Atik Cameras

Author Topic: Atik383-L+ strange bias  (Read 3290 times)

GH-ATIK

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Atik383-L+ strange bias
« on: January 03, 2016, 05:44:05 PM »
Hi there,
in the last time. I got a strange bias-pattern ( see picture ) , the pattern ist observed in the final-picture. Is there anybody with a solution of this problem ( the bias is an average of 50 pics, -15C )

Thanks a lot

Gerhard

Max

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Re: Atik383-L+ strange bias
« Reply #1 on: January 04, 2016, 06:50:58 PM »
Hello Gerhard,

my Atik383 has the same behavior.
Please have a look to the picture (master Bias: 50 frames, binning 1x1, -25).
SW: TheSkyX Camera Add on, CCDStack.

Thanks
Max


GH-ATIK

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Re: Atik383-L+ strange bias
« Reply #2 on: January 04, 2016, 08:29:51 PM »
dear Max,

thanks a lot, I have two cams, one of them shows no interferrences, the other one showes this effect. unfortunately , these waves at the left side beats by the final picture.
I try out pixinsight and deep sky stacker for calibration, I think, there ist no mistake in the workflow.
Max, do you see this effect in your final picture, or ist this effect corrected with picturecalibration ?

Thanks a lot

Gerhard

Max

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Re: Atik383-L+ strange bias
« Reply #3 on: January 04, 2016, 08:51:15 PM »
Hello Gerhard,

yes and its terrible, especially in the OIII images there is the effect strong disturbing.

Please have a look to the picuture.
All work were done with CCDStack to be sure that there are no side effects.

The effect remains me on SBIG ST11k the banding problem.
There is a special SW for the SBIG banding effect: CCDBand-Aid.

Thanks
Max

GH-ATIK

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Re: Atik383-L+ strange bias
« Reply #4 on: January 05, 2016, 08:35:45 AM »
Hi there,

Yes, I have the same effect. the question is : is the cam defect or were a fault in workflow responsable ?
It seems, there is a problem in the electronicdevice during reading the electons from chip , or the chip is in incorrect condition.

Question : is the cam a case for atik-service ?

Thanks, Gerhard


Max

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Re: Atik383-L+ strange bias
« Reply #5 on: January 05, 2016, 10:56:44 PM »
Hi,

I made an experiment in four steps.

All Darks (40 x 900s) and Bias frames taken one with -25C.
The Dark Master has the same behavior as the Bias Master (banding on the left side).

All light frames are also from one night taken with -25C. (02/03-November-2015)

First Step:
The Dark Master has the same behavior as the Bias Master. So lets do some pixel math.

Please have a look to the picture. DarkMaster-BiasMaster.jpg
PixelMathe in CCDStack: MasterDark BiasMaster -> it looks got, no banding.

Conclusion:
Bias and Master should not be the problem (by this example).

Max

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Re: Atik383-L+ strange bias
« Reply #6 on: January 05, 2016, 10:57:49 PM »
Second Step:
CCDStack work: Calibrate (Darks, Bias, Flats), Register, Normalize, Data Reject and Stack.

Third Step:
Stack all frames from the night (43 x 900s frames)

Please have a look to the picture: Mean OIII3nm_allFrames-43x900s_.jpg
Funny: When I take all frames from the night then I see the banding on the right side of the picture.

Max

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Re: Atik383-L+ strange bias
« Reply #7 on: January 05, 2016, 10:58:50 PM »
Fourth Step:
Stack only with the frames before the meridian flip (24 x 900s).
Please have a look to the picture: Mean OIII3nm_beforFlip_24x900s-Frames_.jpg
Funny: When I take only the pictures before the meridian flip its looks fine, no banding!

Conclusion:
So it seems (by this example) its a problem caused from the light frame. I really dont know why the key factor is the meridian Flip (by this example).

Maybe: It could be the moon. It was half-moon, that means after midnight (and so also after the meridian flip) the light from the moon was disturbing the frames.

Thanks
Max

GH-ATIK

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Re: Atik383-L+ strange bias
« Reply #8 on: January 06, 2016, 10:17:10 AM »
Hi Max,

thanks, good idea, I tryed out a lot of combination in Pixinsight, but no chance. I think, I know the reason why : I performed my lights with dithering, and so, all frames were a bit moved and there is no way to get a congruent stack , no wonder for interferrences.
In future, I try out a session without dithering.

Thanks a lot , Gerhard

Max

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Re: Atik383-L+ strange bias
« Reply #9 on: January 06, 2016, 07:06:37 PM »
Hi Gerhard,

I performed also all my lights with dithering.
Today I took a closer look to my lights the behavior is not because of the meridian flip.

The banding in the bias frames are exactly the same as in the darks.
It seems that the banding in the light frames is changing over the night.

Thanks a lot,
Max

GH-ATIK

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Re: Atik383-L+ strange bias
« Reply #10 on: January 06, 2016, 07:25:32 PM »
Hi Max,

than it seems difficulter, as expected. If the banding is not stable, it is nessesary to take in every session, a new block of bias.

I try to observe this behavoir, and in the meanwhile , I think, the cam ist not ok.

Obviosly, we are now the only one, with these effect. Perhaps, there are some readers, who judge, if this behavoir is for some cameras normal or not.

In the moment, Im not satisfied, when the banding moves every day.

Thanks a lot, Gerhard


Max

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Re: Atik383-L+ strange bias
« Reply #11 on: January 06, 2016, 11:58:55 PM »
Hi Gerhard,

How old is your Atik with the banding problem and how old  is the other one without banding?
And what about the power supply?

I bought my Atik in December 2011.

Thanks a lot
Max

GH-ATIK

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Re: Atik383-L+ strange bias
« Reply #12 on: January 07, 2016, 09:54:16 AM »
Hi Max,

The first one was bought in march 2011 , and was in service in summer 2014 , because the sensitivity was under 30% , the mainboard was substituted.
The new one was bougt in februrary 2014 , there is a lttle banding visible.

I use a sabilisized powersopply at 13,5 Volt.

Today I tryout a 12V DC-car-battery , suprised what happend .....

best regards Gerhard

GH-ATIK

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Re: Atik383-L+ strange bias
« Reply #13 on: January 07, 2016, 01:34:28 PM »
Hi Max,

The last information was wrong :

It was a stabilized power-supply , adjusted to 12,5 V

here the to-day-old data :  n=50  1x1bin  -15C

GH-ATIK

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Re: Atik383-L+ strange bias
« Reply #14 on: January 07, 2016, 01:35:21 PM »
the same today n=20 :