Kodak’s venerable black & white films were Panatomic-X with an ASA of 50, Plus-X with an ASA of 100, and Tri-X with an ASA of 400. Yes, they all started with lower exposure indexes, but those were the speeds they ended up at and thus the ones most people would be familiar with. You can probably see the relationships in the names: add one stop to Panatomic and you get Plus, add three stops and you get Tri.
There are many people experimenting with Tri-X simulations in the digital world today. There are even ‘filters’ built-in to some software to give your images that Tri-X look with a click of a button. There seems to be an obsession these days with ‘high speed’ exposure indexes, as digital cameras go up to ISO 6400 or more. That’s +6 stops from ‘normal’ daylight speed. Where are you planning on shooting? In the bottom of a mine shaft? Of course use of such high numbers then gives you the opportunity to complain about (and try and remove) the ‘noise’, which is the digital equivalent of film’s grain. In my day we tried to avoid that.
Here’s me, the old contrarian, complaining about the opposite; cameras’ minimum ISO setting seems to be 100. This is fine, but just as higher speeds have advantages so do lower speeds. You may find that hard to fathom because the problems of lower speeds are what drive us to use higher ones. Yet neutral density filters sell. Everything is a compromise. Just be thankful you aren’t using glass wet plates, okay?
So why would we want lower speeds? Not just for blurring motion or limiting depth of field (I will die before I use that stupid ‘b’ word). Just as high speed gives you more contrast, low speed gives you more range. In black & white we’re talking about defined gray tones. Think of it like this: let’s say Plus-X gives you ‘X’ (I wonder where I got that algebraic variable from, eh?) tones. Tri-X gives you less than ‘X’ tones, and Panatomic-X gives you more than ‘X’ tones. It’s like having more colours on your palette – only they’re all gray.
Mostly as an exercise in further exploring digital photography for myself, I set out to try and simulate Tri-X and Panatomic-X. The first was easy to achieve, and every bit as disappointing as the original film. Frankly I never liked using Tri-X because it was grainy and contrasty. It’s not my style. I’m really a boring, Kodacolor kind of guy. Nevertheless, this was an experiment for science!
There are two steps to it: determining what the difference is between how the camera shoots and how the film looks, then finding a way to make the camera output look like the film. It’s not as easy as it sounds: merely changing the camera setting to monochrome doesn’t work as it relies on what the manufacturer thinks is the right tonal quality and gradations. Slipping on a neutral density 2 filter to knock the ISO down to 50 doesn’t solve the problem either; it just lowers the EV. In fact, even in combination it comes up lacking. Why? Because your camera is biased about colours.
Black & white film (aside from specialty films) is made to be fairly even in its sensitivity to all of the visible spectrum. It doesn’t necessarily achieve this, and under certain lighting circumstances some adjustment is needed to render an image that is satisfactorily normal. If you’re familiar with shooting B&W you’re probably familiar with adding a K2 (yellow) filter to heighten contrast of the sky. In this case the bias in the camera’s sensor has to be overcome in a like manner.
I found my cameras all lean towards green. In converting the colour images to B&W (my preferred method – you’ll see why later) the various colours become gray tones based on luminosity or lightness or a combination of the two. If a colour does not reflect ‘equally’ it will slide into an incorrect tonal range depending on what conversion method is employed. Thus a colour may become lighter or darker gray than it should be. Admittedly this will not be noticed by most people, and probably doesn’t really matter. So long as you like the end result, it’s fine.
In my preliminary testing of that which I knew would happen, I shot the back end of my Xterra next to grass so I had red tail lights and green foliage to look at. Sure enough, changing to monochrome produced different results with different methods. All would have been acceptable by the end user, except where the ‘end user’ is me trying to simulate wide-tone Panatomic-X film. So it was time to apply some thinking, and some filtration.
Knowing which process turns which colour which way is a good place to start. My finding was: Lightness makes red tail lights lighter, green grass darker, yellow flowers darker; Luminosity makes red tail lights darker, green grass lighter, yellow flowers lighter. The second key to the puzzle was knowing the camera favours green. So we have to make the red tones lighter and use the luminosity function in order to get the most accurate conversion.
Enter the orange filter. Fortunately this is not a true ‘Wratten 21’ orange as that would be too extreme I think. Just enough to shift the colour, and incidentally require 1 more stop of EV – effectively lowering the ISO to 50. (The Wratten 21 would be 2 stops.)
I have to say I spent some time adjusting the camera’s “picture type” settings as well, to see if that would help. Subtle 1 step changes didn’t really show at all – or at least I couldn’t see them. I went with as ‘neutral’ as the settings could be, with an increase in sharpness to help the definition. I also reduced the MP to 4.5 for shooting, with a further reduction for Internet display. Yes, I realize this alters what you see. So does your screen and your eyes. You’ll just have to take my word for it that it’s right.
First, the picture as-shot. It’s a kind of snap-shot thing because I wanted to get a lot of variety in the composition; it helps with determining the quality of the final result as well as aiding the computer in doing the conversion (the more monochromatic the original, the more inaccurate the change to B&W).
Next, the black-and-white version. True blacks, true whites, and many gray tones in between:
Last, the colour-corrected version. This is why I like shooting in colour all the time; if this had been monochrome but would have looked better as colour, it would be lost. As it is the filter correction for B&W is subtle enough to be eliminated and deliver an acceptable quality colour rendition as well:
Perhaps a tad magenta. That could be fixed if I wanted to spend the time working on it.
Here’s a more dramatic series, same processing order. You can see what I mean about what happens when starting with a fairly monochromatic image.
Anyway, I plan to shoot some more like this and some starting with monochrome but ‘slowed down’ with a neutral density filter to see how that compares. It may be just as good, or better, or worse.
I also plan to try simulations of Kodachrome and Ektachrome once I’ve worked out the initial settings. But probably not Agfachrome with its muddy “European” colours. 😀