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INDI Library v1.9.3 Released (11 Nov 2021)

Bimonthly Stable INDI Library release introduces new drivers and fixes for existing ones. Some highlights:

ASI 2600mc pro: how to set the correct sensor temperature ?

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Hi,
I finally have on my hand a cooled CMOS camera for deep sky imaging.
This is my first times with this kind of camera (so I'm a newbie) and my camera is a ASI 2600mc pro.
I have not yet test it with indi but I hope that all will works fine :)

So, I have a not technical questions here.... but I have a concepts question regarding how I'll need to adjust correctly the temeprature of cam.
I understood that this should dependig on external environment temperature and also by time exposure... but what are the guide lines?
For example if my exposure times is 300 sec which wuould be the temperature sensor... 0°C, -10°C, -20°C... ?
And what is the relation with external temperature and which would be the value to consider in order to set the sensor temperature?

I hope I was clear with my questions :)


Thanks to all in advance.
Paolo
1 year 5 months ago #55812

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Paolo,

the cooling temperature is up to 35 degrees below ambient. The important thing IMO is to have reproducible conditions, say -10 degrees C for all images. Accordingly, your dark frames should be taken at -10 degrees, too. If you decide to take lights at other temperatures, you have to take additional sets of dark frames at these temperatures, too. With modern sensors like the one in your 2600 the difference in noise level between -10 and -20 degrees is negligible and not worth the extra effort IMO.
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Last edit: 1 year 5 months ago by Alfred.
1 year 5 months ago #55814

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I agree 100% with Herrhausen. I have been using an ASI1600MM-Pro Cool for about 2 years now and I do exactly that: always cool to -10º and always use the same gain and offset. I have shot a dark library for that for different exposure times so I can always use a master dark of the same exposure time as the lights. For the ASI1600 this is necessary because of the amp glow. Recently I acquired an ASI6200 which has no amp glow so I made one master dark at -10º and use that for all my lights.


Clear skies, Wouter
Wouter van Reeven

ASI6200MM and 7 slot 2" filter wheel with a SkyWatcher Esprit 80 ED on a SkyWatcher HEQ5-Pro
ASI1600MM-Pro Cooled and 5 slot 1.25" filter wheel with an 8" TS Ritchey-Chrétien on a SkyWatcher EQ6-R
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1 year 5 months ago #55815

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how do you like the 6200 over the 1600 ?
1 year 5 months ago #55818

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Hi guys,
thanks a lot for your answers!
I really appreciate it.

@wvreeven what kind of gai and offset you are using?
From my asi2600 quick guide is suggested to use the highest dynamic range, this mean that the gain is set to zero.
With gain at zero which is the correct offset?
However always from the quick guide is written that the ASI PRO cameras don't provide offset (and also USB limit) any more.... so I should no need to set the offset... right?

What you says about the master dark is wonderfull, in this way it is very convenient and saves you time during photo session... you will only need to take light frames.
The same thing colud be performed whit bias... with a master bias, right?
Regarding the master dark, the noise is not always distribuited in the same manner over the sensor, so in theory should be better to take the dark frames at the same time of light frames... but at this point I think that with the master dark or using the dark frame per session there is no much more difference in noise reduction, right?

thanks in advance!
Paolo
1 year 5 months ago #55820

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@suvowner: I had some initial problems getting it to work. It requires a USB3 port otherwise it refuses to work. Apart from that, it works really well. Processing the images is quite a challenge since they are HUGE.

@astropaul: I also use gain 0. The offset is not cast in stone in the sense that you need to use a certain offset for a certain gain. I use offset 80. Not sure anymore where I got that number from. It seems to work for me though. I didn't know that ASI PRO cameras don't provide offset anymore though.

As for BIAS, I don't use them. I have read reports that say that BIAS images taken with ASI1600 cannot be trusted because they are not uniform. I use APP for image processing and with that I use a Master DarkFlat to calibrate the Flats and create a Master Flat. Then I use the Master Flat and a Master Dark to calibrate the lights. Again, I have taken DarkFlats at 1, 5 and 10 sec and make sure that my Flats always use any of those exposure times and I am done.


Wouter
Wouter van Reeven

ASI6200MM and 7 slot 2" filter wheel with a SkyWatcher Esprit 80 ED on a SkyWatcher HEQ5-Pro
ASI1600MM-Pro Cooled and 5 slot 1.25" filter wheel with an 8" TS Ritchey-Chrétien on a SkyWatcher EQ6-R
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1 year 5 months ago #55822

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@wvreeven thanks again for your answers.
You are using e very short exposure time for your photos, your technique is to make many shot at short time exposure ?
If yes, why do you prefer this metod instead of less photo at long time exposure?
The second metod should grant better quality imge, more dynamic range ... or not?

Paolo
1 year 5 months ago #55823

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OK sorry, I should have been clearer. Those short exposures are for the Flats and DarkFlats. For my Lights I take 30, 60, 120 etc exposures depending on the light pollution, the object and the filter used. For the Lights I use Master Darks with the same exposure time as those Lights when I use the ASI1600. With the ASI6200 I use the same 60 sec Master Dark regardless of the exposure time of the Lights.
Wouter van Reeven

ASI6200MM and 7 slot 2" filter wheel with a SkyWatcher Esprit 80 ED on a SkyWatcher HEQ5-Pro
ASI1600MM-Pro Cooled and 5 slot 1.25" filter wheel with an 8" TS Ritchey-Chrétien on a SkyWatcher EQ6-R
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1 year 5 months ago #55825

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Ok wvreeven now is more clear for me :)
Thanks and compliments for your nice photos posted in your profile.

Today will be a clear night without moon, so I'll take my first photos with my new camera... always if will not occur problems.

Paolo
The following user(s) said Thank You: Wouter van Reeven
1 year 5 months ago #55826

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you should almost certainly not use gain 0 with these new Sony sensors, the read noise is much higher at gain 0, but at gain 100 the read noise drops significantly with a slight gain in dynamic range. it is something unique to these Sony sensors, this logic does not apply to the asi1600.

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Last edit: 1 year 5 months ago by Brent.
1 year 5 months ago #55828
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Thanks for pointing that out. I failed to take the bottom diagram into account. I will start using gain 100 from now on. Luckily the lack of amp glow means that I only need to re-shoot one series of dark and that it!
Wouter van Reeven

ASI6200MM and 7 slot 2" filter wheel with a SkyWatcher Esprit 80 ED on a SkyWatcher HEQ5-Pro
ASI1600MM-Pro Cooled and 5 slot 1.25" filter wheel with an 8" TS Ritchey-Chrétien on a SkyWatcher EQ6-R
1 year 5 months ago #55829

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@suvowner thanks a lot for your explantion.
So I'll use always gan 100 for better results.

Paolo
1 year 5 months ago #55833

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