Histogram - planetary imaging

[jambouk]

Can someone explain why the histogram of my Logitech 4000 Pro is much broader than that of the ASI120MC, and has a less symmetrical appearance in Sharpcap? No IR cut filter on either in this test (and adding the IR cut filter doesn't alter things much); I adjusted gain, gamma, brightness, white balance etc and nothing changed the appearance of the two greatly. Both cameras pointing at the same light source (window) in this test and exposures adjusted to get about 50% along the X axis.

 

James

 

 

[Astroboffin]

The shutter speed on the ASI is around 6 times faster that the Logitech looking at your frame rate, so that would be the cause, or do you have them set on the same exposure length ? If,so then I have no idea.

AB

[jambouk]

Yes, I think you are right.

The ZWO can achieve shutter speeds of 0.000064 seconds, whereas the fastest I can get the Logitech is 0.0001 seconds.

So I think the longer time the shutter is open for means that more light is allowed in and results in a greater dynamic range amongst the pixels, broadening the histogram. It's hard, but running the ZWO at a a much slower exposure (0.2 seconds) results in a broadened histogram - I suspect there must be differences in pixel homogeneity and QE too and other things.

But yes, it is due to exposure length. Thanks for that.

James

[Astroboffin]

I think there Will be a large number of differences between those two cameras, so will be very hard to do a proper comparison, chalk and cheese really...

AB