17fps cap?

Discussion of features and issues relating to Altair Astro Cameras
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Lokifish
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17fps cap?

Post by Lokifish » Thu Oct 01, 2020 4:07 pm

I have a 183C, and have been fighting with a frame rate cap. No matter what settings I use, the FPS never exceeds 17fps. For example;

RAW8, 1x1, full frame, 2ms, Frame Rate Limit and USB Speed max: 17.6fps
RAW8, 2x2, full frame, 2ms, Frame Rate Limit and USB Speed max: 17.6fps
RAW8, 4x4, full frame, 2ms, Frame Rate Limit and USB Speed max: 17.6fps
(AltairCapture, I'll get 17.6, 50, and 60 respectively.)

So is there a hidden setting or config file hack in SharpCap that I'm missing? I'd rather not have to use AltairCapture as it lacks a number of critical features I use regularly.

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Re: 17fps cap?

Post by admin » Thu Oct 01, 2020 6:49 pm

Hi,

I think that if you select the lower resolutions on Altair capture, the software is not actually binning – I think it is actually just selecting every second pixel in both directions (with appropriate adjustments to make sure you pick up pixels all the different colours). There is a section in the Altair capture controls called 'sampling' – this is where you could change the behaviour between skipping alternate pixels and binning pixels if the camera supported it. With the 183 I think you will see this section continue to be greyed out.

Effectively then, Altair capture is only pulling one in four pixel values from the camera which allows it to achieve higher frame rates.

Cheers, Robin

Lokifish
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Re: 17fps cap?

Post by Lokifish » Thu Oct 01, 2020 9:54 pm

Thanks for the details. I guess I'll have to keep bouncing back and forth between AltairCapture and SharpCap until I can afford to get rid of the camera. That's unless there's a way to get SC Pro to do skip sampling when needed.

If not, then what 183 based cameras have skip sampling support in SharpCap? I ask because they all list higher than 17fps capability at lower resolution/sampling?

celkins
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Re: 17fps cap?

Post by celkins » Fri Oct 02, 2020 8:32 pm

I managed to achieve much higher rates with my ZWO ASI 183MM/C by selecting a lower resolution, which gave me a window onto the sensor frame: if the AA behaves as you’re describing, I’m glad I didn’t buy one from them - ZWO brought out the Pro first!

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Re: 17fps cap?

Post by admin » Sat Oct 03, 2020 1:41 pm

Hi,

just to clarify, the Altair camera gives a higher frame rate if you select an ROI region so that you are not collecting data from the whole sensor (for instance you might collect from an area of 1280x1024 - for me this increases the frame rate from 19 FPS to 83 FPS). The point I make is that the frame rate doesn't increase when you select 2x2,3x3 or 4x4 binning.

Wanting to have a high frame rate when running in a binned mode seems a bit odd to me - normally binning is used for faint targets and therefore longer exposures anyway, which means that the frame rate is not usually important.

Cheers, Robin

Lokifish
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Re: 17fps cap?

Post by Lokifish » Sat Oct 03, 2020 7:59 pm

admin wrote:
Sat Oct 03, 2020 1:41 pm
the Altair camera gives a higher frame rate if you select an ROI region so that you are not collecting data from the whole sensor (for instance you might collect from an area of 1280x1024 - for me this increases the frame rate from 19 FPS to 83 FPS)
My 183C never gets better than 17fps in SharpCap, even with a 320x240 ROI, binned or not. It might be because it's one of the very first 183C's sold. Heck, Altair even thought I was joking when I said it was a v1.0 running v1.4 firmware. So it lacks a number of features found on later versions.

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Re: 17fps cap?

Post by admin » Sun Oct 04, 2020 2:04 pm

Hi,

okay, that makes more sense – there have been a couple of cases where cameras have received a 'mk2' style update in later production models. Altair seem to do this without a great deal of fanfare, which sometimes makes it awkward to know whether you have an early or late model version. Mind you, other manufacturers can get a bit desperate sounding by introducing these updates with new model names like XXX Pro.

Cheers, Robin

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