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Old 26-01-2012, 10:22 AM
TrevorW
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Binning

Would someone care to explain or refer me to a link on how and why you'd use binning when capturing image data

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Old 26-01-2012, 12:26 PM
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mill (Martin)
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http://www.starrywonders.com/binning.html
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Old 26-01-2012, 12:34 PM
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Binning (2 x 2) is mainly used on mono camera's for colour data collection. Basically it shortens the capture time needed to get a good signal. The binned colour subs can then be combined with a 1 x 1 lum stack to give a good image. Binning is not very useful on OSC camera's as you can no longer debayer the image and all colour data is lost. Just depends on whether you like colour or greyscale images. The thing to remember about binning is the image size is reduced by 4X at 2 x 2 as 4 pixels are treated as a single pixel during data download and resolution is also much lower. I guess binning could be useful on longer focal length scopes when trying to achieve the correct sampling scale but I am yet to try that. I have never used 3 x 3 or 4 x 4 myself but others on this site have. I have found 2 x 2 binning very useful on guide cameras (setting in maximDL) as it gives a stronger signal thus fainter stars can be used for guiding.

Mark
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Old 27-01-2012, 07:15 AM
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Binning 2x2 approx doubles the signal to noise ratio of the same length exposure. It comes at the cost of less resolution as 4 pixels are now averaged into one.

A common practice is to shoot luminance at 1x1 binning (ie each pixel counts only as one) and rgb each at 2x2 binning as their usually is less detail in colour so less resolution is not as important as getting the signal quickly.

If seeing is poor 2x2 binning on luminance makes more sense as the seeing will limit the resolution anyway so no loss.

When imaging galaxies though and you want max resolution binning both luminance and RGB can make sense. You can then add a desaturated rgb combined image into your luminance for a bit of extra signal.

Binning faint Ha objects like the Helix can also make sense to reduce the time to get the signal up. I find binning Ha on my CDK17 gets great results. It can also help reduce vignetting from light pollution as the signal becomes stronger than the background more eaily etc.

Greg.
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Old 27-01-2012, 04:53 PM
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Thanks all from what you say I assume it really only makes a difference for mono cameras
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Old 27-01-2012, 05:05 PM
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Quote:
Originally Posted by TrevorW View Post
Thanks all from what you say I assume it really only makes a difference for mono cameras
If you are shooting Ha with a one shot colour you may as well shoot 2x2 as there may be a small amount of Ha getting through the green, blue microlenses.

Greg.
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Old 28-01-2012, 01:49 PM
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Thanks Greg will try that when I get around to a having a clear sly again
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