In an excellent post on discussion thread in the Bad Astronomy / Universe Today forum, Mike (of IceInSpace) noted that the ToUcam Pro would compress data to achieve over 10 frames per second over its standard USB 1.1. This would degrade the quality of anything over this frame rate from the camera.
I happened to have discovered the fps control on my ToUcam over the weekend and took 2 avis of the Plato crater, one at 30 fps and the other at 10fps. This provides an excellent test case for this finding.
I have attached two jpgs, one from processing each of the AVIs in Registax. Both were processed in the same way:
- aligned with a single 256k box centered on the middle of the crater
- A reference shot of 50 frames was created and sharpened in wavelets
- The stack was limited to 60% and optimize
- The top 200 frames were selected and stacked
- The image was sharpened with wavelets 9.2/26.0/13.2
- Saved as TIFFs from Registax, JPGs and PNGs from Photshop, quality=80
No other adjustments were made to the images. The PNG images are below.
At 10 frames per second:
At 30 frames per second:
My first take is that the 30fps image has less noise. Seeing was not good, and that could be a major factor, since the improvements from faster frames could have overtaken the noise introduced from the compression in the camera.
TIFFs are available at the Observatorio de la Ballona FTP site.