C9.25 vs VC200L?

[citivolus]

I'd like to solicit opinions regarding the Celestron 9.25 vs the Vixen VC200L. This would be on a side by side mount with a Megrez 90, which would be alternately the guide or imaging scope. I don't want to go much larger than either of these OTAs, for portability and mount budget reasons.

Primary targets would be DSOs, as I would use the Megrez for wide field. There is also the potential for some planetary imaging, hence the C9.25.

I'm looking for something with decent optics, easily transported, photography optimized (Canon 40D).

As I currently see it, they each have the following working for/against them:

VC200L pro:
-No image shift due to fixed primary and secondary
-visual path is optimized for photography

VC200L con:
-r&p focusser
-spider
-I've heard focus lock can cause image shift (minor)
-Vixen proprietary accessories

c9.25 pro:
-no spider
-historically good optics
-more light gathering

c9.25 con:
-larger OTA
-image shift when focusing


Any and all input is welcome.

Regards,
Eric

[gbeal]

Haven't had either, but both are highly rated. What are the respective costs though?

[Dennis]

VC200L

Optimised for wide field astrophotography, such that stars at the edge are fairly tight with little evidence of coma. For large chip DSLR’s this is probably very important. For small CCD chips where you are only using the centre of the FOV then less important.
Limited back focus. I could not achieve focus with an off axis guider (Taurus Tracker II) and my Pentax 35mm film SLR.
Limited range of 3rd party accessories.
Mine had nice optics, somewhere between my C9.25 and my Mewlon 180, although this is a highly subjective guess based on last using my VC200L some 7 or 8 years ago.
When prime mirror requires re-coating, you need to ship it back to Vixen. I heard of one owner who had his mirror re-coated locally and it ruined the figure, and his investigations led him to believe that the process that Vixen uses contributes to the final shape/correction of the prime mirror.

C9.25

Probably need to use a Reducer/Corrector for wide fields.
Rare to have back focus problems.
Vast range of 3rd party accessories.
Nullify effects of image shift by using a 3rd party Crayford focuser, e.g. Moonlite, JMI, etc.

Cheers

Dennis

[JohnG]

Why don't you throw the Takahashi Mewlon 210 into the mix as well, with the AU/Yen at the moment it is also an attractive option.

Cheers

[citivolus]

Yeah, I started wondering about the Mewlon scopes. Looks like I have some more research to do :)

Thanks all.

Eric

[JohnG]

I am actually going through the same comparision as you, I don't want to change my mount (G-11 with Gemini) so those same scopes are coming up for me. I mainly use the Tak FS-102 refractor at the moment for photographic work but want a larger scope for both visual and photo's, this will be coupled to an SBig ST4000XCM and AO-8 in the new year.

The Mewlon has the lead in my book at the moment. :thumbsup:

Cheers

[citivolus]

Hmm, it looks like the 210 would be over my budget, forcing me down to the 180.

Dennis, did you stop using your VC200L when the fungus moved in, or were there other factors involved such as the purchase of the C9.25?

At this point I would say I am leaning towards the C9.25, just in case I ever go planetary. How badly does the C9.25 vignette with a 1.6 crop DSLR?

[citivolus]

For reference, this thread from last year has some useful info/opinions on the Mewlons:

http://www.iceinspace.com.au/forum/showthread.php?t=15373

[Terry B]

I own a VC200L and have never looked through a 9.25 but do use a 14"SCT at our club. One other difference betwen the 2 scopes is the problem of dew. The SCT is much more prone to dewing up very quickly. I do get dew on the secondary but never on the primary. The clubs 14" dews up the corrector plate much more quickly despite it being in a dome and mine being out on the grass.
The stars are very tight on the VC200L but is doesn't have the light gathereing power of the 14" obvoiusly. I'm not sure how much difference there would be with the 9.25

[Dennis]

Guys

Here are the stars A through F in the Trapezium with the Mewlon 180 from early this morning.

Cheers

Dennis

[Alchemy]

the vc 200 l has a flat field at normal f9 with no coma etc, the reducer however does introduce some abberations albeit slight. its no where near the celestron for planetary imaging. For some stange reason the genuine reducer has a different thread than the genuine photo adapter and ive had to use tape over the reducer to screw it in.( not impressed with that) but it does work, the vc tube also is fairly lightweight, as it has an open front dewing is less of a problem and cooldown times are quicker.

the 9.25 has almost legendary optics (to do with mirror ratio F/l stuff) which is not on other s/c s and also accesories are easier to get.

