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What do people see in Schmidt-Cassegrains?

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#26 Bomber Bob

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Posted 02 October 2014 - 08:51 PM

I've never owned an SCT, but I had a Meade ETX-90RA for about 4 years, and I was very impressed with the optics -- near refractor clarity & resolution.  Minimal setup time.  Extrenely portable, and with the rugged foam-lined case, I took it lots of places.  Poor man's Questar.  But I got tired of the plastic flower pot mounting -- flimsy, and it rattled, and was toy-like.  Too bad!!  I returned to Refractor Land.  But I agree that Celestron sold a boatload of SCTs because they are so versatile, and are well-suited to imaging, especially compared to the long achros & newts that I used in my youth.  IMO, for visual, there are still better & cheaper options; but for serious AP, I'd go with a C8 --> C14 versus an expensive APO.



#27 ehallspqr

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Posted 02 October 2014 - 09:18 PM

LOL@John!

 

 

Yeah this is nothing but a thread to stir the pot.

 

It's working.

 

Celestron Edge HD 8". All around perfection.........



#28 Ed D

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Posted 02 October 2014 - 09:47 PM

What do I see in Schmidt-Cassegrains?  Actually nothing, I don't own one.  I do own a couple of Maks, a few refractors both short and long, as well as a couple of Dobs.  I see in my Maksutov-Cassegrains the same thing that I see in my refractors and in my Dobs, beautiful heavenly objects.  Each one of my instruments excels at a given task.  To be fair, a friend of mine owns several SCTs, and they also have something to offer.  How's that for a concrete answer?   :question:

 

Ed D



#29 ehallspqr

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Posted 02 October 2014 - 09:52 PM

You want to see real pot-stirring? :mrevil:
 
 
 
> What do people see in Schmidt-Cassegrains?
 
Mushy images.
:rimshot:
 
 
 
 
How's that?

 

Touche. Mid'lin sharpness but improved with the EdgeHD series.

 

So how about Mak-Cassegrains? That addresses sharpness/contrast. We won't talk about cool down times and small field of view.


Edited by ehallspqr, 02 October 2014 - 09:53 PM.


#30 Ed Holland

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Posted 02 October 2014 - 11:04 PM

We should retitle this "What do people see with Schmidt Cassegrains?"

 

There are thousands upon thousands of objects..... 

 

What do people see in Schmidt Cassegrains?

 

Usually their own reflection :)


Edited by Ed Holland, 02 October 2014 - 11:05 PM.


#31 milleniumfalcon

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Posted 03 October 2014 - 03:28 AM

Don't worry about it - I'm not trying to stir up an argument. 

From a theoretical point of view, a schmidt-cassegrain can never quite have the same contrast and brightness as a newtonian.

 

Just seeing everyone's opinion.



#32 Jon Isaacs

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Posted 03 October 2014 - 05:08 AM

 

I do most of my observing with a 210 mm F/7 Mikage Newtonian reflector on a Pentax MS-5 GEM with a PE of +/- 3.5 arcseconds.  It is optically and mechanically as close to perfection as you can get but is 1980s technology and at 175 kg is not very portable.  Still, I would never trade my steel GEM and OTA for a telescope made out of particle board that you have to keep pushing if you want objects to stay centered.     

 

Stephen:

 

I have seen the photos of your scope and it is a beauty.  Still, at 175 kg and 210mm, it is massive and not easily transported.

 

These days, if manual tracking is not your thing, there are a variety of alternatives that provide motorized tracking for a Dobsonian.  For "premium Dobsonians, the Servo-Cat provides tracking in the Alt-AZ mode.  One can also use an equatorial platform, that provides about an hour of continuous equatorial tracking before a simple reset is needed.  These are available at a variety of price points and qualities and can be built at home for a $100 or so worth of parts. In the US, the high end is represented by Tom Osypowski's aluminum EQ platforms.  These mounts (as seen in previous photo) weigh about 30 lbs for a mount capable of handing an 18 inch scope.  They add about 4-6 inches to the height of the Dob so the ergonomics and easy set up of the Dobson are not lost.  Orion of course provides their GOTO Dobs which provide both accurate tracking and accurate GOTO.

 

If particle board construction is not to your taste, there are the traditional truss style Dobs built on the Obsession model, high quality plywood with aluminum truss tubes.  These are works of art, quite beautiful.  Other manufacturers like Stars-Structure have taken the truss design further and use aluminum structures with combined modern composites technologies.   

