Questions about B&W negatives: 2-humped camels and other beasties

I see this is a discussion that can easily become deflected by talking at cross-purposes and addressing different issues. I may be partially guilty to that myself. The point I was trying to make is a rather narrow one: it's difficult to match the native tone response curve in film, which was adapted to analog media, with that of digital processing.

The net effect is that you easily get too high midtone contrast, and too low/compressed shadow and highlight contrast. The result is an image that just doesn't look right, even if you have the endpoints set correctly.

In the histogram it may translate to a hump in the low values, and a hump in the high values - and a valley in between. That was the OP's question (or one of them at least) that I was trying to address.

Of course, a bi-humped histogram may also occur in a typical landscape shot: dark landscape and bright sky.

This will be particularly pronounced with color transparencies, while b&w negatives are less affected due to the higher dynamic range recorded in the film, and less need for an S-curve in the tone response curve to compensate. But there is still an S-curve. Color negative film is somewhere in between.

Coming late to this forum thread with interest (and the expert answers).

I am scanning B&W (6x4.5) negs in my Epson V700 scanner.

Using [B&W Negative Film] option -renders previews as positives.

Image Type as [16-bit Greyscale] at Resolution [3200]

My confusion is understanding how to set the Histogram 'white' and 'black' slider points to produce a good image.

1) This is what I see when Epson reads the neg (auto-exposure I guess!).

2) This is what I see when I click and hold the [Show Output] button

Note the position of the 'black' pointer.

3) I have been shifting the (left) black slider to the left until I see this in [Show Output]

4) And my images in Lightroom seem to be have a suitable histogram from which I can see shadow and highlight detail.

If anyone would care to comment, I would be appreciative.

Am I understanding the Epson histograms  and approaching my scan exposures correctly?

Also not really understanding the output scale- where Epson 'clips?'  10-200.

Kind Regards

Robert

In my experience, black & white negative film has a much larger dynamic range than even the best digital sensors.

When exposed for the shadows, and properly developed, the highlights can hold an amazing amount of tone and detail, although they may be completely white in a straight print made in the darkroom. The tone and detail can be brought out by burning in,  or even better, burning in with soft (yellow) light using multigrade paper. 

For the image below, a pyro developer was used, which produces a yellow stain in the negative which is proportional with density, and causes lower contrast in the highlights when printing on multigrade paper.

These highlight tones and details can also be brought out in a scan.

Look at the details in the fluorescent tubes in this image,  exposed at 20 seconds, f/32, TMAX 100 film.

As for the camel humps in the histogram, I'm seeing that a lot in my landscape photos shot with a digital medium format camera.

I think it's mainly because film doesn't have anywhere near the dynamic range of a modern digital image. So in order to reproduce well on analog media, it was compensated with a fairly steep S-shaped curve in the film's tone response curve. A color transparency, for instance, had a useful range of only five stops or so. This gave reasonable mid-tone contrast, but very compressed highlights and shadows.

Pull this out to the full range of a digital image, and you get a "hole" in the middle, and compression at either end. Hence the bi-humped histogram.

I've struggled tremendously with digitizing old transparencies and negatives. I get the detail, and I get the color right - but getting a decent, natural-looking tone curve is a nightmare. Once I have a good midtone contrast, I'm usually left with muddy highlights and a weird, foggy effect in the shadows where all detail is lost. It's usually there if I go dig for it, but integrating it into the rest of the image is not easy.

I stopped scanning when I discovered I got much better results photographing with a good flat-field macro lens. But there is still a problem with the film's tone curve.

Thos who claim analog is "better" than digital clearly have other goals than I do 😉

I had a go at the BC 130 image, and tried to edit it in a way that makes the blacks less prominent.

I started out with the uncorrected image, and used the Camera raw filter to do the edits.

The whole image received the edits on the left, and the bottom third was given the edits on the right, using a graduated filter.

The Blacks +30 reduces the density of the blacks, so there are no true blacks in the image, which I don't think matters.

The histogram is a graphic representation of the distribution of tones in the image, from shadows (left) to highlights (right).

So the dip in the histogram for this image means that there are relatively few pixels in the upper midtones.

I have no other answer to your question than that, I'm afraid.

I have scanned hundreds of negatives of images that I used to print in the darkroom, and the histograms have all sorts of shapes, it all depends on the image.
I can easily edit a scan to make it almost identical to a darkroom print, but I prefer to make it better, because I can get a much better inkjet print (tonally) than what I managed to get in the darkroom.

The important thing (which you seem to have done) is to capture all the information in the negative, with no clipped shadows or highlights, and the histogram in the scanning software is an important tool to achieve this.

Other than that, I don't really care what the histogram looks like, I just edit the image to my liking.

The image below looks fine to me, and the histogram also looks fine.

The "black beetles" in this image are caused by clipped, or almost clipped shadows, caused by the frontal lighting.

The general contrast is low, but local contrast is high, and this can be tricky to edit.

Try raising the black levels a bit, combined with local adjustments, like negative clarity or contrast with an adjustment brush or gradient in the Camera raw filter.