high magnifications, it ought to. However there are places a 6 inch F/5 will go that a 9.25 inch F/10 cannot and that's the reason to own both these scopes. One of them is capable of a 3 degree field of view, one of them is capable of a 1 degree field of view..

The right scope for the job at hand is what it all about. There are objects that are best suited for an 80mm F/5 with a 2 inch focuser, there are objects that are best suited for a 635mm aperture.. The California nebula is not much to look at in a 0.7 degree TFoV.

Jon




Well, the California Nebula is not much to look at in scopes with even a two to 2.5 degree true field of view. To see the whole thing, I need my 100mm f/6 refractor. Still, in my 9.25 inch SCT (59x, 1.12 degree true field of view) using the H-Beta filter at my dark sky site, I can see some of the broad filamentary detail in that nebula by panning around somewhat.

As for the question about why people buy SCT's, the answer is plain: Because they WORK! They may not be exactly the very best in certain areas, but they can be a very effective instrument for the amateur astronomer (I know mine is). Clear skies to you.


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junomike
Carpal Tunnel
*****

Reged: 09/07/09

Loc: Ontario
Re: Why do people even buy SCTs??? new [Re: David Knisely]
      #6224671 - 11/30/13 07:19 AM

SCT ~ Sufficient Compact Telescope.

The "Jack of all trades, master of none."

Mike


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Wmacky
Carpal Tunnel
*****

Reged: 11/24/07

Loc: Florida
Re: Why do people even buy SCTs??? new [Re: drago]
      #6224704 - 11/30/13 08:12 AM

Quote:

Quote:

Quote:

built quality?

SCT have no chances to good newtonian, imho.




So... What is a good Newtonian?

Strehl doesn't matter if your focuser cannot hold your CCD camera.




i there talking about visual instrument. if we talking about a photographic, then statements is another. large central obstruction and mediocre optics quality there are no problem...




Who said this thread was only about visual? I don't care for ugly diffraction spikes, inherent coma which the Edge scopes lack. Limited back focus. You every look through a Newtonian while on a GEM? Was the focuser stuck underneath the scope? And no you can't use a dob mount if you have a observatory with a centrally mounted GEM unless you want to get stuck using only one scope. What's the current most used scope for Planetary imaging? I had to give away my last newtonian as the coating flaked off do to humidity exposure after 7years out in the observatory. That's what happens to unprotected mirrors in this location.

Now all that said, I DO like newtonians,and plan for a big Dob in the future, but if you think that size is the only advantage to a SCT's, well........

Edited by Wmacky (11/30/13 08:33 AM)


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kansas skies
sage


Reged: 12/02/12

Loc: Kansas, USA
Re: Why do people even buy SCTs??? new [Re: Jon Isaacs]
      #6224743 - 11/30/13 08:37 AM

Quote:

Quote:

My first real scope was an SCT and I doubt that I will ever be without one. They may not be perfect, but that cannot be beat for size, performance AND price. I have yet to feel the desire to haul around a 6-foot plus tube or a hugely heavy collapsible newt that must be completely disassembled for transport




A data point:

I used to setup my 12.5 inch Tube Dob alongside a variety of guys with 12 inch LX-200s. I could do it in less than a minute, the tube was about 51 inches long... I never did see someone setup a 12 inch LX-200 in less than a minute...

Jon




Are you not comparing apples to oranges here? I'm assuming that beyond the optics comparison, there's also the alt-az vs equatorial comparison. How much difference in setup time would there be if the mountings were similar?

Bill


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drago
sage


Reged: 01/11/08

Loc: Latvia
Re: Why do people even buy SCTs??? new [Re: Wmacky]
      #6224753 - 11/30/13 08:43 AM

Quote:

Quote:

Quote:

Quote:

built quality?

SCT have no chances to good newtonian, imho.




So... What is a good Newtonian?

Strehl doesn't matter if your focuser cannot hold your CCD camera.




i there talking about visual instrument. if we talking about a photographic, then statements is another. large central obstruction and mediocre optics quality there are no problem...




Who said this thread was only about visual? I don't care for ugly diffraction spikes, inherent coma which the Edge scopes lack. Limited back focus. You every look through a Newtonian while on a GEM? Was the focuser stuck underneath the scope? And no you can't use a dob mount if you have a observatory with a centrally mounted GEM unless you want to get stuck using only one scope. What's the current most used scope for Planetary imaging? I had to give away my last newtonian as the coating flaked off do to humidity exposure after 7years out in the observatory. That's what happens to unprotected mirrors in this location.

Now all that said, I DO like newtonians,and plan for a big Dob in the future, but if you think that size is the only advantage to a SCT's, well........




i have more concentradet on visual side, and as a result, i decide from that side. that's is psychological point \ trap
about photo - i can agree, there rules even a RC of CO about 50 percent or so on.
but on visual side - yes, i too not like a diffraction spikes, and my favorite optical system is the superrior system - refractors. most close to "ideal scope" from all sides.
but its size ( aperture) is limited, and prices, weights and gabarits grow skyhigh as aperture reaches about 200mm.
second good system is newtonian - larges apertures, but manageable, small weights, prices, relatively small central obstruction, and possibility to get high strehl numbers on whole telescope.
on GEM it is not good, i agree - i have orion optics europe 200 on EQ5, and can confirm - most of poses is very uncomfortable. but dobsonian mount, as i hear and imagine, is very good for this, as so i not see a problem, unless a GEM is a thing, without who you cannot living at all...
a catadioptrics in that matter, as there is always said, is "jack of all trades, and in all trades he give a bad result"...:D


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bobhen
professor emeritus


Reged: 06/25/05

Re: Why do people even buy SCTs??? new [Re: drago]
      #6224914 - 11/30/13 10:37 AM

I use my 11 inch Celestron mostly for what Tom Johnson intended – “astro-friendly” photography. Well, these days it’s video viewing. Their compact (with all the advantages compactness brings), have many available accessories, with video can be made to work from F2 to F20, and they don’t need to be super high quality to deliver great results. Thank you Mister Johnson.

