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Equipment Discussions >> Cats & Casses

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crow
sage


Reged: 07/09/12

Loc: BC, Canada
Re: Why do people even buy SCTs??? new [Re: BKBrown]
      #6240813 - 12/08/13 01:17 PM

What gets me in that link even over the Jupiter imagery is the pic of Neptune, rather

Some great images from yourself Brian, thx for the link.


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Arizona-Ken
Pooh-Bah


Reged: 08/31/08

Loc: Scottsdale, Arizona
Re: Why do people even buy SCTs??? new [Re: BKBrown]
      #6240820 - 12/08/13 01:21 PM

Great thread.

Good to bring out the elitists.

"Most observers do not have the observational experience or seeing conditions conducive enough to appreciating the difference between SCT's and world class Newtonians, apos and Maks. I'm sure if more observers spent some time viewing with some really world class optics in the right seeing locations, they'd have an awakening."

Oh Please! I guess if we disagree, we just don't have the experience!

SCT's - the Rodney Dangerfield of telescopes.

Arizona Ken


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Vondragonnoggin
Post Laureate
*****

Reged: 02/21/10

Loc: Southern CA, USA
Re: Why do people even buy SCTs??? new [Re: Arizona-Ken]
      #6240850 - 12/08/13 01:30 PM

Quote:



SCT's - the Rodney Dangerfield of telescopes.

Arizona Ken




SCT - "I'll take my praises like my steak.....very rare" "no respect, I tell ya"



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JJK
Carpal Tunnel


Reged: 04/28/08

Re: Why do people even buy SCTs??? new [Re: crow]
      #6240905 - 12/08/13 01:57 PM

Quote:

I love the circular logic by people in this thread, I think the OP's point has been proven, the sct can't get a break.

If its good down the eyepiece, its because you got a 'good one', if it produces jaw dropping images, well its probably not too good down the eyepiece, if its via hyperstar its not really a C14 image, only 'average consumers' use them, but nasa launched one into space (ignore that) and so on.....

Well in Eddgie, you hit the nail on the head.




Perhaps we read nearly 20 pages of posts in a different thread, but I don't think many members here attacked the use of SCTs. If anyone raised legitimate issues with SCT, that's not refusing to give the design a break. It's simply being objective (pardon the pun). Now, if a few folks appear to be ornery, let them be. If they hate SCTs, who cares?

Some here eschew large Newt-Dobs or refractors, but I don't hear anyone here suggesting those folks be lynched.

You alluded to a sort of conundrum or paradox that some suggest SCTs might not be good at the EP (either due to poor thermal issues or relatively bad seeing), but others raise the fact that really nice planetary images are taken with similar scopes. There is no paradox. We all know that fast frame lucky imaging, in which the dogs are culled, differs substantially from how your eye works (and the camera never gets tired or loses patience). That is also true for more expensive and better engineered Cats, e.g., AP's 254 mm Mak-Cass, although in that particular example, the thermal management is better, which gives the AP has the potential to be a better visual instrument more of the time than a similar sized SCT (ignoring the fact that the optics are smoother, etc.).


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crow
sage


Reged: 07/09/12

Loc: BC, Canada
Re: Why do people even buy SCTs??? new [Re: JJK]
      #6240924 - 12/08/13 02:11 PM

I'm not sure where I said people attacked sct usage or recommended them to be lynched. I commented on the circular logic of taking a positive of the design and people experiences and immediately moving it into the negative. So now an sct owner cherry picks his best image, but what...a refractor owner doesn't? Give me a break.

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JJK
Carpal Tunnel


Reged: 04/28/08

Re: Why do people even buy SCTs??? new [Re: crow]
      #6241047 - 12/08/13 03:45 PM

Quote:

I'm not sure where I said people attacked sct usage or recommended them to be lynched. I commented on the circular logic of taking a positive of the design and people experiences and immediately moving it into the negative. So now an sct owner cherry picks his best image, but what...a refractor owner doesn't? Give me a break.




