I wouldn't recommend underexposing negative film for scanning - if anything give generous exposure to keep the shadow detail away from the toe. Colour negative film will show higher graininess with less exposure, and there should be no need to underexpose to preserve highlight detail in all but the most extreme lighting conditions. Colour negative film has a large dynamic range but a low gamma, so D-max is not excessive.
I'm puzzled about why Max is having problems with highlights 'blocking up' in a slide scanned on a Coolscan 9000. Something's wrong there. What pixel value are you setting your white point at?
B&W negs.
I use a couple of Minolta Elite 5400 (not the 'II' version) scanners for my 35 mm B&W negs. These are the best low-cost scanners I have come across for silver-image film, and I have a few (Polaroid 4000, Nikon 4000, Nikon 5000, Nikon 8000, Nikon 9000) along with ten years of experience scanning film.
Negatives that have been exposed and processed for printing by enlargement onto plain old silver gelatin will usually scan very well. You should be able to get every last bit of detail out of them.
Best,
Helen
Oh, Helen dear. You always seem to have these oh-so-easy be-all-end-all solutions to such common problems. How fortunate for you. You should write a book. I'm sure you'd make a killing solving everyone's problems with simple theoretical propositions. While I admire your scientifically-geared testing, most of your results are not replicable by mere-mortals. You must have a silver halide touch.
As for color negative film, I'm well aware of it's general capabilities, including its tolerance for overexposure. Grossly underexposing the film will introduce a lot of grain into the shadows just as you say...not so much with slight underexposure, though the effect of underexposure on grain will multiply in the faster films. Flatbeds especially have a very hard time dealing with fine highlight detail, whatever the film type. Color neg is no exception. I've devised this method precisely because this is a routine problem, not one that rears its head on rare occasions of "extreme lighting conditions."
The Nikon scans are uncorrected TIFF. But perhaps you're right. There must be something terribly wrong going on in the multi-million dollar multimedia lab I work in. The Nikon, for all its reliable and excellent general performance, still does have its shortcomings. One need only compare it against a Flextight or better yet a drum scanner to see that.
As for black and white, I can't speak for Minolta as I've never used it. But the SprintScan series are really terrible pieces of crap as far as I'm concerned. When I wrote earlier about these problems occurring with black and white negatives, I was referring mostly to flatbeds, though I have had the occasional problem on nicer equipment. Either way I think black and white is a moot point. I don't advocate anyone underexposing all of their shots unless they really know what they're doing, i.e. do it as part of a finely-tuned shooting workflow (Nick Brandt, for example, grossly underexposes his subjects in order to nail the background/sky and then sucks every bit of detail out in post that he can find). What I was speaking on was not whether you should underexpose b&w, but rather whether average quality scanners are capable of recovering fine detail from a normal exposure. Applying this method to black and white film, in many cases, would produce underwhelming results.
Please bear in mind the audience I am speaking to here. Mostly I am not speaking to those with access to excellent equipment as I stated in my original post, but to people with everyday equipment who shoot to digitize and have had chronic difficulties. The problems I've described are endemic to most consumer and "pro-sumer" grade scanners. This is simply a proposition of one way to cope with their shortcomings.
If you have some better alternative, please, by all means, speak up because I'd love to use it myself. But for most, feasible does not include spending large amounts of money on a scanner (and let me preempt you by noting that judging from your previous posts, your idea of a modest equipment price has a seriously inflated price tag).
Best,
Max