StellaLyra Classical Cassegrain & Ritchey-Chrétien Telescopes

[vlaiv]

2 hours ago, HollyHound said:

Exactly, I routinely keep my C5 setup with the f6.3 focal reducer on it, giving me about 800mm (same as the StellaMira) but with 5" aperture... it's "almost" like a 5" APO, but supremely lightweight... I can lift it, the ScopeTech and Report outside with one hand 

For visual there might already be suitable focal reducer. It's not very affordable, but it is not overly expensive either. If I had the scope, I would certainly try to see how it works.

It is x0.67 reducer CCD47 which is copy of CCD67 - AP reducer.

Only problem is that it requires around 85mm distance and that means it can't be used in front of 2" diagonal as 2" diagonals are around 100mm or more of optical path. Possibly T2 diagonal from Baader - it should have shorter light path, or 1.25" diagonal with some sort of M48 adaptation.

I tried to use this focal reducer on my Evostar 102 F/10 achromat and 2" diagonal - but it was too much reduction and I could not reach focus as it requires too much inward focuser travel.

[RobertI]

2 hours ago, vlaiv said:

With x0.33 reducer - it would be very interesting EEVA platform. It should provide around 12-13mm of usable field in this configuration and F/4 system with 6" of aperture - what is not to like with ASI533 / ASI183 type cameras?

I use the 6”RC for EAA and I have found it perfect, and at F9 and with a fixed mirror it’s much more useable than my C8 for EAA. I can reduce it down to F4.5 and with a lodestar it’s fine with just a little coma...sometimes... but with smaller chipped camera it should be perfect!

I am very impressed with the build quality of these GSO scopes and very tempted to replace my C8 with the Stella Lyra Classical Cassegrain for visual. I would love to see someone do a head to head between a CC8 and a C8 or 8” Newt. 
 

Well done @Lockie on your purchase, a fabulous observatory scope. 🥳

Edited October 8, 2020 by RobertI

[Chris]

5 minutes ago, RobertI said:

I use the 6”RC for EAA and I have found it perfect, and at F9 and with a fixed mirror it’s much more useable than my C8 for EAA. I can reduce it down to F4.5 and with a lodestar it’s fine with just a little coma...sometimes... but with smaller chipped camera it should be perfect!

I am very impressed with the build quality of these GSO scopes and very tempted to replace my C8 with the Stella Lyra Classical Cassegrain for visual. I would love to see someone do a head to head between a C8 and a CC8! 

I read a C8 vs CC8 vs 6" Apo head to head write up the other day but can I find it now! lol It's on the web somewhere?

[RobertI]

2 minutes ago, Lockie said:

I read a C8 vs CC8 vs 6" Apo head to head write up the other day but can I find it now! lol It's on the web somewhere?

Ooh, you tease! 

[Chris]

1 minute ago, RobertI said:

Ooh, you tease! 

I've Just invented telescope review burlesque...it's now a thing 😆

[johninderby]

Having owned two C8s and now the CC 8”and going from memory the CC has better sharpness and contrast and cools down so much faster and of course no dew problems. Have been comparing the CC to my 10” dob and haven’t decided which shows more detail. 🤔

Edited October 8, 2020 by johninderby

[Chris]

3 minutes ago, johninderby said:

Having owned two C8s and now the CC 8”and going from memory the CC has better sharpness and contrast and cools down so much faster and of course no dew problems. Have been comparing the CC to my 10” dob and haven’t decided which shows more detail. 🤔

That's good to hear, I'm surprised it keeps pace with your 10" Dob though because the CC8 vs C8 review I'm trying to re find was talking about how the small central obstruction means the primary mirror is effectively slightly undersized at 7.3". I really need to find the review! 

[johninderby]

Yes I read that review and concluded that the author was to put it politely a bit confused. Vlav had some comments on his testing methods that agreed with my opinion.

I think for DSOs the 10” dob is better with it’s wider fov but on lunar / planetary not much difference although thought the CC had more contrast. As I mentioned couldn’t really decide which was better (on lunar / planetary that is) which may have something to do with focal length. 🤔

Hope to see a few more CCs out there now and the opinions of the buyers.

Edited October 8, 2020 by johninderby

[Chris]

5 minutes ago, johninderby said:

Yes I read that review and concluded that the author was to put it politely a bit confused. Vlav had some comments on his testing methods that agreed with my opinion.

I think for DSOs the 10” dob is better with it’s wider fov but on lunar / planetary not much difference although thought the CC had more contrast. As I mentioned couldn’t really decide which was better (on lunar / planetary that is) which may have something to do with focal length. 🤔

Hope to see a few more CCs out there now and the opinions of the buyers.

Well for what it's worth I found it: 

https://www.cloudynights.com/articles/cat/user-reviews/telescopes/gso-8-inch-true-cassegrain-r3215

[RobertI]

1 hour ago, Lockie said:

Well for what it's worth I found it: 

https://www.cloudynights.com/articles/cat/user-reviews/telescopes/gso-8-inch-true-cassegrain-r3215

An interesting article, thanks for tracking it down Chris. I think the very generalised conclusion is that the scope excels at planetary where it is generally better than the C8 due to increased contrast and is on a par with the 150ED. Sounds like it gave a 150ED a run for its money on doubles which I would imagine would make it better than a C8. I guess this tallies with @johninderby's experience. Interesting about the effective aperture being 7.3", as they have reduced the size of the secondary to increase contrast, but 'miss' some of the light cone from the main mirror as a result. So presumably the resolving power of an 8" but the image brightness of a 7.3"?