I didn't say or imply that lucky imaging isn't needed when imaging planets with a refractor. Of course it is. That said, if seeing isn't an issue, it's conceivable that a refractor might have less thermal issues, and therefore possibly one would need to cull fewer frames. This is my guess based on what I've seen at the EPs of top-notch apos and SCTs over a decade ago (the apos had an easier time chasing the dropping temperatures over the course of a night). Obviously, this doesn't mean SCTs aren't effective at planetary imaging (they of course are).

To be clear, the SCT is a successful and versatile design, and its implementation over the past 40 years by the big two have provided many of us with very low cost and fun instruments. Like any other scope design (including apo refractors), the SCT isn't ideal for every application, and their low cost comes at an engineering price (the optics aren't as smooth as those in high-end refractors, which may or may not bother the user; some mechanical and thermal management issues, etc.).


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David PavlichAdministrator
Transmographied
*****

Reged: 05/18/05

Loc: Mandeville, LA USA
Re: Why do people even buy SCTs??? new [Re: Daniel Mounsey]
      #6241112 - 12/08/13 04:34 PM

Quote:

Ed,
In my opinion, the SCT design is generally soft, but good enough for the average consumer. Most observers do not have the observational experience or seeing conditions conducive enough to appreciating the difference between SCT's and world class Newtonians, apos and Maks. I'm sure if more observers spent some time viewing with some really world class optics in the right seeing locations, they'd have an awakening. That is not to say there hasn't been a few really good SCT's out there.




Hey Daniel...your post points out a theme that seems to pop up any time SCs are compared to other scopes. You mention SCs compared to "world class Newts", etc. What if somebody decided to take the SC design and put the same amount of effort in the optics as, say, Mike Lockwood puts in his mirrors or Roland puts into his lenses? SCs are always off the shelf and more so than not, compared to what are essentially hand crafted Newts and refractors.

I know it would not be cost effective to make such a hand crafted SC, but were I to hit the lottery, I'd get a C14 shell, have Mike make the mirrors and Roland make the corrector plate and then have a viewing. Now there'd be a telescope that I'd have in my obs.

David


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maknewtnut
Member
*****

Reged: 10/08/06

Re: Why do people even buy SCTs??? new [Re: Arizona-Ken]
      #6241125 - 12/08/13 04:39 PM

Not a great thread. Several solid contributions both pro and con, but past that...knee jerk reactions and ad hominem rather than acknowledgement and understanding.

Full circle? Absolutely, but not just from one camp. My most memorable quote from Rod Mollise is practically identical to the comment made by Daniel Mounsey. Does that make him a dreaded 'elitist' as well?

Adios!


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JJK
Carpal Tunnel


Reged: 04/28/08

Re: Why do people even buy SCTs??? new [Re: David Pavlich]
      #6241173 - 12/08/13 05:05 PM

Quote:

Quote:

Ed,
In my opinion, the SCT design is generally soft, but good enough for the average consumer. Most observers do not have the observational experience or seeing conditions conducive enough to appreciating the difference between SCT's and world class Newtonians, apos and Maks. I'm sure if more observers spent some time viewing with some really world class optics in the right seeing locations, they'd have an awakening. That is not to say there hasn't been a few really good SCT's out there.




Hey Daniel...your post points out a theme that seems to pop up any time SCs are compared to other scopes. You mention SCs compared to "world class Newts", etc. What if somebody decided to take the SC design and put the same amount of effort in the optics as, say, Mike Lockwood puts in his mirrors or Roland puts into his lenses? SCs are always off the shelf and more so than not, compared to what are essentially hand crafted Newts and refractors.

I know it would not be cost effective to make such a hand crafted SC, but were I to hit the lottery, I'd get a C14 shell, have Mike make the mirrors and Roland make the corrector plate and then have a viewing. Now there'd be a telescope that I'd have in my obs.

David




I'll take one also.