[Dennis]

Hi Eric

I started ccd imaging with a PixCel 255 ccd camera and found the VC200L 1.8m fl too daunting, so began to use my Vixen 4” refractor (918mm fl) which made imaging reasonably easy. By the time I got back to the VC200L the fungus had grown and I never got round to using it again.

It did give me excellent service and is a very competent ‘scope, but in my opinion, not as good at the Mewlon series.

Cheers

Dennis

PS – If you would be interested in a knock down price for my VC200L, just let me know as I still have it, and the matching F6.4 FR and adapter. You are welcome to try before you buy.

[citivolus]

I have to remind myself to get what I will use now, not what I might use in a couple years, as that inevitably changes. I can always buy another OTA, after all. My use in the near term is as a guide scope for the Megrez for wide field, and for DSO imaging in the opposite configuration once I get my technique down. I'm looking at using a Vixen SXD mount with a side by side mounting with the Megrez, so the VC200L is about as heavy as I can really go, with the C9.25 really pushing it but just bearable.

I think the Mewlon scopes would be wasted on me at this time. One thing I don't get is how on the VC200L, the spider is "bad" for planetary via the spider causing difraction spikes and killing contrast, yet the Mewlon scopes have a hefty spider too, and seem to be considered good planetary scopes for their aperture.

Dennis, regarding your old OTA, I suspect Vixen would charge an arm, leg, and a few other assorted body parts to return it to flight readiness. I already have a couple photo adapters for the VC200L, purchased a few years ago when I first got approval from my wife to get one. I may have to take you up on a reducer, though, if I go that route and it were still available.

Terry, you mention dew on the secondary/corrector. How easy is it to run a dew heater in there without obstructing the light path?

One more question: Does anyone know a shop that actually carries the VC200L these days? You can PM me if you like.

Regards,
Eric

[Terry B]

I have seen a pic of this being done but I never bothered. I have just used a hairdryer. I made a dew shield out of black cardboard and have not had an episode of dewing since then.

[citivolus]

I wondered about that. I guess you would have a hard time determining that dew was forming on the secondary, due to it not being directly visible, other than a slow loss of contrast.

I guess the dew shield is still the way to go, as it cuts down on the heat chimney effect you would likely get with a heated secondary. It isn't like the dew shield really impacts portability or usability.

At this point I've found a Vixen SXD mount with HAL-130-SX tripod for $2785 (myAstro), and a VC200L for $1889 (astro-optical). The VC200L price compares very favourably to the Celestron OTA, with the obvious decrease in planetary performance. Maybe in a couple years when dealers have finally realized there is a free trade agreement in place the Celestron will come down in price and I will pick that or a Mewlon up for planetary, but until then the VC200L looks like the way I will end up going as it does what I need in the near term. While I wish I could throw a 14.5" RCOS and 150mm APO on a Paramount ME in a permanent observatory, my retirement years are still too far away :lol:

Thanks,
Eric

[Terry B]

To check on dew on the secondary I just shine my red light down the tube. You can see the secondary easily. If you can see the glass rather than the reflection of the focuser tube then there is dew on it.

[Aster]

Looks like I might be a bit late, But what was wrong of not including the 250mm LX200R TAO in the equation?

Would be interested as I am also looking at the Vixen and Celestron.

Alexander

[citivolus]

For me the 250mm scopes were avoided as I currently have one and am looking to bring the size down a bit to increase portability. I'm targeting a Sphinx SXD mount at this point with a Megrez 90 on a side by side mount with whatever other OTA I end up with, so the extra 3.7Kg of going from a C9.25 to a LX200R 10" would be noticed.

The Megrez + C9.25 + plates would be at the imaging weight limit of the SXD.

I'd go with a CGE mount for the extra capacity, but there is no way I'm paying that mark up. Also, it is heavier than what I have already, which isn't really what I was going for this time around. The extra $2000 to go from an SXD to a G11 would also be noticed. This leaves 200mm as my practical limit as long as I am planning on having the refractor on there, even if the LX200R is a similar price to the C9.25.

I have no real problems with the Meade OTA; it just doesn't fit the mount I have in mind.