ASI1600-MMC banding with TEC

vehnae

Hello,

I received my ASI1600MM-Cool a while ago and have been doing some initial testing. Otherwise the camera looks very promising but I noticed that the bias frame exhibits random horizontal banding when the TEC is on. Their location is random in each frame so they cannot be calibrated out, and their intensity varies directly with the current TEC power (%). When the TEC is turned off the banding vanishes completely.

I have the latest software versions (driver v1.3.5.20, ASCOM v1.2.0.9) and have tried using a different power supply etc.

Here is a sample of the problem:

And here are download links for single bias frames with TEC at 80% and off (at the same sensor temperature).

https://www.dropbox.com/s/rx98iohx8i1g9l9/ASI1600%20-20c%20TEC%2080%25.fit?dl=1

https://www.dropbox.com/s/mh672t6n331uu5o/ASI1600%20-20c%20TEC%20OFF.fit?dl=1

I haven't heard reports of this behaviour from other users so I figured that something could be wrong. Any suggestions?

Best Regards,

++ Jari

Sam@ZWO

we saw this problem sometimes and we suspect this is because of magnetic field effect caused by power supply cable

seems it will disappear when the target temperature is reached

vehnae

The banding consistently appears when the TEC reaches 15-20% power or more. Depending on how much cooling is needed this may or may not be a problem after the target temperature is reached and the TEC stabilizes. Any practical suggestions? Should I try making my own power cable from a well shielded cable?

Thanks!

Sam@ZWO

we didnot try shielded cable as it won't have problem with the final image

but you can try and feedback

vehnae

Hello Sam,

I tried making a shielded power cable from coaxial cable but this didn't have any effect.

I had a chance to compare my camera with another ASI1600MM-Cool. With the same setup/cabling (just switched the camera) the other camera does not exhibit this kind of a problem. My target application would be imaging very faint nebulae in narrowband, so I'm a bit worried that although very faint, this might affect the final image. Would it be possible to have my camera exchanged?

Best Regards,

++ Jari

Sam@ZWO

Hi Jari

I think the line will disappear when you get a stable temp?

I am afraid all cooled cameras have such issue

just don't know when it will appear

we saw it for many times

pipplo

Bumping up this old thread. Does anyone have any more details on this over the last few months? I'm starting to see this show up in my images too. (As linked here: http://www.cloudynights.com/topic/564547-horsehead-nebula-asi1600mm-cool-horizontal-pattern/)

Is it something that just needs to be overcome with more frames?

vehnae

Unfortunately I didn't find a solution for this. But in my case I set the camera to -20C and thanks to Finnish weather the cooler stabilizes to such low power (5-10%) that the banding is not visible even with narrowband exposures. But in practice this means that I can't take high-quality bias/dark frames indoors.