Henrik you write "
all the Sinarbacks are very much better at iso 50" however the lowest iso setting on my eMotion75 is 100 so maybe I am missing something?
Looking into this further I found this information in a post by Thierry Hagenauer in
this old thread that confuses me even more:
Try the eMotion at ISO 100 and try another back from another brand at ISO 100. Compare the images and the histogram. Most probably you will see that the eMotion is 1 stop brighter than the other back, or that you have to switch the other back to ISO 200 to get the same exposure/density. Or in other words, "our" ISO 100 is equivalent to ISO 200 from another back.So does this mean digital iso is not standardised as film iso, and also that:
1) digital iso setting (eg on a MFDB) may represent a different exposure value than film iso (ie "correct" exposure at 100iso according to a reading from an old light meter may not be right for a MFDB set at 100 iso)?
2) doubling digital iso does not necessarily double the amount of light as doubling film iso (ie double the iso = exact same effect on exposure as opening up 1 f-stop or halving shutter speed),
3) lower digital iso does not necessarily translate into better IQ (since some MFDBs have a base iso of 200 while others have a base iso of 50 0r 100 asa)?
Obviously I don't know and please correct if I am wrong but all this makes me want to know even more the actual "optimal" iso setting for the eMotion75 as it seems like digital iso depends on whatever any manufacturer decides is best rather than any international standard.