target temperature

Now that it is getting warmer outside, so is the camera (SBIG ST-10). What should be my target temperature? The SBIG manual says something like 40 below ambient, but that is rare for me. What are people on this forum getting? I don't have a water pump, but should I?

Also, while the camera is cooling, I see some VERY odd transient things on flat field images that I take. Are these ice crystals on the filters? (I live where there is no humidity to speak of.) I usually end up going below my target temperature by 5-10 degrees and then "warming" the camera to get these things to clear up faster. Late at night I have usually been able to get to -20C eventually, but that has been getting harder recently. The whole process usually takes close to an hour. Is this normal?

Thanks for any help,
Charlie

Hi Charles,
Don't concern yourself with target temperatures, but with the % of cooler usage. Start with a cooler temperature about 15 degrees below ambient and work your way down until the cooler is working at about 75%. As a general rule, you don't want to go over ~80%. If you're going to experience a large ambient temperature drop during the course of the night, you can start at something higher, say 90%, and can then be reassured that you won't experience problems.
Don't bother with water cooling until you're familiar with your camera. The vast majority of users never use it anyway.
You certainly don't want to be taking flats while the camera is cooling. Wait until it's stabilized. I take flats and especially darks at the end of a session.
Do you know what frost on the cover slip looks like? It certainly sounds like that is what you're experiencing. Post a jpeg of what you're seeing if you're unsure. It's an easy fix-just bake your dessicant. Follow the directions and don't forget to take the O-ring off.

dan