CCD frosting

[rfdesigner]

Help!

Having got my shiny new 383L+ I just had to get out the other night and start playing.

slight cloud and a full moon didn't put me off either, I didn't want to get a decent shot, I wanted to bed the camera into my setup, get the problems out the way while it's cloudy.

So I encountered one problem which I am well aware of and I know roughly how to attack, but I am still just guessing and maybe someone can suggest a known fix.

the problem is CCD frosting.

The scope is a Newontian, the CCD is being used without a filter wheel until the bank balance recovers. What I believe is happening is that the cooled air in front of the CCD is falling away allowing new warm/damp air to come in contact with the CCD window.

To solve this I can:

A: use a less agressive setpoint temperature.

B: put a filter of some sort in the way to prevent the cooled air infront of the CCD window from escaping. I would anticipate that the additional filter will in time then cool down and the problem would be repeated.

C: change the setup so the CCD is pointed upwards so cooled air then doesn't fall off the CCD window. At the moment this will necessitate unbalancing the OTA so I'm reluctant to do this.

Is there another way?.. how do newt imagers prevent CCD frosting?

Derek

[robbieince]

Hi Derek

Nice camera. As you say, its quite a common problem with a few ways of approaching it - I use a small dew heater on the nosepiece of the camera - this warms the cover slip glass and stops the air in front of the chip cooling too quickly.

A couple of thoughts - the 383L should have a dessicant that has removed the moisture from the gas in front of the chip - this may need changing. Equally, doesn't the 383L have a setting to have a heater turned on for exactly this purpose? If think I heard it has to be turned on in an ini file before use though.....

[rfdesigner]

Thanks

I'm not aware of a heater.. I'll recheck the instructions.

The frost isn't happening inside the camera, (the image is showing broad dark and light bands after time, consistant with dew/ice forming on the cover glass not on the CCD glass or silicon itself.)

anyway yes a heater would help, I'll look into it.

Derek

Edit: looks like the Atik 4000 cameras have it, but no mention on the 383.

[robbieince]

The dew band will sort it- see here http://stargazerslounge.com/showthread.php?t=157321

Regards

Rob