GSO RC update

[Tandum (Robin)]

I notice the VMC is down to US$1099 from optcorp.
It's the model that comes bareboned, no flipmirror, finder etc.
http://www.optcorp.com/product.aspx?...624-1087-10683

[TrevorW]

I've always liked the bare bones look of the Vixen nothing fancy but what appears to be good optics at a reasonable price. All the reviews I've read tend to favour it over other SC's, it's my preference for an SC in the 8 - 10 " category when I get too buy one.

[Prickly]

In relation to the VC200L you can get a focal reducer I think that brings it back to around f6 which is not too shabby.

Also as for vixen having better optics - they seem to meet their specs which is perhaps more of a QA thing. I had read elsewhere that some of the optics is now being made in China but the QC checked. I suppose good optics are good optics whereever they are made. Had read a rumour that GSO produce the lightbridge mirrors. (wonder who makes the Meade RC mirrors?).

The GSO optics Ive seen have been great but theres more to a telescope than just that too. They would have be absolutely excellent for 3K. but there are also many other excellent options.

Cheers
David

[Zuts]

Hi,

I am now thinking the GSO 8 inch RC is not the same as the Astro Tech one as it is far too expensive.

For 3,000 USD you can get a Takahashi Mewlon 210, at least as good and probably better than the Vixen.

So price wise with Vixens and Mewlons costing the same or less the 3000 USD GSO would have a hard time competing. If Takahashi can make and sell an 8 inch Mewlon for 3000 USD then GSO can make and sell an 8 inch RC for less than 1500 USD.

Paul

[madtuna (Steve)]

I LOVE my VC200L... with the reducer it makes for a brilliant imaging scope, it's just me that lets her down....I think I'll name her Princess!

[Satchmo]

Originally Posted by Zuts

If Takahashi can make and sell an 8 inch Mewlon for 3000 USD then GSO can make and sell an 8 inch RC for less than 1500 USD.

The Takahashi Mewlon is a Dall Kirkham design ( 4 X the Coma of even a Classical Cassegrain) which uses a prolate elipsoid shaped primary and a spherical secondary mirror. The elipsoid primary would be twice as easy to make as the hyperbolic primary and secondary of a true Ritchey Chretion design .

[Zuts]

Originally Posted by Satchmo

The Takahashi Mewlon is a Dall Kirkham design ( 4 X the Coma of even a Classical Cassegrain) which uses a prolate elipsoid shaped primary and a spherical secondary mirror. The elipsoid primary would be twice as easy to make as the hyperbolic primary and secondary of a true Ritchey Chretion design .

I know this, the point I am trying to make is that if Takahashi can make and sell an 8 inch very high quality folded design with takahashi class fit and finish for 3000 USD then GSO should be able to do far better than 3000 USD, so I will wait until the GSO is released as a GSO before I will beleive the current guessed at price.

Paul

[netwolf]

I have seen two used Mewlon 180's on Opt for 2295$, these i belive are not made anymore. The Vixen's optics according to there HK dealer are made in Japan, only the samller VMC's are made in China but checked for QA by Japan. The 8" and larger VMC and VC's are made in Japan. Though the wave number for these is not know, I would guess better than 1/8 given its made in Japan. There are some nice Japanese scopes out there to chose from that is for sure. VMC, VC from Vixen and then Tak have the Epsilon's, Mewlons, CN, BRC etc etc. No Shortage of scopes. And given the current Yen to USD conversion is the lowest in years its a good time to buy Japan optics. The Japanese are pretty big on QA and so even a a Chinese optic passed via Japan would be better.

Regards
Fahim

[TrevorW]

Do we really know where the optics are being made. Sony for many years was made in Japan and enjoyed a reputation for quality then they went offshore but people still assume they are made in Japan, nowdays Samsung is my preferred electronic goods supplier. At the end of the day it all boils down too the manufacturing and QC take WO for example made in Taiwan.

[Prickly]

Im very impressed with my chinese NA140SSf vixen refractor. Ive read that the "f" on the models means that the optics are made in China and QA checked in Japan. Photographically its very sharp across the frame, as it is supposed to be. Im sure the VC200Ls / VMCs etc would be the same and the images they produce attests to that.

I wouldnt be too worried where things are made but more about the overall QA, specs and consistency of the products. I've never looked through a bad vixen.

Cheers
David

[robgreaves]

The only thing to bear in mind with the VC-200L is the VISAC optical coatings form the figure of the mirror.

When the coatings go bad, you have to send the mirror back to Vixen to have it coated and figured.

Normal aluminising won't produce the figure on the mirror.

I've had a VC-200 before, and yes, big imaging circle for big chips

Regards,
Rob

[gregbradley]

Originally Posted by Starkler

$1600 is serious coin for a 6" scope

I believe RC scopes are preferred for astrophotography, but how much better results would you expect compared to say a 6" f5 newt + coma corrector?

