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Pixel Scale

Processing Plate Solving Deep Sky
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Yusra Q. avatar
Yusra Q. avatar
Hello all,

I have a small (maybe foolish) concern. I’ve shot all my images with the same telescope, flattener and camera. But the pixel scale that is posted below the astronomy details of the images is not the same. I’ve only cropped some images more than others.

For my gear the pixel scale is about 2.02 arcsec/pixel. My images are showing 2.007 and some are showing 1.003. Is this fine?

Many thanks in advance for the insight offered.

Yusra,
cs.
Tommy Blomqvist avatar
Tommy Blomqvist avatar
1003 and 2007 sound like 1:2 factor - do you switch between bin1 and bin2?
Any cropping may also affect the scale.
Jeffrey Stirman avatar
Jeffrey Stirman avatar
The difference you mention in pixel scale between 2.02 and 2.007 is less than 1%, so yes that's fine. Also your calculation of pixel scale are based on nominal values for the focal length of you system. The real value maybe somewhat difference and fall within that range of difference you see. As for the 1.003 values, in those images you have ~4x the number of pixels, but use the same camera. So either you upscaled the image in your processing program or used 2x drizzle during stacking. Cropping does not affect the pixel scale but upscaling or drizzle will!
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Yusra Q. avatar
Yusra Q. avatar
Hi, all bin was 1x1.
Yusra Q. avatar
Yusra Q. avatar
Thank you, maybe it was because of drizzling.
Jeffrey Stirman avatar
Jeffrey Stirman avatar
Go back and look at your data after stacking and during processing. I'm sure it will have 2x the resolution that you expected. I have done this before on accident when I had the 2x drizzle selected.
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Yusra Q. avatar
Yusra Q. avatar
Yes Jeffrey, I recall not drizzling at times to save time. So what you are saying makes sense. The bin reply was for ‘Tommy’.

Thanks a lot.
Jeffrey Stirman avatar
Jeffrey Stirman avatar
Sure! You are welcome!