How to scan a test roll?

[blacklight]

Hi,

I have shot a roll of Tri-X to test it with Rodinal. I exposed for shadows @ EI 400 and then in half steps to +2 and -2. I am not very experienced in judging the nagtives, so I have scanned the film - but when I've scanned it as usuall (and I've used Epson Scan and Vuescan) and have adjusted black and white points, all the scans, especially those overexposed look pretty much the same in shadow, but also more or less in highlight areas, so it's kinda hard to tell which EI would be the best.

So the question is, how to scan this test roll. Am I doing something wrong? Should I leave the black and white points at some fixed values?

Thanx

[40oz]

I'd think you'd want the negative that requires the least amount of adjustment. I would judge them without adjusting the white and black points. I'm thinking you are looking for the widest range of tones on the negative, so presuming the scan that has the widest separation between white and black is the negative with the widest tonal range, that's the one you'd probably want.

But I'm no expert.

[Xmas]

With underexposure you will lose detail in the shadows. In high contrast sceanes the shadows will be further away from an average meter point.

The normal EI has a 1.25 stop margin, (or over exposure).

I have to rate films 1/2 the box speed or lose a lot of shadow detail, even in flat sceanes...

Noel

[kaiyen]

I did a test of Delta 100 in a bunch of developers a while ago.

http://photos.kaiyen.com/photoBlog/?p=80

You can see my method there. You can't really use your scanner as a densitometer - it produces relative values, not absolute ones. But if you lock your exposure, then stick to a particular film and CI profile, you can see differences in the shadow areas that are noticeable. It is easier if you shoot a scene that is almost all Zone III, or at least without Zone VI and VII. Just makes the curve easier to read. Mine was a nice big hump that moved to the right and left as I increased and decreased exposure, respectively.

allan

[denishr]

Well, if you're adjusting all the frames to look more or less the same, I don't see the point... unless you're shooting and developing with the aim of scanning only, and using only the scans (without making actual "wet" prints).

If that is your intention, you should find the best combo (personal EI and developing process) which yields good results with the least amount of "tweaking" and post-processing. Once you find a suitable combination, you should "lock" the scanner settings adjusted to that particular combo.

I use Silverfast, and have saved a personal profile for e.g. Efke KB100 and Efke PL100 (large format negatives) in NegaFix, which I apply to new scans of the same type of film. If the result is not satisfactory, the film is either under/overexposed, or there's an error in film processing.

However, I have never been completely satisfied with all that twiddling with software and scanning. Nowadays I can evaluate negatives "by eye", and if I need a quick "scan" of the entire roll, I just make a contact print in the darkroom.

Now, THAT gives really accurate representation of what's on film. Not to mention that it's actually a LOT faster than scanning and tweaking even a short roll of 35mm film

Denis