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Equipment Discussions >> Cats & Casses

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rmollise
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Reged: 07/06/07

Re: reflector vs sct question new [Re: Jon Isaacs]
      #5659638 - 02/03/13 09:58 AM

F/5 is not f/6, and field curvature is correctable with the f/6.3 r/c.

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Jon Isaacs
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Re: reflector vs sct question new [Re: rmollise]
      #5659653 - 02/03/13 10:12 AM

Quote:

F/5 is not f/6, and field curvature is correctable with the f/6.3 r/c.




F/5 is also not F/4.5 and coma is correctable with a Paracorr. Not much one can do though about those 30% plus Central obstructions..

But like I said, if I had to choose between a commercial GOTO SCT and a commericial GOTO Dob, I would probably go with the SCT... I must confess that I have been keeping my eye out for a C-5 to replace the one I gave away a few years ago. Not long ago an original Nexstar 5 showed up on CL for well under $200, it seemed like a reasonable deal.

Jon


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rmollise
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Re: reflector vs sct question new [Re: Jon Isaacs]
      #5659767 - 02/03/13 11:21 AM

OK Jon...well, let's just agree to disagree. If we are...not really sure.

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azure1961p
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Re: reflector vs sct question new [Re: rmollise]
      #5660031 - 02/03/13 01:51 PM

I love the use of animates here.

Pete


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Jon Isaacs
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Re: reflector vs sct question new [Re: rmollise]
      #5660036 - 02/03/13 01:54 PM

Quote:

OK Jon...well, let's just agree to disagree. If we are...not really sure.




Oh no, not agree to disagree, what fun is that?

I will let you and Eddgie battle out the question of field curvature and coma versus coma and eyepiece astigmatism.

To my mind, the comparison a non-issue. If one is looking for a larger aperture scope capable of bright, wide fields of view, a Newtonian is the obvious choice, it's a wonderful added dimension. Otherwise, the field curvature of an SCT only is an issue at the lowest magnifications and at the higher magnifications, the ability to use less expensive eyepieces at F/10 along with an acceptable amount of coma (comparable to a F/6 is what most seem to agree upon) with the SCT are definitely advantages.

In the big picture, I think the difference in the optics are not the guiding factor, both are reasonable, neither is perfect. The ease of use, the convenience, the size of the scope, probably come down on the side of the C-11. If the choice were between the Meade 12 inch SCT and a 12 inch Dob, I think the answer would be different.

Jon


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rmollise
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Re: reflector vs sct question new [Re: Jon Isaacs]
      #5660127 - 02/03/13 02:44 PM

I like disagreeing with you Jon, it is the prospect of possibly AGREEING with you that I find frightening!

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orion61

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Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: reflector vs sct question new [Re: rmollise]
      #5660294 - 02/03/13 04:25 PM

Biggest difference I can see is what you are going to be viewing, If Deep Space is your Primary then I'd nod toward a truss dob, I had a 12" and it was easy to transport in one piece. Lighter than my 12" LX200!
If you are like me, and I think Unk Rod from past posting,
Planetary can be a real pain with a Dob.
My 12" has superb optics, with my F 6.3 FF/FR it is well corrected for Deep Space.
You will never convince one another to trade Horses...


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Jon Isaacs
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Re: reflector vs sct question new [Re: rmollise]
      #5660398 - 02/03/13 05:23 PM

Quote:

I like disagreeing with you Jon, it is the prospect of possibly AGREEING with you that I find frightening!




Touche...

I know it would be difficult for you to agree with me... in public that is.

And yet we both know you've had that 12.5 inch F/4.5 Truss Dob for years and are a big fan of the 4.5 inch F/4 Starblast, particularly when there is the possibility of using a Paracorr with it..

Jon


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Jan Owen
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Reged: 02/12/06

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Re: reflector vs sct question new [Re: Jon Isaacs]
      #5660494 - 02/03/13 06:05 PM

Awww!!!

I don't seem to spend nearly as much time in this kind of discussion, as in days of yore... I've spent much of the last 15 years just enjoying the scopes that I have, and occasionally adding a new one...

Rod, Jon, & I go WAY back, deep into the jungle of the SAA days... I used to answer questions into the wee hours of the morning when I had to get up at 3 to get ready to go to work. I posted as many as 600 messages in a single month there... Jon was in the same ballpark, and Rod was close.

