Oh dear - I need some help please?

[Hawklord]

Have just been testing out my ST-8300M attached to the 80 APO. using a revelation field flattener. Started on 5 minute subs. setpoint at -20deg. Stacked about 5 of them to give this image. All darks applied. There is a dreadful halo in the centre of all the subs. Does anyone have any idea what it is? Dew perhaps, stray light. I took a quick 0.05s flat by using the computer screen showing a complete white. It too has the strange anomoly. I 'm sure someone will know what it is, but I'm new to all this cooled CCD stuff.

Cheers

[Hawklord]

Forgot to also mention that there is a 2" skywatcher lpr filter at the front of the flattener.

[Tim]

I'd say that was ice or dew on the chip or filter

[Hawklord]

Thanks. So how do I deal with that then?

[Hawklord]

Ok it's probably dew or ice near the back of the flattener. Has anyone any experience of dealing with it? How about a dew heating band around the flattener?

[Hawklord]

Ah, after doing a bit of searching it looks like it's a known problem. Time to get out the soldering iron!!!!!!

http://www.sbig.com/pdffiles/8300Heater.pdf