Black reference when scanning?

[newfilm]

Hey guys, from your experience, when scanning (black and white negative), should I be using the "blank unexposed" part of the film to be the base line for "true black" colour?

I shoot a few type of black and white film, and they all seems to have a slightly different base clear film colour.

While we're on topic what about the "true" white? Shoot a white index card on the first frame as reference? or just use the exposed film leader as base line?

I'm trying to get a consistent base line "true black" and "true white" (per film type?) so I can gauge if I did expose the film in the "correct" exposure (as some would say a good negative)

 

[x-ray]

Sounds like a good way to do it. Better yet if you can pick up a densatometer and read the values direct. I'd suggest reading Ansel Adams The Negative.

 

[Larry H-L]

In theory, your idea to scan a blank frame / solid frame sounds OK. But in practical terms, I don't feel you need to put in the extra time and effort. And I don't think in street shooting situations that you would be able to nail exposure and development that closely from frame to frame, roll to roll.

The histogram on your scanning / editing program should give you plenty of information. The clear base around the frame should be near the black clipping point and the very brightest area in the exposed frame should be near the white clipping point. And of course the mid-tones should be near 128.

A slightly "thin" negative usually works best for scanning.

Making some basic presets from well-exposed and properly developed frames as you scan them should get you very close to what you are suggesting, IMHO.

 

[BernardL]

I don't think you should lose sleep about "true black" and "true white". Suppose you have a film with a large dynamic range, a long straight section in the D-versus-logE curve. And you shoot a scene exposing generously to lift the shadows off the toe region; apart from longer times under the enlarger, a perfectly good exposure, with the benefit of god shadow separation.

If you define blank film as "true black", the deep shadows of your scene will be muddy black. Is that what you really want? Ditto for whites.

For scanning of color negatives it's a different story: see the "set film base color" button in vuescan, essential to avoid a color cast in the shadows.

 

[froyd]

Agreed. Scanning the clear par of the negative is useful for color scanning, because you can achieve better color fidelity by eliminating the orange mask, but with BW you could skip this step and achieve good scans.

 

[mfogiel]

In B&W scanning, the point is to get as much tonal detail in as possible, without clipping the highlights, so your basic concern should be to see ( in preview ) a histogram that fills out the entire space, and DOES not spike on the right. In order to obtain this, you should first of all avoid selecting blank (non film) space, and if you want a black border around the image, then check that in the preview the histogram fills out the range. Once you have a good scan, you can define your black and white intensity with curves.

 

[craygc]

Vuescan lets you do this in the menu options and save an emulsion specific profile you can load each time. Generally if exposed well, B&W films deliver a maximum Dmax of around 2.2. Depending on the scanner you use, many scanners can exceed this - especially dedicated film scanners , which means you will need to stretch something out in software to get a full tonal range.

From testing I did with a Nikon 4000 a number of years ago, what I found was that it is better to anchor your black point in scanner and stretch the other side for the white point in software. This was because, in general, the more you stretch/twist the tonality/contrast with B&W scans, the more you start to get a salt and pepper appearance and this tends to occur in the shadow areas well before you see problems in the lighter areas. When you stretch your white point out the impact to the shadows is lessened.

 

[newfilm]

many good advises!

By the way, after I anchor the "black" and "white" point by pointing at both end at the bell curve (minus the long tail that clips), I then left with choosing the "mid-tone (?)", which will then influence the image looks more contrast vs foggy, where would then the "correct" value would be? always in the middle?

I suppose I am trying to find the characteristic of the film itself (if there is such a thing!)

 

[CK Dexter Haven]

What Marek said is what i was always taught — capture the full tonal range, and then define black and white points in Curves (Photoshop), either manually or with the eyedropper. IF that's what you want in your final image. There's no rule that says your print has to have absolute black and absolute white within it, though.

 

[Larry H-L]

Once you have your basic range from dark to light, place your mid-tones where you think they look best. Unless you are doing something scientific, aesthetics are totally up to you, nothing needs to be "correct."

 

[x-ray]

In B&W scanning, the point is to get as much tonal detail in as possible, without clipping the highlights, so your basic concern should be to see ( in preview ) a histogram that fills out the entire space, and DOES not spike on the right. In order to obtain this, you should first of all avoid selecting blank (non film) space, and if you want a black border around the image, then check that in the preview the histogram fills out the range. Once you have a good scan, you can define your black and white intensity with curves.

A full histogram doesn't always make the best image. Compressing shadows or clipping highlights are sometimes needed. I see a lot of really flat scans doing this. More than just a flat scan curves are generally needed. When I had my Fuji Lanovia Quattro, (it's not a car) I scanned everything as a linear scan and then applied curves and levels later. This is how the professional software Fuji designed worked unlike most consumer software / scanners.