StellaLyra Classical Cassegrain & Ritchey-Chrétien Telescopes

[johninderby]

BTW GSO 230mm tube rings will fit the CC 8”. Useful for using the scope with an Alt-Az mount. Takes some minor DIY to attach the stock dovetail bars to the tube rings but not too,complicated.

[Geoff Barnes]

4 minutes ago, RobertI said:

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! 

Yes an 8 inch CC will be a piece of cake after my 12 inch Dob! I can handle the Dob no problem but I have recently discovered I have a serious spinal condition which is not going to get any better with age so I'm just planning ahead really.

[johninderby]

13 minutes ago, RobertI said:

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! 

A handle makes lifting the scope much easier. 😁

        johninderby (aka The Handle Guru )

Edited October 9, 2020 by johninderby

[Sp@ce_d]

Just when I thought I'd give my 8"RC a rest from it's 5 year tour of duty & go for an Esprit 150 they go and do this!.. That 10" looks sooo tempting! I've been very pleased (well its been on the mount on auto for 5 years!) with my 8" carbon Altair version. My only concern would be the focusser. Hard to tell from the pics, but they do have the same look. Hopefully these ones are all metal. Mine (Altair) wasn't very good at holding a FW OAG and a 314L+.. it eventually split as the bottom piece  was partly plastic. The nice folk at FLO got me a Moonlite & motor which I totally recommend.  Looks like the size needs updating for the 10" as its saying 2" at the top 3.25" at bottom.. another typo there FLO.  Any option to have these bench check'd & tested?

[johninderby]

The focuser they are now fitting to the 6” and 8” are better and quite usable although I fitted a Baader Steeltrack which has more drawtube travel.

The 10” uses a M117 thread for the focuser. TS does sell an M117 to M90 adapter though so you could keep your Moonlite if you got the 10”.

Edited October 9, 2020 by johninderby

[FLO]

1 hour ago, Sp@ce_d said:

Looks like the size needs updating for the 10" as its saying 2" at the top 3.25" at bottom.. another typo there FLO.  

Oops. Sorry. The text now says 3.25" focuser top and bottom 🙂 

1 hour ago, Sp@ce_d said:

Any option to have these bench check'd & tested?

Currently we don't think that is necessary but will monitor and review our decision over time. 

We have had our eye on these models for some but waited until the designs had matured. 

1 hour ago, johninderby said:

The focuser they are now fitting to the 6” and 8” are better and quite usable ...

A good example ^  Collimation has improved too 😎 

Steve

[johninderby]

And tilt adjustment  is now built in. 👍🏻

Edited October 9, 2020 by johninderby

[Sp@ce_d]

1 hour ago, johninderby said:

And tilt adjustment for the focuser is now built in. 👍🏻

Aha.. you read my mind.. I added that to mine

[johninderby]

47 minutes ago, Sp@ce_d said:

Aha.. you read my mind.. I added that to mine 

You can still use the TS tilt adjuster. After further reading looks like using a seperate tilt adjuster just for the focuser may be better? 🤔

Edited October 9, 2020 by johninderby

[FLO]

21 hours ago, vlaiv said:

You know what would be nice addition to StellaLyra line of scopes?

x0.5 and x0.33 focal reducers. 

We don't have a x0.5 or x0.33 but we do have a 0.75x Reducer for StellaLyra / GSO Ritchey Chretien OTAs. 

 

[Chris]

7 hours ago, FLO said:

We don't have a x0.5 or x0.33 but we do have a 0.75x Reducer for StellaLyra / GSO Ritchey Chretien OTAs. 

 

 

Ah if I had known I would have grabbed one the same time as the RC8 but I've just bought Kirkster's CCDT67 reducer. Good that you stock a reducer for the RC's and I wonder if you can reduce the CC's effectively? 

[vlaiv]

2 minutes ago, Lockie said:

Ah if I had known I would have grabbed one the same time as the RC8 but I've just bought Kirkster's CCDT67 reducer. Good that you stock a reducer for the RC's and I wonder if you can reduce the CC's effectively? 

