Hi,
I only starting this amazing hobby one lunation ago - and joined this forum at the same time. I am pretty pleased with my photos to date, although very much in awe of what many are able to do on this site. In that vein, I hope the answers to these technical questions will help me improve.
My photos have primarily taken with Canon 6D MkII, 200mm lens at f/4 on Sky Adventurer mount 1hour total exposures with 45-60sec subs at 3200ISO. 15xdark & 15xflat every night .
1) I am rejecting about 20-30% of my lights due to poor tracking (elliptical images, double images, random walk images). Is this normal? I have tried to track down possible sources (wooden deck v concrete base), non-snagging leads from intervalometer, anti-dewer, tightening clutches etc. But with no appreciable luck.
2) My tracking appears to be otherwise good, successive 1min exposures can show minimal sub-pixel shifts when reduced with Pix insight, but then there is the inevitable 10-20pix jump. [Note: PixInsight does give me a typically best value of 0.7 for my ellipticity, but the stars look round to me - I wonder if that reflects the slight coma towards the sensor edge]
3) With these jumps I am reluctant to go too much longer, in case all frames are rejected. I am running at 3200 ISO, which gives me also 7stops of DR. I worry that this too much for the Canon 6k II - although it is supposed to have good performance at high ISO. I also wonder if this is why some of my targets (e.g. Rosetta, Eta Car and Trafid look a little washed out in colour. Although it could be because I have done anything after applying the standard STF colour curves to my background and colour corrected images in PixInsight.
Many thanks in advance to anyone who might be able to provide me some pointers for my next lunation.
Brian
I only starting this amazing hobby one lunation ago - and joined this forum at the same time. I am pretty pleased with my photos to date, although very much in awe of what many are able to do on this site. In that vein, I hope the answers to these technical questions will help me improve.
My photos have primarily taken with Canon 6D MkII, 200mm lens at f/4 on Sky Adventurer mount 1hour total exposures with 45-60sec subs at 3200ISO. 15xdark & 15xflat every night .
1) I am rejecting about 20-30% of my lights due to poor tracking (elliptical images, double images, random walk images). Is this normal? I have tried to track down possible sources (wooden deck v concrete base), non-snagging leads from intervalometer, anti-dewer, tightening clutches etc. But with no appreciable luck.
2) My tracking appears to be otherwise good, successive 1min exposures can show minimal sub-pixel shifts when reduced with Pix insight, but then there is the inevitable 10-20pix jump. [Note: PixInsight does give me a typically best value of 0.7 for my ellipticity, but the stars look round to me - I wonder if that reflects the slight coma towards the sensor edge]
3) With these jumps I am reluctant to go too much longer, in case all frames are rejected. I am running at 3200 ISO, which gives me also 7stops of DR. I worry that this too much for the Canon 6k II - although it is supposed to have good performance at high ISO. I also wonder if this is why some of my targets (e.g. Rosetta, Eta Car and Trafid look a little washed out in colour. Although it could be because I have done anything after applying the standard STF colour curves to my background and colour corrected images in PixInsight.
Many thanks in advance to anyone who might be able to provide me some pointers for my next lunation.
Brian
