Dark and Light and Fridges

[avandonk]

The first image is a dark. the second a light and the third light minus dark.

The fourth is a dark at 20C.

These are all the same region at 100% crop.

All were eight minute exposures at 200 ISO with the Canon 5DH. The fridge the camera was in was at -12C.

All were processed exactly the same before subtraction.

Bert

[h0ughy]

does make a remarkable difference Bert. I am impressed with the cooling of the camera. You have a some interesting noise in the camera that shows up in the image, and upon subtraction has left some artifacts i nthe final image. But there is a huge difference between the raw image and the processed one.

[avandonk]

Actally h0ughy I lied. The darks were taken at -10.7C and the light was at -12.3C hence the residual after subtraction. I just could not be bothered to do the darks again. Just shows how important it is to take darks at exactly the same temperature as lights. Thats why I swear By ICNR. I was manually controlling the fridge temperature. I am in the process of designing an electronic version. Pulse width modulation of one of the Peltiers should control the temperature adequately without any major sawtoothing. Peltiers also have a nasty property that if you lower the current you get a DROP in temperature for a delta time and then it rises again.

Bert

[Lester]

Thanks for the comparison images Bert.

Your fridge is so cool.

[Dennis]

Nice work Bert - good to see this so graphically demonstrated.

Cheers

Dennis