Dark frames for Canon DSLR?

[gthomas]

I've done some testing with my Canon 450D and confirmed what I've read that the camera is pre-procssing the RAW image such that the background level is always around 1024.

As this suggests that darks cannot, therefore, be scaled meaningfully, is there any need for darks at all with this camera or would a master bias be enough?

[Photosbykev]

have you turned off all the noise reduction features of the camera before shooting the lights and darks? I use darks taken on my 7d and 5D MkII and imo they do make a difference.

[gthomas]

Yes I have all those settings turned off.

[RikM]

I always shoot darks for my 1000D as well. I get a better result with the darks.

[gthomas]

According to what I've been reading on-line (mainly stark-labs website) I think this pre-processing is a feature of the older Digic III based cameras and the newer models behave in a more normal manner.

[RikM]

the 1000D has a Digic III procesor. I don't scale my darks, I take a temperature matched set each time, but they certainly work.

[dph1nm]

I always shoot darks for my 1000D as well. I get a better result with the darks.

Curious - I find they are useless. In fact I found no difference between a 5min dark and a bias (1/4000 sec) exposure on my 1000D. RAW levels are the same (with all in-camera noise reduction switched off).

NigelM

[themos]

The 1024 in the 450D is the offset/bias level.

[Psychobilly]

Curious - I find they are useless. In fact I found no difference between a 5min dark and a bias (1/4000 sec) exposure on my 1000D. RAW levels are the same (with all in-camera noise reduction switched off).

NigelM

I also stopped using darks with my 1000D...

Peter...