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Startup settings for ZWO ASI 294MC-PRO


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You want to set the camera gain to where the HCG (High Conversion Gain) mode is enabled. This ensures lower read noise with little loss in dynamic range as shown in the graphs. It's also around unity gain which is recommended when starting out. There's debate as to what the gain setting is where HCG mode is enabled with quotes of 117, 120 and 121. From the graph it's a bit hard to tell but the difference between the gain values is minimal so gain 121 to be safe as scotty38 suggests.

It's easy to find out though, if you wish, by just taking a bias or a short exposure dark image, ie. exposure with the camera front cap on, at different gain settings. Look at the image statistics readout in your capture software and check the SD (Standard Deviation) value which corresponds to the noise in the image. As the bottom graph indicates the read noise drops significantly at the gain setting (and above) where HCG is enabled. The SD of the image will also drop significantly at this point.

Untitled-1.png.4900a17e25a38ad74130a9b786a546c0.png

I assume wbr is white balance. This isn't used in astro cameras as you want to record the raw data from the camera before any manipulation. Any colour adjustments are done later during stacking and processing.

Optimum exposure depends on your level of light pollution and 'speed' of your scope. For an f5 or f6 scope in moderate light pollution around 3 mins is a reasonable starting point. If dark skies with low light pollution around 6 mins. For an f2 scope around 1 min exposure. It's all to do with exposing until the noise from your sky background is significantly higher than the camera read noise, around 5 times larger is a commonly used figure. If you want more details on how this is determined and why feel free to ask, but the exposure examples given are fine for starting out.

Leave the camera offset at the default value. It's generally set a bit higher than it need be, but that's not a problem. It's when it's set too low and you get black clipping in your image, that it's bad. 🙂 

Alan 

Edited by symmetal
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13 minutes ago, symmetal said:

You want to set the camera gain to where the HCG (High Conversion Gain) mode is enabled. This ensures lower read noise with little loss in dynamic range as shown in the graphs. It's also around unity gain which is recommended when starting out. There's debate as to what the gain setting is where HCG mode is enabled with quotes of 117, 120 and 121. From the graph it's a bit hard to tell but the difference between the gain values is minimal so gain 121 to be safe as scotty38 suggests.

It's easy to find out though, if you wish, by just taking a bias or a short exposure dark image, ie. exposure with the camera front cap on, at different gain settings. Look at the image statistics readout in your capture software and check the SD (Standard Deviation) value which corresponds to the noise in the image. As the bottom graph indicates the read noise drops significantly at the gain setting (and above) where HCG is enabled. The SD of the image will also drop significantly at this point.

Untitled-1.png.4900a17e25a38ad74130a9b786a546c0.png

I assume wbr is white balance. This isn't used in astro cameras as you want to record the raw data from the camera before any manipulation. Any colour adjustments are done later during stacking and processing.

Optimum exposure depends on your level of light pollution and 'speed' of your scope. For an f5 or f6 scope in moderate light pollution around 3 mins is a reasonable starting point. If dark skies with low light pollution around 6 mins. For an f2 scope around 1 min exposure. It's all to do with exposing until the noise from your sky background is significantly higher than the camera read noise, around 5 times larger is a commonly used figure. If you want more details on how this is determined and why feel free to ask, but the exposure examples given are fine for starting out.

Leave the camera offset at the default value. It's generally set a bit higher than it need be, but that's not a problem. It's when it's set too low and you get black clipping in your image, that it's bad. 🙂 

Alan 

Thankyou both.

I mentioned white balance because when I first connected to ASIAIR + I was just getting a white screen and initially thought my backfocus was out but putting my hand over OTA and I saw an image and had to muck about with the gain/exposure and to a small degree wbr and wbb in the ASIAIR before I got any picture. I give a gain of 121 a go and do a lot more test shots.

Thanks again.

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1 hour ago, scotty38 said:

Probably try gain of 121 and offset 30 to start with. If your calibration files are fine and dandy then all good, any issues and you may want to try a gain of 200 as a "fix"

Just go gain 200 in the first place it still leaves you with plenty of dynamic range. 

Edited by Adam J
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5 minutes ago, CraigT82 said:

Get sharpcap pro and run a sensor analysis and then the smart histogram tool, will give you good info on what’s best for your particular sensor

Ironically the license has not long expired on Sharpcap, I did initially connect to Sharpcap but was only getting a white screen and thought I had problems with backfocus. The OTA is a SW Esprit 80ED and it seems their is an "old version" of the field flattener and "newer" version and each has a different spacer size.

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