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Vixen VMC 200L - Opinions?

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145 replies to this topic

#51 astrogeek64

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Posted 18 November 2017 - 07:59 PM

With a plastic tube. Medicine tube for example or anything that fit into the baffle tube.

Gutter drainpipe can work. You push the o-ring with the pipe.

Don't use metal pipe.

Here's what I've done; I had some Protostar flock board lying around. So, instead of o-rings I cut out four strips 10mm wide and the length to fit tight against the walls of the primary baffle and spaced them about 6mm apart starting from the focuser end of the tube. If you get the length just right, they "snap" into place and conform to the walls nicely. The result is a readily noticeable.

 

It's a good tweak but it takes patience and a steady hand with a pair of 10" long hemostats. I was extremely careful not to scrape the walls with the metal stats, although they have no sharp edges really.

 

Dave


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#52 jjack's

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Posted 21 November 2017 - 06:34 AM

You have done the most important thing : blackening the tube wall. Also look at the diagonal wall. Sometime they need to be blackened too. In a cassegrain, the loss of contrast is there.

Enjoy your improved scope wink.gif


Edited by jjack's, 21 November 2017 - 06:37 AM.


#53 TOMDEY

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Posted 04 January 2018 - 11:22 PM

Will the VCM 200L take a “regular” 2-inch star diagonal and come to focus OK? The directions show their dedicated flip mirror diag, which I don’t want to use. My preferred eyepiece will probably be the University 50mm Plossl, to give 39x. I would like to use it as a Finder on my 36-inch scope… honest!  Tom


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#54 astrogeek64

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Posted 05 January 2018 - 10:42 AM

Will the VCM 200L take a “regular” 2-inch star diagonal and come to focus OK? The directions show their dedicated flip mirror diag, which I don’t want to use. My preferred eyepiece will probably be the University 50mm Plossl, to give 39x. I would like to use it as a Finder on my 36-inch scope… honest!  Tom

Yes, it will. I use the Baader "Click Lock" diagonal.



#55 jjack's

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Posted 05 January 2018 - 10:42 AM

Yes the VMC 200 L take easily a 2"diagonal. Mine is a kepler d

ielectric.

Is this scope difficult to collimate ? Not more difficult than a newton ! It is exactly the same method.

 

Center the secondary older into the end of the primary baffle tube with the focuser screws, then center the primary image into the secondary with the secondary screws, then center the poisson dot at high power and near the perfect focus with the rear primary screws. The first and second step need to be adjusted only if you dismantle the scope. Otherwise you only need to adjust only the primary mirror screws during a star test. Don't tighten theese screws or you get astigmatism (diamond shaped stars and soft images).

 

Let it cool down completely with the focuser up before collimation.


Edited by jjack's, 05 January 2018 - 08:11 PM.


#56 astrogeek64

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Posted 05 January 2018 - 06:56 PM

I have one and wrote a very simple shootout between it and a C8.  I think that the advantages are full 2" eyepieces, better focusing, mak vs SCT corrections, larger field.  The disadvantages are no visual FR, less in travel.  The VC200L is more oriented towards imaging, it is a corrected DK vs field mak.

 

Personally I think both scopes have cool down issues, the C8 is worse for sure.  VMC would be easier to fix, all it needs is some fans blowing up the back, but it would be hard put on there.  

 

IMHO, I would look for one used.  I got mine for 600.  I saw one on astromart for 475 a month or two ago.  They routinely are for sale for 600-700. 

 

I would look for one used.  Be very careful with the collimation.  It can be collimated by secondary, focuser, and main mirror.  Vixen's instructions only say to adjust the main mirror.  People like to tinker.  I have only touched the main mirror personally. There is a great explanation of collimation on this scope from a gentlemen in Australia.  He also recommends flocking and thinning the spiders.  

You got that right. Mine somehow got slightly out of collimation so, following instructions, I started adjusting the primary to no avail. So, then I moved on to the secondary.......... To shorten it up, I quickly had a mess. I did find, download and print out some more in depth collimation instructions from Vixen that were very helpful. All is well, now, but it was a bit of a pain getting everything back. 



