385MC "amp" Glow worse at lower temperatures

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saguaro
Posts: 33
Joined: Sun Oct 02, 2016 4:51 pm

385MC "amp" Glow worse at lower temperatures

Post by saguaro » Thu Jan 24, 2019 8:49 pm

I have a 385MC with firmware version V 3.0. I've now had a chance to use the camera during the warm summer months as well as the cooler winter months. I've noticed that the "amp" glow in my master darks (created with SharpCap Pro 3.2) is much worse at cooler temperatures.

Here are two 15-second master darks, created at the Lowest Read Noise setting (Gain 300 Brightness 140). The only difference is the sensor temperature recorded by SharpCap when the master dark was created.

15.2C master dark:
dark_10_frames_15.2C_2019-01-24T02_54_01.jpg
15.2C master dark
30.6C master dark:
usb left again_dark_10_frames_30.6C_2019-01-24T15_30_05.jpg
30.6C master dark
Does the anti-amp glow circuitry perform worse when the sensor is colder? If not, what could be happening to cause the "amp" glow to be worse at colder temperatures? Thanks

-Robin

saguaro
Posts: 33
Joined: Sun Oct 02, 2016 4:51 pm

Re: 385MC "amp" Glow worse at lower temperatures

Post by saguaro » Thu Jan 24, 2019 8:53 pm

Also, here are two live-stacked image saved from SharpCap Pro 3.2 with the 15.2C master dark applied. There is still a blue glow in the upper right corner of the image that does not calibrate out.

M74 Gain 300
M74-26x15sec.jpg
M74, 26x15sec Gain 300 with master dark
Horsehead Gain 300
Horsehead-Neb-29x15sec.jpg
Horsehead, 29x15sec Gain 300 with master dark

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chad
Posts: 529
Joined: Thu Feb 09, 2017 4:58 am

Re: 385MC "amp" Glow worse at lower temperatures

Post by chad » Fri Jan 25, 2019 2:46 am

Hi Robin,
Got your problem.
But I have to say, at low temperature, the amp glow is not worse, on the contrary, it is better. But more obvious than high temperature。At high temperature, it is just not obvious.
Usually, we think the amp glow is caused by the heat of circuit and dark current. At a high temperature, dark current and heat also will be big for all of the pixels, as a result, the amp glow will be covered by them. But in low temperature, those pixels that are not affected by glow will perform better, but for other pixels, even their dark current also reduced, but the improvement was not great, which increased the gap between them. This in turn causes the amp glow to become more obvious.
Like a fire, you will feel warmer in winter than in summer. But in fact, the same fire loses heat faster in the winter, so it just widens the gap so that you can feel it more clearly.
Thanks
Chad
ZWO Driver Engineer
Location:lon=120.6 lat=31.3
SuZhou China

saguaro
Posts: 33
Joined: Sun Oct 02, 2016 4:51 pm

Re: 385MC "amp" Glow worse at lower temperatures

Post by saguaro » Fri Jan 25, 2019 2:14 pm

Thanks Chad. I created the master dark just before I started my live stacking. But the amp glow did not fully calibrate out with the master dark during live stacking. Do you have any suggestions as to how I can get the master dark to fully calibrate out the amp glow?

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chad
Posts: 529
Joined: Thu Feb 09, 2017 4:58 am

Re: 385MC "amp" Glow worse at lower temperatures

Post by chad » Mon Jan 28, 2019 1:16 am

Hi Robin,
Please take care of the temperature.
Usually, you should make sure all of the fields are at the same temperature. For cool camera, it is easy. but for uncool camera, it is not a easy job.
Thanks
Chad
ZWO Driver Engineer
Location:lon=120.6 lat=31.3
SuZhou China

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