Step-by-step cooling of a CCD camera is a fairly common theory among French astrophotographers, who believe that too rapid cooling could cause damage to the CCD sensor. Since this idea is supported by a few big names in the French-speaking astro community, it has become a basic rule. I'm quite divided; when I think about it, I apply steps for cooling, but when I don't think about it, well, not much serious happens. I've browsed a lot of foreign forums, I haven't read this cooling method elsewhere. A colleague of mine applies the following rule: he drops the temperature by 5°, he waits 5 minutes. And so on, to reach -15°. His photos are superb; but is his cooling method essential? I'm not totally convinced... Otherwise, there must be a way to make a script to automate the method.