Great Deal for Beginners

Post by **weixing** » Sun Sep 17, 2006 10:48 pm

Hi,

Haa McGill said it is Mak Cass. I was wondering why it did not have a meniscus lens.

It not an Mak Cass, I think it is the same design as VC200L (Vixen Sixth-Order Aspheric Cassegrain).

Have a nice day.

ariefm71 · Post by **ariefm71** » Sun Sep 17, 2006 10:55 pm

Definitely not the same design as VC200L, it's closer to VMC200L. The VC has correction elements inside the focuser tube whereas the VMC in front of the secondary

alvinsclee · Post by **alvinsclee** » Sun Sep 17, 2006 10:58 pm

Just checked Vixen catalogue... VC200L is VISAC... but VMC200L is "Modified Cassegrain". One key modification is the inclusion of a meniscus lens in front of the secondary mirror... I guess this function like the meniscus in front of Mak-Cass OTA, but has the advantage of open-tube design and light-weight.

rlow · Post by **rlow** » Sun Sep 17, 2006 11:36 pm

I agree with Weixing, I am not too keen on the huge central obstruction, and not the flip mirror either, unless it is of Questar standard. Also, you can't upgrade to a 2" dielectric diagonal in future. I am also not sold on the corrector element behind the secondary mirror, because it will be problematic if fungus creeps in-between. This VMC system apparently has poor internal baffling that causes central ghosting on daytime images, hence it is not suitable for daytime viewing or imaging. It is apparently also more difficult to achieve sharp focus due to image shift (as usual) plus a narrow range of focus. It's good quality is the light weight and the price!

Frankly I would be slow to recommend this scope package as a greal deal for beginners though it is cheap, unless I have tested it and I know it is good scope in the long run.

Post by **Airconvent** » Mon Sep 18, 2006 12:08 am

river wrote:look at the last pic on link, that's one way to mount a camera on the scope
but look at the mount... it is a GEM.

You still can take some astro images with non tracking mount, a tracking mount enable you to do more.

Hi
The GEM mount is only for reference purposes only. The package comes with the alt-azi Vixen Porta mount...

Post by **Airconvent** » Mon Sep 18, 2006 12:12 am

ariefm71 wrote:No, it's a klevtsov cassegrain, there is no corrector plate.
still, if you can sell the mount for $650 to airconvent, the scope is a great bargain.
if you like maths, here's something from mr. klevtsov himself, comparing his design with schmidt-cass and mak-cass: http://www.telescopes.ru/articles/article1.phtml

Hi Arief,
I had based the price on the fact that a 127mm Mak OTA would have cost around $900, so this price including a Portamount essentially is quite good a deal. Purchased separately, it would have cost around $1400.
BTW, the Portamount is already selling at $650 by itself right now.

Post by **Airconvent** » Mon Sep 18, 2006 12:18 am

rlow wrote:I agree with Weixing, I am not too keen on the huge central obstruction, and not the flip mirror either, unless it is of Questar standard. Also, you can't upgrade to a 2" dielectric diagonal in future. I am also not sold on the corrector element behind the secondary mirror, because it will be problematic if fungus creeps in-between. This VMC system apparently has poor internal baffling that causes central ghosting on daytime images, hence it is not suitable for daytime viewing or imaging. It is apparently also more difficult to achieve sharp focus due to image shift (as usual) plus a narrow range of focus. It's good quality is the light weight and the price!

Frankly I would be slow to recommend this scope package as a greal deal for beginners though it is cheap, unless I have tested it and I know it is good scope in the long run.

Hi all,
wah....most of you are talking about 2" dielectric diagonal and huge central obstruction but I am taking this as a beginner scope which gives best bang for buck, its faults notwithstanding. Most important is not if it performs very well but that it is decent enough for a beginner to get acquainted with what's available in the night sky.

rlow · Post by **rlow** » Mon Sep 18, 2006 12:42 am

Hi all,
wah....most of you are talking about 2" dielectric diagonal and huge central obstruction but I am taking this as a beginner scope which gives best bang for buck, its faults notwithstanding. Most important is not if it performs very well but that it is decent enough for a beginner to get acquainted with what's available in the night sky.

For another $50, here's another good package:

http://www.mcgill.com.sg/shop/product_i ... 6d6c545f69

Post by **Airconvent** » Mon Sep 18, 2006 1:03 am

rlow wrote: For another $50, here's another good package:
http://www.mcgill.com.sg/shop/product_i ... 6d6c545f69

Hi RichardII

Between a more expensive 80mm achromat and a bigger aperture compound scope, I would prefer the latter. Its more compact , making transport easier too and can take higher magnification for planetary viewing which is what beginners tend to taregt. But that's my preference of course...

RichardI

rlow · Post by **rlow** » Mon Sep 18, 2006 1:29 am

Well, you can also go for the A80SS ota instead, which is shorter and more compact, like what Weixing got. Generally, refractors have less maintenance and no collimation issues, compared to catadioptric telescopes, and this may be appropriate for beginners. Beginners usually have more problems dealing with collimation of the secondary mirror, or else they view images which are less sharp, then the planetary views will suffer. It may be more awkward to clean the primary mirror and corrector meniscus of this open tube system since the opening is so small.