Originally posted by Vertex Ninja I think this is where I'm confused. A negative has a maximum density. It is finite, and in the case of color it does not exceed most scanner's D-Max. You don't have to do multipass to scan everything on Portra NC and it contains far more stops than RVP50, for example. The scanner doesn't understand stops, only values of 0-1. We can also apply the same thinking to B&W negatives. I don't know what the maximum density of any given B&W negative is, but lets say 3.0-3.5d. So we could say the negative needs a capture range of B+F to ~3.0d to get everything off it, regardless of how many stops the scene had. If your scanner has a true D-max of 3.5 and a D-range of ~3.2, then it should in theory, be able to capture everything on the negative in a single go.
None of the amateur scanners reaches the advertised specs, be it the resolution or be it things like Dmax and dynamic range. I think, this is something we unfortunately have to agree upon. Than we must realize, that the deltaD a scanner gives is includes the maximum range, he is capable of capturing by adjusting its light source brightness or gain. I am not convinced, that the usual cheap scanners actually cover the advertised range in one single scan pass.. An indicator for this might be, that Silverfast and Vuescan both include Multiscanning features and that in my experience these produce very visibly wider contrast ranges than any single scan pass.
I am not a big fan of Ken Rockwell, but he sums quite nicely the confusion about Dmax and dynamic range:
"D range is a more meaningful spec than D max, and here's why: Remember that marketing departments may choose to measure Dmax with the analog gain or the light bulb turned all the way up, in which case you can see into deeper blacks, but will lose the highlights. You have to read and ask carefully, everyone lies differently. If you see a spec of Dmax 4.2 and D range 3.9 that means that the D max of 4.2 is really a hoax. It means you really can't get to D max of 4.2 unless your highlights are dull gray at 0.3D. The only way a scanner like that gets to see 4.2D is by turning up the light bulb a stop and blowing out highlights at less than 0.3 D. With a decent transparency this hypothetical scanner really only has an effective D max of 3.95, with a D min of the good transparency probably 0.05D. " (quoted from:
Scanner Technology)
The conclusion is, that a scanner needs multiple expsoures to cover the whole range and than automatically merges these exposures to an DRI image.
I see the Dmax quoted everywhere, where a discussion about scanners evolves - but it is really only half of the story. The dynamic range is much more important.
Originally posted by Vertex Ninja You are exactly right about having a flat image once scanned in. However, since you are now digitized and assuming 14/16-bit capture, you make tone decisions in software. The "hdr" happened at developing time.
That's true. You do the tone mapping with the final scan, as its deltaD is much higher, than any print medium would cover. But it is basicvally the same thing, you did in the wet darkroom with doging/burning and split epossure.
Originally posted by Vertex Ninja As far as developing, a 2-bath solution for roll film is pretty nice. Multiple images on a single roll make doing something like Zone or BTZS much harder... in my limited experience anyway.
That's true. And AA developped the zone system from out of his LF experience. Working with that on roll film is a pain - I never did. I know some people do that, by marking film parts with stickers for different developping times etc. But I really think a 35mm neg is not worth that much effort. That's probably a purely personal thing, though.
Ben