I think that both scopes can be effectively reduced with such reducers as long as you understand "process of reduction".

For example, RC 8" has corrected and usable field slightly less than APS-C sized chip. Already at APS-C size, you'll notice slight field curvature in the corners (depending on what exact sensor size we are talking about - is it 26.7mm or 28.4mm). Let's say that we have close to perfect correction up to 26mm.

If you use x0.67 reducer - you are effectively squeezing down same field and you can't expect field much larger than 26mm to be corrected when squeezed down - this reducer has very mild field flattening effect, but it is not dedicated field flattener.

26 * 0.67 = 17.42mm

This means that you'll have roughly corrected field up to 18-19mm diagonal. Even ASI1600 will start showing aberrations in corners with this reducer simply because you are using field that is curved and has aberrations in far corners (ASI1600 has about 22mm diagonal so you are effectively imaging 32.8mm unreduced field with this reducer and ASI1600).

Many people on internet suggest to use this reducer with ~ x0.72 - x0.75 reduction factor.  Reason is given above, 26mm x 0.75 = 19.5 and with slight field flattening that could almost stretch to 22mm of ASI1600 diagonal.

If you have ASI183 or ASI533 then yes, you can use this reducer at even x0.67 and it will work ok on RC8"

It should even work better on CC - because it is slower beam and there is less field curvature, but again - one needs to know how large fully corrected field is (not fully illuminated - we don't really care about illumination as much as pin point stars here) and shrink that accordingly.

[Chris]

7 minutes ago, vlaiv said:

I think that both scopes can be effectively reduced with such reducers as long as you understand "process of reduction".

For example, RC 8" has corrected and usable field slightly less than APS-C sized chip. Already at APS-C size, you'll notice slight field curvature in the corners (depending on what exact sensor size we are talking about - is it 26.7mm or 28.4mm). Let's say that we have close to perfect correction up to 26mm.

If you use x0.67 reducer - you are effectively squeezing down same field and you can't expect field much larger than 26mm to be corrected when squeezed down - this reducer has very mild field flattening effect, but it is not dedicated field flattener.

26 * 0.67 = 17.42mm

This means that you'll have roughly corrected field up to 18-19mm diagonal. Even ASI1600 will start showing aberrations in corners with this reducer simply because you are using field that is curved and has aberrations in far corners (ASI1600 has about 22mm diagonal so you are effectively imaging 32.8mm unreduced field with this reducer and ASI1600).

Many people on internet suggest to use this reducer with ~ x0.72 - x0.75 reduction factor.  Reason is given above, 26mm x 0.75 = 19.5 and with slight field flattening that could almost stretch to 22mm of ASI1600 diagonal.

If you have ASI183 or ASI533 then yes, you can use this reducer at even x0.67 and it will work ok on RC8"

It should even work better on CC - because it is slower beam and there is less field curvature, but again - one needs to know how large fully corrected field is (not fully illuminated - we don't really care about illumination as much as pin point stars here) and shrink that accordingly.

Thanks Vlaiv, I never realised you could simply multiply the corrected field in millimetres by the reduction factor. Very handy because I knew using a reducer would limit the corrected field, but didn't quantitively know by how much exactly, so thanks for that! 

I guess I can just crop out the edges reduced with my Fuji and Sony mirrorless and the little sensor of my ZWO ASI385 wouldn't have to worry. I've been eyeing up the 533 for some time but need to look at what arcsec per pixel it's gives at different focal lengths. There's no point over or under sampling by too much. 

Thanks

[vlaiv]

2 minutes ago, Lockie said:

I guess I can just crop out the edges reduced with my Fuji and Sony mirrorless

Here is the thing - why use reducer in the first place if you end up cropping away stuff because of poor edge correction.

This means that sensors already capture all possible information from the scope (whole corrected field). Maybe sampling is not tuned in, but you have software binning to take care of that.

