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Vixen VC200L - First Impressions...

RichieJarvis

By RichieJarvis
in Member Equipment Reviews

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RichieJarvis

RichieJarvis

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Hi All,

As some of you may have heard, I've been asked to review a Vixen VC200L. I thought I'd post my initial thoughts here though... The full article will be published later (I hope!)

Initial Thoughts

The scope is well built - I got just the OTA to review. There is a nice carry-handle, and it came with a pre-attached skywatcher format dovetail.

This is not a normal SCT type catadioptic though, theres no corrector visible in the front. A spider holds the secondary mirror in the front of the 8" tube. There is a big baffle in the middle of the primary mirror.

Its not that heavy either.

Design

The system in use is Vixens own - the VISAC or Vixen's Six-Order Aspherical Cassegrain system. This puts the corrector in front of the secondary. Which also happens to be deep in a barrel near the focuser.

Very clever. The next bit is the primary mirror - its fixed - there is no mirror flop possible here.

Visually, I haven't been able to detect coma either.

Initial Tests

I am still processing my moon shots, taken with my Lumenera 2-1C and F/7.1 focal reducer, but I can see that this field is flat.

This brings the scope to the usual F/6.4 that we all know and love. Natively, this is an F/9 scope, not F/10 - 2000mm aperture and 1800mm focal length.

The collimation also has survived a trip with Royal Mail and to and from SGL5.

Initial Conclusions

Its good - the results pleasing, and its easy to use. Lighter than the C8 as well.

I'll post more when I have more info ;)

Cheers,

Richie

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Euan

Euan

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No - I don't - If you know someone with a copy who I could send a sub to and get an analysis, that would be cool ;)

If you email me a few I will post up the results, will PM you my email address

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Euan

Euan

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CCD Inspector throws a bit of a wobbly with these Ritchie, probably not much good to anyone

What was the guiding like during the shots? It can get really picky about slight elongations on stars, it also gave me an error that there was not enough stars for an accurate messurement

..oh well, worth a try anyway!

post-16116-133877443926_thumb.jpg

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RichieJarvis

RichieJarvis

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Thanks Euan - I did wonder, the guiding wasn't all that great tbh - I was guiding with the WO66mm, but have now switched to the Genesis, which should improve matters somewhat!

I'll post some more once I get more data...

Cheers,

Richie

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ollypenrice

ollypenrice

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Guiding with the Genesis????????????? AAARRGGGHHH the shame of it!!!!

Hi Richie,

I'm very interested in this review. I thnk that even if it doesn't need it you might think of testing the collimation since it is something of a talking point on this scope. Some say it is easy, others the opposite.

There was a long discussion about mis-shapen stars on one thread I followed when considering this scope. The thick spider which the design requires does seem to produce 'square' stars in some images, maybe depending on the star size in the feild. It would be good to see some Milky Way images in dense starfeilds.

Aonther odd thing that I read was that the mirror is parabolized by the addition of extra aluminium rather than by means of a parabolic grind. Hmmm....

It should be a great scope to review. Have fun and I look forward to more.

Olly

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skybadger

skybadger

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Hi

I have had one of these ( the VC200L white tube version) for the last 10 years or so. Seems a bit late to begin reviewing it now...

There's a good yahoo groups site for this scope with reams of info on it and some it on my website.

The good points for this scope are

It cools down quickly

Its steady as a rock night after night, hardly a refocus required

it takes a robofocus easily

It has a very flat field according to CCD Inspector ( looking for my results somewhere)

its quite lightweight

The downsides are:

its hard to use tube rings with due to the weight balance of the OTA

The dovetail can be subject to differential flex to the guider unless the guider is side-by-side

The focuser is not the best but is solid and has a little in-out image movement

The spider has a large width on the supports leading to strong spikes and the central obstruction is large compared to the overall diameter

Collimation can be tricky since it is very sensitive. I'd like someone to eyeball mine since it can be a spot mushy visually on low-contrast things like planets and I think it could be better.

Stars are normally very nicely shaped as round spots across the total field (43mm with the canon EOS adapter ) unless the mirror is pinched, the focuser misaligned or the collimation screws overtightened. This normally leads to triangle shaped stars. Squares is not one I've seen or heard of.

Finally, I use mine on a Vixen Gp/DX with SS2K in the obbo. Pointing has not been the best but is now substantially better with a massive pier attached to concrete and a gear mod to up the torques by factor 2x. I normally use this with a focal reducer to f/6.4 due to the previous inability to track well. Nowadays most of my images are 5 min at 1200mm on a nikon DSLR and come out at about 60% success rate when autoguiding with Guidedog and a Vixen 80mm f/5 & sc1.5 webcam.

there are some images here...

www.skybadger.net/images/2009dec22

and more in the images section under www.skybadger.net using a Hx916 CCD camera.

Hope this helps

regards

Mike

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ollypenrice

ollypenrice

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Mike, I may have misremembered the square/triangular stars thing. Forgive me. It will be good to see what Richie finds out. Since the scope has only a niche following and maybe deserves more, maybe a new review is still well worth having.

Olly

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skybadger

skybadger

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Hi Olly, Rich

Just seems a bit odd to review such a old scope but if there is a gap in the reviews go for it - happy to help if required. There are a lot of good imagers out there using one. Not so much the VMC I feel, compared to the VC200.

The primary mirror is a parabola with 6th order coatings where the coatings are used to adjust the correction. I have seen no evidence for this and can't imagine how its done but it has been repeated on multiple groups, including by people who had to send their mirrors to Japan for recoating. Wonder if its true ?

