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Moon/Planet(/Sun?) video file size

planet astrophotography solar moon
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#1 gfryhof

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Posted 15 October 2019 - 07:43 PM

Hi all,

 

I'm very new to astrophotography. I have a Celestron NexStar 8SE with a f/6.3 focal reducer. In terms of cameras I have a ZWO ASI183MM for deep space (I am realizing I probably should have gotten the ASI1600MM) and ZWO 290MC (maybe should have gotten ASI224) for planetary imaging.

 

I'm not saying the camera was best suited, but I recently tried using the 183MM on this setup to image the moon using SharpCap, which I believe at shorter exposures defaults to saving files as a .avi movie file rather than individual images.

 

In my naivete, I took a 5 minute video of the moon a couple of weeks ago using the native 183MM camera resolution (5496 x 3672) and 1x binning....I ended up with a 40 gigabyte file size. I'm sure if I had kept imaging for longer I would have ended up crashing my cheap-o ($300) windows imaging laptop (because at the end of the day I decided it was better to buy a cheap windows imaging laptop than to try to get stuff compatible with a MAC).

 

Bottom line, is everyone getting huge file sizes like this (40+ GB) for moon/planetary/solar imaging (anything with short exposure time that is saved as .avi), or is something wrong with my settings -- should I be imaging at lower resolution???

 

Given the large (>40 GB) file size, I wasn't able to even begin to stack my .avi file using autostakkert, let alone move into PixInsight for further processing.

 

What I am doing wrong? See attached for one frame of my moon attempt frown.gifhttps://astrob.in/bpncnl/0/

 

Thank you for your help,

 

-George


Edited by gfryhof, 15 October 2019 - 08:02 PM.


#2 Jim Davis

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Posted 15 October 2019 - 07:51 PM

I don't shoot at native resolution. With planets I mostly do 800x600. I live in a place with poor seeing, so I am running with very short exposure times. I also never take a 5 minute video, unless I am trying to capture a ISS transit or something like that.



#3 gfryhof

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Posted 15 October 2019 - 08:06 PM

Thank you, Jim!

 

So how long are your typical videos? The lower resolution makes a lot of sense and was my first thought about what to fix. How long of a video is enough for stacking with Autostakkert (if that's what you use)?



#4 Jim Davis

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Posted 15 October 2019 - 08:37 PM

Thank you, Jim!

 

So how long are your typical videos? The lower resolution makes a lot of sense and was my first thought about what to fix. How long of a video is enough for stacking with Autostakkert (if that's what you use)?

I normally capture 500 or 1000 frames, depending on the seeing.



#5 DSOs4Me

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Posted 15 October 2019 - 09:16 PM

I just shot the moon last night, I believe 700 frames and it is only 8GB.  I used a ASI183MM Pro in Sharpcap. With the "Output Format" set to AUTO mine always defaults to a .SER file under 2 seconds. Did you have Mono 8 or16 selected ?



#6 gfryhof

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Posted 16 October 2019 - 06:01 AM

These were my camera settings:

[ZWO ASI183MM Pro]
Pan=0
Tilt=0
Output Format=AVI files (*.avi)
Binning=1
Capture Area=5496x3672
Colour Space=MONO8
Hardware Binning=Off
High Speed Mode=Off
Turbo USB=100(Auto)
Flip=None
Frame Rate Limit=Maximum
Gain=250
Exposure=0.001485
Timestamp Frames=Off
Brightness=8
Temperature=30.5
Cooler Power=0
Target Temperature=0
Cooler=Off
Auto Exp Max Gain=225
Auto Exp Max Exp M S=30
Auto Exp Target Brightness=100
Banding Threshold=35
Banding Suppression=0
Apply Flat=None
Subtract Dark=None
#Black Point
Display Black Point=0
#MidTone Point
Display MidTone Point=0.5
#White Point
Display White Point=1
TimeStamp=2019-10-05T01:39:02.6320504Z
SharpCapVersion=3.2.6086.0

#7 RedLionNJ

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Posted 16 October 2019 - 04:38 PM

Common practice is to use a reduced ROI (region of interest) for planetary imaging. If we ignore the moon and the sun (for now), there's really no reason (with good tracking) to go above a 400 x 400 pixel region. That means each frame (let's assume 24 bits per pixel) can be 400 x 400 x 3 = 0.48 megabytes.  So even with 3000 frames, we're only talking around 1.4 gigabytes.  This can be fairly typical for planetary.

 

HOWEVER, when we bring in the sun or the moon - that's a lot more real estate on the sensor. Something like the 183 chip has a LOT of pixels.  We're generally restricted by the USB bandwidth in this case, though - so maybe 16 frames a second at full resolution is reasonable. File sizes will still grow dramatically fast, though. Just be really careful and only keep around data which you consider "good".

 

In a typical planetary imaging evening, I can bring in around 200-250 GB of video data.   And that's after culling the atrocious recordings.

 

We're talking big data, for sure.



#8 gfryhof

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Posted 16 October 2019 - 04:45 PM

Thank you, @RedLionNJ, that's very helpful!  So you may accumulate 200-250GB of data in a given night, but how large might your individual file sizes be? Maybe it's just a function of my processing laptop's limited capabilities (8GB RAM, Macbook Air with SSD), but Autostakkert was unable to stack such a large .avi file size.

 

Do you obtain multiple smaller video files?  Or just have a computer that can handle the file sizes?

 

Thanks again.




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