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Canon Live View Capture: What if I…

dslr imaging
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#1 BQ Octantis

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Posted 24 September 2020 - 06:20 AM

…recorded at 1× zoom?

 

faint.gif

 

Hear me out!…

 

Let's say I'm doing a Live View capture of, say, Theophilus crater. At 5x zoom at f/58, it's quite the blow-up—indeed, the crater doesn't entirely fit on the 1024×680 crop. I want to make a high-res crop of the central uplift, but I also want to paste the image into a bigger context of the image. Something like this:

 

(Click.)

gallery_273658_12412_273509.jpg

 

I can do a quick RAW capture for the full sensor image (like I did), but it's just a single frame—complete with poor SNR, exceptional shot noise, and impoverished acutance. But I'm also getting the full view in LiveView at 1×.

 

(Click.)

gallery_273658_12412_337851.jpg

 

Can't I just to a Live View capture of that, too, and stack it? I mean, in the time it would take me to reconfigure for intervalometer capture and shoot the required 100+ RAWs (with delays in between for the mirror slap to settle), I could get several 3-minute .mp4s comprised of 2000 frames each. Has anyone tried Live View capture at 1×?

 

Would I lose my shooting license or Canon AP merit badge if I did? laugh.gif

 

BQ

 

P.S. It didn't dawn on me to try last night. And it's clouds for the foreseeable future…


Edited by BQ Octantis, 24 September 2020 - 07:19 AM.

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#2 DubbelDerp

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Posted 24 September 2020 - 07:37 AM

Don't tell anyone... but I did just that with my little AT60ED refractor on my skyguider pro to take shots of the crescent moon that mostly filled the frame. Obviously not at the resolution you'd get with a bigger scope and shooting a ton of RAW frames, but hey, took me just a few minutes to get a couple thousand frames!



#3 BQ Octantis

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Posted 24 September 2020 - 07:47 AM

Don't tell anyone... but I did just that with my little AT60ED refractor on my skyguider pro to take shots of the crescent moon that mostly filled the frame. Obviously not at the resolution you'd get with a bigger scope and shooting a ton of RAW frames, but hey, took me just a few minutes to get a couple thousand frames!

Ha! I won't tell a soul! laugh.gif

 

How was the quality? I'm curious whether the sensor bins the pixels or just decimates them.

 

BQ



#4 DubbelDerp

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Posted 24 September 2020 - 07:50 AM

I wasn't terribly impressed, but I had just finished shooting at full resolution with my SCT the night before. I'll post an image as soon as I can get to my workstation.



#5 jgraham

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Posted 24 September 2020 - 08:56 AM

If I recall right the idea of using the 5x zoom is to work around the image compression. This might not be a big issue for a wide field context image, it's more of an issue for planetary imaging. I wonder what the file size will end up being. For lunar imaging I usually shoot 64 still frames and they are soooo over-sampled that I'll bin them 2x2 before stacking them.

Food for thought.

#6 BQ Octantis

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Posted 25 September 2020 - 03:03 AM

The file size depends on the camera and the app used for capture. The 600D/T3i Live View frame size is 1024×680. With AstroDSLR 1.3 (Mac OS), I get 9.5 fps; it outputs .mp4 files that are 54 MB for 200 seconds.

 

The trouble with decimation (keeping every 5th pixel) over binning (averaging every 5 pixels) is that you don't get the SNR benefit of zooming out. But as I ponder it, with decimation I should still get the same SNR with 1024 frames as I do at 5× zoom. So I'd have to stack the same number of frames at 1× as 5×.

 

BQ




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