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On using video capture

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5 replies to this topic

#1 Airbrush

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Posted 27 September 2021 - 10:15 AM

I first saw video capture when I was at a star party about 6 years ago. Guy was using a webcam in an sct. We watched the video grow and get more detailed on a tv screen, then it would go away and repeat the cycle again. He was feeding the image to a dvd recorder and told me he would stack the images later.
I am using a zwo and sharpcap, sometimes asistudio, I was under the impression that it was stacking still shots.
So when does a series of still shots become a video?
Isnt it the same thing?
James

#2 matt_astro_tx

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Posted 27 September 2021 - 11:38 AM

It sounds like you're describing live stacking a.k.a. EAA (or Electronically Assisted Astronomy) for which there is a forum on CN.



#3 Airbrush

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Posted 27 September 2021 - 11:21 PM

No. When I do EAA. I do live stacking by capturing a bunch of still frames that is stacked. I was under the impression that you guys were taking videos of the planets. I think I can take videos with the zwo camea but Im not sure.
Which led me to the question:
What is the difference between a series of pictures and a video? Does it matter?


Never mind. I will go back to EAA. Hint: those guys don't do planets. Looks like I wont either.
James

#4 Tom Glenn

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Posted 28 September 2021 - 12:50 AM

Although the OP may have resolved his issue here, the questions below are good ones that many people out there may have.  

 

 

So when does a series of still shots become a video?
Isnt it the same thing?

 

What is the difference between a series of pictures and a video? Does it matter?
 

A video is indeed a series of images, but videos are almost always intended to be played back at the same frame rate as they were captured, which results in a moving image that is intended to be viewed as such (eg motion pictures or movies).  This has important implications, because it means that the individual frames of the video can be lower in quality than still photographs, but those deficiencies are covered up during the playback.  This is why regular cameras that are capable of producing very high quality still images record video at much lower resolution.  The file sizes would be prohibitively large if the videos were recorded at the full resolution of the sensor.  In addition to downsampling the sensor, most video files are also heavily compressed.  This greatly reduces quality of the still images that compose each frame, but since the recording was intended to be viewed as a movie, it doesn't matter.  In planetary imaging, we do capture videos, but they are not intended to be played back, and are instead captured at the raw sensor resolution.  This produces massive file sizes, but allows the video recording to be broken apart into the individual frames, which retain the same quality as still photographs.  These frames are then processed into final images.  So the data is recorded as a "video", but the end result is a series of many raw images, so the process differs from traditional videos that are intended to be viewed as motion pictures.  


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#5 matt_astro_tx

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Posted 28 September 2021 - 07:44 AM

Never mind. I will go back to EAA.

I sincerely apologize for misunderstanding your question.  Don't go!

 

I was under the impression that you guys were taking videos of the planets. I think I can take videos with the zwo camea but Im not sure.
Which led me to the question:
What is the difference between a series of pictures and a video? Does it matter?

Yes sir, we do take video of the planets.  As Tom articulated it's not "video" per se, but just very high frame rate image capture.  We sometimes save these images in a video file format, so it could be misleading.

 

All astro cameras to my knowledge can do this, but will have varying degrees of success as it all depends on what frame rate the camera is capable of achieving.  Could you help us out by telling what model ZWO camera you have?

 

Additionally, you'll need to download software for planetary capture as most DSO/EAA purpose software isn't designed for planetary - as you pointed out.  Most of us use FireCapture, which is free.

 

This web site has a series of great videos that will help you get started doing planetary imaging.  But we're always happy to answer questions.



#6 Airbrush

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Posted 28 September 2021 - 11:19 AM

To Tom Glen and matt_astro_tx
Thank you!
This stuff is confusing. Those answers and links help.
James


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