I use an Optec Gemini focuser and make extensive use of its temperature compensation routines. Since TC is enabled in the ASCOM driver, it can be enabled at the beginning of the night and run continuously all night. However, I use SGP’s auto focus routine to perform auto focusing on a regular basis. Basically, SGP gets a good focus at the start of a sub and the auto TC maintains that focus during the exposure. When taking 30 minute narrow band images, the TC keeps the frame in focus during that 30 minutes. On a night of rapid temperature drop, a sub can easily drift out of focus during a long exposure.
With my focuser and my 12" Meade LX850 OTA, the temperature compensation is around +800 steps / degree C. With my 130mm APO, the TC is about -275 steps / degree C. These numbers are atypically large due to the very small step size of my focuser.
The data maintained by SGP’s Image History can be used to calculate the temperature compensation value for your focuser. For me, this has proven more accurate than using the various TC wizards in SGP and in Optec’s software. One note – be sure to protect the temperature probe from wind. Wind will cause the temperature reading to fluctuate randomly.
Getting a really accurate temperature compensation value will require some effort.