VC200L question

[tims]

Hi all

On my short list for an astrograph is a Vixen VC200L that I believe has been around since the 90's.
I believe there have been some upgrades to the design and wondered if anyone can advise what the differences are between the older and current model so I know what to look for on the used market.

Thanks

Tim

[gregbradley]

Not exactly what you asked but there was a VMC260 for sale on astromart recently that had been nicely decked out with a new focuser and better rings with a Losmandy dovetail for about US$3300.

Greg.

[Tandum (Robin)]

Gotta watch out for different focusers on these vixens, the focal reducers are designed to fit the vixen focusers. There is a VC200L on astromart now for $1180 including US shipping so there's a deal to be done there or a new one ex-hongkong for HK$10,500 plus shipping. Shipping will be the killer in either scope.

[tims]

Thanks for your replies. Robin, would you mind giving me a link for the Hong Kong seller?

Thanks

Tim

Originally Posted by Tandum

Gotta watch out for different focusers on these vixens, the focal reducers are designed to fit the vixen focusers. There is a VC200L on astromart now for $1180 including US shipping so there's a deal to be done there or a new one ex-hongkong for HK$10,500 plus shipping. Shipping will be the killer in either scope.

[Manav (Yugant)]

I could be completely incorrect here however, I was told by salesperson when scope hunting that the VCL's have a issue with a thick spider vanes which causes blochy spikes on stars during imaging?

Sorry for being a party popper

[garymck (Gary)]

The VC200l's haven't changed optically over the years. There have been varying colours (white and green) and varying accessories with them eg some came with flip mirrors, some not. The thick vanes aren't a problem as lomg as collimation is spot on- this can be difficult, but once done it stays collimated. Virtually all optical problems with them are due to collimation. I bought one secondhand from an Icinspacer, I regard it as the best astronomical purchase I've made in 20 years...a wonderful imaging scope!

Gary

[Manav (Yugant)]

There you go! Thats why you should'nt always trust a salesman Thanks Gary!

[bmitchell82 (Brendan)]

Even with collimation absolutely spot on, the thick spidervanes do cause some what diamond shaped stars. its a function of their actual size and diffraction pattern.

leinad has a VC200L and won IOTW with M20 about a month or 2 ago, I milled his spidervanes down from 5mm to 2mm, they are still very rigid but you now have Round stars not Diamond shape!

The are a lovely scope, when fitted out with milled spidervanes and a good high quality focuser. Other things to think of getting is a 6.3 reducer unless you have a good mount and are dedicated to the F9 native focal length... difficult.

[Manav (Yugant)]

I spoke too soon!

[bmitchell82 (Brendan)]

http://i611.photobucket.com/albums/t...ffid_final.jpg

Thats the image taken with a OSC Qhy8 + EQ6. they are a great scope!

[DavidU (Dave)]

Tim, here is a very in depth test on one......
http://translate.google.com/translat...istory_state0=

[garymck (Gary)]

Diamond shaped stars dissappeared when I got collimation to better than 2 arc seconds according to ccd inspector. In my case I am extremely happy with the results. Whilst not a visual scope, for imaging it is great.....

Gary

Originally Posted by bmitchell82

Even with collimation absolutely spot on, the thick spidervanes do cause some what diamond shaped stars. its a function of their actual size and diffraction pattern.

leinad has a VC200L and won IOTW with M20 about a month or 2 ago, I milled his spidervanes down from 5mm to 2mm, they are still very rigid but you now have Round stars not Diamond shape!

The are a lovely scope, when fitted out with milled spidervanes and a good high quality focuser. Other things to think of getting is a 6.3 reducer unless you have a good mount and are dedicated to the F9 native focal length... difficult.

[tims]

Thanks again for all your replies - very useful info regarding the scope.

Dave, I couldn't figure out what the test was about with the link you gave me but I did find this: http://translate.googleusercontent.c...cjxg#post42589.
Reading it I didn't follow it to well (mainly lack of knowledge on my part!) - did the test find the optics were under-corrected?

Thanks

Tim

Originally Posted by DavidU

Tim, here is a very in depth test on one......
http://translate.google.com/translat...istory_state0=

[gregbradley]

Here is another VMC260L for sale:

http://www.astromart.com/classifieds...fied_id=683272

Or you can get one new from OPT (optcorp.com) for about US$3400.
Shipping would be about US$325 and GST would be about AUD$450.

There is a specific Vixen reducer but chances are lots of reducers may work. The AP67 reducer is often used with RCs so perhaps that will work with it.

I got a VMC95L as a new guide scope. It has a curved spider which also makes for little or no diffraction spikes.

Milling down the spider or replacing it with a curved aftermarket one, plus a feathertouch focuser, reducer of some sort and perhaps rotating Parallax rings would make nice future improvements to the scope. A Tak collimating scope or laser collimator would also be useful if it is sensitive to collimation.

