Flattener/Reducer for GSO RC-8" ?

[Jeff]

Hi All,

I'm considering purchasing a GSO RC-8" OTA for DSLR DSO imaging, but am unsure whether I will need to also purchase a flattener. :shrug:

Apologies if this has already been covered in another thread, but can anybody advise whether a flattener is required, and if so then what brand/model best suits?

Cheers,
Jeff

[dpastern]

I don't think GSO has released a flattener yet, I think others are making do with flatteners from other manufacturers (WO and Takahashi spring to my memory).

Dave

[rat156]

I'm trying a flattener from APM scopes out, will let you know how it works.

Cheers
Stuart

[Paul Haese]

From what I have heard the flattener/ reducer is not expected for some time and it will be a reducer rather than just a plain flattener. I don't understand the logic of making a reducer only as the idea is to have the scope at narrow field really.

I have been using a Tak flattener and it appears to work fine. Excepting of course that is you run CCD inspector over it the actual image is not flat at all. However it really looks flat and that is the main thing.

If you use a slight smaller sensor say something around 3300 odd pixels the images appear quite flat anyway.

[Jeff]

Thanks guys.

I've been using a W.O P-FLAT2 flattener/0.8reducer with my ED80, but I suspect it might be a little to aggressive for the GSO RC-8, which I understand has a reasonably flat focal plane.

Paul - I've seen some of your wide field RC-8 shots, and they look pretty sharp to me. Which Tak flattener have you been using?

[Paul Haese]

Jeff I have been using the Tak flattener for a TSA 102 or TOA130. It works pretty nicely.

[Moon]

I know quite a few people have this scope now, and might be interested in this. I did a test with the TS Flattener (TSRCFlat2) and STL-11000M camera and GSO 8 RC.
Here is a link to the sample image:
http://deepspaceplace.com/show.php?id=ngc3293b

I had to slightly crop the image at the very edges due to vignetting. Perhaps the performance could be improved slightly with a tweak to the collimation/focusing/spacing, but I think I was reasonably close. I had a dedicated adaptor made up so the spacing should be close.

I suspect it might work better on a 10 inch scope too - it would be interesting if someone can try this out.

Although it's not perfect, it is a big improvement over the uncorrected version with the same camera/scope:
http://deepspaceplace.com/show.php?id=ngc3372stl

Remember this camera has a very big sensor, so if you are using a camera with a smaller sensor, the performance should be better.

Quick CCDIS dump attached from uncropped raw subs - not intended to be scientific, but does give a visual indication of what is going on.

James

[Tandum]

Astro Tech (http://www.astronomics.com/main/product.asp/catalog_name/Astronomics/category_name/7U1FFR2KKXEB8L34WN0HW6E3L3/product_id/AT2FF) have one now as well.

[Moon]

I have one of those too, but the thread on the camera side is too small - it would cause too much vignetting in my camera.

The TSRCFlat2 has a bigger clear aperture.

James