[Chris]

2 minutes ago, vlaiv said:

Here is the thing - why use reducer in the first place if you end up cropping away stuff because of poor edge correction.

Hi vlaiv, I'll try and answer this question from my honest experience. Although I understand what you're getting at and the argument for the f/ratio myth, and it indeed does make sense of paper. I can't get away from my experience of trying to use C8's and a C8 Edge natively for imaging DSO objects. I literally couldn't detect DSO's on my subs at f10, but when reduced to f/7 Boom! there they were. I think F8 natively will be ok but I would like the flexibility of being able to reduce the focal length and field of view from an image brightness point of view as well as being able to crop to taste rather than what the FOV depicts. In other words I might be ok with a little bit of curvature in the corners if it frames the object I'm imaging a little better. I guess it's about flexibility in a nut shell, and image brightness.  

[vlaiv]

4 minutes ago, Lockie said:

Hi vlaiv, I'll try and answer this question from my honest experience. Although I understand what you're getting at and the argument for the f/ratio myth, and it indeed does make sense of paper. I can't get away from my experience of trying to use C8's and a C8 Edge natively for imaging DSO objects. I literally couldn't detect DSO's on my subs at f10, but when reduced to f/7 Boom! there they were. I think F8 natively will be ok but I would like the flexibility of being able to reduce the focal length and field of view from an image brightness point of view as well as being able to crop to taste rather than what the FOV depicts. In other words I might be ok with a little bit of curvature in the corners if it frames the object I'm imaging a little better. I guess it's about flexibility in a nut shell, and image brightness.  

I understand what you are saying and this one is not so much about F/ratio myth or anything like that.

It is just common sense - we use focal reducers to try to capture as much sky as we can given the sensor size. If sensor is already big enough to cover usable field of scope - then there is not much point in reducing that field - from perspective of capturing more sky - sensor is already capturing as much as can be captured.

For smaller sensor it makes sense - focal reducer lets you capture more of the sky in "single go" - or shell we be precise - more of the sky having fully corrected image.

Only when you start thinking about the speed and you put pixel size into the mix then we are entering the "realm of F/ratio myth" - and from that perspective, what you are saying makes perfect sense - capturing at F/10 vs F/7 will match your experience - provided that you don't do anything to change pixel size.

However, if you change pixel size things start to change and F/10 can be faster than F/7 - but that was not what I wanted to talk about - I just wanted to point out that as far as capturing more sky - you don't have to do it with focal reducer if you already have the sensor large enough to capture the whole corrected field.

Having smaller sensor and using focal reducer still makes perfect sense from this perspective.

[nfotis]

On 09/10/2020 at 01:23, johninderby said:

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.

The weight, though... (and the price takes a big jump)

Too much for my HEQ5 mount (and the 8CC is practically the limit for one-man handling/mounting).

I wonder, where's the difference between this series and the other GSO-built CCs? The badge and paint scheme? The accessories?

I fail to see any difference in construction between them.

N.F.

 

[Chris]

8 minutes ago, nfotis said:

I wonder, where's the difference between this series and the other GSO-built CCs? The badge and paint scheme? The accessories?

I fail to see any difference in construction between them.

They are quite openly GSO scopes as stated by FLO, and I doubt there will be any real difference to GSO or Orion badged scopes. From what I have heard so far ( I'm happy to be corrected if wrong) FLO were keeping an eye on this range by GSO as they saw their potential, but they were waiting for any early scope issues to be ironed out. E.g. having to add a third party tilt plate to correct any malalignment of the optical axis. I believe this is now incorporated where the focuser meets the back of the OTA?

I guess the livery and the name Stella Lyra is FLO being happy to put their name to a product, and I've heard many a time they only stock telescopes they believe in. 

[johninderby]

Yes you can adjust the optical axis of the focuser and primary.using the push pull scews around the base of the focuser. If you want to adjust the focuser tilt separately then you would need the seperate tilt adaptor. Downside of using a seperate focuser tilt adaptor is that you can no longer rotate the focuser without having to to readjust the tilt. 

