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  #21  
Old 10-06-2020, 09:24 AM
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Camelopardalis (Dunk)
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Ah well, in that case I'll have to try harder

Just keep in mind that there is well established maths and physics involved, and "alternative facts" like in the realms of faith and power don't cut it.

Regarding the gain and ADC situation, it doesn't matter all that much (generalising hugely). What's important is total exposure time. Run the calculations and you'll see... so long as the subs are sky-limited, then 6x10 minute subs will average out to the same as 60x1 minute subs.
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  #22  
Old 10-06-2020, 09:58 AM
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The_bluester (Paul)
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I will have to reshoot my demo to show how the ASI294 behaves in the two situations by way of gain (To either allow the highest full well at about 4e/ADC at "zero" gain versus unity gain of just over 1e/ADC) I actually made the experiment earlier this year as when I first bought the camera I used to use zero gain and then changed to unity a few months later, but I had changed so many things in a short time it was hard to compare the data. The difference between images using the same total exposure time at different gain settings was pretty stark. Basically I shot M42 for three hours at each setting using 5 minute subs for both, with flats and darks shot at the same settings as each set of lights and integrated in APP using the same settings. Unfortunately I built myself a new processing PC last week (Talk about timing) and decided when I was moving data over that I didn't need to keep that!

I am in the middle of a mosaic that I will be lucky to finish this season unless the weather gods are really nice to me, once I knock that over I will pick a suitable target and do it again for the point of the exercise and post the results here, happy to prove myself wrong if that is what happens.

Maybe it is just that the ASI294 behaves in a peculiar way that is leading me to my assertions? Given it is the only camera I have, I don't have any way to test that, but they are certainly known for being tricky to calibrate by way of flats.
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  #23  
Old 10-06-2020, 06:26 PM
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Camelopardalis (Dunk)
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Hmmm that’s interesting...which was better? The zero gain or the unity gain?

The 294 does seem to be a bit different than those that came before it. The 1600 is very predictable, a solid performer. The 183 seems to work well too, but it has some frightening amp glow that calibrates out well most of the time.

The newer sensors in the 2600 and 6200 feature the High Conversion Gain mode as does the 294. I guess we’ll have to see how they perform when more of them are out in the wild
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Old 10-06-2020, 07:09 PM
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The_bluester (Paul)
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Unity gain produces the nicer looking subs by a long way with the 294. I am just trying to negotiate with the minister for finance on a 2600 at the moment. I would love a 6200 mono but the finance just won't go there for now. I would hope to use the 2600 on zero gain, which conversion wise equals about the same as the 294 at unity gain (120 gain in ZWO speak for that camera) but at the lowest gain the 2600 has half the read noise of the 294 at lowest gain, I reckon it has the possibility of being a very useful gain level with loads of full well capacity to hopefully bring out star colours and still quite low noise.
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