GSO RC's?

Apocrisiary (Michael) · #1 27-03-2008, 07:23 AM

The change to the 18 point mirror cell on Meade 16" LB happened in about September of last year.
The black tube rings on the GSO only within the last month as production started.
The new bearing can be adjusted up and down the tube but from the technical diagrams looks like a fiddly procedure using screwdrivers with the scope off the mount.
The new bearing incorporates a brake system. This will probably become standard on all GSO Dobsonians down the track to do away with having to pull down stiff springs.
....Although this has been the longest running telescope launch in memory I think it will be overshadowed by the announcement of the GSO Ritchey Chretien OTAs next month!

.....Watch this space.
Michael from Bintel

ving (David) · #2 27-03-2008, 11:58 AM

GSO RCs! you jerkin my gerkin!

i personally will kill for this scope, so if anyone want someone else knocked over just say the word. (just kidding)

looks very cool imo and very easy to use. i recon it'll be a hit

snowyskiesau · #3 27-03-2008, 12:18 PM

The GSO website doesn't give anything away except to say the 10" F9 RC is to be released next month - which is only a week away !

Stephen65 · #4 27-03-2008, 12:27 PM

Are these going to be real Ritchey-Chretiens (hyperbolic primary, hyperbolic secondary, no corrector) or SCT's in disguise like the Meade "RC" though?

Apocrisiary (Michael) · #5 27-03-2008, 01:49 PM

They will be the real thing with 2 mirrors. They were going to do a Really Advanced Ritchey Chretien with only 1 mirror but thought better of it.
Here are some sneak previews including a test image.

Apocrisiary (Michael) · #6 27-03-2008, 02:32 PM

Maybe this should all be under a new thread.....

iceman (Mike) · #7 27-03-2008, 02:52 PM

Done.

Satchmo · #8 27-03-2008, 07:47 PM

,

Hope they have a matching field flattener 'in the works'.

okiscopey (Mike) · #9 27-03-2008, 07:55 PM

Quote:

Originally Posted by Apocrisiary

...I think it will be overshadowed by the announcement of the GSO Ritchey Chretien OTAs next month!
Michael from Bintel

Michael, don't you know there's a law against making these sort of announcements? Funds are not unlimited around here! ("Mike from Bondi" ... soon to be "Mike from Kandos").

[1ponders] (Paul) · #10 27-03-2008, 08:07 PM

Well I was just getting all excited and about to demand to see performance specifications until I saw the crazy standard crayford focuser. Why would someone produce a RC for imaging and not put on a 10:1 focuser at least. How about automation for the focuser?

Shades of Meades RCX and still having to buy a wedge

Zuts · #11 27-03-2008, 08:12 PM

Quote:

Originally Posted by [1ponders]

Well I was just getting all excited and about to demand to see performance specifications until I saw the crazy standard crayford focuser. Why would someone produce a RC for imaging and not put on a 10:1 focuser at least. How about automation for the focuser?

Shades of Meades RCX and still having to buy a wedge

That will be on the deluxe version, 50 bucks extra

Paul

Satchmo · #12 27-03-2008, 08:13 PM

I doubt a 10:1 focusser is really necessary at F9 focal ratio.

wavelandscott (Scott) · #13 27-03-2008, 09:10 PM

Quote:

Originally Posted by ving

GSO RCs! you jerkin my gerkin!

i personally will kill for this scope, so if anyone want someone else knocked over just say the word. (just kidding)

looks very cool imo and very easy to use. i recon it'll be a hit

We may talk "off-line"...There may be an assignment for you soon that might help fund your next purchase...

Apocrisiary (Michael) · #14 27-03-2008, 09:28 PM

The adequacy of the focuser has already been mentioned to the manufacturer. Not just because it doesn't have 24:1 reduction but also not being able to hold SBIG/filter wheel combinations with the standard GSO focuser whilst pointing at the zenith.
As for the corrector flattener - it is coming. But I can't understand why it would be needed on a telescope that only employs 2 mirrors and no refracting elements....Oh thats right other "real" RC manufacturers fail to mention that other optics are necessary to make them work well.
Looks like Meade got burned on that one...their corrector/refractive optics were far too obvious right up front of the scope.

jayscheuerle · #15 28-03-2008, 02:44 AM

Quote:

Originally Posted by Apocrisiary

The change to the 18 point mirror cell on Meade 16" LB happened in about September of last year.

