Somewhat light negs after development - underdevelopment ?

[alexz]

Yes, I tend to believe there is no issue in underexposure, neither overexposure is envolved. What makes me to think about is - applying less agitation thereby trying to keep highlights within the limits and somewhat extending development time (by 15-20%) to gain more dense shadows without loosing details...
I'll cut the next roll into two pieces, one will be developed for 1 minute longer then I did so far (7 and half minutes instead of 6 and half for dill. B), the second piece will be developed in dill. H for 13 minutes, both with quite restrained, moderate agitation (first 30 seconds, then 2-3 agitations per minute).
I just need to tailor the negs for my scanner ....

 

[John Bragg]

Good plan Alex.
It would not hurt to include a frame or two with just one stop over and under as a control and scan them too. Negative film is far more tolerant of over rather than under exposure and by deviating just a little from your normal EI 400 you can learn a lot about how it behaves. I use such downrating as a way to control tone and Grain.......


Regards, John.

 

[Doug]

If the histogram data is shifted to the right, and the highlights are clipped, then I'd say scanner exposure is incorrect. Rescan to move the data to the left and see if adequate highlight detail appears in the scan. If so, you're all set. If there's some "dead" area at both ends of the histogram, then scan exposure is good but neg contrast is on the low side. Better than clipping both ends!

 

[alexz]

Well, Doug, just tried playing around scanner exposure: making it -0.3 stops to -0.5 stops avoids clipping highlights but doesn't extend the shadows to the left which is trange (in my eyes at least)...I would expect doing that will shift entire histogram to the left, not just saving highlights...
The image however shows to be darker in he whole proprotionally the amount of decreased exposure so that the shadows are darker accordingly. I wonder why this isn't expressed in histogram ...

 

[40oz]

consider that the histogram only shows where each value falls on a scale from pure white to pure black. In the case of a negative scan, you'll only see pure black when the negative is absolutely clear. So the fact that your histogram isn't all the way to the left is normal. You have details in your blacks, and at the same time, have areas of absolutely pure white in the window and reflection of the desk.

If you want the histogram to be evenly distributed over the whole span, you need to take pictures of gradients from pure white to pure black. And even then, your scan has to discount the base "opacity" of your negative. Tri-X, for example, is a purple-gray even when completely unexposed, while the completely blown-out highlights will be completely opaque. A straight scan will never have any data on the far left of the histogram, as long as the film itself isn't perfectly clear.

The histogram doesn't really tell you anything you can't see by looking at the scan itself. It certainly shouldn't replace examining the actual scan. Or the negative itself.

 

[alexz]

consider that the histogram only shows where each value falls on a scale from pure white to pure black. In the case of a negative scan, you'll only see pure black when the negative is absolutely clear. So the fact that your histogram isn't all the way to the left is normal. You have details in your blacks, and at the same time, have areas of absolutely pure white in the window and reflection of the desk.

If you want the histogram to be evenly distributed over the whole span, you need to take pictures of gradients from pure white to pure black. And even then, your scan has to discount the base "opacity" of your negative. Tri-X, for example, is a purple-gray even when completely unexposed, while the completely blown-out highlights will be completely opaque. A straight scan will never have any data on the far left of the histogram, as long as the film itself isn't perfectly clear.

The histogram doesn't really tell you anything you can't see by looking at the scan itself. It certainly shouldn't replace examining the actual scan. Or the negative itself.

Oh, great, that sounds to be the revelation and the actual explanation of what has happened to the histogram. I just checked the negatives (tri-X) - the darkest areas of the positive image (thus the lightest on the negative) are as the film base, i.e. not the pure clear transparent but rather kind of slight purple-tinted. That might indeed be the reason of the histogram cutting the shadows a bit to the right of the zero position. That means I need just to stretch it artificially (by either Curves or Levels) to the left, i.e. re-defining black point for the particular film.
Many thanks for opening up my eyes, now things appear much clearer to me, and examining the negatives I tend to believe there is no problem with them exposure or development-wise - they appear to be well-balanced.

I guess what I need to do - it to proceed with some kind of scanner calibration for particular film (Tri-X) - shot a frame with total black, white and mid-gray tones, develop as I usually do (or will do), scan and one and for all define the black point for the film with particular base type. Then, for all the rest scanning (bearing the same development applyed) of that kind of film, I'd apply that "profile" which will tailor it properly.

 

[40oz]

Actually, I pretty much just let photoshop's Auto Contrast do it for me now. Something might be under-exposed or over-exposed, in which case a "calibrated adjustment" would be better than the straight scan, but not ideal for that frame. And the whole point is to print/display each frame to the best effect, rather than to a technical standard regardless the image.

I think the AutoContrast function in most programs does the same thing - adjusts the black and white points according to the histogram. Which is all I do anyway. Occasionally I need to move the mid-point slider in Levels, but rarely, and only when the image is either royally screwed or just a tough scene.

 

[alexz]

Yes, indeed I also either applied Auto Contrast or just squeezed the shadows lever in Levels a bit to the right to place.
I tend to agree about striving to achieve the best appearance per each particular frame with tis own adjustments, but also consider a "calibrated" approach to be useful for clarity - at least following one and once obtaining blocked shadows or burnt out highlights I'll know for sure I screwed up in exposure or development but this is not my scanner to blame for.
In general it appears to be good idea to define a black point for particular film type to avoid such kind of confusion in the future...

On the other hand, I noticed there is noticeable percentage of the frames on my two rolls of Tri-X showing a signs of burnt out highlights. Frankly, I rarely remember the actual scene - whether it really contained wider dynamic range then the film can cope with which makes difficult to judge and fine tune my development technique. I think I need to do the tests shooting to obtain dev. approach that will control highlights of normal scane...

 

[40oz]

you'll be able to tell if your exposure is off just by looking at the scans. If your highlights are consistently blown but you have details in brown hair and woodgrain in shadow, you might try just cutting back on developing time or reducing the temp a few degrees. Of course, a sunny sky through a window is a bit much for most films if you are exposing for the indoor shadows.