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crow
sage


Reged: 07/09/12

Loc: BC, Canada
Re: Why do people even buy SCTs??? new [Re: maknewtnut]
      #6241207 - 12/08/13 05:27 PM

A bit of spirited debate never hurt anyone.

I curse the -17 weather that forced me into this debate.

jjk, I wouldn't disagree with any of that. I think we were talking at cross purposes to some extent.


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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: Arizona-Ken]
      #6241258 - 12/08/13 05:52 PM

Quote:


Good to bring out the elitists.

"Most observers do not have the observational experience or seeing conditions conducive enough to appreciating the difference between SCT's and world class Newtonians, apos and Maks. I'm sure if more observers spent some time viewing with some really world class optics in the right seeing locations, they'd have an awakening."




Honestly.. We know Daniel is someone who seeks out the best planetary equipment and lives in an area where the seeing can be exceptional. One doesn't show up at an observing session with those guys with a scope that is not exceptional..

I am OK with that, I know that my equipment would not pass muster... I have been in bicycle races that included world record holders, Olympic Gold Medalists, I have raced a motorcycle against Kenny Roberts, 3 time world GP champion..

I know my place, I am just an average joe who enjoys stargazing, an average cyclist, a below average motorcycle racer.. I listened to those guys, learned from those guys just as I listen and learn from Daniel..

Jon


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BKBrown
Post Laureate
*****

Reged: 08/23/09

Loc: Northern Virginia, USA
Re: Why do people even buy SCTs??? new [Re: JJK]
      #6241288 - 12/08/13 06:07 PM

Quote:

I didn't say or imply that lucky imaging isn't needed when imaging planets with a refractor. Of course it is. That said, if seeing isn't an issue, it's conceivable that a refractor might have less thermal issues, and therefore possibly one would need to cull fewer frames. This is my guess based on what I've seen at the EPs of top-notch apos and SCTs over a decade ago (the apos had an easier time chasing the dropping temperatures over the course of a night). Obviously, this doesn't mean SCTs aren't effective at planetary imaging (they of course are)...




Unfortunately it doesn't work out this way in practice (I wish it did!). First off, tube thermal issues should never be a problem if you are doing this right, a thermally equilibrated scope is essential regardless of type. So what is the main discriminator? In short, 6" and less refractors are light starved compared to an 11" to 14" SCT. Consequently, you have to use longer exposure times to ensure you get useable data...and this means fewer frames in the same amount of time. For instance, I typically shoot Saturn for five minutes to stay well inside the rotation "safe zone", although with current techniques I could easily double this. In that five minutes I will typically be able to shoot 40-45 frames per second with the TEC 140, but 100 frames per second with the C11 Edge, leading to a massive difference in the final frame counts. In addition, the SCT frames will typically be better exposed. It's just the way things work. Jupiter is a more forgiving target, but a larger scopes resolution and light gathering power are the winning ticket day in and day out...

Clear Skies,
Brian


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azure1961p
Postmaster
*****

Reged: 01/17/09

Loc: USA
Re: Why do people even buy SCTs??? new [Re: drago]
      #6241322 - 12/08/13 06:34 PM

Quote:

Quote:



I would bet this test would be far more revealing of a greater apertures advantage. Here's where small aperture would "hit the wall" before the CO effects do.

Pete




we there not discuss about a 4" apo without CO is better contrast than 14" SCT
there, in big appertures, are always good alternative to SCT - a newtonian.
and there, when you compare 14" SCT with CO, say, 38% ( not know, what exactly CO is in 14" SCT, but near, i suppose), and 14" newtonian with, say, 23% obstruction - there is a reasonably difference, i sure.
and contrast differences, when we look at already low contrast objects, cannot be overrated.




I wasn't making a literal comparison of a 4" apo to a C14 - just refractors in general against larger SCTs.

