ZWO ASI485MC acquires noisy images with exposures over 1000ms

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IcyTofu
Posts: 2
Joined: Tue Oct 12, 2021 12:13 pm

ZWO ASI485MC acquires noisy images with exposures over 1000ms

Post by IcyTofu »

I'm beginner user. (This is first post)
I had start to use sharpcap with zwo asi485mc this week.

I noticed that noise suddenly appeared from a certain exposure time.
Here I set exp time 999ms gain 300, then I get histogram peak on 6.5 percent from left at dark frame.
Next I had change exp time to 1000ms and same gain 300.
Then histgram peak was move to 34 percent.

Is this normal?
Could you point it out me if I had misunderstanding of these behavior?

Using version is 4.0.8244 and ASI camera driver 3.17.
And sorry if there is already a similar post.

Regards,
Yamma
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admin
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Re: ZWO ASI485MC acquires noisy images with exposures over 1000ms

Post by admin »

Hi,

this isn't something I've heard of before, but the fact that it changes at exactly 1000ms seems suspicious - maybe somewhere in the ZWO ASI driver and SDK there is a change to the way the camera is operated when the exposure goes above 1s? SharpCap switches the camera from video mode to still mode at 2s exposure, so it will not be related directly to that changeover.

What I can suggest is

* try alternative software to see if the same thing happens at 1s in other software - if it does then it is definitely something in the ZWO code
* try asking on other forums - I'm not sure if there are any other 485MC users on here, but it would be useful for you to find out if others are seeing the same.

cheers,

Robin
IcyTofu
Posts: 2
Joined: Tue Oct 12, 2021 12:13 pm

Re: ZWO ASI485MC acquires noisy images with exposures over 1000ms

Post by IcyTofu »

Thanks for quick reply,
For now, ASICap v2.5.2 of ASIStudio is the only alternative software I can test.
But I couldn't see same things on exposure 999ms and 1s.

I will try to check other forum as well.

Thanks,
Yamma
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