|
very interesting discussion this. Its a very sound idia of measuring temperature by hot pixel.
Because my camera isnt temperature controlled, the software i use Iris has the ability to do "adaptive dark subtraction. I draw a small box covering at least 10 x 10 pixels or more on a light frame on an area free of stars. Iris measures the dark noise there and compares it to the dark frames. if there is a difference, it accounts for it. That way if a dark frame is hotter or colder then the light images, a good subtraction will still happen. Of course such a process is not 100% perfect, and I still try and take my darks right after the light images.
It would probably be fairly easy for a software programmer to write a small piece of software to measure the dark noise, and read the ISO and exposure time, and from that calculate a chip temperature.
I thought of a way to calibrate it by measuring the chip temp direct. I have a non contact thermomenter, that reads temperature by sampling IR ratiation from the object. I might take some long exposures and point the thermometer in towards the sensor and see how far above ambient the sensor gets
Scott
|