Author Topic: Help me understand overscan coordinates  (Read 136 times)

Offline joelshort

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Help me understand overscan coordinates
« on: 2019 February 09 08:59:22 »
I have a new camera and I'm using the overscan regions enabled.  I feel like it should be easier or more obvious but I'm just not getting the numbers involved. 

My camera has the following pixel dimensions:
Overscan - 4630 x 3694
Active pixels - 4524 x 3624  (overscan disabled)

I'm trying to calibrate some flats (4630x3624) with a master bias (4630x3694), and I'm running into a problem regarding the overscan region.  When I try to calibrate the flats I get an error message "Inconsistent overscan geometry."  So my settings are not correct.  I just don't understand the description of the boxes in the overscan settings.  Any ideas?
Joel Short
www.buckeyestargazer.net
CFF135 f6.7, SV80ST, G3-16200M, QHY163M, QHY183M

Offline joelshort

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Re: Help me understand overscan coordinates
« Reply #1 on: 2019 February 09 11:36:48 »
So originally I was trying to calibrate flats with a Master Bias.  Apparently there is some issue with the master bias.  If I load up the flats in ImageCalibration and just have the overscan parameter enabled (no master bias) the process completes and I'm left with files that have been cropped to 4524 x 3624. 

I don't get it (clearly).  Both the flats and master bias are the same pixel dimension at 4630 x 3694.
Joel Short
www.buckeyestargazer.net
CFF135 f6.7, SV80ST, G3-16200M, QHY163M, QHY183M

Offline RickS

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Re: Help me understand overscan coordinates
« Reply #2 on: 2019 February 09 13:39:25 »
Nothing stands out that I can see.  My KAF-16803 camera has an overscan area to the right of the image and the parameters are:

Image region:0 0 4096 4096
Source: 4107 0 9 4096
Target: 0 0 4096 4096

So long as all frames are captured with overscan enabled everything just works as expected.

Offline joelshort

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Re: Help me understand overscan coordinates
« Reply #3 on: 2019 February 09 14:03:33 »
Thanks for the reply. 

All images (lights, darks, flats, bias) were taken with overscan enabled.  But whenever I try to calibrate any subs with a master (bias, flat, dark) I get the "Inconsistent overscan geometry" message. 

I don't know if the problem is related to my overscan settings, or my masters.  But the masters have the same pixel dimension as all subs.  This is truly maddening. 
Joel Short
www.buckeyestargazer.net
CFF135 f6.7, SV80ST, G3-16200M, QHY163M, QHY183M

Offline joelshort

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Re: Help me understand overscan coordinates
« Reply #4 on: 2019 February 09 17:03:22 »
So I'm showing my ignorance here...I didn't realize the overscan calibration needed to be done on each individual sub prior to combining for the masters.  So I was trying to combine the raw bias into the master bias, and then run the overscan during flat calibration with a master bias.  I haven't done any actual calibrating yet but I believe this was my problem. 
Joel Short
www.buckeyestargazer.net
CFF135 f6.7, SV80ST, G3-16200M, QHY163M, QHY183M

Offline RickS

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Re: Help me understand overscan coordinates
« Reply #5 on: 2019 February 09 18:37:12 »
I didn't realize the overscan calibration needed to be done on each individual sub prior to combining for the masters

Glad you figured it out.