Calculating DSLR Noise Sources Including LP

[STEVE333]

Thanks Rick - I wasn't familiar with that nice Script

Glad I could help, Steve.  I have just been through the process of characterising a couple of new CMOS cameras.

Rick - Do you know if that Script works on DSLR cameras where some "unknown DNR stuff" that can include messing with the baseline goes on?

Steve

[RickS]

Rick - Do you know if that Script works on DSLR cameras where some "unknown DNR stuff" that can include messing with the baseline goes on?

Hi Steve,

It will depend on what pre-processing is being done by the camera.  If it is some sort of noise reduction then that would definitely produce incorrect results.

Cheers,
Rick.

[STEVE333]

I mention all of this because it is not always easy to find or calculate the e-/ADU value for your camera

It's actually quite easy.  All you need is a pair of bias frames, a pair of flats and a short and a long dark.  Plug them into the BasicCCDParameters script and it will estimate gain, read noise, dark current and full well capacity.  All very useful parameters to know...

Rick - I tried the BasicCCDParameters script with my DSLR data. Unfortunately it doesn't work well. I believe the problem is that Canon DSLR cameras subtract counts from the RAW signals before they save the images. They attempt to keep the mean ADU value from becoming too large because of dark current during long exposures. However, this screws up any calculations that assume the data is linear (which it is for the cooled CCD cameras). Too bad!!

Steve

[RickS]

That's a shame, Steve.  I've always used CCD cameras and tried some DSLR wide field stuff recently but really wasn't happy with the pink stars and other issues.  It was possible to make a nice image but a lot of effort went into fixing the deficiencies in the data.  So, I decided to limit the DSLR to daytime landscapes and bought a couple of cheapish ZWO CMOS cameras...

Cheers,
Rick.

[STEVE333]

That's a shame, Steve.  I've always used CCD cameras and tried some DSLR wide field stuff recently but really wasn't happy with the pink stars and other issues.  It was possible to make a nice image but a lot of effort went into fixing the deficiencies in the data.  So, I decided to limit the DSLR to daytime landscapes and bought a couple of cheapish ZWO CMOS cameras...

Cheers,
Rick.

Those ZWO cameras look pretty interesting, especially with the reasonable prices. I've been eyeing them myself.

All the best,
Steve