Recently I got a brand new CGEM II mount and have been trying to do 5 minute long exposures. My OTA is a Celestron 8SE with 6.3 reducer and I autoguide it with PHD2 + orion startshoot autoguider + mini guidescope. Imaging camera is a modified T4i.
In all of my photos I am seeing a weird streaking pattern. Left and right upper corners seems to have streaks in opposite directions while lower left is kinda straight. I did east heavy balancing and a fair polar alignment using polar drift align tool. Not sure if it is differential flexure or issue with the OTA / Mount. Hope other experience folks here could guide me in right direction. Attached is a 1.5 hours of stacked image stretched in pixinsight and corresponding PHD logs.