I am upgrading my primitive astrophotography setup. I began with GSO 8 in, F4 OTA, Canon EOS M3. My new camera QHY 268C is just arrived.
My current interests are DSOs ( primarily galaxies and bright but tiny nebulae). An an example, Messier objects and NGCs which are of similar size of Messiers. ( at the moment, I am excluding too faint and tiny NGC).
Now my main problem is as follows. Considering the GSO F4 OTA, there is a need for Coma Corrector. Further, considering 268C CMOS size 23.5mm X 15.7mm, the approximate FoV would be 1.66deg X 1.11deg which is huge for the proposed DSOs. So I need a Barlow say 2.5X or more, to be able to map intended DSO as a sizable portion in the captured frame.
One of the solutions came up was "coma correcting Barlow" by APM. They offer 2.7X Coma correcting Barlow. But this is 1.25" with clear diameter 22mm as per the APM specifications.
Will this APM barlow work well for my setup, without vignetting?