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Crescent moon 29MAR2020

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#1 kbev

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Posted 30 March 2020 - 08:18 PM

Boy has it been a while since I've posted an image in the forums.  Got out last night and collected 23 videos of the moon with my 10" Meade at f/10 and finally got everything processed today; talk about knocking the rust of the old skills!  I was also racing the clock as just after I started I realized the moon would soon pass behind one of my neighbor's trees so I wound up doing 1000 frames per video and grabbed the last two just as I started seeing the display fluctuate from the leaves in the high branches.

 

Stacked all videos with AS!3, deconvolution processing in Pixinsight, image mosaic created in ICE and final image adjustments in GIMP.  During processing I realized there is a tiny corner cut out of the upper limb from a missing segment, but it doesn't detract from the overall image.

 

moon_0329_small.jpg


Edited by kbev, 30 March 2020 - 08:19 PM.

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#2 james7ca

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Posted 30 March 2020 - 08:49 PM

I think you've got some fairly good data but the image seems a little dark and I can see the square boundaries where the frames meet the outer background (the black level is higher there than in the remainder of the field). I think you could fix both of those issues with a levels and/or curves adjustment. Is it possible that the exposures were too low?



#3 Tom Glenn

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Posted 31 March 2020 - 02:19 AM

Nice image Kevin.  I agree with James, but I don't think the image was underexposed.  I've recently learned that the raw, linear images captured by the camera are maintained as linear all the way through AS!3, and if you open them in Photoshop or GIMP there is no embedded profile to tell the program how to display the file.  So you get no gamma encoding, but you do have gamma decoding from your display, so the image is dark.   Assuming the image above hasn't been modified with a gamma stretch in processing, then the image is not underexposed, and just needs some gamma modification for display.  If it has already been gamma adjusted, then yes, it was underexposed.  In any event, the data looks like it has good potential. 



#4 kbev

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Posted 31 March 2020 - 02:58 AM

I'm guessing you guys probably have much better monitors than my laptop, cuz I'm not seeing the frame boundaries.  I did underexpose the videos a bit, around 60% on the histogram according to Firecapture.  I just wanted to make sure that I didn't overexpose some of the bright crater rims as I have in the past during post processing.  I did apply a very small stretch to the final mosaic in GIMP,  but considering it's the first decent chance I've had to image in a few months I'm happy with how it turned out.  I'm just trying to get rid of the cobwebs and dust before prime imaging season shows up later this spring.



#5 Tom Glenn

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Posted 31 March 2020 - 03:23 AM

I did underexpose the videos a bit, around 60% on the histogram according to Firecapture. 

Kevin, that's not really an underexposure.  The Firecapture histogram is linear.  I still advocate for going to 75% most of the time on the Moon, but I now realize that this is essentially a strong exposure to the right.  Even a 50% histogram puts the brightest pixels at only 1 stop below saturation, which is fairly trivial to recover in processing.  As for the frame boundaries, I've encounter this before when imaging in changing sky conditions, such as with clouds, the setting sun, or leaves, in your case.  



#6 james7ca

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Posted 31 March 2020 - 05:06 AM

I agree with Tom, a 60% histogram level shouldn't be an issue. That said, I still think the image appears a little too dark and those frame boundaries are pretty clear on my NEC display.

 

Have you checked your display using a gray step scale like on the following website?

 

  https://www.cambridg...calibration.htm




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