#57 astrogeek64

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Posted 19 April 2018 - 04:25 PM

Even following Vixen's instructions this thing is a pain in the a$$ to keep collimated. Even when the star test looks perfect, the view is soft at anything higher than about 150.... What gives?

#58 Peter Besenbruch

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Posted 19 April 2018 - 07:19 PM

Even following Vixen's instructions this thing is a pain in the a$$ to keep collimated. Even when the star test looks perfect, the view is soft at anything higher than about 150.... What gives?

You might post pictures of the defocused star test. That said, a lot of people seem to top out at about 150x with these scopes.



#59 Exnihilo

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Posted 20 April 2018 - 10:50 AM

You might post pictures of the defocused star test. That said, a lot of people seem to top out at about 150x with these scopes.

Not really much of a planetary scope.



#60 JohnH

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Posted 20 April 2018 - 11:15 AM

https://translate.go...MaQ9661Zvwv9bgQ



#61 KevH

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Posted 20 April 2018 - 11:16 AM

Not really much of a planetary scope.

There are several reports on this site where VMC200Ls have been directly compared to C8s and side by side were reported as being very much equals.  I'm not sure where the previous poster is getting "most" top out at 150x.  Maybe he is confused with the smaller Chinese made VMC110 and VMC95?  Those models have mixed reviews but actual reports on this site seem to indicate otherwise for the larger VMCs.  I think they are very susceptible to tube currents given that the corrector is hanging out in the middle of the tube but I'd expect more than 150x on a good night when acclimated.  Most users report very smooth optics on them with some expected contrast loss due to the largish obstruction.

 

https://www.cloudyni...vs-celestron-8/

 

https://www.cloudyni...-vmc200l/page-3


Edited by KevH, 20 April 2018 - 11:20 AM.


#62 JKAstro

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Posted 22 April 2018 - 11:14 PM

I suppose the moon is an easy target, but just I had it up to 200x to 240x with a Baader zoom and it looked pretty good.  I think if seeing were better 240x would have been fine.  On the other hand, stars at medium to high powers have always been a blobby mess for me.  Still trying to figure that out.



#63 Peter Besenbruch

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Posted 23 April 2018 - 10:01 PM

There are several reports on this site where VMC200Ls have been directly compared to C8s and side by side were reported as being very much equals.  I'm not sure where the previous poster is getting "most" top out at 150x.  Maybe he is confused with the smaller Chinese made VMC110 and VMC95?  Those models have mixed reviews but actual reports on this site seem to indicate otherwise for the larger VMCs.  I think they are very susceptible to tube currents given that the corrector is hanging out in the middle of the tube but I'd expect more than 150x on a good night when acclimated.  Most users report very smooth optics on them with some expected contrast loss due to the largish obstruction.

 

https://www.cloudyni...vs-celestron-8/

 

https://www.cloudyni...-vmc200l/page-3

I'm thinking of one that a club member owns. Stars look reasonably round, but the images were not all that sharp. There are lots of complaints on cloudynights.com (and elsewhere) as well. The scope is rather difficult to collimate. The central obstruction is large. The spider veins are very thick. Optical performance is uneven out of the factory. In particular are issues with astigmatism and undercorrection. You can minimize these issues, but it's a complicated, three part procedure to be able to do so.

 

Here is another horror story on astro-foren.com. Recurring issues reported by one person with multiple units:

- the focuser
- the secondary holder
- the centering of the various optical elements
- the correct lens separation and tilt
- ventilation and cooling
- poor light control
- setting the correct focus position

 

The second link lists a series of units with Strehls in the 40-70% range at the bottom of the page.



#64 KevH

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Posted 24 April 2018 - 06:47 AM

I'm thinking of one that a club member owns. Stars look reasonably round, but the images were not all that sharp. There are lots of complaints on cloudynights.com (and elsewhere) as well. The scope is rather difficult to collimate. The central obstruction is large. The spider veins are very thick. Optical performance is uneven out of the factory. In particular are issues with astigmatism and undercorrection. You can minimize these issues, but it's a complicated, three part procedure to be able to do so.

