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Ritchey-Chretiens: How many choices do I *really* have?

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#51 ChrisPA

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Posted 08 August 2018 - 10:53 AM

I was very interested in getting a VMC or VC200L a while back. I still kind of want one - there are a few things I like about those scopes more than my RC, such as the weight, the handle, the higher focal length and the smaller central obstruction (better for planetary). I ultimately decided against them due to a few factors such as the price (the VC200L was about $250 more than the carbon fiber RC I got [on sale]), the price of the reducer (outrageous, although it looks like the CCDT67 would have worked as well), the difficulty in getting the VISAC mirror recoated if needed (although this might be an issue with the RC as well), the overly thick spider vane (I like diffraction spikes, but I like them subtle), the lack of a carbon option (I almost never refocus after setting it for the night), etc. There's also just the cachet of having a scope with the same optical design as the Hubble... The VMC seems to not have as flat of a field as the VC, but I nearly pulled the trigger on a used one - the timing just wasn't right though. It'd still be cool as a grab and go, but it seems a little redundant with the RC.

 

I'd love to get a VMC260L for visual and planetary imaging - it's probably my ideal visual scope, but the price is not in line with the competition (assuming a VERY flat field, it should be somewhere between a C9.25 EdgeHD and C11 EdgeHD, but it costs more than the latter with a lower aperture). I'm still paranoid about cracking a corrector, but I'm thinking my next scope would be a C9.25 EdgeHD - perhaps I could have two rigs running at once and have the RC gather color data while the 9.25 gets luminance, for example (reduced at 0.7x, their focal lengths are almost identical - 1625 vs 1645 mm). Then I could also use it for visual, planetary and potentially even Hyperstar. I'm clearly getting ahead of myself here though...



#52 ChrisPA

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Posted 08 August 2018 - 10:56 AM

By the way, last night I (unexpectedly) got around to processing one of the three images I'm working on:

 

NGC 6781: https://www.astrobin.com/360176/


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#53 skyler

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Posted 10 December 2018 - 07:22 PM

How about the Vixen VC200L? I have one, and I would have to warn anyone thinking of getting one to consider the pros and cons carefully. There seem to be sharp quality differences, but some people get excellent results from them. It does have an extremely flat field, is more or less immune to dewing, has nice fat spider vanes for those who like spikes, and can be completely collimated. They are tough to collimate, though, and the optical quality varies so much that I get the impression that they go out the factory door without ever seeing Quality Control. But it is an option to consider...

I am so with you on this.  I have read so many reviews and specs on the VC200l. I owned a couple, years ago and always regretted giving them up. At the time, the last one picked up stray light from a bright star in my imaging field and that threw me off to sell it. That was not a major issue in retrospect (just wanted to buy something new) but as I waded through many 8 inch scopes from the RCs, Newts, Mod'd Dall Kirkams, Cass, Schmidt-Cass etc..., I wanted something light, would hold collimation, F10 or less, not dew up, cooled reasonably quickly, inherent flat field with pin point stars, works right out of the box w/o mods n well built,  and it's primary function for imaging.  Well, came right back to the VC200l.  BUT I recently just about bought an 8" Edge instead since I could live with the cooling issue and have wanted one for some time since I had owned older C8 thru C11 scopes. Then at the last moment when I was shopping for it's reducer, I found that the 8" image circle with reducer was designed for an APS-C camera and not with my full frame cameras.  I would need to go up to the 9.25 or the recommended C11 Edge.  I could consider it but the weight was well beyond my preferred limits since it would need to be hauled in and out every night for setup. So I canceled the C8 edge order and am firmly planted back into the VC200L which I know the two reducers for it will work well with my cameras from prior experience. MIGHT have to consider trying the AP reducer mentioned too. This is one consideration I have not read about anywhere as you hear all of the other VC200L pros and cons.  Yes, I think the Edge seems to have a tad sharper image but it just misses the boat for me when imaging at a lower F-ratio and wider field of view for my purposes.

 

BTW, this was a great post to hear about the RC considerations. I unofficially owned the TPO 8  RC but got cold feet and sent it back since it was never unpackaged.  I read about some of the issues noted here and I decided otherwise but I know it might have been a good scope to own as well.


Edited by skyler, 10 December 2018 - 07:28 PM.



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