Refractor v RC for imaging

telecasterguru (Frank) · #1 17-03-2009, 05:55 PM

I am looking at getting a new imaging scope. Am looking for feedback as to which is better, a 127mm APO or a 200mm RC.
I will be doing deep space mainly and am currently using a 200mm Newt on an EQ6. I have a 350d unmodded and a DSI II which I still have not sorted out. I also guide and image with an ED80 but still relatively new to the game.
Any thoughts would be appreciated.

Thanks
Frank

marki · #2 17-03-2009, 06:03 PM

Oh no. Cat vs Refractor, theres going to be tears

.

Bassnut (Fred) · #3 17-03-2009, 06:32 PM

Yeah, that choice is a world of pain. Wide and narrow field imaging is a subjective choice you need to make way before deciding on gear, neither is "better". If you decide you like what you see with longer FL, then upgrading the mount (say to a G11?) would count way more than the OTA type, and an RC would have a FL longer than a newt , so the mount is even more important. I bet your newt on a better mount would give better results than a 200mm RC on the EQ6.

multiweb (Marc) · #4 17-03-2009, 07:14 PM

Quote:

Originally Posted by telecasterguru

I am looking at getting a new imaging scope. Am looking for feedback as to which is better, a 127mm APO or a 200mm RC.
I will be doing deep space mainly and am currently using a 200mm Newt on an EQ6. I have a 350d unmodded and a DSI II which I still have not sorted out. I also guide and image with an ED80 but still relatively new to the game.
Any thoughts would be appreciated.

Thanks
Frank

Your scopes are way better than any of the gear I've got. Get a better mount and your images will improve by a ten fold. Money better spent than on scopes (for now)

Baron von Richthofen (Vaclav) · #5 17-03-2009, 07:14 PM

Hi All
As I was made to understand by a professional astronomer a Schmidt-Cassegrain scope is a jack of all trades master of non meaning it is ok for both planetary and deep sky observing but not as good as a decanted scope Refractors and Maksutov are very good for planarity work and Newtonian are very good for deep sky

marki · #6 17-03-2009, 07:30 PM

An RC is not a SCT, nor is a corrected DK. A newtonian would struggle to illuminate the full field of a large chip and suffers from coma (yes can be corrected). Not sure how a small RC (i.e 200mm) would fare and would probaly go for the refractor. That said a better mount could never hurt your chances of producing a decent raw image.

Mark

Quote:

Originally Posted by Vars191

Hi All
As I was made to understand by a professional astronomer a Schmidt-Cassegrain scope is a jack of all trades master of non meaning it is ok for both planetary and deep sky observing but not as good as a decanted scope Refractors and Maksutov are very good for planarity work and Newtonian are very good for deep sky

KenGee (Kenith Gee) · #7 17-03-2009, 08:15 PM

Frank, the answer is easy get both, you can never have too many telescopes. As noted by others they are for different things. I have a 132mm refractor for wide field and 250 RC for narrow.

gregbradley · #8 17-03-2009, 09:12 PM

The standard answer to this type of question is invest in the mount first.

As pointed out, virtually any scope with excellent mount tracking can produce a nice image.

The other standard answer is if learning go short focal length and do long focal length later on.

Why? Everything is magnified with long focal length including the tracking errors. So until you have balancing your mount/scope, go-tos working well, polar alignment near perect, autoguiding under control with low errors and focus perfect then long focal length makes all these things harder.

Even finding the object in your camera can be very difficult with long focal length without accurate go-tos. That comes from excellent polar alignment and use of the software that controls the mount.

The other thing to consider is work back from the type of image you would like to produce.

Pick out images you see on the net you like and decide what scope that was and use that.

APO127mm can image quite a range of things and is well suited to a DSLR. You'd be busy for ages with one of those before you felt it were time to upgrade.

A 200mm RC adds also the need for collimation skills. Others can tell you more but from what I have read on this site the 127 is good value except for the focuser which can be upgraded. Refractors generally don't need to be collimated.

An Orion EON120 may be another nice choice. Nice Taiwanese manufacturing.

Greg.

telecasterguru (Frank) · #9 17-03-2009, 11:01 PM

Thanks for all the help. I understand that different scopes have strengths and weaknesses. It's just that these new RCs are around the same price if not a little cheaper than the APOs so the choice has become harder.
I think that the idea to look at what scopes were used for what images is a good idea. A decision can then be based on an objective (subjective?) appraisal.
I also agree that a G11 would be a fantastic purchase but a little out my price range at the moment.
Maybe I should put off buying the scope and put an effort into getting a great mount although I don't think the EQ6 is a slouch either.