 

Here is another horror story on astro-foren.com. Recurring issues reported by one person with multiple units:

- the focuser
- the secondary holder
- the centering of the various optical elements
- the correct lens separation and tilt
- ventilation and cooling
- poor light control
- setting the correct focus position

 

The second link lists a series of units with Strehls in the 40-70% range at the bottom of the page.

There are lots of complaints about SCTs too.  Plenty of horrible test reports as well.  I don't think I'd ever broadly characterize that most SCTs top out at 150x though.  



#65 Peter Besenbruch

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Posted 24 April 2018 - 04:19 PM

There are lots of complaints about SCTs too.  Plenty of horrible test reports as well.  I don't think I'd ever broadly characterize that most SCTs top out at 150x though.  

Two things. First, I don't consider SCTs to be very good scopes, overall, and comparing the VMC200L to an SCT is damning with faint praise. Second, in all fairness to the SCT, there are lots more of them out there than the Vixen product. A lot of bad reports is far more damning when a scope sells with relatively few numbers.

 

Both scopes have systemic issues. The SCT has smoothness issues, an issue usually traced to the corrector plate, and occasionally to the secondary mirror. The Vixen is different. The individual components tend to be good. If you have an optical bench, and are willing to go through the complex rebuild required, a lousy Strehl tends to transform into a good Strehl. Vixen's problem is one of sending well adjusted scopes out of the factory that stay well adjusted, except for minor adjustments to collimation. Vixen compounds the issue with a reputation for poor customer service (at least in the U.S.).


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#66 Wm Rison

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Posted 25 April 2018 - 05:28 PM

I really like the one I have and have done a little astrophotography with it.

Here is an 1 hour 15 mins. (25 at 3 mins.) of M8 I did a while ago.

I used an Astro-Physics APCCDT 67 reducer.  Tried the vixen VMC200L reducer but got a lot more edge coma that with the AP reducer I already had.

 

http://ip.miltonhill...PG 25Pct 02.jpg

 

I think Vixen is one of the under rated companies out there.  Also have a SXD2 mount with the star book ten that is far better than any mount I have used.  It's a lot more fun to use too.


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#67 Peter Besenbruch

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Posted 25 April 2018 - 10:29 PM

I really like the one I have and have done a little astrophotography with it.

Here is an 1 hour 15 mins. (25 at 3 mins.) of M8 I did a while ago.

I used an Astro-Physics APCCDT 67 reducer.  Tried the vixen VMC200L reducer but got a lot more edge coma that with the AP reducer I already had.

 

http://ip.miltonhill...PG 25Pct 02.jpg

 

I think Vixen is one of the under rated companies out there.  Also have a SXD2 mount with the star book ten that is far better than any mount I have used.  It's a lot more fun to use too.

Very nice picture, but it says nothing about high power, visual usage. Interesting comment about the reducer. Funny how those things work out.



#68 Paul Sweeney

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Posted 27 April 2018 - 06:28 AM

I unfortunately bought a VC200L years ago. Quality? If you look into the link above to the astro-foren, mine is the second to last. A magnificent strehl of .49 in red light! The worst part is, I had been having a running battle with "Vixen Germany", the distributor who I will not name, and he stated, in writing, that the scope was in A-1 condition and my complaints were groundless. They even claimed it was one of the best that they had ever seen, even though it was unable to form an airey disk of an artificial star in their warehouse after they had collimated it. I had it tested because I just had to know. When I then complained to Japan, they said that they couldn't help.

 

I liked the scope because it is handy, cools quickly and is light. But the optical quality is nowhere near what it should be. And there are too many complaints for the small number sold. So if you really are interested in moving up from an 8 in Cat, look to the higher quality brands where you can be relatively sure of getting the quality you are paying for.



#69 astrogeek64

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Posted 03 May 2018 - 12:41 PM

I really like the one I have and have done a little astrophotography with it.

Here is an 1 hour 15 mins. (25 at 3 mins.) of M8 I did a while ago.

I used an Astro-Physics APCCDT 67 reducer.  Tried the vixen VMC200L reducer but got a lot more edge coma that with the AP reducer I already had.

 

http://ip.miltonhill...PG 25Pct 02.jpg

 

I think Vixen is one of the under rated companies out there.  Also have a SXD2 mount with the star book ten that is far better than any mount I have used.  It's a lot more fun to use too.