 

The use of particle board is a mass-production technique, allowing the manufacturer to provide a simple, solid mount that is sturdy and yet inexpensive though not aesthetically pleasing. 

 

Jon



#33 Jon Isaacs

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Posted 03 October 2014 - 05:10 AM

 

Heck, even Roland Christen used to have a C8...  Probably still does...

 

Indeed. It was the optical quality of his C-8 that inspired Roland, he felt the amateur community could benefit from higher quality optics.  

 

Jon



#34 Sarkikos

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Posted 03 October 2014 - 07:29 AM

What do people see in Schmidt-Cassegrains?]

 

Planets, the Moon, double stars, deep sky objects, the sun. That's what I see ... except for the sun.  I don't do solar.  

 

Mike


Edited by Sarkikos, 03 October 2014 - 07:29 AM.


#35 George Methvin

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Posted 03 October 2014 - 07:46 AM

Ok heres how I see it, I have owned several SCT over the years and they have brought me much enjoyment. I have owned just about every type of scope and they all do a good job, some better at  some things then others. My main scope for the last 13 year has been a SCT and its has been a great scope for me. Recently I have retired and about two years ago I bought a 12 dob and found that I preferred the views and the eases of use to that over the 10inch sct.   Many of the pluses of the Sct  I just don't use or need anymore, like I don't do astro photo or use goto or travel to dark site lol all my scopes are keep in the garage and all  my scopes have wheels on them so I just roll them  out when I want to use them, take about two mins lol.  As I said about goto I am 62 and been into this hobby since I was 10 years old if I don,t know my way around the night sky by now I need to find another hobby. I do like that I can sit and do my viewing through the sct but that can also be done with most scopes. Sct are great scopes but like fine tools you have to pick the one that doe's the best job for you, or like many here on CL just own one of each type of scope lol.  Clear skys



#36 George Methvin

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Posted 03 October 2014 - 07:48 AM

LOL where did those lines come from??? well I am not going to retype lol.



#37 David Pavlich

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Posted 03 October 2014 - 08:21 AM

Not much difference up to 14" of aperture.  After that, portability becomes a Dob winner.  The other item would be FOV.  Not a really big deal, but about 95% of what's out there fits into the FOV of an SC.  But there are some objects like M45 that the SC falls flat on its face...in its native form.  Having said that, I'm a big SC fan and always will be.

 

David



#38 Hesiod

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Posted 03 October 2014 - 08:45 AM

Don't worry about it - I'm not trying to stir up an argument. 

From a theoretical point of view, a schmidt-cassegrain can never quite have the same contrast and brightness as a newtonian.

 

Just seeing everyone's opinion.

 

Schmidt-Cassegrain/Maksutov Cassegrain are only a cheaper way to build a Cassegrain reflector: so they are a sort of compromise.

I suppose that it was mainly a marketing concern that pushed the producer of mass-market Schmidt-Cass towards faster f/ than the "typical Cassegrain" (which in some case could have also a faster Newtonian f/, but of course this option was highly uneconomical) and supposedly to the lower contrast than a Mak-Cass.

Think it is totally unfair a comparison between Celestron/Meade SCT and Intes Mak-Cass, while between Synta's Mak and Schmidt Cass I found more difference between single samples than between the 2 groups (and in my limited experience Celestron SCT showed less scattering than Skywatcher MCT, hence a slightly greater contrast).

 

Fom a theoretical point of view, there would be only slow f/ apochromatic doublet refractors (plus some Petzval and triplet for wide field and AP) ...others designs are only heaps of aberrations and obstruction :grin: :flowerred:

 

Mass-market SCT have indeed a lot of shortcomings, but even mass-market Newtonians or refractors have their skeletons in the cupboard. Wild f/, tons of scattering, so-so mechanics...one can go further with the list but think is an empty exercise: the fact is that a scope with a "better" design could be a poorer performer than a "bad" design

 

IMHO the really meaningful thing is that we can choose between a wide range of products and pick the most suited to our needs and tastes.



#39 Special Ed

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Posted 03 October 2014 - 09:29 AM

Don't worry about it - I'm not trying to stir up an argument. 

From a theoretical point of view, a schmidt-cassegrain can never quite have the same contrast and brightness as a newtonian.

 

Just seeing everyone's opinion.

 

Holy cow--what's your other hobby?  Poking hornet's nests with sticks?  :lol:

 

Putting theory aside, in the real world seeing is going to be more important than central obstruction just about every time...



