This M45, Pleiades (七姊妹星團) was taken with an APM-TMB 105/650 with WO’s FLT flattener in 24-11-2011 at Pak Tam Chung, Hong Kong. I didn’t optimize the back focus for the flattener in present of P2 filter. The performance was good. I need to wait for clear skies to do the optimization, but the sky in HK is always disappointing. Maybe I need to use artificial star to do the optimization. Although the distance is not infinity, it gives an approximated back focus adjustment. This can save me some time during field test.
APM-TMB 105/650, FLT, P2, Canon 5DII, HEQ5Pro
ISO 1600, 5 mins x 10
DSS, PS4, cropped