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How to change the size of the AVI file in planetary mode




I have 2 cameras. Canon 600D, and an ASI294 MC PRO.

I am trying to use them both to capture an AVI movie of Saturn.
When I use the ASI camera and use the planetary tool, the resulting AVI file has the same size as the sensor. So the AVI is 4144 x 2822.
When I use the 6000D, and use your planetery tool, the resulting AVI file size is 1024 x 680, yet the 600D sensor is 5184 x 3456.

Is there a way to tell BYE to use the full size of the 600D sensor, and to use 5X mode to set the pixels to 1 x 1?
Or, is there a technical reason that I do not want to do this?




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Well, I am trying to learn the detailed differences between these systems.
So the resulting picture of Saturn after I used Autostakkert on the AVI from the ASI camera is much larger than the resulting picture from the 600D.
And not just the whole picture size, but the actual planet is much bigger.

So, I am trying to learn how this is the case. The 600D sensor size is a bit larger than the ASI camera and the pixel size is very close as well.

So, why aren't the planet sizes about the same?


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Size of an Image is not the same thing as Pixel Resolution.  To calculate the latter, you need to know both the size of the Sensor's Pixel and the Focal Length of the Scope.  Do some exploring with https://astronomy.tools/calculators/field_of_view/.

The 5x Planetary Video Mode of BYE produces a near 1:1 Pixel Ratio of the resulting Image to the Sensor, which is most desirable for Planetary Imaging.  If the Full Sensor were to be used as in the 600D's "normal" HD Video mode, it would interpolate the 5184 x 3456 Sensor Image into a 1920 x 1080 Video Image (interpolating 5184/1920=2.7 Horizontal Pixels and 3456/1080=3.2 Vertical Pixel into each output Image Pixel).  This would also shrink the apparent size of the recorded Target.  Instead, BYE taps into the 5x LiveView feed, which is almost 1:1 to produce the smaller 1024x680 Image.

You are correct that there is something unusual about the results of your ASI294MC vs 600D images:

  • If you are using the same Optics with both Cameras, then because the Pixel Sizes are rather close to same size, the projected image of Saturn would cover almost the same amount of  Sensor Pixels on each Camera.
  • If you are comparing File Size (bytes) the ASI294MC should produce a significantly larger Image File than the 600D 5x Planetary Video mode (4144x2822 vs 1024x680).  Similarly, the 600D HD Video should be smaller than the ASI294MC Video (4122x2822 vs 1920x1080).
  • If you are comparing Image Sizes (pixels) then the Saturn Image should be substantially smaller from the ASI than the 600D.
  • Per your description above, neither of these is true.  So, are you sure that your ASI Capture Software is not performing an ROI (Region of Interest) Crop??  Or your Image Processing software (RegiStax)??  Or is your Software performing a Post-Processing Crop??
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Per your four bullet points:

  • Same optics, just changed the cameras.
  • I was not looking at the file sizes. I realize they would be different.
  • Don't understand this one. Perhaps the next bullet will help to see why I don't understand this one.
  • If the ASI software was doing an ROI Crop, then wouldn't the AVI file be smaller than the ASI's sensor size?

When I tried to use the FOV calculator on astronomy tools, I maybe didn't use it correctly.
The results showed the planet in the middle of the view, and in both cases, the planet was the same size, but the total field of view boxes were quite different.


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Unfortunately, we may be talking a bit past each other.  Or not explaining the processes expected /employed to get the results described.

Astronomy Tools FOV Calculator will output much as you describe - IF you select the Camera Parameters and click "Add to View".  This is because the base purpose of this Calculator is to show comparative FOV (and not the resulting "Magnification" if the "Output FOV" is held constant).  It would be better if you opened separate Browser Tabs to the FOV Calculator and input the Parameters for one Camera in each Tab.  The result for the Canon 600D with Resolution set to the 5X LiveView 1024x680 would show significantly larger image of Saturn than that for the Full-Sensor ASI294MC.

These displays will show what one would expect - if no other uneven modifications are performed (perhaps un-knowingly by the Image Processing Software - or the Image Browsing/Catalog/Display software).

Bottom line:  If (as you describe in the OP) the ASI294MC Image results in a Larger Saturn Image than that of the Canon 600D 5x-LiveView Image, then something MUST be expanding the View that you are describing.  This is because of the Physics of Optics and Digital Photography Sensors and the relative sizes of the Actively-recorded areas of each Sensor.

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