It really comes down to long focal length versus short focal length in the above comparison.


An F5 Newt has mirrors that are easy to make so the quality would likely be higher even if much cheaper. But it will be widefield and forget imaging galaxies or small objects. But you'd image widefield at F5 really quickly if you setup each time as opposed to F9 which is slow and requires several hours for each image to get a decent image.

Fast Newtonians seem to be quite popular and rightly so. They can offer sharp optics and fast speeds but the cost is perhaps a bit fussier in collimation and only able to do wide field.

I think it works backwards. Work out what type of image you want to produce and then the scope and camera combo comes from that.

No scope is perfect for every application no matter what brand or cost.

Greg.

[Satchmo]

Originally Posted by gregbradley

But it will be widefield and forget imaging galaxies or small objects. But you'd image widefield at F5 really quickly if you setup each time as opposed to F9 which is slow and requires several hours for each image to get a decent image.

Wouldn't adding a 1.6X-2X 2" barlow lens to the F5 Newtonian achieve the same focal ratio as the RC and be essentially coma free over a 35mm frame ?

Mark

[gregbradley]

Originally Posted by Satchmo

Wouldn't adding a 1.6X-2X 2" barlow lens to the F5 Newtonian achieve the same focal ratio as the RC and be essentially coma free over a 35mm frame ?

Mark

The only barlow I am aware of that gives coma free over 35mm film size is the Baader flatfield fluorite converter (FFC). It is quite expensive with all the adapters (about US$1000 from AstroPhysics). Also I don't know if you can combine a coma corrector and a barlow - perhaps you can. Its becoming a lot of glass though if you can (I doubt it - you generally can't use a reducer and a flattener together with refractors).

Other smaller barlows will vignette/ give coma and eggy stars in the corners. You may be able to get away with it with a small chipped camera but DSLR sized chips and above probably not. You can always crop the image though and it may not be too bad depending on the barlow (Peter Wards recent Eta C had some star elongation in the corners from the AP barcon/STL11 (an AP barlow) but it wasn't too bad. The Baader though goes up to 8X and I believe no eggy corner stars in a 35mm film sized chip.

Its not really practical to make one scope all things and hence the approach of having a few different scopes specialised for wide field, narrowfield etc.

[Merlin66 (Ken)]

That's not the case.
Klee, back in the 80's designed his Barlows and Petoria eyepieces specifically for fast newtonians, to provide corrections.
It was well detailled in a copy of the ATM magazine of the time ( my copy is still in storage somewhere in Oz!)
I use the Klee x2.2 and x2.8 barlows and find they do a creditable job.
I also used the 28mm Pretoria for a while on the 18" f4.5, I think it beat the a**** of the Nagler!!
It would be well worth the effort to trial a Klee Barlow on your system.

[netwolf]

How does the VC200L compare in Field Flatness to a C9.25? As i understand it the C9.25 was made a bit diffrent to the C8 and C11 to cater for DSO imaging. Also the C9 would not suffer from the thick vanes as the VC200 does.
It was mentioned that VC needs to be sent back to manufacturer for recoating of mirrors. Is this not also true for SCT Mirrors or RC Mirrrors?

[Zaps]

I'm really looking forward to seeing the first results and reviews of these new Chinese made RC scopes.

Hopefully the Chinese and Taiwanese can do for RCs what they did for refractors: make them excellent quality - competitive with the flash brands - while keeping them affordably inexpensive, as well as readily available.

The fact that there's clearly a ready market for good quality and inexpensive RCs suggests that outfits like GSO and Synta will rush to meet it, the same way they have the other segments of the amateur astronomical market. How can that not be win-win for us?

[Gama]

Originally Posted by netwolf

How does the VC200L compare in Field Flatness to a C9.25? As i understand it the C9.25 was made a bit diffrent to the C8 and C11 to cater for DSO imaging. Also the C9 would not suffer from the thick vanes as the VC200 does.
It was mentioned that VC needs to be sent back to manufacturer for recoating of mirrors. Is this not also true for SCT Mirrors or RC Mirrrors?

You left out the CDK scopes as well. Basically any laser aligned main mirror will need to back to mama's house for recoating !.

Theo

[gregbradley]

Originally Posted by Merlin66

That's not the case.
Klee, back in the 80's designed his Barlows and Petoria eyepieces specifically for fast newtonians, to provide corrections.
It was well detailled in a copy of the ATM magazine of the time ( my copy is still in storage somewhere in Oz!)
I use the Klee x2.2 and x2.8 barlows and find they do a creditable job.
I also used the 28mm Pretoria for a while on the 18" f4.5, I think it beat the a**** of the Nagler!!
It would be well worth the effort to trial a Klee Barlow on your system.

That's interesting. Where do you get them from?

Greg.

[netwolf]

Greg, I think Frontier optics cary these.

Theo thanks, I thought so I am guessing we should also add KC to the list.