The argument often - very often infact - seems to bypass the fact that a larger aperture can put more detail in a smaller area. When you get right down to the square arc second as opposed to the whole planet there's a very fundamental advantage greater aperture has . I can't say like Edd Ive contested a C11 against a 6" AP or a 5" apo against an 8" sct on this method. Like many folks a lot of the folks here my comparison experiences have been at star parties with other people's equipment. Its got its problems in the strictest sense to call that a definitive method. That aside - I tend to see these sct bashing app proud comparos not even addressing the issues at resolutions threshold. My unspoken question with say, an 8" sct versus a 5" app - what's happening at the sub arc second level? The finest spots on Jupiter or the shadings on Ganymede - is the 5" apo really even close to equal here in such tight spaces? I often wonder if the higher contrast of a give. Feature through an apo is too generalized a judgement and that when both instruments push to there diffraction mark - is the larger scope with a huge obstruction showing paler contrast but more detail in tighter spaces or less contrast and EQUAL SIZED detail despite higher angular res for the larger SCT? I recall Larry Carlino (whose reviews Ive always liked ) compared his 6" maksutov to his 4.5" TAK app and said the tak was a little better on Jupiter. Ok fair enough. But that's Jupiter. Say we go down to the nutty gritty diffraction limit on a 1.7" Ganymede - both scopes are working at 50x per inch and its excellent seeing - is the 4.5" Tak going to show as much or any detail on Ganymede at all??? Its a given that the 6" Mak (and 6" apo can).

The Refractors in these two examples might show a better aesthetically pleasing clean disc (perhaps) but whose walking off with the highest resolution prize in this kind of test?

Pete


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BillP
Postmaster
*****

Reged: 11/26/06

Loc: Vienna, VA
Re: Why do people even buy SCTs??? new [Re: Eddgie]
      #6241415 - 12/08/13 07:31 PM

Quote:

Rather it is just a rant about how so many people perceive so much wrong with a design that I have loved dearly over the decades, but now feel as if may be damaged by the perception that there is so much wrong with them.. So sad. Great telescopes.




Eddgie,

Do you like SCTs? If you do, then why do you care what someone else might think? All that is important is what you think. Stop caring about the voices of others and just pay attention to the voice from within...without trying to convince others to follow your voice and without being convinced by their voices.

Honestly, if people think that physics or engineering can dictate one scope being better than another scope, that is really so far off base that it's comical. Scopes are like mates. There is no set of discrete universal qualities that make one person better than another for a mate. It's all personal based on the individual's likes and dislikes. I certainly don't listen to others about what my choices in friends, significant others, book, movies, food, or telescopes should be. I know what I like and why I like it and could care less what others feel I should or should not like. Respect everyone else choices, but most of all respect your own choices!

-Bill


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JJK
Carpal Tunnel


Reged: 04/28/08

Re: Why do people even buy SCTs??? new [Re: BKBrown]
      #6241476 - 12/08/13 08:06 PM

Quote:

Quote:

I didn't say or imply that lucky imaging isn't needed when imaging planets with a refractor. Of course it is. That said, if seeing isn't an issue, it's conceivable that a refractor might have less thermal issues, and therefore possibly one would need to cull fewer frames. This is my guess based on what I've seen at the EPs of top-notch apos and SCTs over a decade ago (the apos had an easier time chasing the dropping temperatures over the course of a night). Obviously, this doesn't mean SCTs aren't effective at planetary imaging (they of course are)...




Unfortunately it doesn't work out this way in practice (I wish it did!). First off, tube thermal issues should never be a problem if you are doing this right, a thermally equilibrated scope is essential regardless of type. So what is the main discriminator? In short, 6" and less refractors are light starved compared to an 11" to 14" SCT. Consequently, you have to use longer exposure times to ensure you get useable data...and this means fewer frames in the same amount of time. For instance, I typically shoot Saturn for five minutes to stay well inside the rotation "safe zone", although with current techniques I could easily double this. In that five minutes I will typically be able to shoot 40-45 frames per second with the TEC 140, but 100 frames per second with the C11 Edge, leading to a massive difference in the final frame counts. In addition, the SCT frames will typically be better exposed. It's just the way things work. Jupiter is a more forgiving target, but a larger scopes resolution and light gathering power are the winning ticket day in and day out...

