In an excellent post on another thread, Mike noted that the ToUcam would compress data to achieve over 10 frames per second over its standard USB 1.1.

I happened to have discovered the fps control on my ToUcam over the weekend (after 2+ years ) and took 2 avis of the Plato crater, one at 30 fps and the other at 10fps.

I have attached two jpgs, one from processing each of the AVIs in Registax. Both were processed in the same way:

1. aligned with a single 256k box centered on the middle of the crater
2. A reference shot of 50 frames was created and sharpened in wavelets
3. The stack was limited to 60% and optimized
4. The top 200 frames were selected and stacked
5. The image was sharpened with wavelets 9.2/26.0/13.2
6. Saved as TIFFs from Registax, JPGs from Photshop, quality=80

No other adjustments were made to the images. The 10fps image should be listed first, the 30fps 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.

I have posted PNGs with this discussion on my site, and TIFFs are available by FTP.

Attached Images

	Plato-f20-070427-10fps_ST200.jpg (77.3 KB, 37 views)
	Plato-f20-070427-30fps_ST200.jpg (55.1 KB, 37 views)

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Observatorio de la Ballona

hi Andy,

very interesting comparsion.

my experience with webcams is:
-even if it`s the same type - images are often very different: some webcams can do only 10 fps without compression others are capable fo 30 fps.
this is why I have chosen for a mono chrome fire wire camera DMK 21F04

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Dietmar
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i have a logitech and i find at 5 frames a sec i see more clearly the images then lets say 15f or 30
yes i will get more images per frame but i find that the quility is not as clear as lower frames , so i try to stay at lower frames 5 to 10f

ill even do 2 movies of 5 frame and put them together when stacking

funny to say i was looking at ur tiffs and the 10 frames as more detail maybe a bit more noise but more detail

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10FPS looks sharper, but 30FPS has less noise.

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I'd agree with Ingo there.
Interesting comparison Andy. I think you're right that it would be more conclusive in better seeing.

I look forward to more!

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Mike
. mikesalway.com.au - Astronomy and Photography by Mike Salway
. IceInSpace - The Australian Amateur Astronomy Community
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A couple of thoughts based on the responses.

The apparent better detail in the 10 fps vs. the 30 fps could have resulted from how Registax ranks frames. Not that I know the details (speculation alert!), but the more even image, good or bad, from a longer exposure got details overall better ranked.

On the other hand, the rapid exposures of the 30fps had less seeing noise in each, hence less seeing noise overall.

In conclusion, the seeing, at 2/5, dominated the test.

It was fun to have recent data available for a test even as the test was suggested.

Clear skies (none here),

--Andy

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Observatorio de la Ballona

Was the exposure length kept the same during the 10fps and 30fps captures - the exposure length and frame capture rate can be set independently on the toucam.

The exposure was identical on both. Which would account for the final pictures being very similar. But where does that leave us on detail vs. noise?

Watching the AVIs, they look very different. This is probably the visual effect of the different frame rates instead of a material difference in the frames themselves.

Hmmmmmmmm

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Observatorio de la Ballona

I'd agree with that. The live screen at 30fps always looks much better - easier for focusing, and can be deceiving with the judgement of seeing.

Sometimes it looks good at 30fps, and when you get around to processing it later, it actually was terrible

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Mike
. mikesalway.com.au - Astronomy and Photography by Mike Salway
. IceInSpace - The Australian Amateur Astronomy Community
. My Bio | My Jupiter 2007 Gallery | My Image Gallery

I'm beginning to question the validity of the test...

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Observatorio de la Ballona

With identical exposure length - you have essentially taken seeing out of the equation - since freezing out atmospheric turbulence only depends on the exporure length - not the capute rate.

The 30fps may look less noisy because perhaps it has a smoothing algorythm applied as part of the compression - noisy images take up more space than smooth ones.

Personally - although the noise is more evident in the 10fps - it definately shows more detail.

I think the test was valid - it seems to show that you can get a smoother image using 30fps - but you scarificing fine detail. I guess stacking more 10fps frames would further reduce the noise.