Quote:
Originally Posted by traveller
Luka, I experiment with my DSLR settings. I set ISO at 800 for brighter objects like 47 Tuc and M42, but for fainter objects, I go for 1600.
I have done 5 mins at 1600, but they are very noisy (sensor running at 30c) ....  |
Bo where are you getting that sensor temperature data from? The CMOS sensor, does not contain a temperature sensor. The temp data you see in the EXIF is actually the DIGIC processor temperature which is on the separate main board. The processor is likely the hotest part of the internals but can be used as a proxy for the CMOS although it will actually be a little cooler. The processor is heating up the other components but not directly. If you have a multiprocessor camera, and some later mdels have two DIGIC chips then more heat is generated. You can try to reduce processor workload, and heat, by turning off functions that require the processor - like internal noise reduction, camera dark generation, etc. All those auto functions generate more heat. If you shoot separate darks, and bias frames, you don't need the internal dark generation or noise reduction processing. Of course cooling the CMOS sensor directly is the only way to get frames and darks to match at any sub duration. In that situation, where bias and darks match (which is around 0C in a 450D) you can stop doing darks, or just shoot a group at 0C and then use the Master Dark and Master Bias for all your stacking.