Now I mostly just enjoy the night-time skies, when they cooperate.

I have scopes in most categories, and enjoy them all for what they can do... So, to some extent, this is a circular discussion... One can be very happy with a large SCT or a similar sized Newtonian... The new Edge scopes deliver stunning images edge to edge. So will a quality Newtonian with a Paracorr... The SCTs are quite versatile, and more compact. The Newtonians, if you spend some time adapting them to the type of observing you do, can be, if not compact, then quite portable, and still deliver views to die for. Probably even just a tad beyond that of the SCT, with it's larger CO.

I will say, though, as I near 70 years of age; I've been moving my aperture downward with each passing year, and right now, while I still have decent aperture in both SCT & Newt, I'm starting to get serious about an 8" Edge... Even though I have a superb 8" Spooner Newtonian that can equal or outperform the Edge in virtually every way (except bulk)...

But, at this age, bulk gets more important with every passing day. So, I'm just gonna' get some more popcorn, and sit back and enjoy where this all goes...


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rmollise
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Re: reflector vs sct question new [Re: Jon Isaacs]
      #5660515 - 02/03/13 06:18 PM

Quote:

Quote:

I like disagreeing with you Jon, it is the prospect of possibly AGREEING with you that I find frightening!




Touche...

I know it would be difficult for you to agree with me... in public that is.

And yet we both know you've had that 12.5 inch F/4.5 Truss Dob for years and are a big fan of the 4.5 inch F/4 Starblast, particularly when there is the possibility of using a Paracorr with it..

Jon




Why are you trying to make me admit these strange NEWTONIAN DESIRES of mine?!


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rmollise
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Re: reflector vs sct question new [Re: Jan Owen]
      #5660518 - 02/03/13 06:20 PM

Quote:

Aw

Rod, Jon, & I go WAY back, deep into the jungle of the SAA days...




Hey! Now they KNOW how old we are. Didn't I first meet you on FIDONET ASTRONOMY?!

Aperture reduction? Yeah. Believe it or not, I was mildly contemplating a 16 - 20-inch Dob not long ago. But now...I don't think so. 12-inches is just fine, I've had Old Betsy for twenty years and we know each others' quirks.

Edited by rmollise (02/03/13 06:30 PM)


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Jon Isaacs
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Re: reflector vs sct question new [Re: rmollise]
      #5660558 - 02/03/13 06:45 PM

Quote:

Quote:

Aw

Rod, Jon, & I go WAY back, deep into the jungle of the SAA days...




Hey! Now they KNOW how old we are. Didn't I first meet you on FIDONET ASTRONOMY?!

Aperture reduction? Yeah. Believe it or not, I was mildly contemplating a 16 - 20-inch Dob not long ago. But now...I don't think so. 12-inches is just fine, I've had Old Betsy for twenty years and we know each others' quirks.




Jan (and Rod):

It is good to hear from you... Aperture reduction has not become a necessity for me... yet. As long as there is room to store the stuff, that's all it takes, there is no need to downsize.

As far as Uncle Rod and his 12.5 incher, Olde Rebel Yell, I mean Old Betsy... a 12.5 inch Dob is a wonderful size, I could be very happy if my 12.5 inch were my largest scope.

On a completely different note. This thread in Beginners could use Uncle Rod's expertise. It may end up here in CATs and CASSes but here's a link:

Spider Webbing on an SCT Lens

Jon


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rmollise
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Re: reflector vs sct question new [Re: Jon Isaacs]
      #5660600 - 02/03/13 07:18 PM

I just posted over there. Hard to say what it is...but it may be a job for good, old Mane and Tail.

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Jon Isaacs
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Re: reflector vs sct question new [Re: rmollise]
      #5660635 - 02/03/13 07:54 PM

Quote:

I just posted over there. Hard to say what it is...but it may be a job for good, old Mane and Tail.






I love it, not exactly something one would find in Roland Christens cleaning supplies but I am sure it does the job.

Jon


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rmollise
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Re: reflector vs sct question [Re: Jon Isaacs]
      #5660656 - 02/03/13 08:11 PM

Rednecks gotta be rednecks, Jon...

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