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Re: absolute point of focus processing technique

Posted: Sat Jun 09, 2018 6:54 am
by PDB
Yes I tried, but had to find out the alternatives in Gimp first (not same commands). It is a lot of work and it works. But if it is really so much better than other sharpening techniques? Probably, but I did not get bettter results (but thats probably me, giving up too fast)

P.

Re: absolute point of focus processing technique

Posted: Sat Jun 09, 2018 6:00 pm
by Bruce Girrell
At the end of the intro video, Kaltseis suggests that we read the "additional information" PDF file before viewing the next video (at 4:15 in the video). I can't seem to locate the PDF file. Anyone else know where it is? Is it maybe the information on the main page with the red label "usage" that then starts off "additional APF-R informations"?

I also have to ask a newbie question. The instructions state "if your system provide a pixel scale by 0,8" (arcsec) and your seeing is 2" (arcsec) ..."
How do I determine those values?

Thanks

Bruce G

Edit: After viewing video #2, I think that the "additional APF-R informations" that I referred to above is the part that he wants you to read.

Re: absolute point of focus processing technique

Posted: Sat Jun 09, 2018 7:03 pm
by Bruce Girrell
OK... I'm going to have to view that a couple of times. I'm good up to the conversion to smart objects and then I start to lose it. Apparently it is this part that is represented by the R of APF-R. The technique up to that point is essentially a multi-resolution unsharp mask.

It is clearly an effective method. I would be reluctant to attach the word "focus" to it though, as it is not a physics-based process (such as deconvolution). Kaltseis notes that if you do deconvolution, it should be done first and should be gentle. The APF-R method is very effective at achieving local contrast enhancement and to our brains, contrast is almost the same as sharpness.

Re: absolute point of focus processing technique

Posted: Sat Jun 09, 2018 7:03 pm
by PDB
Hi Bruce,

Pixel Scale in " can be calculated as follows (if I remember correctly):

2*ArcTan("PixelSize in Micrometer"/ 1000/2/"Focal Length in mm")*206265

Seeing Value: that is difficult. You have an average seeing for your location (meteoblue gives some indication) but in lucky imaging you probably need an average value reported from an Solar Seeing Scintillation monitor (commercially available or DIY viewtopic.php?f=9&t=16746)

P

Re: absolute point of focus processing technique

Posted: Sun Jun 10, 2018 12:45 pm
by _Zakalwe
Its not a focus technique, but a post-processing sharpening routine.