I have that same mount and love it. I have read some glowing reviews of other Vixen scopes including this ones big brother, the VMC260. But, this VMC200 has been a PITA. I have a Chinese made 8" F/4 that gives me far sharper results, holds collimation well and cost half as much. Would I buy Vixen again? Sure. In fact I was tempted with a good deal on an ED115s just minutes ago. But, this particular VMC200 has me running out of patience. It's not bad for low magnification visual.............. and that's about it.


Edited by astrogeek64, 03 May 2018 - 12:42 PM.


#70 JKAstro

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Posted 08 May 2018 - 03:10 PM

I've owned my VMC200L for almost 2 years and have often wondered about its performance, but last night I finally had very good seeing on Jupiter and was quite pleased with the sharp images I had during those clear moments. It slightly bested my 4 inch APO, they both displayed sharp details on the cloud bands but the VMC200L's aperture advantage gave a noticeably larger and brighter image.  It helped me put to rest my concerns about the scope and answer the question as to which to choose for lunar and planetary when conditions are right.  It also helped that temperatures were steady and the scope had plenty of time to cool.


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#71 sdufoer

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Posted 09 May 2018 - 07:26 AM

What horror stories !!  Some positive points now because these comments don't do this pearl justice.  For me the VMC200L is my absolute n°1 workhorse, but I only use it for CCD observations with a ST8XME.  Never looked though it.

I had a C9 before but I had numerous issues with it in terms of stability.

 

The VMC200L is:
1) Compact.
2) Keeps its collimation.  Is also fairly easy to collimate.  It only needed collimation once many years ago.
3) No mirror shift/flop.
4) Very fast cooldown.
5) Even with the F6 reducer pretty corrected field with not much vignetting (easily corrected with flats).
6) Focuser is easy to adapt with robofocus and precise.
7) Cheap for what you get.
8) FWHM between 2.5 and 3".
9) Stable and tight, the components don't move at all.

 

It's just that kind of scope that you buy and you forget about it because it does its job day in day out.  I have investigated the market before I bought it, and (for me) this is the only telescope that suits my needs.  There were no competitors.

 

But I would only use it when you need a compact en reliable astrograph.  That obstruction is too big.


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#72 astrogeek64

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Posted 17 May 2018 - 12:32 PM

What horror stories !!  Some positive points now because these comments don't do this pearl justice.  For me the VMC200L is my absolute n°1 workhorse, but I only use it for CCD observations with a ST8XME.  Never looked though it.

I had a C9 before but I had numerous issues with it in terms of stability.

 

The VMC200L is:
1) Compact.
2) Keeps its collimation.  Is also fairly easy to collimate.  It only needed collimation once many years ago.
3) No mirror shift/flop.
4) Very fast cooldown.
5) Even with the F6 reducer pretty corrected field with not much vignetting (easily corrected with flats).
6) Focuser is easy to adapt with robofocus and precise.
7) Cheap for what you get.
8) FWHM between 2.5 and 3".
9) Stable and tight, the components don't move at all.

 

It's just that kind of scope that you buy and you forget about it because it does its job day in day out.  I have investigated the market before I bought it, and (for me) this is the only telescope that suits my needs.  There were no competitors.

 

But I would only use it when you need a compact en reliable astrograph.  That obstruction is too big.

Yeah, I don't understand why this particular one has been such a headache for me. I'm not ready to give up, however. I'd rather continue working on the issue until I've resolved it. That's just my nature.



#73 Bomber Bob

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Posted 29 August 2018 - 11:12 AM

I have the vmc200l as a complimentary scope to my apm 152 f/8 e. d doublet apochromat...

 

I'll have the same set up shortly -- just bought the used VMC200L on CN Classifieds.



#74 Charlie B

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Posted 29 August 2018 - 03:57 PM

I have the vmc200l as a complimentary scope to my apm 152 f/8 e. d doublet apochromat...

 

I'll have the same set up shortly -- just bought the used VMC200L on CN Classifieds.

