Trying to understand the best way to describe sensitivity in digital cameras. We describe dynamic range with a simple number, but is there an equivalent for how well a camera performs in low-light? Most people seem satisfied to just understand that the F55 is good and the Blackmagic is bad, but HOW good and HOW bad? It seems that most people learn whatever ISO is too high for them on a given camera and just stay below that... but wouldn't it be useful to quantify?
I've researched the "aperture @ lux" method, where you find the t-stop that gives you a 100 IRE reading of a white card with 89.9% reflectance at 2000 lux, but without also defining the ISO, I don't see how the test can be consistent.
That led me to look at signal-to-noise ratios, which as far as I can tell seems like the answer, as they don't vary with the ISO. The F55's SNR of 57dB won't tell you how far you can push the ISO (that's still something that everyone has to decide for themselves based on how much noise they can tolerate), but it WILL allow you to compare it to the C300's SNR of 54dB and say "those two are about equally sensitive". Right? And perhaps if it became a more widely understood term, we WOULD be able to easily correlate it to ISO ("an SNR of 57dB means I'll be able to go to about 2000ISO and it'll be acceptably clean to me").
Or am I way off the mark? Is there more to it that makes it such a hard thing to quantify (image processing in camera, for example?)
Thanks in advance for your help!
I've researched the "aperture @ lux" method, where you find the t-stop that gives you a 100 IRE reading of a white card with 89.9% reflectance at 2000 lux, but without also defining the ISO, I don't see how the test can be consistent.
That led me to look at signal-to-noise ratios, which as far as I can tell seems like the answer, as they don't vary with the ISO. The F55's SNR of 57dB won't tell you how far you can push the ISO (that's still something that everyone has to decide for themselves based on how much noise they can tolerate), but it WILL allow you to compare it to the C300's SNR of 54dB and say "those two are about equally sensitive". Right? And perhaps if it became a more widely understood term, we WOULD be able to easily correlate it to ISO ("an SNR of 57dB means I'll be able to go to about 2000ISO and it'll be acceptably clean to me").
Or am I way off the mark? Is there more to it that makes it such a hard thing to quantify (image processing in camera, for example?)
Thanks in advance for your help!