Dew Intrusion ?

[cbweb]

Hi,

I'm not sure if I need to send my Atik383L+ in for a service.

Last imaging session I appeared to have moisture buildup contaminating my images right from the start. See attached M31 raw file stretched in Fits Liberator and reduced in size in PS but you can see the problem.

Central portion of the image looks ok apart from a dust bunny removable with flats, but then there is this narrow grey border beyond which what the heck looks like a smeared jeloid contamination with a peculiar texture.

Upon seeing these images I did a quick strip down of the camera and quick clean of the camera sensor and changed the desiccant tablets but on return though the contaminated border area had reduced, it was still there.

I use a dewbuster and dew shield and Focal Reducer. Could this combination be trapping cold air in the tube a SCT 11" and creating a fringing effect on outside areas of my images. Is there a problem with my tec setting of -25. Could there be moisture buildup on the objective, didn't want to lose my target so didn't examine this lens. The fact that I checked the camera hopefully eliminating it as the source of the problem has got me stumped.

Perhaps someone with greater experience of this than I can recognize the problem. If so, appreciate any heads up on this or thoughts on how to avoid same.

Cheers,

Colm

[Duczmal]

Hi Colm,

I also had a similar issue recently. Remove the three desiccant tabs and put them over an incandescent lamp for at least 24 hours, and keep the camera inside a warmed box (at 30C+) during three days, with the desiccant plug removed. Wait for the desiccant tabs to cool down before inserting them in the camera again. Some stains caused by the ice still remain over the CCD, but I hope they could be removed with flats. Next time, after turning off the cooler, wait for at least one hour with the camera turned on to warm its interior and avoid humidity.

Clear Skies!