My two scopes are the VMC200L and SV115-T2.  I've yet to get a good first light with the VMC, which means I don't have anything to report.  I've added the JMI motofocus and the Orion thin OAG for this one.  I'm all in astrophotography and I needed a light scope for this purpose.  I chose the VMC because of the weight and not needing a dew heater.  It replaces my Meade SN8, which is getting too heavy for me.  I did some views of Jupiter and Saturn, but weather has been too bad for much photography.  

 

However, this OTA is built solid and is easy to handle.  I need more practice with long focal lengths to produce much good.  Maybe at the star party next month.

 

Regards,

 

Charlie B


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#75 Bomber Bob

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Posted 07 September 2018 - 10:56 PM

My VMC200L arrived yesterday evening, but I didn't get it unpacked until after work today -- thanks to Tom for a very thorough packing job, it made it from Cali to Alabami with zero damage.  The collimation was close, and I tweaked the primary to get it closer to dead center, but I didn't have time for a push-me/pull-you with Allen wrenches -- I had to get it in the shed to temp adapt (high today was 92F / HE 101F).  Also, I noticed that the collimation point on the laser shifted very slightly as I racked the focuser in & out, so that'll have to be tightened up. 

 

It has the built-in long dovetail, so I put a pair of Sheldon's machined aluminum couplings on my TAK EM-1S + the large counterweight (I'll try to get a photo of the rig posted tomorrow), which is on a vintage Filotecnica wooden surveyor tripod.  With the spikes pressed in it's a very stable platform, and the TAK tracks near perfectly when the load is balanced.

 

Star Tests:  I started with Arcturus.  It was lower than I prefer, but I needed to align the 50mm finder.  Took longer than usual -- that thing fought me!  Used a UO HD OR9mm.  Tight rings, but very very slightly off center -- as expected.  Lots of wash that low, so I spun over to Sadr, which was nearing the meridian.  Much more stable image, but same pattern.  I really can't blame the scope, I knew the collimation wasn't perfect. I expected the stars to be smeared at focus, but they were small & tight.  Not the micro-dots of my Vixen 80mm fluorite, but not blobs, either.

 

Seeing:  Gordon saturated the ground, and it was clear & HOT today, so The Swamp had its usual haze band from the horizon to 15* - 20* -- variable thickness.  The Vixen 80 was out to confirm seeing.  Jupiter was already in the mire, but Saturn was well placed, with practically no haze.  Still, seeing hopped between 6 & 8, so magnification went from 98x to 260x.

 

First of all, Saturn was bright -- about like my APM 152 F8 ED.  At 98x, besides Titan, I spotted 3 other moons -- and possibly a 4th in the variable seeing.  I ran most of my 1.25" eyepieces through first, and had no problem reaching focus while using a Baader prism diagonal.  It was while I was testing my vintage spectros Plossls that I got a long period -- at least 15 minutes -- of 8/10 seeing, which is when I topped out at 260x with the 7.5mm.  These are Swiss-made .965" eyepieces that I think are very close to my Zeiss for quality.  I got my best views of Saturn's disk at 195x with the PL10 - one of my favorites in the set.  Saw 4 belts.  IIRC, from the EQ, colors were subtle, gray-green, pale yellow-tan, very light rose, &  dark gray (I didn't make notes, so the order my be off).  Pewter to gray polar region.

 

Switched to DSO mode.  Truth:  I toted the complete rig from the north end to the center of the back yard -- at least 60 feet -- without pain or injury.  Swapped the Baader for a GSO 2" dielectric mirror + vintage UO Erfle 32mm for 61x.  Set the Vixen 80 close enough to compare views, with the Baader + vintage Jaegers Erfle 16mm for 40x.  M57 is a true smoke ring in the VMC with a black center.  M56 is brighter & larger than in my 6" reflectors, but no better resolved.  Star colors in the VMC look a bit redder than in the V80 fluorite, which to me has the most natural colors of any of my scopes -- really saw this with Sadr.  Naturally, all my favorite star fields from Sadr to Deneb are richer in this 8" scope.

 

Overall, I'd call this a good first sky test.  With exact collimation, I think the planetary views could compete with my 6" APO at equivalent powers, but I doubt this CAT can stay sharp at 80x per inch like the frac.  OTOH, it's a good choice when I don't feel like hauling out that much heavier rig -- that is not mobile at all.


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