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Re: Dark Current Enable Tool

PostPosted: Wed Apr 05, 2017 8:10 pm
by jbeyer
Ah, way beyond my expertise. I still have all the RAW images. Could restack and save as FITS in Pixinsight or another Mac program if it comes without cost. Honestly not looking to make much of a monetary investment in trying to solve this since the subs and stacked images look quite good when taken with the native settings.

Re: Dark Current Enable Tool

PostPosted: Thu Apr 06, 2017 5:08 pm
by astronomer
jbeyer wrote:Ah, way beyond my expertise. I still have all the RAW images. Could restack and save as FITS in Pixinsight or another Mac program if it comes without cost. Honestly not looking to make much of a monetary investment in trying to solve this since the subs and stacked images look quite good when taken with the native settings.


It is perfectly solvable. Definitely try re-stacking them. I do think a lot algorithm out there are not well optimized.

Re: Dark Current Enable Tool

PostPosted: Wed Apr 12, 2017 11:37 am
by jbeyer
I restacked bias frames taken with the dark current tool active at two different ISO values in DX and FX formats. They were taken to calibrate images. Stacking was done using linear fit clipping algorithm and saved in FITS format.

Stack of ISO1600 bias images in DX format - 210 images

https://drive.google.com/file/d/0By0EPP ... sp=sharing

Stack of ISO400 bias images in FX format - 50 images

https://drive.google.com/file/d/0By0EPP ... sp=sharing

Up to this point I have not used dithering at all. I've got my polar alignment to the point where there is no perceptible field rotation as I blink through all the light images - all are nearly identical. I'm wondering if this may at some level be contributing to the fixed pattern noise.

Re: Dark Current Enable Tool

PostPosted: Fri Apr 14, 2017 8:15 pm
by astronomer
Based on your stacked bias, that type of banding is perfectly normal, just like my D7000. CMOS itself has banding noise.

I do think it's the stacking algorithm not taking care of this properly. Is the banding noise present in the master dark or master flat? Because in my master dark frame, even with very strong stretching, none of those banding noise is visible.

Re: Dark Current Enable Tool

PostPosted: Sun Apr 16, 2017 4:54 pm
by jbeyer
It's there. The banding is pretty obvious in the master dark using the dark current tool. There's none at all in the master darks without the tool active. Interesting since the all the dark frames were calibrated with the masteries before stacking. In addition there's also a small horizontal band at the top and bottom of the stack. Here's a screen shot. Interesting because Pixinsight recommends the linear fit clipping algorithm for stacking anything greater than 20 images.

https://drive.google.com/file/d/0By0EPP ... sp=sharing

Re: Dark Current Enable Tool

PostPosted: Fri May 05, 2017 8:32 am
by astronomer
I'll use my D600 in dark current mode in my next photographic session. And Let me see if that problem persist.

Re: Dark Current Enable Tool

PostPosted: Tue May 16, 2017 3:55 am
by tokafondo
Hi all and thanks (again) for Dark Current.

I'd like to know if the mod has a real benefit to standard (and I mean non-astronomical) photography.

Could the supression of the in camera raw processing lead to better pictures when processed off camera?

Thanks.