Michael, my dealer in the U.S. says he knows nothing about the change from the non-floating 27 point cell to the 18 and that his Meade representative knew nothing either! It's not even advertised on Meade's web-site!

You must be moving enough to get the freshest batches. I can only find one second-hand report as to a 16" Lightbridge having the GSO 18 pt. cell.

I'm putting off my purchase until my dealer can confirm it! - j

Satchmo · #16 28-03-2008, 11:03 AM

Quote:

Originally Posted by Apocrisiary

As for the corrector flattener - it is coming. But I can't understand why it would be needed on a telescope that only employs 2 mirrors and no refracting elements....Oh thats right other "real" RC manufacturers fail to mention that other optics are necessary to make them work well.

It would probably only be an issue with large or 35mm size chips. Its also hard to tell from spot diagrams what aberrations would actually be visible in real life. There are so many factors like quality of atmosphere, guiding, size of chip and importantly the size of the pixels in relation to the airy disc. Perhaps someone with experience in this area can comment.

I don't know the exact precription for the 10" F9 GSO, but tracing a generic design with 250mm back focus shows the situation on a flat field . The two off axis distances are for a 30mm and 46mm diameter field ( @46mm equivelent to the corner of a 35mm frame). What you are seeing basically is astigmatism not coma.

The aberrations will be much minor for a 20mm diameter field , typical of the current 10mp DSLR's.

No doubt a simple field flattener/correcter will produce diffracation limited spots over the whole field as only field curvature and astig to be corrected as the RC id a coma free instrument.

These spot diagrams may be interesting ( a generic 10" F9 RC ). The second shows the through focus spots when we simply take out just the field curvature of the instrument ( about -338mm focal plane radiusof curvature ) which leaves a more minor amount of pure astigmatism. This can be done with just a simple single element plano concave lens if close to the focal plane. Notice how only 0.1mm defocus, ( second spot row from the right) , actually produces pretty round images!

Regards the focussers , I'm sure it would be easy to upgrade to a Moonlite or other stronger one with existing adapters.

Bassnut (Fred) · #17 28-03-2008, 06:22 PM

Quote:

Originally Posted by Apocrisiary

The adequacy of the focuser has already been mentioned to the manufacturer. Not just because it doesn't have 24:1 reduction but also not being able to hold SBIG/filter wheel combinations with the standard GSO focuser whilst pointing at the zenith.
As for the corrector flattener - it is coming. But I can't understand why it would be needed on a telescope that only employs 2 mirrors and no refracting elements....Oh thats right other "real" RC manufacturers fail to mention that other optics are necessary to make them work well.
Looks like Meade got burned on that one...their corrector/refractive optics were far too obvious right up front of the scope.

Yes, focuser payload is often missed as a feature. If you were serious about astrophotography, and spend money on an RC , youde probably use an electric focuser anyway, and consider the payload.

Always need a flattener on an RCOS RC?, well not really. My ST8XME works fine on a small RC without one, although a flattener is recommended with large chips (I know of one user with a 12.5" RC and and an ST11K without a flattener, and it seems fine to me). I suspect almost all scopes would need a flattener with a full 35mm sensor.

davewaldo · #18 28-03-2008, 06:32 PM

So do we know a rough price yet? Even a ball park figure?

Stephen65 · #19 28-03-2008, 07:13 PM

Quote:

They will be the real thing with 2 mirrors. They were going to do a Really Advanced Ritchey Chretien with only 1 mirror but thought better of it.

Wouldn't a Really Advanced Ritchey-Chretien need to have two lenses and one mirror?

Now that I think about it my doublet refractor (two lenses, one diagonal) would count as a Really Advanced Ritchey-Chretien!

Jokes about telescope marketing aside, its really good to hear that they will be genuine RC's. A very very interesting development.

monoxide · #20 28-03-2008, 07:53 PM

i just hope they don't try to make them too cheap and have the scope suffer because of it.

also how would go you about collimating one of these babies? lol