Bang for you buck it doesn't have a lot of competitors. The main competitor now are the Astrotech RC scopes. Perhaps an Edge HD 11 or a Meade ACF 10 or 12 inch. But they have corrector plates which means more likely to have dew problems (the Vixen would be somewhat dewproof) and perhaps some colour aberrations from the corrector plate (not a lot really). I believe it is also quite light.

Greg.

[bert (Brett)]

The VC200 does work a lot better with the vanes milled down. My vc200 has been converted to carbon fibre truss and has had the vanes milled down. No scope is perfect but the big plus that the vc has is the fixed primary mirror, ie no mirror flop in exposures (the vmc series over 200mm is floating primary).

So the pluses are;

Flat field.
No coma or spherical abberation
No chromatic abberation
Dedicated reducer
fixed primary mirror

The minuses are;

Focuser has a lot of backlash (I use a fli df2 focuser for automated focusing via focusmax)
collimation is difficult (I have not mastered it yet, from what I am told rc's are harder still)
Mirror has to be recoated at the factory in japan

If you have got the patience to collimate it to within an inch of it life, go for it!

Brett

ps Greg, the tak collimation scope requires a centre spot on the secondary which the vixen does not have.

[leinad (Dan)]

Having a an older white tube,dark green base vixen and newer all white Vixen; there aren't too many differences, except for the newer vixen has used a black ring around the edge of the primary mirror which I'm told improves contrast but I cannot confirm whether this does actually do that.
The newer Vixen also has a plastic focuser knobs; and thats really only the difference.

The only warning with the older Vixens VC200L's would be the condition of the primary itself. The coating that Vixen Japan use can only be redone in their factory; and over 5-10yrs the coating of course if not looked after(cleaned/storage conditions) will be affected by fungi and damage the coating. This may not be obvious until the mirror has been cleaned.

I'm using a Feathertouch 2.5" focuser with automated focuser(focusmax automated) and milled spider vane to 2mm as Brendan(reps) mentioned.

Collimation is a simple process one you've done it a few times.

As a buyer I would be very cautious of the primary mirror condition and thats about it. I would even consider a brand new purchase from Aus(check with Steve at MyAstroShop), considering that if you do get one with a bad primary mirror coating, it's going to cost you $800 or thereabouts to ship it to Japan and back for recoating.
Brand new they should be around ~ $2200.

Hope that helps.

[tims]

Hi all

Thanks again for your replies - I had read that the mirror was built by adding layers of aluminum so I was going to ask about re-coating so thanks for that info.

Tim

[JohnH]

Originally Posted by gregbradley

There is a specific Vixen reducer but chances are lots of reducers may work. The AP67 reducer is often used with RCs so perhaps that will work with it.

NO!!!!

The Vixen FR is essential withthe VC200L - it goes inside the focuser draw tube and nothig else will fit and the draw tube alos contains the corrector.

The corrector in the draw tube is the reason why there are so few (I think moonlite were going to make one) after market focser options for the scope.

Collimation is critical - and not easy either but industrial strength when done due in part to the large spider vanes and large central obstruction - for the same reason it is not a good planetary scope.

The tube itself is flimsy so take care with mouting guidescopes - solid rings are required to avaid flexure.

F9 is a pita unless you have huge pixels on your ccd (ie not a DSLR) and the FR is therefore essential, unfortunately it means you lose some of the scopes legendary flatness.

There are different locations used to manufature Vixen scope - hencew the Green paint tubes were preferred as they were known to be made in Japan only - some white tube Vixen otas come from China. I do not believe the VC200Ls have ever come form there - or at least the optics do not.

Finally bear in mide the mirror has non-uniform coatings that are integral to the optical system - recoating means return to Japan.

There may be better options out there depending on your ccd and targets - but it is a good option.

John.

[tims]

Hi guys

Just wanted to follow up on all the excellent advice you gave me regarding the VC200L scope.
I decided against buying it as there were a number of factors that didn't suit, such as:
being a beginner in AP I thought the longish focal length might work against me; I didn't want to buy used as I couldn't be sure about the state of the mirror and getting it re-coated seems an expensive task and finally, the price was a bit beyond my budget at the moment.

What I have ended up getting is a used Intes MN-56 (127mm Mak Newt) from Astromart. I'm losing quite a bit in aperture as compared to the Vixen but the reviews I've read seem positive so I'm pretty happy with the purchase. I've also purchased a used sbig ST-7E from Astromart as well so hopefully the two should be a good match!

cheers

Tim

[Starkler (Geoff)]

Originally Posted by gregbradley

Here is another VMC260L for sale:

Be aware that the VC and VMC are very different beasts.
The VC is the one you want for AP.