Firecapture and camera settings 174m

[Rustang]

I'm starting to get used to using Firecapture but wanted to make sure I'm not missing anything. I'm going to be using firecapture to do Solar Ha imaging with my Altair 174mono. I have the Ascom driver and Firecapture recognises the camera so thats all good. So firstly the fan goes on automatically when firecapture opens, i cant find any settings to control this so is it ok just running at what ever speed/settings it's currently on?. Next -is there any settings i need to set behind the scenes, as in, in Ascom or is everything simply controlled in firecapture as for solar it looks you only really need to adjust the gain, exposure and gamma which is all done in the software. being mono is that a setting somewhere? and how is the frame rate controlled? I think i understand what ROI does but I'm unsure what to have it on, I know the more of my sensor i use the slower the frame rate is.

Anything I may have missed!?

Edited August 26, 2022 by Rustang

[symmetal]

The fan coming on isn't an issue. It may turn off by itself later when no cooling is requested.

Camera gain and offset settings should be available in Firecapture itself. There may be options like camera dew heater on/off in the ascom driver which you could turn off but no problem if left on.

Firecapture will detect it's a mono camera so options like R and B colour gain and debayer options will not be available anyway.

Frame rate is set automatically to be as high as possible. Frame rate will be limited by the processing power of the computer running Firecapture and the camera itself, but is initially  determined by the exposure duration. How many exposures will fit in 1 second. It's the reciprocal of the exposure. An exposure of say 10mS or 0.01 seconds gives a maximum frame rate of 1/0.01 fps which is 100 fps. A 5mS exposure gives a maximum of 200fps.

You won't achieve these maximum framerates if the full sensor is used as the camera can't process the full frame data fast enough. A smaller ROI will enable higher framerates to be achieved, up to the exposure determined maximum, though the camera may max out at 250fps or similar where an even smaller ROI doesn't help.

It's only the height of the ROI that determines the frame rate available, so the ROI width can be left at maximum if you wish, for no loss in fps.

Don't enable gamma when capturing the video, leave it unticked or at 50 which is off anyway. Gamma processing each frame takes considerable processing time so your frame rate will suffer. You can easily gamma adjust the final image later in PS or whatever you use. I've found it useful to set the gamma to 0 in Firecapture when previewing the image as it enables focus to be determined more easily as the image has more contrast but turn off the gamma before starting a capture.

Aim for an exposure around 5mS if possible, and adjust the camera gain to get the histogram maximum around 70% of full. Having a very high camera gain is not a problem and will benefit from lower read noise. Although the preview may look very noisy, once several thousand frames are stacked in post processing this noise will disappear.

Check that the histogram peak corresponding to the 'black' sky background is not butted up against the left edge of the histogram and that the left side of the peak is just visible. Set the camera gain first, and then the camera offset to set the 'black' background peak position on the histogram.

Alan

Edited August 26, 2022 by symmetal

[Rustang]

55 minutes ago, symmetal said:

The fan coming on isn't an issue. It may turn off by itself later when no cooling is requested.

Camera gain and offset settings should be available in Firecapture itself. There may be options like camera dew heater on/off in the ascom driver which you could turn off but no problem if left on.

Firecapture will detect it's a mono camera so options like R and B colour gain and debayer options will not be available anyway.

Frame rate is set automatically to be as high as possible. Frame rate will be limited by the processing power of the computer running Firecapture and the camera itself, but is initially  determined by the exposure duration. How many exposures will fit in 1 second. It's the reciprocal of the exposure. An exposure of say 10mS or 0.01 seconds gives a maximum frame rate of 1/0.01 fps which is 100 fps. A 5mS exposure gives a maximum of 200fps.

You won't achieve these maximum framerates if the full sensor is used as the camera can't process the full frame data fast enough. A smaller ROI will enable higher framerates to be achieved, up to the exposure determined maximum, though the camera may max out at 250fps or similar where an even smaller ROI doesn't help.

It's only the height of the ROI that determines the frame rate available, so the ROI width can be left at maximum if you wish, for no loss in fps.

Don't enable gamma when capturing the video, leave it unticked or at 50 which is off anyway. Gamma processing each frame takes considerable processing time so your frame rate will suffer. You can easily gamma adjust the final image later in PS or whatever you use. I've found it useful to set the gamma to 0 in Firecapture when previewing the image as it enables focus to be determined more easily as the image has more contrast but turn off the gamma before starting a capture.

Aim for an exposure around 5mS if possible, and adjust the camera gain to get the histogram maximum around 70% of full. Having a very high camera gain is not a problem and will benefit from lower read noise. Although the preview may look very noisy, once several thousand frames are stacked in post processing this noise will disappear.

Check that the histogram peak corresponding to the 'black' sky background is not butted up against the left edge of the histogram and that the left side of the peak is just visible. Set the camera gain first, and then the camera offset to set the 'black' background peak position on the histogram.

Alan

Thanks, much appreciated 👍

[symmetal]

I forgot to mention that you may as well use 8-bit capture and enable the 'high speed' option if it's there, in the camera setup panel. This will get the highest framerate. 'High speed' uses less bits for conversion like 10 or 12 bits which you might as well use if you're saving in 8-bit.

Stacking at least 100 8-bit frames will gain you around 4 extra bits of image depth so will be equivalent to a 12-bit image. This is only if noise is present in the individual frames, which there will be. Here's the theory behind this by Craig Stark The Effect of Stacking on Bit Depth, which is an interesting read. 🙂

Alan

[Rustang]

On 27/08/2022 at 02:30, symmetal said:

I forgot to mention that you may as well use 8-bit capture and enable the 'high speed' option if it's there, in the camera setup panel. This will get the highest framerate. 'High speed' uses less bits for conversion like 10 or 12 bits which you might as well use if you're saving in 8-bit.

Stacking at least 100 8-bit frames will gain you around 4 extra bits of image depth so will be equivalent to a 12-bit image. This is only if noise is present in the individual frames, which there will be. Here's the theory behind this by Craig Stark The Effect of Stacking on Bit Depth, which is an interesting read. 🙂

Alan

Thanks, is this better than capturing in 16-bit in Firecapture then?

[symmetal]

37 minutes ago, Rustang said:

Thanks, is this better than capturing in 16-bit in Firecapture then?

You'll generally double the frame rate capturing at 8 bit compared to 16 bit which is an advantage. Planetary type imaging doesn't involve large stretching to the black areas of the image like DSO imaging so a high bit depth isn't so necessary. I doubt you'll see any difference in the final result between a 16 bit image and an effective 12 bit image resulting from a stacked 8 bit capture.

Try both methods and see if you can spot any difference. 😃

Alan