#40 dpippel

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Posted 03 October 2014 - 09:34 AM

Every design has it's compromises. I think that SCTs fill the bill as far as portability, all-around performance, and affordability go for most people. They strike a good balance. Are they perfect? Of course not, but this is most certainly a first world problem we're discussing. I just feel fortunate that at this point in time, as amateur astronomers, we have such a PLETHORA of high-quality telescopes and accessories available to us. The hardware we use to indulge in this hobby has come a long, long way. No matter which instrument(s) you choose to observe with, it's a great time to be alive and out under the stars, contemplating life, the universe, and everything.



#41 Atjous

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Posted 03 October 2014 - 10:08 AM

Every design has it's compromises. I think that SCTs fill the bill as far as portability, all-around performance, and affordability go for most people. They strike a good balance. Are they perfect? Of course not, but this is most certainly a first world problem we're discussing. I just feel fortunate that at this point in time, as amateur astronomers, we have such a PLETHORA of high-quality telescopes and accessories available to us. The hardware we use to indulge in this hobby has come a long, long way. No matter which instrument(s) you choose to observe with, it's a great time to be alive and out under the stars, contemplating life, the universe, and everything.

Good statement; I feel e x a c t l y the same about this subject. Plus the fact that my two cats show me more than I could ever dream of when I was a kid, messing with my dad's old 8x30 bino. I am sure other scopes can do that too, but those two are mine  ;)



#42 gene 4181

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Posted 03 October 2014 - 10:39 AM

Don't worry about it - I'm not trying to stir up an argument. 
From a theoretical point of view, a schmidt-cassegrain can never quite have the same contrast and brightness as a newtonian.
 
Just seeing everyone's opinion.

 
Holy cow--what's your other hobby?  Poking hornet's nests with sticks?  :lol:
 
Putting theory aside, in the real world seeing is going to be more important than central obstruction just about every time...

I wrote a response early this a.m. but I deleted it, what's the use anymore. i'm tired of theory, buy one , see what it'll do, FOR YOURSELF , parroting what we read on the threads gets old. IN THE REAL WORLD SEEING IS GOING TO HAVE THE LARGEST IMPACT, not c.o. or coma or whatever. I like to show respect to those that have learned how to get the most out of their sct's, newt's or other's scopes. they spent the time doing it

#43 Gastrol

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Posted 03 October 2014 - 11:17 AM

SCT vs Newtonian, Lump vs Charcoal, Carbon Fiber vs Titanium.......we get these in every hobby out there......LOL...



#44 Jon Isaacs

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Posted 03 October 2014 - 11:30 AM

Ok heres how I see it, I have owned several SCT over the years and they have brought me much enjoyment. I have owned just about every type of scope and they all do a good job, some better at  some things then others. My main scope for the last 13 year has been a SCT and its has been a great scope for me. Recently I have retired and about two years ago I bought a 12 dob and found that I preferred the views and the eases of use to that over the 10inch sct.   Many of the pluses of the Sct  I just don't use or need anymore, like I don't do astro photo or use goto or travel to dark site lol all my scopes are keep in the garage and all  my scopes have wheels on them so I just roll them  out when I want to use them, take about two mins lol.  As I said about goto I am 62 and been into this hobby since I was 10 years old if I don,t know my way around the night sky by now I need to find another hobby. I do like that I can sit and do my viewing through the sct but that can also be done with most scopes. Sct are great scopes but like fine tools you have to pick the one that doe's the best job for you, or like many here on CL just own one of each type of scope lol.  Clear skys

 

George:

 

Those are just diffraction spikes, it's that Dob you have in the house.   :lol:

 

On to reality:  It's one the font choices in the editing window.  It's the S with the strike through.  This is what your post looks like with Strike Through deselected:

 

"Ok heres how I see it, I have owned several SCT over the years and they have brought me much enjoyment. I have owned just about every type of scope and they all do a good job, some better at  some things then others. My main scope for the last 13 year has been a SCT and its has been a great scope for me. Recently I have retired and about two years ago I bought a 12 dob and found that I preferred the views and the eases of use to that over the 10inch sct.   Many of the pluses of the Sct  I just don't use or need anymore, like I don't do astro photo or use goto or travel to dark site lol all my scopes are keep in the garage and all  my scopes have wheels on them so I just roll them  out when I want to use them, take about two mins lol.  As I said about goto I am 62 and been into this hobby since I was 10 years old if I don,t know my way around the night sky by now I need to find another hobby. I do like that I can sit and do my viewing through the sct but that can also be done with most scopes. Sct are great scopes but like fine tools you have to pick the one that doe's the best job for you, or like many here on CL just own one of each type of scope lol.  Clear skys"

 

Jon



#45 jgraham

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Posted 03 October 2014 - 11:33 AM

"From a theoretical point of view, a schmidt-cassegrain can never quite have the same contrast and brightness as a Newtonian."

