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ZWO OAG+guide camera and Baader coma corrector

ZWO OAG-L Guiding Coma
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Stefano Pesci avatar
Stefano Pesci avatar
Hi,
I would like to upgrade my set up with a OAG and ASI guide camera.
I have technical question concerning OAG coupled to a 20cm f/4 Newton with a coma Baader coma corrector (55mm backfocus).
Can the OAG+guide camera be used with the coma corrector?
I've heard that it may lead to grossly deformed stars on the guide chip.
Thanks Stefano
andrea tasselli avatar
andrea tasselli avatar
The answer is yes, it can.
Bogdan Borz avatar
Bogdan Borz avatar
Of course it can. You don't care about the shape on the guide chip; if your field correction is not good, of course the peripheral stars (those captured by the OAG) will have severe coma. If your coma correction is good the stars will look good too. But that is not very important for the guiding. 

CS

Bogdan
Andy Wray avatar
Andy Wray avatar
Stefano Pesci:
Hi,
I would like to upgrade my set up with a OAG and ASI guide camera.
I have technical question concerning OAG coupled to a 20cm f/4 Newton with a coma Baader coma corrector (55mm backfocus).
Can the OAG+guide camera be used with the coma corrector?
I've heard that it may lead to grossly deformed stars on the guide chip.
Thanks Stefano

I use the OAG on a 20cm F5 Newtonian with the Skywatcher coma corrector that has a backfocus of 55mm.  It all works fine.  Yes, the stars at the outermost edge of the OAG guide camera are elongated a bit, but that doesn't affect guiding at all.

Below is a picture of my setup:  the order is: Coma Corrector->OAG->spacer->filter wheel->ASI camera.  I use an ASI290mm mini as the guide camera and the helical focusser on the OAG to make it easy to focus.
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Kristof Vandebeek avatar
Kristof Vandebeek avatar
I use a Baader MPCC in combination with a ZWO OAG and Omegon 1200M guide camera (looks the same as a ZWO 120) on a 130PDS and it works without problems.
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Brian Fulda avatar
Brian Fulda avatar
Stefano Pesci:
Hi,
I would like to upgrade my set up with a OAG and ASI guide camera.
I have technical question concerning OAG coupled to a 20cm f/4 Newton with a coma Baader coma corrector (55mm backfocus).
Can the OAG+guide camera be used with the coma corrector?
I've heard that it may lead to grossly deformed stars on the guide chip.
Thanks Stefano



Yes, just make sure to use the correct adapters included with your ZWO cooled camera. ZWO has a good guide on how to achieve 55mm back focus with any camera and any ZWO accessory like an OAG, filter wheel, or filter drawer. Head to that link, find your camera's sensor size, and then find the correct diagram for your setup to get 55mm.
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