My other 5 telescopes are all refractors – for all the right reasons.

Bob


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JJK
Carpal Tunnel


Reged: 04/28/08

Re: Why do people even buy SCTs??? new [Re: ATM57]
      #6224943 - 11/30/13 11:03 AM

Quote:

Quote:

Quote:

Quote:

Quote:

Quote:

Quote:

Quote:

I have had all ... refractors, apo's, reflectors, SCT's and sorry, aperture rules! A really sweet scope like my Meade 14"ACF is awesome. Imagine having a 14" refractor, oh my goodness, I'd need a crane to haul THAT around!




Yeah, a 14" refractor would be a monster to be sure even if it was an APO. My C-9 is currently satisfying my large planetary scope needs. A 9" refractor could not be afforded even if I built my own hence my "modded" C-9. We all satisfy our needs in different ways.

Scopejunkie




While SCTs have their virtues, it would take much less than a 9" refractor to outperform a 9" SCT.




Not mine.

Scopejunkie




Which 9" refractors did you test your 9" SCT against, and on which targets?




I have built 3 8" refractors. Two at F/12 and 1 at F/9. I know how 8" refractors perform and would compare to my modified C-9.

Scopejunkie




Did you grind the lenses, what style (achro, apo) where they, and what were the specifications of the objectives (smoothness, zones, coatings)?




I won't go into the details concerning the three 8" refractors I have built. That's not the reason for this thread. I will say that the lenses were tested before I built scopes around them though.

Scopejunkie




The answers would obviously help frame your earlier comment, but if you don't want to share them, that's your choice. Frankly, I think it's interesting to hear the lengths that some folks go through to build their own equipment. I wish I had the time to learn how to properly grind, polish, test, and coat refracting lenses with my own hands.

To my original point, I doubt a 9.25" (Celestron or Meade) SCT would outperform even a top-notch 7" apochromatic refractor (e.g., made by a company in the league of Astro-Physics or Zeiss). And that wouldn't stop me from considering one for purchase. However, I did not buy any 11" SCT I tested about a decade ago, because none of them performed well enough for the intended purpose (critical high magnification visual work). At that time, I didn't have interest in retrofitting them to see if it was a thermal issue.

In 1999, I critically tested Roland Christen's 8" and 10" Mak-Cass prototypes in very good seeing against his 180 mm and 200 mm class refractors (one was Sue & Alan French's scope that is a Moon killer). The test target was Saturn. The 8" Mak-Cass delivered images on par with the 7" apos, and the 10" just edged out the 8" refractor, but not by much. Given the compact nature of the Mak-Cass, I ordered a 10" varietal, and received it a few years later. When the seeing is good, that scope is stunning (it had better be for the list price of $10K), and I've never seen even an 11" SCT come anywhere close to this instrument's capability. I often use the Mak-Cass at 1000x to see the central star in the Ring Nebula, something I have not been able to accomplish with any 11" SCT. Roland's 10" Mak-Cass doesn't defy the laws of physics. When I want to hunt down very faint galaxies, I use a 25" Dob-Newt.

All that said, I don't expect a far lower cost SCT to perform at the same level of a much more expensive scope. However, I would like it to perform better than the ones I tested long ago. I'm in the market for one (or two).


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JJK
Carpal Tunnel


Reged: 04/28/08

Re: Why do people even buy SCTs??? new [Re: Jon Isaacs]
      #6224947 - 11/30/13 11:05 AM

Quote:

Quote:

My 9.25 SCT kicks my F/5 6" Newts backside.




I imagine it does when it comes to working at high magnifications, it ought to. However there are places a 6 inch F/5 will go that a 9.25 inch F/10 cannot and that's the reason to own both these scopes. One of them is capable of a 3 degree field of view, one of them is capable of a 1 degree field of view..

The right scope for the job at hand is what it all about. There are objects that are best suited for an 80mm F/5 with a 2 inch focuser, there are objects that are best suited for a 635mm aperture.. The California nebula is not much to look at in a 0.7 degree TFoV.

Jon




I agree!


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drago
sage


Reged: 01/11/08

Loc: Latvia
Re: Why do people even buy SCTs??? new [Re: JJK]
      #6224951 - 11/30/13 11:08 AM

Quote:

I often use the Mak-Cass at 1000x to see the central star in the Ring Nebula, something I have not been able to accomplish with any 11" SCT. Roland's 10" Mak-Cass doesn't defy the laws of physics. When I want to hunt down very faint galaxies, I use a 25" Dob-Newt.





very interested - looks like you have a 10" top quality mak, and 25" dob. do you try compare it both side by side on planets?


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