ASI1600MM COOL PRO SENSOR ANALYSIS

mAnKiNd
Posts: 181
Joined: Sun Jun 11, 2017 4:55 pm
Location: Long Island, NY
Contact:

Re: ASI1600MM COOL PRO SENSOR ANALYSIS

Post by mAnKiNd » Sun Jun 24, 2018 1:04 am

Hi Brian,

Hah! That's great to hear about the reduction in dark current! Proof of concept for cooling I suppose :)

Yes I had it enabled and yes, I realise you're the responsible party for that implementation! :P In my mind, I've always felt compelled to keep the data as raw as possible for post-processing, even if it does "look" darker in the post-calibration/stacking result. I'm happy to hear and accept arguments against this for astrophotography though..

Let me know how the rest of the data analysis goes!

Cheers
Minos

User avatar
oopfan
Posts: 456
Joined: Sat Jul 08, 2017 2:37 pm
Location: New York
Contact:

Re: ASI1600MM COOL PRO SENSOR ANALYSIS

Post by oopfan » Sun Jun 24, 2018 3:31 am

Minos,

Here are the results. It's pretty much base 10 logarithmic but for clarity I'm scaling it linearly here. I gotta get me one!

Thanks, Minos. Wouldn't it be nice if manufacturers provided this information? It seems like something that lends itself to automation. A good summer project for an intern.

By the way, your value at +20C matches almost precisely my value at +68F for my Altair 290M (uncooled).

Brian
Attachments
Dark Current vs Sensor Temperature (ZWO ASI1600MM-C).jpg
Dark Current vs Sensor Temperature (ZWO ASI1600MM-C).jpg (94.35 KiB) Viewed 856 times

mAnKiNd
Posts: 181
Joined: Sun Jun 11, 2017 4:55 pm
Location: Long Island, NY
Contact:

Re: ASI1600MM COOL PRO SENSOR ANALYSIS

Post by mAnKiNd » Sun Jun 24, 2018 3:42 pm

Brian, wonderful, thanks for the analysis! :)

Looks like there is not a big reduction in dark current for -20°C vs -10°C and since I'm powering the camera with a portable lithium battery, it may be better for power conservation to keep the camera at -10°C, so as to last longer.

Cheers
Minos
Last edited by mAnKiNd on Sun Jun 24, 2018 3:47 pm, edited 1 time in total.

User avatar
oopfan
Posts: 456
Joined: Sat Jul 08, 2017 2:37 pm
Location: New York
Contact:

Re: ASI1600MM COOL PRO SENSOR ANALYSIS

Post by oopfan » Sun Jun 24, 2018 3:46 pm

Minos, I agree with you if you are running off a battery pack but if you are running off of mains I would go down to -20C. The benefits look small due to the linear scaling of the vertical axis. Perhaps Robin can add to this discussion since it is a little out of my realm of experience.

Brian

mAnKiNd
Posts: 181
Joined: Sun Jun 11, 2017 4:55 pm
Location: Long Island, NY
Contact:

Re: ASI1600MM COOL PRO SENSOR ANALYSIS

Post by mAnKiNd » Sun Jun 24, 2018 3:47 pm

Good points Brian!

User avatar
admin
Site Admin
Posts: 2745
Joined: Sat Feb 11, 2017 3:52 pm
Location: Vale of the White Horse, UK
Contact:

Re: ASI1600MM COOL PRO SENSOR ANALYSIS

Post by admin » Sun Jun 24, 2018 4:46 pm

Hi folks,

the dark noise plot above looks fairly typical in shape (you can find similar plots online). The choice of how far to cool basically comes down to the sky background brightness.

If you are imaging with light pollution with no filters and your sky brightness is 1 e/pixel/s (or higher) then there's really not much point in going beyond about +10C - total noise is going to be 1 e/pixel/s from the sky and a bit over 0.1 from the sensor, so maybe 1.12 e/pixel/s. Cool it down to -20 and you still get about 1.01 or so, which is only a 10% improvement - not really worth it.

Change to a dark site or go to narrowband with sky brightness of 0.1e/pixel/s or lower and it's now worth cooling as far as you can, since the drop from 0.12 to ~0.01 is worth it compared to the smaller sky brightness.

hope this helps,

Robin

mAnKiNd
Posts: 181
Joined: Sun Jun 11, 2017 4:55 pm
Location: Long Island, NY
Contact:

Re: ASI1600MM COOL PRO SENSOR ANALYSIS

Post by mAnKiNd » Sun Jun 24, 2018 5:09 pm

Thanks Robin, makes sense.

Minos

RolandK
Posts: 1
Joined: Fri Dec 14, 2018 10:52 am

Re: ASI1600MM COOL PRO SENSOR ANALYSIS

Post by RolandK » Fri Dec 14, 2018 10:55 am

Hi guys,

I am a bit confused how to interpret SCap gain values while using ASI...
Lets say, I set up Unity Gain on ASI driver (139),
and how SC treats that gain number? =139 also? or 0? or 100?

A bit confusing...

User avatar
admin
Site Admin
Posts: 2745
Joined: Sat Feb 11, 2017 3:52 pm
Location: Vale of the White Horse, UK
Contact:

Re: ASI1600MM COOL PRO SENSOR ANALYSIS

Post by admin » Fri Dec 14, 2018 4:54 pm

Hi,

the gain value displayed in SharpCap for the ZWO cameras will match the values shown on their sense of charts on the ZWO website. So if you're looking for unity gain at a value of 139 then just set the SharpCap gain value to 139. ZW0 cameras measure the gain in tenths of the decibel above the minimum camera again, so a value of 139 means that the actual gain is 13.9 dB above the minimum value.

Hope this helps, Robin

Post Reply

Who is online

Users browsing this forum: No registered users and 1 guest