Tilt is more of a problem with the RC version as it’s mainly for imagimg whereas the CC is better suited to visual..

Edited October 10, 2020 by johninderby

[RobertI]

8 hours ago, Lockie said:

They are quite openly GSO scopes as stated by FLO, and I doubt there will be any real difference to GSO or Orion badged scopes. From what I have heard so far ( I'm happy to be corrected if wrong) FLO were keeping an eye on this range by GSO as they saw their potential, but they were waiting for any early scope issues to be ironed out. E.g. having to add a third party tilt plate to correct any malalignment of the optical axis. I believe this is now incorporated where the focuser meets the back of the OTA?

I guess the livery and the name Stella Lyra is FLO being happy to put their name to a product, and I've heard many a time they only stock telescopes they believe in. 

I think the adjustment of the optical axis (main mirror) has always been there Chris - my 6" RC is nearly 7 years old and has it. I am guessing when FLO talk about waiting for the design to mature they are talking about the CC versions which are fairly recent (although identical to the 'mature' RCs in every way except the mirrors as far as I can see) and possibly the truss versions, not sure how long they've been around.

I can't really fault mine to be honest, amazing build quality for the price, and even cheaper now through FLO.

I was out observing with my C8 last night - the mirror inevitably dewed up after an hour without dew control and the focuser was pants for fine focussing on Mars - my 6" RC has NEVER dewed up amazingly (not to say it can't of course!) and has a lovely dual speed Crayford - an 8" CC is SO tempting.

Edited October 10, 2020 by RobertI

[Chris]

4 minutes ago, RobertI said:

I think the adjustment of the optical axis (main mirror) has always been there Chris - my 6" RC is nearly 7 years old and has it. I am guessing when FLO talk about waiting for the design to mature they are talking about the CC versions which are fairly recent (although identical to the 'mature' RCs in every way except the mirrors as far as I can see) and possibly the truss versions, not sure how long they've been around.

I can't really fault mine to be honest, amazing build quality for the price, and even cheaper now through FLO.

Thanks Rob, I knew you could buy a tilt plate for RC's so thought that was to rectify the lack of one from the factory, so that's good to hear you have it built in   Yes amazing prices at FLO and and I love the black stealthy livery. I only ordered mine like Thursday night and I have a DHL message saying it will be delivered today!  Very exciting

[RobertI]

19 minutes ago, Lockie said:

Thanks Rob, I knew you could buy a tilt plate for RC's so thought that was to rectify the lack of one from the factory, so that's good to hear you have it built in   Yes amazing prices at FLO and and I love the black stealthy livery. I only ordered mine like Thursday night and I have a DHL message saying it will be delivered today!  Very exciting

Looking forward to unboxing and first light reports!

[johninderby]

Awfully tempted by the 6” CC as a more portable scope than the 8”. My manual alt-az setup with the berlebach Report tripod would just handle it. Not much difference in weight to the StellaMira 80mm f/10 so would still be grab’n’go. 🤔

Would have to sell a couple of bits though to psy for it.

Edited October 10, 2020 by johninderby

[RobertI]

3 minutes ago, johninderby said:

Awfully tempted by the 6” CC as a more portable scope than the 8”. My manual alt-az setup with the berlebach Report tripod would just handle it. So would still be grab’n’go. 🤔

Would have to sell a couple of bits though to psy for it.

Just out of interest John, would you choose a 6" CC over an 8" SCT? I'm asking as the weight of the CC/RC is their main (possibly only) downside and the 6" CC weighs the same as an 8" SCT. Just curious.....

[johninderby]

I’m thinking more of the much quicker cooldown and lack of dewing and proper focuser and of course there is a huge price difference. And already having the CC8”.

Would expect the 8” SCT to perform better than the 6” CC with it’s greater aperture although on lunar / planetary the difference wouldn’t be as noticeable. 

Wouldn’t buy a new 8” SCT though as they are common second hand for a fraction of the new price.

Edited October 10, 2020 by johninderby