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M45 & Comet C/2014 Q2 (Lovejoy) - The Final Cut (Using Synthetic Flats)

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This is the final version of this image, I have spent 3 nights on it struggling with flats. The flats were doughnut shaped in that the inner was darker than the surround then dropping off at the corners/edges again. I just couldn't get rid of the gradients that the flats caused without hard processing and in the process losing data...introducing synthetic flats...

The synthetic flats worked a treat in removing these irregular gradients. I used them as a last resort, I had taken about 6 different sets of flats, spent ages with DBE and GradientXterminator but nothing would shift them. I am not advocating their use, but they made this particular image a lot easier to process. I need to figure out why the centroid of the image is dimmer in my flats...could be something to do with the 70-200mm lens on a full frame camera? Never noticed it before though.

The tail isn't as prominent in this version but is still there and there is more detail in the comet head, but I have had enough with it...perhaps I will revisit it again sometime.

Oh well, enough excuses...here's the details:

Unmodified Canon 6D
Canon 70-200mm f/4 L IS @ f/4, 135mm
Unguided AstroTrac TT320X-AG
20x 120 second lights (ISO 800)
25x darks
25x bias
Synthetic Flats

Taken on 17th January 2015 on Badger Farm in Lincolnshire at the ELAC meeting.

Thanks for looking (again)...




Comet C/2014 Q2 (Lovejoy) passing M45 (Pleiades) - FINAL by StuartJPP, on Flickr

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