ASI183MM Grid Artifacts

joecool1211

Hi!

I received a new ASI183MM camera and managed to try it out today with a H Alpha image of the sun.

I noticed on FireCapture that I could see a grid pattern on the preview. The stacked image also showed artifacts (exaggerated below):

ASI183MM_Artifacts.png

I do not encounter this with my ASI290MC.

Any advice?

Thanks!

Support@ZWO

What settings in capture do you use? such as gamma, gain, exposure, bandwidth.

Did you try the horizental banding reduce function in Autostakkert!3?

Could you send us a original video, you can put it on dropbox. <1GB will be fine. We only need for test.

joecool1211

Thanks for the prompt response.

The optical chain was:

Lunt LS80Tha -> B1800 Blocking Filter -> Televue PowerMate 2x -> ASI183MM

Here are FC settings:

FireCapture v2.6 Settings

------------------------------------

Observer=XXX

Camera=ZWO ASI183MM

Filter=L

Profile=Sun_HAlpha

Filename=2018-05-24-0250_6-JC-L-Sun_HAlpha.ser

Date=20180524

Start=025013.813

Mid=025038.710

End=025103.607

Start(UT)=025013.813

Mid(UT)=025038.710

End(UT)=025103.607

Duration=49.794s

Date_format=yyyyMMdd

Time_format=HHmmss

LT=UT +8h

Frames captured=4658

File type=SER

Binning=no

ROI=800x800

ROI(Offset)=0x0

FPS (avg.)=93

Shutter=5.294ms

Gain=130 (28%)

USBTraffic=100 (off)

SoftwareGain=10 (off)

Brightness=8 (off)

FPS=100 (off)

HighSpeed=off

AutoGain=off

Gamma=50

HardwareBin=off

AutoHisto=75 (off)

AutoExposure=off

Histogramm(min)=1643

Histogramm(max)=2737

Histogramm=66%

Noise(avg.deviation)=n/a

Limit=none

Sensor temperature=43.2°C

For AS!3, I did not use the banding reduction.

Here is the link to the raw file, which I truncated with PIPP.

https://www.dropbox.com/s/wmdq3yfsugkf0cw/2018-05-24-0250_6-JC-L-Sun_HAlpha_pipp.ser?dl=0https://www.dropbox.com/s/wmdq3yfsugkf0cw/2018-05-24-0250_6-JC-L-Sun_HAlpha_pipp.ser?dl=0

merlin66

Joe,

Not sure what the problem is, but I also used the ASI183MM (and the ASI 174MM) for solar imaging - either a 102mm PST mod or the SM60/ ED80 combo and haven't experienced these artifacts.

I'm using a fast MSI laptop with good USB3 , 16 Gb memory and 1Tb SSD drive. I also use FireCapture.

Support@ZWO

we will try to find out the reason

joecool1211

Hi!

I did more testing today. I tried various combinations of USB speed, gain, exposure time, etc. But the results are the same. Here is a screenshot of FireCapture. The pattern is easily seen.

FC-GridPattern.png

It seems to be some sort of interference pattern (this is Halpha imaging) aligned with the sensor matrix grid.

Hopefully your investigations yield some clue as to the issue.

Thanks!

Support@ZWO

We have another users report same issue. We checked all original files form both of you, for now, I think in Solar narrowband imaging, if bandwidth <0.1nm , there will be a pattern. But for visible light solar imaing, lunar imaging, and DSO imaging, everything looks perfect.

Did you try visible light solar imaging with baader film or hershel prism?

joecool1211

Thanks for the response.

Yes, that is my experience also. I have tried imaging the moon in white light and did not see any pattern.

So far, I have noticed the pattern only when imaging in narrowband Halpha (<0.1nm).

merlin66

Sean,

What's the answer for solar Ha users????

Support@ZWO

Merlin66 wrote:
Sean,

What's the answer for solar Ha users????

For now, I think 183 is not suitable for Ha solar imaging. We would like to do some test by ourselves, but the weather this month is to bad, never got a clear day.

joecool1211

I don't think that is a good response. The product description even says "Fast FPS can be used in solar and lunar imaging, as well as for live viewing/EAA."

Appreciate a solution (or otherwise provide options for exchange/return) for those who have purchased the camera for solar imaging based on the published description and specifications.

merlin66

Sean,

I've sent you a PM........

Support@ZWO

joecool1211 wrote:
I don't think that is a good response. The product description even says "Fast FPS can be used in solar and lunar imaging, as well as for live viewing/EAA."

Appreciate a solution (or otherwise provide options for exchange/return) for those who have purchased the camera for solar imaging based on the published description and specifications.

I'm sorry we didn't mean to mislead everyone, we didn't found that issue before.

Actually there are two things in this case.

1. horizental lines, usually your can use unity gain to reduce the problem, also Autostakkert have a such function for IMX174， reduce horizental lines.

2. patterns on Ha solar imaging, it's like a gridding. if use some subtransparent cover the telescope and take flats will solve it.

Such patterns is not appears in white light solar imaging, lunar imaging and DSO imaing.

If someone choose this camera only for Ha solar imaging, please send us a email to support(at)zwoptical.com, we will help you switch to a suitable model.

joecool1211

Just to close things off.

As the resolution of the camera was a good match for my solar/planetary interests, I finally made a decision to move to the cooled version of the ASI183MM so I could do some other astrophotography with it, too. ZWO was helpful in arranging an exchange and even shipped the items I bought separately from their website together with the replacement camera. Quite amazing they noticed the new order going to the same place!

And even more surprisingly, the replacement camera did NOT exhibit the same fixed noise pattern! My conclusion is that whether the pattern appears at very narrow bandwidths really depends on the individual unit. It seems that different people with the same model of camera can have different quite different experiences.

Thanks again to Sean and ZWO for the support!

Support@ZWO

joecool1211 wrote:
Just to close things off.

As the resolution of the camera was a good match for my solar/planetary interests, I finally made a decision to move to the cooled version of the ASI183MM so I could do some other astrophotography with it, too. ZWO was helpful in arranging an exchange and even shipped the items I bought separately from their website together with the replacement camera. Quite amazing they noticed the new order going to the same place!

And even more surprisingly, the replacement camera did NOT exhibit the same fixed noise pattern! My conclusion is that whether the pattern appears at very narrow bandwidths really depends on the individual unit. It seems that different people with the same model of camera can have different quite different experiences.

Thanks again to Sean and ZWO for the support!

You are welcome! Well, looks like the sensors have different characteristic. Enjoy the camera!