Cheers

Mike

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pete_gamby

pete_gamby

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Since it was me that caused the delivery of the VC200L to Richie, I guess I had better put my oar in :-)

We at Opticron understood that although the Vixen range is a) long in the tooth in the most part and :D probably in need of refreshing, there are some at least fair to middling tubes in the line up. But, we couldn't find much evidence in UK press/forums etc of independent reviews carried out in "real world" situations, by real imagers/observers and over an extended period of time i.e. weeks, not days.

So, we came up with a plan to place as many tubes and mounts with as many keen but experienced UK astronomers as we could find and cope with in the hope that we get feedback, postive and negative, to pass back to Vixen to improve and update the range over the coming years.

Richie got in the queue as did another enthusiast who buys from MC2 in Frome. I have a handful of business cards on my desk from others that have expressed interest at and since Astrofest.

I have promised Richie a VMC200L to compare and contrast with the VC200L so we can understand the shortcomings/benefits of each from the keen imagers point of view.

In relation to the question about the mirror configuration, I will ask the question to Vixen Japan and post the reply if it adds to the community knowledge.

So, while this is not a hot off the press product, I hope Richie has some fun with it and we hope to learn how to get better solutions for FLO and the rest of the retailers to sell.

And if anyone wants to put a hand up as a potential reviewer, feel free to PM me. The requirements are few - you must exist i.e. have a geographical address, phone number, full name and preferably be known to an astro society and/or retailer. Beyond that, if you have two heads, are purple with fluffy bits and have a preference for listening to Six Music, it matters not :-)

Mods: please edit as necessary if this is too close to advertising/selling etc.

Cheers, Pete

Sales and Marketing Manager - Opticron - Vixen UK Distributor

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ollypenrice

ollypenrice

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I think Pete's point is perfectly valid. It is also worth considering that cameras and techniques have changed. I'm looking forward to reading about this instrument in a modern context. It has been 'on my list' and is still not entirely off it.

Olly

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skybadger

skybadger

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I read Pete's response and spent a few minutes thinking what my issues are...

This scope has always exceeded my ability to image with it so the optics aren't my primary issue, nor has it ever dewed up on me.

The drawtube is larger than anything I want to image so vignetting, back focal length and photographic field width limitations aren't an issue.

I think after all this time my primary issues with this scope are the thickness of the secondary vanes and the tweakiness of collimation.

Here's a URL to a guy who replaced the whole tube with a custom carbon truss to remove this issue. Vixen VC200L CF truss conversion - IceInSpace

and another to thin the vanes

http://www.starrywonders.com/vc200lvanes.jpg

My experience of Vixen overall in relation to this scope includes:

1, the focal reducer arrives without the drawtube adapter which is an additional extra and shouldn't be (Mine's a Borg part in the end)

2, the 2" eyepiece tube was an additional to the vc200 when I bought it. I hope it's standard now.

3, Buy the vixen 10:1 focuser speed reducer. I use robofocus all the time but manually can be quite tricky to get perfect focus.

Cheers

Mike

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  • 3 months later...
pete_gamby

pete_gamby

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Sorry to bump this but I'm hoping to have news from Richie on the final text of the review very soon (the planned issue of Look Up! that it should have been in didn't get published in the end).

Also in response to the points in Mike's post #18:

1. The FR is still not supplied with an adaptor to attach cameras etc but we can supply it with a 60mm to T-thread adaptor if required (this is what Richie used in testing). It does screw straight into the draw tube though - perhaps I've misunderstood what you mean Mike? I've posted the user guide for the FR on our website - http://www.vixenoptics.co.uk/PDFs/User%20Guides/VC_Focal_Reducer_User_Guide.pdf

2. We now supply a 2" eyepiece adaptor tube free of charge if wanted by the purchaser

3. The dual speed focusser is now standard on most other Vixen OTAs and is available for the VC200L as an option

Now that this review is over, I can look back at the queue of those that expressed an interest in reviewing Vixen kit.

Cheers, Pete

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RichieJarvis

RichieJarvis

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Thanks Pete - I'll post the review on my website as well, and post a link back here once done...

The interesting thing you should note is that I brought it, so if thats anything to go by, its a great piece of kit :D

I'll followup this thread once the review is fully written.

Cheers,

Richie

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skybadger

skybadger

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Hi Richie

just read your review. Very interesting.

I note through talks with Pete that Vixen look like they have changed the Visac in recent years. For example the spider on yours looks less chunky, the drawtube on mine is 60mm not 78mm and the Focal reducer is not a direct screw-in but requires a 56-60mm adapter ring.

It looks like improvements all the way though. Good to see you bought it.

Cheers

Mike

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NickH

NickH

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Good review (though not sure what those donuts were in that H18 image you posted?)...

I have also to applaud this approach by Pete/Opticon. I know the people who got the starbook etc from MC2 (very good mate of mine!)..and the issues he had, but this approach, despite the hiccups, along with their willingness to listen and put ALL comments (and mine on the AX103 were quite cutting!), back to Vixen Japan. Working as I did for 16 years for a Japanese company, I know how tough it is to get people to change their ways...but slow, sure and informed input from people using kits in the real world is a good way to start. If Vixen USA adopted the same approach, it would help, as I know that Japan tend to listen more if a MAJOR player says "jump"..

Anyway...good stuff, good report and a good thread all round

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