 

There is absolutely no way you can make a generalization like that. It depends on the specifics of the optical systems that you are comparing.

 

Enjoy your scope.



#46 tim53

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Posted 03 October 2014 - 11:34 AM

 

SCTs are, especially when mounted on GEMs, much more portable than a Newtonian.

 

I agree, at least until you get over 10" aperture.  Then, I find big SCTs on fork mounts to be more hassle to set up and take down than an equal aperture Newt.

 

And though I'm more inclined toward GEM-mounted Newts and Cassegrains (classicals and dall kirkhams, so far), I do own several SCTs.

 

Best thing about SCTs from my perspective is that they are so plentiful that you can find excellent used examples for very good prices.  My favorites are the Orange Tube Celestrons from the 70s.

 

I was fortunate to find a mint-condition 1975 C8, with a bunch of original accessories, for $250.  Even more fortunate, it's got the second-best optics of all my SCTs (Serial #135, "Tinky", is slightly better, but they're both very good).  Even if I hadn't been so lucky as to get such a good price, the abundance of old SCTs pretty much would limit a reasonable price to a few hundred dollars at most.  Sure, people do as for more, but the used SCT world is a buyer's market, unless we're talking about rare limited edition models.

 

-Tim.

 

post-6788-14073809916287_thumb.jpg

 

Jupiter with the 1975 C-8:

post-6788-14073813946849_thumb.jpg

 

Mars:

post-6788-14073858632472_thumb.jpg



#47 De Lorme

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Posted 03 October 2014 - 11:51 AM

The reason I bought a C14" is because of aperture and I have to sit while observing.  If you want to really bring in globulars and galaxies

than aperture is a requirement. SCT fill this role but as in all things they have their down side; a narrow field of view.  

You can get a reducer or low power eyepieces to help.   

Reflectors are good but they lack the quality tracking that a SCT, or a refractor has on a equatorial mount.

 

Second is money, we{I}just never have enough.{LOL LOL} 

 

Having said all that I would look through a straw with a piece of plastic at the end  if that's all I could afford at the moment.

At the moment means just that.  There is tomorrow.   De Lorme



#48 jgraham

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Posted 03 October 2014 - 12:38 PM

"I find big SCTs on fork mounts to be more hassle to set up and take down than an equal aperture Newt."

 

Yep, that's where I find things begin to shift in favor of my biggo Dobs. I find that even SCTs on GEMs start to become a handful at 10" and up. For high resolution work I much prefer my SCTs and my best high resolution scope is my trusty old 8" SCT. My 10" SCTs come in a close second, but they are often seeing limited. However, when I want to go deep I get out one of my big Dobs, either my 16" Lightbridge (wonderful scope) or my homebuilt 16.5" f/6.5 (aka The Beast). Having said that, I recently bought one of those 6" LX80 SCTs OTAs that are being sold at a nice price. I don't often use the word 'wow' to describe a scope, but wow, I'm impressed with this little scope. I had it out last night splitting double stars and I haven't found the bottom yet. I'm sure that it will easily reach its theoretical resolution under good seeing. Like my little ETX-90, I suspect that I will run out of light before I run out of resolution with this scope.

 

Have fun!



#49 Jon Isaacs

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Posted 03 October 2014 - 12:49 PM

"From a theoretical point of view, a schmidt-cassegrain can never quite have the same contrast and brightness as a Newtonian."

 

There is absolutely no way you can make a generalization like that. It depends on the specifics of the optical systems that you are comparing.

 

Enjoy your scope.

 

 

"In theory, there is no difference between theory and practice.  In practice, there is."  (Various)

 

In my experience, there is a difference between what I see in an SCT and a Dob but the big differences are in the viewing experiences, the observer's relationship with the telescope. These are very personal and very subjective.. The reason I like Dobsonians has more to do with what it's like to own and observe with a Dob and less to do with the differences in what I see through the eyepiece..

 

Jon

 

-



#50 George Methvin

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Posted 03 October 2014 - 12:58 PM

Thanks Jon glad to know that's what was causing that line lol. 




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