Quote:
Originally Posted by Garbz
I'm shooting with a D800 and Celestron C8 mounted on a NEQ6, guided with a 50mm Orion finder guider. I'm using the cropped frame 24x16mm but it's still a relatively large sensor. I get those edge distortions despite using a field flattener. It's worse without it.
|
I have found that field flatteners are quite sensitive to the separation between the imaging chip and camera. It does not appear to be field rotation as the off-centre stars are most definitely out of focus compared to the central region. If possible do some tests with varying distances between the flattener and the camera. Here is a link to my pbase site showing some tests that I did with a Newtonian / Paracorr showing significant improvement when the optimal separation is determined:
http://www.pbase.com/david_fitz_henry/image/124811410