Binning at camera or at Startools?

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Binning at camera or at Startools?

Postby AF7JQ » Wed Apr 25, 2018 7:15 pm

Hello,
I have a ZWO asi1600mc-pro connected to a LX600 12" F8 (or F4.95 w/reducer), so I am dealing with some pretty long focal lengths. I use Sequence generator Pro as my imaging control software. We have wonderful dark skies, but unfortunately we are also on the LEE side of a mountain range about 20 miles to our South. The mountains can cause upper air turbulence that affects seeing. I have been having pretty good results using the binning option in Startools to help. In SGP I have the option of setting the binning (software) for the imaging session. Is it better to image with the full resolution, and plan on using Startools binning, or bin the image from the start at SGP (2x2, or 3x3). Which would be the preferred method for best results?

Thanks,
John :confusion-shrug:
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Re: Binning at camera or at Startools?

Postby admin » Sun Apr 29, 2018 12:10 am

AF7JQ wrote:Hello,
I have a ZWO asi1600mc-pro connected to a LX600 12" F8 (or F4.95 w/reducer), so I am dealing with some pretty long focal lengths. I use Sequence generator Pro as my imaging control software. We have wonderful dark skies, but unfortunately we are also on the LEE side of a mountain range about 20 miles to our South. The mountains can cause upper air turbulence that affects seeing. I have been having pretty good results using the binning option in Startools to help. In SGP I have the option of setting the binning (software) for the imaging session. Is it better to image with the full resolution, and plan on using Startools binning, or bin the image from the start at SGP (2x2, or 3x3). Which would be the preferred method for best results?

Thanks,
John :confusion-shrug:


If SGP's binning method uses software, then keep using StarTools's Bin module, since ST's bin module allows for fractional binning (e.g. you're not stuck with 2x2 or 3x3 values). This allows you to gauge after capture exactly how much binning is required. You will never start losing real detail this way, whereas with 2x2x or 3x3 it may be a gamble.

If your hardware supports binning, you may get better results in some cases by using hardware binning. Hardware binning usually (depends on implementation) cuts down on read noise. However, your CCD wells may overexpose faster - often dynamic range is cut down. Hardware binning is especially recommended when imaging extremely faint objects under very dark skies. E.g. hardware binning is best used in situations where the read noise is the dominant noise contributor, rather than shot noise from, say, light pollution or sky glow.

If stack is of good quality, try binning bit less than the thershold where 1 pixel equals 1 unit of detail. This allows you a bit of headroom to experiment with deconvolution, which can be quite effective in converting seeing-related blur into actual detail.

The point is, doing this all post-capture, will allow you much more room to experiment and postpone such important decisions as binning your data.
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Re: Binning at camera or at Startools?

Postby AF7JQ » Mon Apr 30, 2018 6:14 pm

Thanks for the reply IVO!
Could you explain a bit further....
"If stack is of good quality, try binning bit less than the thershold where 1 pixel equals 1 unit of detail. This allows you a bit of headroom to experiment with deconvolution, which can be quite effective in converting seeing-related blur into actual detail."
What do I look at in the image? Stars are way bigger than 1 pixel. Is there some part of the image that works better than others? I looked at the help file some more but still a bit confused.
Thank again!
John
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Re: Binning at camera or at Startools?

Postby admin » Mon Apr 30, 2018 11:54 pm

When your data is oversampled, it is using multiple pixels to describe one unit of detail. Binning counters oversampling.

If your data is oversampled, detail is "smeared out" over multiple pixels. Atmospheric turbulence is usually the main contributing factor. There are some other factors that "smear out" detail as well (such as your optics / Airy disk).

As a rule of thumb, to "perfectly" bin your data, what you would be looking for, is "small" non-overexposed stars not taking up more than a 3x3 patch of pixels.

Does that help?
Ivo Jager
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Re: Binning at camera or at Startools?

Postby AF7JQ » Wed May 02, 2018 10:13 pm

Yes!
Thank You IVO!!!
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