Originally posted by Alex645 a) Isn't he really testing exposure latitude and not dynamic range? Dynamic range would be shooting a normal exposure in high contrast lighting and seeing at what point do the highlights and shadows lose detail in the film vs. digital.
Agreed, that is the traditional way these things would be done. When I establish a working EI, I use a standard setup in direct sun to challenge the dynamic range based on detail retention. If I can't get a full eleven stops with reasonably smooth tonal gradation and detail retention in all but the extremes, I either decide against the film or look to a different developer.
Originally posted by Alex645 g) And then there is the whole question of post-processing analog vs. digital:
That is the elephant in the room. A more reasonable assessment might be made comparing prints with prints, but that is not Internet friendly. Most film images suffer some from digitization and even more so if an attempt at raising values is made in post. A RAW capture on the other hand, gives the processing software (Yay, ACR!) a great amount of leeway in constructing a reasonable shadow representation from very sparse data. (There are only 8 integer values to represent all tones for the bottom 4 stops of capture data, zero excluded)*. I have done a few simple studies with synthetic images showing that our tools do a considerable amount of work creating expected tonality in the shadows, i.e. creating something out of almost nothing. Adding +2 stops "exposure" in Lightroom to a discrete step image (9 1-stop steps) results in an unexpected value distribution with much of the lowest values being retained, rather than abandoned, and invention throughout.
Steve
(...really needing to do more work with synthetic data, but need a few better tools and some skills with MATLAB...)
* Zero indicating values below the sensor detection threshold (i.e. no data) for a particular capture.