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Jupiter at 33.3ms vs. 6.25ms

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#1 Borodog

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Posted 16 January 2025 - 10:13 PM

Well I experienced a hardware failure tonight. Computer wouldn't connect to the mount. I wasn't about to sit out manually nudging the scope all night so the Io and GRS transits I was going to shoot were right out. So I just shot a couple of videos. Seeing was slated to be poor. The preview was stable but without fine detail. So I made a quick informal study by shooting one video on the Con plan at 1/30s and the other at 6.25ms. That's a factor of 5.3 difference between the two. Here are the two images.

 

Jupiter.png

 

I think the 6.25ms image is marginally better for 5.3 times as much data, although interestingly there do appear to be some areas that appear sharper in the 33.3ms image.

 

 


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#2 Bob Campbell

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Posted 16 January 2025 - 10:24 PM

Well I experienced a hardware failure tonight. Computer wouldn't connect to the mount. I wasn't about to sit out manually nudging the scope all night so the Io and GRS transits I was going to shoot were right out. So I just shot a couple of videos. Seeing was slated to be poor. The preview was stable but without fine detail. So I made a quick informal study by shooting one video on the Con plan at 1/30s and the other at 6.25ms. That's a factor of 5.3 difference between the two. Here are the two images.

 

attachicon.gif Jupiter.png

 

I think the 6.25ms image is marginally better for 5.3 times as much data, although interestingly there do appear to be some areas that appear sharper in the 33.3ms image.

well, sorry to hear bout your trials and tribulations. Hope it get resolved soon. Regards to the two exposures, I think the 1/30 sec is really better all around. The circular feature (what the HECK is that!?) at the mid of the SEB is clearly clearer in the longer exposure, as is the trailing fluid structures to the left of mid in the SEB. The white spot on the NEB is better.

 

I recall reading about this scenario a while back when you and others were discussing it, and I recall the 1/30 sec works best with 1) larger aperture, and 2) good to better seeing

 

Bob


Edited by Bob Campbell, 16 January 2025 - 10:41 PM.


#3 Borodog

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Posted 17 January 2025 - 11:25 AM

Thanks Bob. You know, looking at the images on my big external monitor, I think I do like the 1/30s one a bit better as well.


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#4 Borodog

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Posted 17 January 2025 - 11:53 AM

It occurred to me that I hadn't really followed my own advice, which is that you can get away with smaller APs for higher SNR frames. I had stacked both images with the same AP size, even though the SNR for the 33.3ms frames was more than twice that of the 6.25ms frames. So I went back and increased the size of the APs I used in stacking the 6.25ms video from 64 to 96 (a 50% increase). The number of APs dropped from 102 to 42. The quality of the stacked image was significantly improved. I definitely prefer the 2nd version of the 6.25ms image to either of the others.

 

AP_size.png


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#5 Spacedude4040

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Posted 17 January 2025 - 12:44 PM

I still prefer the 33ms, clearer to me!

Also to be fair you should do three runs of each to try to eliminate better seeing out of the equation.

33,6,33,6,33,6


Edited by Spacedude4040, 17 January 2025 - 01:07 PM.

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#6 Bob Campbell

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Posted 17 January 2025 - 12:52 PM

It occurred to me that I hadn't really followed my own advice, which is that you can get away with smaller APs for higher SNR frames. I had stacked both images with the same AP size, even though the SNR for the 33.3ms frames was more than twice that of the 6.25ms frames. So I went back and increased the size of the APs I used in stacking the 6.25ms video from 64 to 96 (a 50% increase). The number of APs dropped from 102 to 42. The quality of the stacked image was significantly improved. I definitely prefer the 2nd version of the 6.25ms image to either of the others.

 

attachicon.gif AP_size.png

can't tell much difference in the 64 vs 96 for the 6.25msec case, and going back to the 33msec I too like it better.

 

Bob


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#7 KMH

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Posted 17 January 2025 - 03:35 PM

Interesting...

Is it possible for you to post a snippet from the raw video, so we can better appreciate the seeing conditions?

 

Kevin



#8 gfstallin

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Posted 17 January 2025 - 03:41 PM

Fascinating how our eye-brain connections work and differ. For me, on two different screens, the clear winner is the 6.25ms version. I had this impression even with a blind taste test since I had viewed the images before seeing the accompanying captions and had the same reaction. It could be notable that I process color information differently than most, being colorblind. I just don't perceive a lot of color data that is obvious to others. While this has some obvious drawbacks when it comes to processing images and seeing subtler details most evident in color in others' images, it has tended to make me a cheap astronomy date. "You're telling this refractor throws up false color? Get out! I was sure this '60mm 800x Power' refractor was an apo!" 

 

George 


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#9 RobDob

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Posted 17 January 2025 - 03:58 PM

Saw a nice stereo image when I looked at these with my eyes crossed blink.png


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