[JamesF]

They look very interesting scopes, but that's a "cricket ball to the gentlemen's area" level of eye-watering looking at the price difference between the solid tube 8" and the truss tube 10".  Not that I'm saying it isn't justified, but I looked along the models taking in the prices of the smaller ones thinking "If I bought one I could be tempted to go a bit larger perhaps" and then my eyes came out on stalks when I saw the price of the 10"

James

[johninderby]

The 10” truss tube RC is a similar price.

https://www.365astronomy.com/GSO-10-f-8-Ritchey-Chretien-Astrograph-with-Carbon-Fiber-Truss-Tube.html

Wish they would bring out a 10” solid tube CC.

[vlaiv]

12 minutes ago, RobertI said:

So presumably the resolving power of an 8" but the image brightness of a 7.3"?

If this is indeed what is happening, then I'm not sure it would be resolving power of 8" but rather that of 7.3".

For resolving power, you need rays from each point of aperture to reach focus - if rays from edge of mirror don't reach focus point - it does not matter if they are "removed" by aperture mask or by secondary - result is the same - they simply do not reach secondary.

I'm actually not sure if undersized secondary is making that effect of scope feeling less bright. This effect might be due to better baffling and less light scatter.

Let's examine some quotes from that article:

Quote

However, the image seemed to no brighter than that produced by the 150mm refractor and was FAR dimmer than the C-8's image.

I'm going to assume couple of things here:

- C8 has 97% reflective coatings and two air glass surfaces - 99.5% each, 64mm secondary obstruction, 8" / 203mm diameter

- CC has 96% reflection on mirrors, CC has ~7.3" mirror (186.5mm) and 58mm secondary obstruction

- 150mm refractor has decent AR coatings (which really means x4 air glass surfaces with 99.5% coatings).

So image seems to be about equal between 150mm and CC and CC is FAR dimmer than C8.

Let's compare the three:

150ED: 75 x 75 x 0.995^4 = ~ 5513.341

C8: (101.5 x 101.5 - 32 x 32) x 0.995^2 x 0.97^2 = ~8642.825

CC: (93.25 x 93.25 - 29 x 29) x 0.96^2 = ~7238.765

Ratio of brightness between 150ED and CC is x1.313 and ratio between CC and C8 is x1.194

If explanation was that mirror is stopped to about 7.3" and all other specs are fine, one would not be able to conclude that 150ED is about the same brightness as CC and that CC is FAR dimmer than C8.

By the way, x1.194 in light grasp equates to a bit less than 0.2 magnitudes of difference. I'm not sure that I would be able to spot that sort of difference in light grasp and to judge that it is darker.

[johninderby]

I would say that I found the TS CC 8” to be brighter than the C8 if anything so don’t have much confidence in the articles conclusions. Something doesn’t add up. 🤔

TS quotes 99% reflectivity on the their 8” version 🤔

Any way looking forward to other people conclusions after using one. 🙂

Edited October 8, 2020 by johninderby

[johninderby]

And dare I recommend a handle. 😁

https://www.wdscomponents.com/en-gb/tubed-handle-front-mounted-black-wds-8517/c-404/p-920

[RobertI]

7 hours ago, vlaiv said:

If explanation was that mirror is stopped to about 7.3" and all other specs are fine, one would not be able to conclude that 150ED is about the same brightness as CC and that CC is FAR dimmer than C8.

Nicely proven. If the observer really did see this difference, it must have been due to something else then I guess. If others have not seen this then perhaps best disregarded! 

[AstroRuz]

I've had the StellaLyra 6" and 8" f12 models for a bit now. Been thoroughly enjoying the 8" for Mars and the Moon. It's a bit of a beefy scope, and I'm playing with the 6" as well now. Really well made, gorgeous baffles and great for Lunar observations. Reviews coming soon, but yeah. Lovely telescopes.

[johninderby]

RC or CC version?

[AstroRuz]

1 minute ago, johninderby said:

RC or CC version?

Me? CC

[Stuart1971]

2 hours ago, johninderby said:

And dare I recommend a handle. 😁

https://www.wdscomponents.com/en-gb/tubed-handle-front-mounted-black-wds-8517/c-404/p-920

Are those handles adjustable, by that I mean can the tubular handle part be cut in length to suit...?

[johninderby]

1 minute ago, AstroRuz said:

Me? CC

Looking forward to your review. Love my CC. 👍🏻

[johninderby]

1 minute ago, Stuart1971 said:

Are those handles adjustable, by that I mean can the tubular handle part be cut in length to suit...?

Yes the handles are easy to adjust to the length needed by cutting the tube although they do have lots of lengths available.

[JamesF]

It's not widely known, but John has quite a large collection of handles, some of which he's attached telescopes to :)

James

[Geoff Barnes]

I enquired if CC scopes were in FLO's plans back in June and they were ordering them at that exact time, purely coincidentally, and they requested that I keep it under my hat.

I intend to replace my 12 inch Dob with an 8 inch CC as my back is deteriorating with age and I mainly observe lunar and planets.

My plan is to walk into FLO's showroom, say hello and purchase one there and then, when we are back in England in the not too distant future. Exciting!  

[RobertI]

13 minutes ago, Geoff Barnes said:

I intend to replace my 12 inch Dob with an 8 inch CC as my back is deteriorating with age and I mainly observe lunar and planets.

I’m sure you’ve checked this, but they seem pretty heavy, a lot heavier than a C8, but a lot lighter than a 12” Dob I guess!