Celestron's 11" RASA f/2.2 Astrograph

[romi]

Hi,

It's been a while since the new RASA is available. However, I see very limited number of posts discussing the new fellow.

I wonder if anyone who own (and had the chance to actually use) the astrograph, has some insights to share (Pros – Cons).

Of particular interest (for me at least) is what are the limitations in regard to additional accessories one would attach to the OTA, such as OAG and FW (due to the relatively short BF) and the camera (that would benefit from the relatively large image circle).

Some general comments on stability, focusing etc., would also be appreciable.

Cheers

Romi

[nmoushon]

It is basically just a regular C11" SCT with a hyperstar attached. Well at least the premise is the same. The optics are changed quiet a bit and it looks like the tube is longer also. So in terms of cameras and equipement I think it will be very similar to the hyperstar. So a large filter wheel will be cutting into your aperture a lot so a OSC camera is going to be the default. Or having to switch through filter one-by-one. Though in terms of how it performs I can't say. I havent seen any reports or anyone having one. I hope with the new design they took care of all the problems that the hyperstar had, which would be awesome if they did. But at almost $5k and being very restricted in terms of camera usage I'm not sure I would ever go for it. On top of the fact that I'd be limited to F/2 unlike 3 options with the standard C11. But at the same time for an F/2 astrograph the price cant be beat...its cheaper than a the 180mm F/2 Tak Epsilon but several hundred dollars plus it being several inches less in aperture.

[romi]

Yes. The short BF (claimed 55mm) is definitely a major problem. Even a small FW (thought about Mini SX filter wheel + OAG) will

use almost 29mm (+ say 10mm for the adapters) of the 55mm, leaving some not-enough room for a decent large-format CCD.

Interesting to know if anyone has tried a narrowband setup with the RASA  (for me, a OSC is not an option for such an expensive telescope).

Best,

Romi

[ollypenrice]

It is basically just a regular C11" SCT with a hyperstar attached. Well at least the premise is the same. The optics are changed quiet a bit and it looks like the tube is longer also. So in terms of cameras and equipement I think it will be very similar to the hyperstar. So a large filter wheel will be cutting into your aperture a lot so a OSC camera is going to be the default. Or having to switch through filter one-by-one. Though in terms of how it performs I can't say. I havent seen any reports or anyone having one. I hope with the new design they took care of all the problems that the hyperstar had, which would be awesome if they did. But at almost $5k and being very restricted in terms of camera usage I'm not sure I would ever go for it. On top of the fact that I'd be limited to F/2 unlike 3 options with the standard C11. But at the same time for an F/2 astrograph the price cant be beat...its cheaper than a the 180mm F/2 Tak Epsilon but several hundred dollars plus it being several inches less in aperture.

I don't think it is. I have one on test awaiting first light and look forward to giving it a go. I had an accident six weeks ago which rather set me back but I'm feeling a lot more mobile now. It has a significantly less extreme F ratio and claims a far larger flat field. It is one almighty step up in size on a C11 as well. You need to be able to mount it. I wouldn't be wanting to run this on an EQ6...

Olly

[romi]

Hi Olly,

Wish you a fast recovery.

I truly look forward to hear your comments on the issues considered once you have the chance to work with the RASA.

So many unclear questions...

On one hand, it looks as a strong and unique instrument but on the other hand, if it indeed restricts the use of CCD cameras to only OSC and is ineffective in narrowband photography, then it is not a valid option for many of us.

As for the mount, I had in mind the EQ8 which should be o.k. with its weight.

Regards,

Romi

[nmoushon]

I don't think it is. I have one on test awaiting first light and look forward to giving it a go. I had an accident six weeks ago which rather set me back but I'm feeling a lot more mobile now. It has a significantly less extreme F ratio and claims a far larger flat field. It is one almighty step up in size on a C11 as well. You need to be able to mount it. I wouldn't be wanting to run this on an EQ6...

Olly

I should have said it looks like instead of it basically is. Sorry about that. The proportions do look different than the standard C11 though. Looks longer to me in the picture on the Celestron site. I'm positive that they have a new primary design in it otherwise there wouldnt have been a reason to make this in the first place. And I can see that they have the lens (similar looking to a hyperstar) built in to where a secondary normally would go.

What do you mean by less extreme F ratio? F/2.2 is the same as the hyperstar (give or take a couple tenths depending on the specific scope). Are you talking about the new design of the new optics?

I hope you are healing up fine for your accident. Sorry to hear that. But I will be looking forward to your review of it.

[harry page]

Hi

Please look here  http://stargazerslounge.com/topic/213716-new-celestron-rowe-ackermann-f22-astrograph/page-4

Harry

[romi]

Thanks Harry,

Wasn't aware of this thread.

Compiling all the pros and (mostly) the cons with this RASA, I now feel that for a fast scope, it might be still better to compromise on a smaller aperture like the TeleVue-NP127fli (though expensive) and be more flexible with NB imaging and CCDs (of course with more min. to integrate).

Romi

[harry page]

Hi

Yes its not a scope for everbody

Harry

[kirkster501]

I bet the collimation is a SOAB at F2.2? !!!