Bassnut (Fred) · #10 17-03-2009, 11:47 PM

No, the EQ6 is no slouch (for WF). But ill go out on a limb now, just for fun, after all this agonising on which OTA. If you, in a wet dream, morgaged the house and bought a PME (well, at a pinch a G11 or better), a proper cooled astrocam and a craped out S/H ED80/newt and some PS skills, youd produce jaw dropping images to match anything a EQ6/DSI/DSLR/RC could get even close to. This is Astrophograhys dirty little secret, the mount/cam/PS skills count much more than the optics.

telecasterguru (Frank) · #11 18-03-2009, 09:26 AM

Unfortunately, a Paramount, cooled CCD camera and photoshop is probably worth more than my house.

gregbradley · #12 18-03-2009, 09:20 PM

And here's an interesting link to improve your EQ6 tremendously:

http://www.andysshotglass.com/astromo_mod_store.html

If it works half as well as he claims its sensational and it is quite cheap as well.

Then use the money you save on a camera or scope that you like.

Hey try out the cheaper RC. The beauty of Astromart and the sales forum here on this site is you can sell it later if you want to try something else and not lose too much on it. You would regain 70% of its value in selling 2nd hand later on.

Later on you could get yourself the QHY8 that seems to be a nice camera a lot on this forum use and get great results.

Greg.

KenGee (Kenith Gee) · #13 19-03-2009, 12:53 AM

They are right the most important thing is the mount followed by the mount then the camera then the scope. The guy who makes what many people would say are the best refractors going (Astro physics) says spend your money on a mount. That said it's always fun to buy a new scope, just ask Greg.

gbeal · #14 20-03-2009, 07:01 PM

Quote:

Originally Posted by KenGee

They are right the most important thing is the mount followed by the mount then the camera then the scope. The guy who makes what many people would say are the best refractors going (Astro physics) says spend your money on a mount. That said it's always fun to buy a new scope, just ask Greg.

Maybe he does, but also bear in mind he makes mounts as well, lottsa mounts, and lottsa dollars.
Gary

mldee (Mike) · #15 20-03-2009, 08:14 PM

Yep, the mount is the key. And they're not really that expensive! An EQ6 with goto is under $2000! Save and invest.

I just did, and now have a side by side C8 and BD 100 refr, 70 x 100 SW guidescope, plus numerous red dots, finders, all happily mounted on it on my 1m high I beam pier and IT DOESNT MOVE, even when I'm hand focussing.

The best investment I've ever made.

A good mount is like building your house on a granite foundation.

gregbradley · #16 20-03-2009, 08:17 PM

That said it's always fun to buy a new scope, just ask Greg.[/quote]

Yes yes, ooh where's Astromarts URL again I've got the fever!

Maybe its time I got mount fever!

By the way I see your net name is telecaster guru. You're into Fender Telecasters?

I used to have '55 Telecaster. I read recently Jimmy Page used a '54
Telecaster for the solo in Stairway to Heaven which I had assumed was done on a Les Paul.

Greg.

telecasterguru (Frank) · #17 20-03-2009, 08:31 PM

I am into guitars and I have Teles, Strats, Les Pauls and many other electrics and acoustics besides.

Frank

telecasterguru (Frank) · #18 20-03-2009, 08:38 PM

My interest here though, other than guitars, is whether I should buy one of the new GSO RCs or an APO 127. There is also the path of modifying the 200mm newt. It is f5 so would there be any point in adding an MPCC or a field flattener?

Garyh · #19 20-03-2009, 08:45 PM

Quote:

Originally Posted by telecasterguru

My interest here though, other than guitars, is whether I should buy one of the new GSO RCs or an APO 127. There is also the path of modifying the 200mm newt. It is f5 so would there be any point in adding an MPCC or a field flattener?

Good point! Why not just modify the newt! You will need the MPCC for sure and if the newt is collimated well it should give you pinpoint stars across your image. Also faster than the APO and RC!
I have also viewed some test results of the RC on a german site, not very pretty at all!
If I had to choose I would get a nice APO.
cheers

Peter Ward · #20 21-03-2009, 02:51 PM

Quote:

Originally Posted by gregbradley

............I read recently Jimmy Page used a '54
Telecaster for the solo in Stairway to Heaven which I had assumed was done on a Les Paul.

Greg.

I believe it was a '58 Telecaster that Jeff Beck also used

...but...the '54 Strat is the one costs the very serious bucks