Adam, I'm happy that there is success
EXIF temperature is measured inside the camera body, which heats during long exposures. Typically astro exposure rise the temperature with 5-6 degrees. This can be minimized with using longer duration between them. There is a theme in CN with more details on this (
http://www.cloudynights.com/ubbthrea...Number=4199459).
Storing EXIF temperature in the image file name is feature available in the full version only.
Wasyoungonce,I'm trying to find a solution for the overshooting. In fact with my 1000D there is undershooting. The problem is that the different cameras has different delay between the command "Start shoot" and the real start of the exposure. I have already included this delay in the calculations, but looks like rounding is giving 1s difference...