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.

[Oren Grad]

Well yes and no. the assumption is that all curves have a toe and shoulder which within the useable range isn't necessarily true.

Whether the film records usable information across the entire subject brightness range is a matter of exposure and development. If the negative doesn't have enough information in the shadows, you haven't exposed enough. If the highlights are unprintable, you've developed too much. What the curve shape affects is how hard you have to work to get the information from the negative on to the paper such that the tonal distribution in the print comes out the way you want.

If you're not familiar with it, BTW, that's what BTZS is all about - figuring out how to use exposure, development, *and curve shape* to get the result you want.


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.

If you lose highlight or shadow detail when printing to desired local contrast in the parts of the scale that matter to you, it means your exposure and development are not properly calibrated to your printing medium, and possibly - if you're printing in silver - that you're using a film that's poorly matched to the curve of your paper, thereby making your life in the darkroom much harder than it needs to be.

I'm rejecting the teaching that the best film is necessarily the one with the straightest possible curve. It depends on what tonal scale you want to achieve in your prints, and whether you'll be printing in silver (and the characteristics of the silver papers available to you) or in inkjet via scan.

That is, I'm supporting your initial premise - that a straight line response isn't necessarily best for everything - but quibbling with your assumption that it's optimal for situations where shadow detail is what you want to emphasize. You've endorsed an upswept curve for situations where you want enhanced highlight separation. But the same logic points to a shouldered film - i.e., curved *the opposite way* - as optimal for enhanced shadow separation. A straight line is in between.

[Bruce Watson]

If you lose highlight or shadow detail when printing to desired local contrast in the parts of the scale that matter to you, it means your exposure and development are not properly calibrated to your printing medium, and possibly - if you're printing in silver - that you're using a film that's poorly matched to the curve of your paper, thereby making your life in the darkroom much harder than it needs to be.

+1. That last part is really important -- it's what makes some people so frustrated with darkroom printing, and others so happy with it.

I scan everything now, so I'm really happy with a nice long straight line. But clearly YMMV.

[Robert Hughes]

I don't care if they're straight - and I like their curves.

Oh, this is film we're talking about? Never mind...

[BetterSense]

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.

I think this explains a lot to me, but I may be errant in my thinking. I don't have fancy instruments and do everything by the seat of the pants, including exposure often. I live in Texas, and during the summer, I was really favoring both tri-x and especially neopan 400, which was my finer-grained replacement. I would expose both very generously to get shadow detail. This allowed me to more or less plop the negatives onto paper at grade 2 and get pleasing prints. I thought this darkroom thing was pretty easy. Then I was trying to come to grips with tmax films, and I loved the grain, especially for smaller formats, but it always seemed like the highlights blew out when I exposed generously in the sun. I thought I was developing too much, but they didn't really blow out on the negative...I could print the image down and there was detail there in the highlights, but then I lost my shadow detail. Lowering contrast to attempt to get both shadows and highlights on the print resulted in a flat, ugly print. Raising contrast to get good midtones and shadows and then elaborately burning in the highlights was the rule of the day. This didn't do much for my opinion of the films, not when I got good results so easily from neopan 400. On overcast days, the Tmax looked absolutely gorgeous. And to a certain extent, the Tmax was easier to expose, because there was no straight line to get the midtones on...they were on a straight line no matter where they fell. But I went back to my Neopan 400 for roll film. I'd rather let the film burn those highlights in for me. Unfortunately, neither tri-x nor Neopan 400 is available in sheets, so I went to HP5+. I've been pretty happy with it so far, in that it lets me expose 'enough' and then throw the image onto my paper and achieve nice-looking results. I could be barking up the wrong tree in a big way but I think that me and tmax just don't mix, at least not until I get a densitometer and a spot meter and move to Washington state, or something.

[Oren Grad]

BetterSense, one thing you can do if you still have some TMY negatives that you want to print, is to try a paper with a longer toe. The right sort of curviness in the paper can, up to a point, compensate for a film characteristic that's straighter than you're comfortable with.

[Drew Wiley]

TMax 100 is pretty unforgiving of overexposure in the highlights. TM400 is easier to
work with in this respect. HP5 has a longer toe but coarser grain. I use it for 8x10
but not 4x5, but not for highly contrasty scenes unless I print with a supplementary
mask. FP4 has less toe and is a little easier to print from in my opinion, if you can tolerate the lower speed (realistically ASA50 in developers I use). All these are great
films, but each has a personality of its own, which you just have to get used to.

[Mark Sawyer]

I think I agree most with Oren.

My take is that it's a "whole system" thing; in some cases you need the shoulder and toe to keep the detail on the far ends, in others you don't. A lot depends on how the curves of the paper interact with the curves of the film; I have negatives that print wonderfully on Fomatone, but look terrible on Ilford MGIV, and vice versa.

It's often better build a negative that prints poorly as-is (whether straight line or curved), then open shadow or highlight detail with burning/dodging/split filter printing/bleaching/developer choice/water-bath development of the print, etc.

[Oren Grad]

It's often better build a negative that prints poorly as-is (whether straight line or curved), then open shadow or highlight detail with burning/dodging/split filter printing/bleaching/developer choice/water-bath development of the print, etc.

This is an interesting point, but I'd quibble with framing it as a general principle rather than a personal preference.

I'm completely uninterested in spending hours in darkroom calisthenics struggling to get the information from a negative on to paper. If a negative is that ornery I'd usually rather move on to the next one or grab a camera and go make more. So I place a high premium on film/paper combinations that print easily with a tonal scale to my taste.

But by the same token, if you enjoy or at least don't mind the calisthenics, you might well choose a film/paper combination with a less than ideal curve match in order to gain some other benefit that you value more - for example the "look" of a particular grain structure, or a particular image tone or paper surface.

[percepts]

This is an interesting point, but I'd quibble with framing it as a general principle rather than a personal preference.

I'm completely uninterested in spending hours in darkroom calisthenics struggling to get the information from a negative on to paper. If a negative is that ornery I'd usually rather move on to the next one or grab a camera and go make more. So I place a high premium on film/paper combinations that print easily with a tonal scale to my taste.

But by the same token, if you enjoy or at least don't mind the calisthenics, you might well choose a film/paper combination with a less than ideal curve match in order to gain some other benefit that you value more - for example the "look" of a particular grain structure, or a particular image tone or paper surface.

I do agree with you to a point. Fact is I think that B+W photographers think that just because they can expand or contract development then they must. Personally I think you are far better served by going out to make images when the light is right just like the colour photographers do. That way you get negs which fit the paper with good contrast without doing the gymnastics. Now if you can find 3 papers, one with good shadow contrast, one with even contrast throughout the range and one with good highlight contrast, then a neg with straight curve will serve just about all situations.

So what papers and techniques do you use to give good highlight contrast, even paper contrast and good shadow contrast. Personally I think that would would be a better way to deal with things than playing with film contrast except for small range adjustments of maybe only N+1 or N-1.