Straight or Curved

[percepts]

I'm just wondering what peoples take on film curve shape is for B+W.
I was taught that as straight as possible is desirable. But I also learnt that slightly upswept is better for poraits as it gives better separation to the highlights.
But a short toe where the curve gets straight quickly is better for shadow separation which is at odds with having an upswept curve for portraits.
So I'm just curious to know what others think. Do you use one film for landscape where you may want good shadow separation and another for portraits where you want good highlight separation or do you use just one standard film and be done with it.
Do you use different developers for different subject type to achieve a different look.

So which film / dev do you use for which subject type and why?

[Stephen Willard]

I am a color landscape photographer, and I us color negative film to photograph my subject matter. I am probably one of the few who actually builds characteristic curves. I use them to test the effects of how film ages along with comparing the difference between films. I have built CCs for b&w before as well.

I prefer straight line curves without a heal or shoulder. The color negative film I have exhibits that behavior. If the slope of the curve decreases in steepness, then the contrast is lowered on that part of the curve. If the slope of the curve increases in steepness, then the contrast increases on that part of the curve.

A CC that is a straight line will have the same contrast throughout its range. CCs like this are easy to build mask for (which in color land I do extensively) and match with the appropriate paper contrast. A CC that is not straight and changes it slope throughout its range will exhibit different contrast along its span. Films like these are difficult to build masks for or match contrast paper grades. Some people resort to doing split contrast printing to compensate for the variations in contrast of films that have exaggerated heals and shoulders.

A good film-developer combination for b&w that exhibits an excellent straight line CC is Tmax 100 developed with Tmax RS developer. The CC curve from this film-developer combination produces a very good straight line CC over a very long range at the time I tested it many years ago. I believe that John Sexton uses this film-developer combination for all of his work. The problem with Tmax RS developer is that it is very agitative sensitive, and it is almost impossible to get consistent results when developed by hand in trays. You must use a JOBO processor to get repeatable agitation and consistent results with Tmax RS developer.

Hope this helps...

[percepts]

Well my tests indicate that for many developers the arbitrary figure of 0.1logD for zone 1 is too low. There simply isn't enough separation between zone 1 and zone 2 to see a difference in the print and even where there is, a slight increase in print contrast will remove it. Only where the film has a very short toe will you get separation at the deepest shadows. i.e. very straight curve is required.
I think it is important to remember that the paper also has a curve and that when you try and print a shallow film curve on a shallow paper curve, separation is reduced to blocking the shadows. I guess this is why some recoomend zone IV for full detail shadows.

[Bruce Watson]

Do you use one film for landscape where you may want good shadow separation and another for portraits where you want good highlight separation or do you use just one standard film and be done with it?
Do you use different developers for different subject type to achieve a different look?

So which film / dev do you use for which subject type and why?

I use exactly one B&W film and exactly one developer: TMY-2 and XTOL. I use a couple of C-41 films for color work: 160PortraNC and 400PortraNC.

All of these give me a short toe and a long and very straight characteristic curve. I don't have a problem with either shadow or highlight separations.

In particular I like the tonality I get from TMY-2 and XTOL. The real life hues, saturations, and luminances translate to film densities right where I want them. I suppose that makes me a "literalist"; so be it. Works for me. No telling if it'll work for you.

[Stephen Willard]

I use 0.15 instead of 0.10 at a Zone I placement for determining my ISO to insure sufficient detail at the lower end of the scale. The impact this has on the highlights is not significant. I place all of my significant shadows in Zone III, but because my ISO is based on 0.15 density units above film base and fog, it moves my Zone III closer to your Zone IV placement for important shadows.

There are also times when I want notable shadows to reside in Zone II or slightly above for artistic reasons and using a 0.15 density units give me better detail in that region to work with when I construct my mask and prints.

In color negative land, I have to work with three layers - RGB. The red layer is the least dense and that is the layer I enforce the 0.15 density units at a Zone I placement to insure any reds in the shadows get properly recorded. I do landscape photography and outdoor shadows is what I use to determine my ISO setting. Outdoor shadows are very cool because they are light by blue skies and there is very little red in them. So using 0.15 density units on the red CC under a blue sky shadow is probably closer for you using 0.20 or 0.25 density units at Zone I placement in b&w land, and probably explains why I have no heal to my CC. The net result of this is that I expose Portra VC 160 at ISO 80 which is a full stop slower than the suggested ISO setting of 160.

