Any fix for amp glow ASI183MC

johnc3457

Still dealing with the amp glow problem is there any work around, subtracting dark frames does clean it up some but still leaves some problems

Support@ZWO

Hi, there.

Are you use a uncooled version?

johnc3457

The camera is cooled and I still get the amp glow on the right side all read noise is usually taken care of by the cooling but amp glow is still present

johnc3457

ampglow frame 3.jpgAttached file is cooled to -40 this reduced the normal noise but the amp glow at the right is very hard to remove even with dark frames. This was a 300 second exposure of M51 un stretched and with no preprocessing.

davebl

M8_120S_Sm2.jpgI have the Mono version of this camera and I found that lowering the gain and using shorter exposures seem to help. I'm still experimenting, but my skies are filled with smoke right now, so I'm on hold. I'm attaching a 120 second exposure in H Alpha, single frame with dark subtracted. Cooling to -20c.

Dave

davebl

Here's the same image without the dark subtracted. It seems that the darks don't do a lot to hide the amp glow. My gain is set to 0.

Dave

Support@ZWO

Hi

I think it is a inperfect calibration.

Dark frames maybe need to take again. with same exposure, gain, offset and temperature as light frames.

You can directly use master dark to calibrate light frame, without bias this time.

konihlav

for amp-glow tests (calibration tests) you may check my experience where I describe how to quickly check if calibration works (on CMOS cameras)

http://blog.astrofotky.cz/pavelpech/?p=1442

BTW with CMOSes there will always be a very, very little leftovers. Maybe only if you take the individual darks the same night (when camera was turned on) it might be 100% to calibrate out (so far I can reach some 99% which is OK for me).

Also, you have to use moderate gain, not completely zero and not too high.

Support@ZWO

Konihlav wrote:
for amp-glow tests (calibration tests) you may check my experience where I describe how to quickly check if calibration works (on CMOS cameras)

http://blog.astrofotky.cz/pavelpech/?p=1442

BTW with CMOSes there will always be a very, very little leftovers. Maybe only if you take the individual darks the same night (when camera was turned on) it might be 100% to calibrate out (so far I can reach some 99% which is OK for me).

Also, you have to use moderate gain, not completely zero and not too high.

Thank you so much for share your experience, it's a good for all of our users.

johnc3457

Working on the calibration has helped a lot also limiting exposures to 120 seconds. Attached file is of M8 taken from high light pollution skies in downtown El Paso TX, I'm not sure what Bayer pattern is in use but with my old camera all of the Ha areas of the nebula were red, is the chip setup for RGGB or BGGR?

Support@ZWO

The bayer pattern is RGGB.

bellavia

I too cannot get rid of all the amp glow, using a large stack of dark frames that were taken at identical gain, offset, exposure and temperature.

This is a serious issue, that needs to be resolved. It is true for both my 183MM Pro and 183MC Pro.

My most recent experience with non-removable amp glow was at Gain 100 (just below unity), Offset 12 (to prevent clipping the darks), 300 second exposure, -15 deg Celsius, for light frames and dark frames. No bias or flats were used.

Note: I cannot go any shorter than 300 seconds, as I mostly do narrow-band imaging. Even 300 seconds is too short.

I worked very hard on this object (3 nights, while having to go to work the next day), and I am not happy with the end result at all:

https://www.astrobin.com/359918/G/

Steve

Support@ZWO

bellavia wrote:
I too cannot get rid of all the amp glow, using a large stack of dark frames that were taken at identical gain, offset, exposure and temperature.

This is a serious issue, that needs to be resolved. It is true for both my 183MM Pro and 183MC Pro.

My most recent experience with non-removable amp glow was at Gain 100 (just below unity), Offset 12 (to prevent clipping the darks), 300 second exposure, -15 deg Celsius, for light frames and dark frames. No bias or flats were used.

Note: I cannot go any shorter than 300 seconds, as I mostly do narrow-band imaging. Even 300 seconds is too short.

I worked very hard on this object (3 nights, while having to go to work the next day), and I am not happy with the end result at all:

https://www.astrobin.com/359918/G/

Steve

Hi Steve

Thanks for your reply. I understand, if amp-glow such as 183, will be hard for long exposure calibration. I think 183mm/mc pro is more suitable for LRGB and short exposure imaging. I think 1600 is better for narrowband imaging, it's amp-glow is smooth.

Support@ZWO

bellavia wrote:
I too cannot get rid of all the amp glow, using a large stack of dark frames that were taken at identical gain, offset, exposure and temperature.

This is a serious issue, that needs to be resolved. It is true for both my 183MM Pro and 183MC Pro.