Clear Skies,
Brian




My eyes showed me that, where I live, 11" SCTs of over a decade ago couldn't keep up with temperature drops as well as AP's 254 mm Mak-Cass or their 155 f/7 EDF apo did. I didn't compare them with a web cam, but if the view by eye is distorted less of the time, that should translate into fewer discarded frames.

We're on the same page with respect to imaging. You need a relatively long focal length scope to get good image scale and a large aperture for greater resolution. Personally, I wouldn't image planets with a 140 mm apo.

While the AP 155 f/7 apo is great for visual work on Jupiter (Saturn's a little dim for my eyes now), larger scopes that I've used (AP 175 f/8 EDF, 180 f/7 EDF, and 180 f/9 EDT apos, AP 254 mm Mak-Cass, Tak Mewlon 300 CDK) bring out more detail with a more pleasing intensity. For my taste, I'd use at least the 180 f/9 apo and preferably larger scopes for imaging Jupiter & Saturn.


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GeneT
Ely Kid
*****

Reged: 11/07/08

Loc: South Texas
Re: Why do people even buy SCTs??? new [Re: BKBrown]
      #6241504 - 12/08/13 08:24 PM

Quote:

Nobody here but us "average consumers"...
http://www.damianpeach.com/barbados10.htmClear Skies,Brian




Beautiful Jupiter photos. Did you get them with your 11 Edge?


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BKBrown
Post Laureate
*****

Reged: 08/23/09

Loc: Northern Virginia, USA
Re: Why do people even buy SCTs??? new [Re: GeneT]
      #6241515 - 12/08/13 08:31 PM

Oh Gene, I wish! No, those images are by Damian Peach - probably the top amateur planetary imager in the world today. I don't remember if he had moved up from his C11 at that time, he now uses a C14...

Clear Skies,
Brian


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gunfighter48
sage
*****

Reged: 03/18/13

Loc: Mill Creek, Washington
Re: Why do people even buy SCTs??? new [Re: JJK]
      #6241520 - 12/08/13 08:34 PM

I started observing in about 1976 with a Cave 8" reflector. It gave great views but weighed about 90lbs. It was difficult to transport in a car. I sold it and about 10 years later bought a used Meade 2080 SCT. It was much easier to transport in a car. I eventually bought a Nissan pickup and transporting it to dark sites was MUCH easier. It gave excellent views. I really didn't see any drastic difference in contrast. For me the whole CO issue is really a non issue. Last March I bought a Meade LS8 ACF and I love it. It gives great views and I really like the goto mount. I also bought a C102GT and an Orion SkyView Pro Goto mount. The views thru the C102 is very good but the LS8 sees fainter objects and has more resolution. And the CO issue is still a non issue with me.

I like the SCT platform. It gives me the best bang for the buck. I have a telescope that will track objects, gives great views, and is easy to transport. It also doesn't require big $$$ eyepieces like the fast scopes. I could care less what anybody else thinks of them. The C102 is a very good achro but if I want to see more the LS8 beats it. Aperature wins in the end.


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GeneT
Ely Kid
*****

Reged: 11/07/08

Loc: South Texas
Re: Why do people even buy SCTs??? new [Re: BKBrown]
      #6241528 - 12/08/13 08:37 PM

The C11 is the best (no surprise) but I'm really impressed with the TEC 140.

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JJK
Carpal Tunnel


Reged: 04/28/08

Re: Why do people even buy SCTs??? new [Re: GeneT]
      #6241557 - 12/08/13 08:52 PM

Quote:

The C11 is the best (no surprise) but I'm really impressed with the TEC 140.




For imaging planets (i.e.,with the TEC)?


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