Low Frame Rate with Altair 183C v2

Discussion of features and issues relating to Altair Astro Cameras
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Re: Low Frame Rate with Altair 183C v2

#21

Post by admin »

Hi Gordon,

I guess it must be a hardware difference between versions of the 183. I dug out my 183CPROTEC (which is a prototype for that model) and I get the same results as the 183M. Even if I set my USB Speed down to 2 I get faster frame rates that you (except at max resolution, where they match yours). I tried connecting via USB2, but that is a lot slower than your rates, so it can't be a USB2 issue.

I'm afraid I'm not familiar with all the details of what changes happened between various versions of the Altair cameras. I do recall having some discussions with them at one point about updates to some cameras that allowed the ROI to increase frame rates - that could have been 183 related, but I'm really not sure.

cheers,

Robin
Gordon
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Re: Low Frame Rate with Altair 183C v2

#22

Post by Gordon »

Hi Robin,

thanks for the help and I'll contact Altair.

One additional point, I had another check in Altaircapture for FPS. If I start live stack at 5440 x 3648 I hit 17 fps, if I then reduce the resolution to those tested it hits 35 fps at 1824 x 1216 and remains at that for all the others.

If I start live stack at 1824 x 1216 it starts at 54 fps and then hits 61 fps for all the other resolutions.

This was all tested at 8 bit at 1ms. It may explain why people reporting the difference between SharpCap and Altaircapture.

Cheers

Gordon
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Re: Low Frame Rate with Altair 183C v2

#23

Post by admin »

Hi,

I just tried that and I noticed that when you select 'Live Stack' in AltairCapture the resolution selection for 'Live' becomes disabled - I suspect that this means that Live Stack puts the camera into 'Snap' mode. Now, if you have a low resolution (say 1824x1216) set in Snap mode and full resolution (5440x3648) in Live mode, the switch from 'Live' to 'Snap' will increase the frame rate because you are getting back much less of the data from the camera.

So, I suspect that the increase in frame rate is illusory - or at least just the standard trade off of lower resolution gets higher frame rates.

cheers,

Robin
Gordon
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Re: Low Frame Rate with Altair 183C v2

#24

Post by Gordon »

Hi Robin,

Thanks for looking at that and it explains quite a lot. I remember a solar session when I used SharpCap and AltairCapture on the same features. I managed to use the "high" FPS in Altair capture and the detail looked nothing like the same capture at a "lower" FPS in SharpCap. I didn't use AltairCapture again after that as clear skies are precious!

I'm at least happy now that I don't need to spend loads of money upgrading my laptop as it won't yield any improvement with that camera.

Thanks for all the help.

Cheers

Gordon
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