My most recent experience with non-removable amp glow was at Gain 100 (just below unity), Offset 12 (to prevent clipping the darks), 300 second exposure, -15 deg Celsius, for light frames and dark frames. No bias or flats were used.

Note: I cannot go any shorter than 300 seconds, as I mostly do narrow-band imaging. Even 300 seconds is too short.

I worked very hard on this object (3 nights, while having to go to work the next day), and I am not happy with the end result at all:

https://www.astrobin.com/359918/G/

Steve

Could you upload your dark frames and light frames, we will calibrate by ourselves.

bellavia

Hi again,

This is a link to my light (24 X Ha and 24 X OIII) and dark (41X) frames, all 300 seconds long, same gain, offset and temperature (-15C).:

https://drive.google.com/open?id=1K49uW5uw3bs3155E_FwkrE8TJ_90xIks

But except for perhaps one bright line, I am now thinking that the dark frames did calibrate most or all of the amp glow away, and that this is banding.

Dithering might solve this, but my low-end mount can only dither in RA, due to the huge DEC backlash, and RA is also the long direction of the sensor, as I like RA left-right and DEC North-South. But I can can change this and/or try to dither in both directions, with a longer settle time, for the long exposures.

Thanks for looking into this!

Steve

Support@ZWO

bellavia wrote:
Hi again,

This is a link to my light (24 X Ha and 24 X OIII) and dark (41X) frames, all 300 seconds long, same gain, offset and temperature (-15C).:

https://drive.google.com/open?id=1K49uW5uw3bs3155E_FwkrE8TJ_90xIks

But except for perhaps one bright line, I am now thinking that the dark frames did calibrate most or all of the amp glow away, and that this is banding.

Dithering might solve this, but my low-end mount can only dither in RA, due to the huge DEC backlash, and RA is also the long direction of the sensor, as I like RA left-right and DEC North-South. But I can can change this and/or try to dither in both directions, with a longer settle time, for the long exposures.

Thanks for looking into this!

Steve

Thanks, Steve. I will take a look after download complete.

hohr

At the beginning I had also problem with ampglow but it came from bias frame (?). Without bias amp glow is away. But it seems as dark must be taken at same shootout as light frames. edit: I just found out that images I rejected as being responsible for "negative" amp glow were taken another night at gain=0.

What I still see are some horizontal stripes/lines (on my image visible in background as red moire) or on the image posted on 22 July earlier in this thread. Whole background is uneven despite long integration time (115 x 180sec, darks, flats, gain 45). It's not present on flats or I didn't find it there and image with/without flats shows the same pattern. Cooled, to -35C.

Image is crop from center at 100%, processed in AstroArt.

Is it a good idea to do solar imaging with asi183MC like eclipses and so on?

Support@ZWO

HoHr wrote:
At the beginning I had also problem with ampglow but it came from bias frame (?). Without bias amp glow is away. But it seems as dark must be taken at same shootout as light frames. edit: I just found out that images I rejected as being responsible for "negative" amp glow were taken another night at gain=0.

What I still see are some horizontal stripes/lines (on my image visible in background as red moire) or on the image posted on 22 July earlier in this thread. Whole background is uneven despite long integration time (115 x 180sec, darks, flats, gain 45). It's not present on flats or I didn't find it there and image with/without flats shows the same pattern. Cooled, to -35C.

Image is crop from center at 100%, processed in AstroArt.

Is it a good idea to do solar imaging with asi183MC like eclipses and so on?

Yes, 183mc can do solar eclipse as well.

kevinfh

My first Astro cam is the ASI6200MM. Wow!
But, the pixel size is 3.6um and on my 120mm refractor, I can’t resolve galaxies well.
I could have purchased a longer focal length scope, but that would probably be expensive.
I thought the 183MC Pro, with much smaller pixels, might give me something to play with during galaxy season.
It was about $800, less than 1/5th the price of the 6200/filters/wheel.
I had read about the amp glow before purchasing, so I knew what I was getting.
And now I learned about skipping bias calibration, so I’ll redo the two galaxies I already have and are happy with. I did 1000 second exposures; There was some residual amp glow. But it was suppressed and copped pretty well.
The images aren’t free from glow like like the $6200, but then again it didn’t hurt to purchase either.
And, I didn’t process them as well as the could be processed due to AG.

Kevin_A

I have been using the 183mc pro for years and do not have any amp glow at all in my final images. The key is not using bias but using darks, flats and flat darks. The flats and flat darks should be matched, so if your flat is 1 second the flat dark needs to be 1s. The flat dark replaces the bias files. In your post processing software just substitute the bias files with the flat dark files. With all my other 533, 585 and 2600 cameras I use darks, flats and bias… just not with the old tech 183.

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