Help! EdgeHD with DSLR

ZWO ASI290MM Equipment Guiding
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Michael Lev avatar
Michael Lev avatar
OK so i'm about to purchase the EDGE HD 8" for DSLR imaging.
I already have a ZWO ASI290MM-Mini on its way.
My plan is to shoot off axis guided.

Now with the Celestron OAG (the big bulky one) i have no problem doing so.
But if in the future i want to add a Focal reducer, My sensor is going to sit well beyond the back focus distance.

My second choice of OAG is the Orion TOAG but i dont know if it works well with the ZWO guider, nor do i know if i can adapt it to the focal reducer and still get my sensor close enough.

I'm even more troubled that my camera is a Nikon (46.5mm flange distance).

Any thoughts?

P.S.
Do i have to get my sensor exactly on the back focus distance? or is it ok to be a bit closer?

Thanks for any help!
xordi avatar
xordi avatar
The backfocus of the .7 reducer is 102mm, which is big enough to attach any camera + any OAG. I think if you do not keep this distance, star shape will not be so perfect, but you will see. For any case order a flexible adapter, to be able to play around with the distance (something like this: https://www.teleskop-express.de/shop/product_info.php/language/en/info/p4512_TS-Optics-Optics-M48-Zwischenring-Verlaengerungshuelse---Baulaenge-17--23-mm.html)

I have 2 different OAG and 2 different guidecam and both works fine with the my EdgeHd, so I do not think you will have an issue.  I suggest to try the setup first on daylight on a distant target, whether the focus can be set for both camera and if not just change the position of the OAG, moving closer or further from the reducer.

And just one more point, if you want to attach your NikonD800,  you should know, that the sensor is likely too big for the this telescope. C8EdgeHD can be used only in size of APS-C w/o issues…
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