The strategy I use seems to have very little effect at the higher end of the CC. At Zone XIV I am still getting reasonable contrast to use productively. So I get the best of both worlds with great shadows and highlights along with all the juicy stuff in between.

[Oren Grad]

Actually, for darkroom printing on silver paper at least, the easiest way to get open shadow detail is with a film that has a shoulder, not with a straight-line film. This should be obvious if you think about tonal distribution as a zero-sum game - for a given overall density range, greater separation in the shadows must mean reduced separation somewhere else.

I'm very shadow-detail oriented, and my favorite film is TX, which has a long, gentle shoulder. Unfortunately, TX isn't available in sheet film. For view camera work, I've settled on HP5 Plus, which is almost as forgiving in that respect. I use it for just about everything. (When I don't, it's generally for reasons of convenience in getting film for an odd format, not because of subject matter considerations.) My development is standardized as well - for a while now it's been D-76, with a standard time/temp for everything.

Inkjet printing is a zero-sum game tonally as well. But because the processing is done in the digital domain, there's much more flexibility in what you can do with the initial capture (a scan in this case). This makes straight-line films relatively more useful. For example, I'm not a happy camper with TMY in the darkroom. But if I were going to scan for inkjet printing, the properties that give me trouble in making silver prints mostly stop being a problem, and I'd get to enjoy the benefit of its exceptional reciprocity characteristics.

[Stephen Willard]

Actually, for darkroom printing on silver paper at least, the easiest way to get open shadow detail is with a film that has a shoulder, not with a straight-line film. This should be obvious if you think about tonal distribution as a zero-sum game - for a given overall density range, greater separation in the shadows must mean reduced separation somewhere else.

I think your assumption may not be valid. The behavior is more like preexposure that Adams talks about in his book The Negative where the impact of adding density in the shadows is significant while having very little impact on the highlights. However, I could be wrong about this because I have not done any formal testing specific to this issue. However, I have noticed this behavior through informal observations when examining actual field negatives.

[Drew Wiley]

All depends. I keep a lot of different kinds of film on hand. But for most landscape work
I distinctly prefer straight line films. I like to have good detail and value separation all the way from deep shadows clear through the sparkly highlights, at least on the neg; how I choose to print is a lot more subjective, but if the information isn't on the film in the first place, your choices are forfeited. I haven't had any problems with TMax100 in TMRS in trays - the results are very repeatable - in fact, the only time I use this combination is for color separation negatives, which is the fussiest application I can think of. Almost all my field shooting is developed in PMK or some related pyro tweak. Loved the now-discontinued Bergger 200; now use some Arista 200 (Formapan) - very straight line without almost no toe, and am experimenting more and more with the newTM400. For portrait work, I break all kinds of the conventional rules, so don't want to elaborate or give a recipe, except that my film choice is likely to be different than
for landscape work. Commercial work like product shots are likely to end up on TM100.

[percepts]

For portrait work, I break all kinds of the conventional rules, so don't want to elaborate or give a recipe, except that my film choice is likely to be different than for landscape work.

Oh go on do tell...

[percepts]

Actually, for darkroom printing on silver paper at least, the easiest way to get open shadow detail is with a film that has a shoulder, not with a straight-line film. This should be obvious if you think about tonal distribution as a zero-sum game - for a given overall density range, greater separation in the shadows must mean reduced separation somewhere else.

Well yes and no. the assumption is that all curves have a toe and shoulder which within the useable range isn't necessarily true. Where you have a film which has a truly straight curve from zone I to zone X then the separation is equal throughout the range and you can alter the range merely by altering the slope of the curve without introducing a shoulder and still retain highlight detail above zone X. i.e. separation is altered across the full range which may or may not be desirable. But the image may look a little flat when printed at normal contrast. Increase the contrast in printing and you will lose either highlight or shadow detail depending on your print time.