If you have been around photography for very long a couple quick observations come to mind. First, things just sound complicated and in reality they really are not. Math is involved so that puts a certain distribution of people in the tank all on its own! My goal in this article is to show beginning black and white film photographers a way then can produce good quality black and white negatives when printing in the darkroom. Entire books have been written on some of these concepts so keep in mind that I am trying to distill over 100 years of knowledge into a simple, easy to apply set of tips. If you send your film out for development then you are left at the mercy of your lab.
We are going to discuss how to properly expose for shadow detail in your scene and make the appropriate adjustments on your meter/camera. By employing this simple technique and then following up with some simple techniques in the darkroom you will get good quality results.
Rating Your Film
Based on the subject matter in this article I have to assume you don’t know how to properly test your film for you own personal EI (exposure index) rating and you have no working knowledge of the zone system. The best advice I can give a black and white film photographer that is not using a scientifically tested film and developer combination is to rate your film at half the box speed and then develop for a little less time than the manufacturer data sheet instructs. For example if you are using T-Max 100 then rate it at EI 50. If you are using Tri-X 400 then rate it at EI 200. If the manufacturer data sheet says to develop at 6 minutes then develop for 5 or 5 1/2 minutes. Something in the range of 15% is the rule of thumb that I would suggest. In effect you are doubling the light to your film by cutting your ISO in half and then you are compensating two stops because our meters read the scene in zone 5. If you refer to the illustration below you will see tone difference between zone 5 and zone 3 and my explanation should become obvious.
Calculating Your Exposure
For my style of photography I want to control my depth of field so by default I meter and think in terms of aperture priority. I use all manual cameras and use a hand-held spot meter. You may be different and just adjust as necessary. When you meter your scene with your camera or exposure meter look for an area that is the darkest area that you still would like some detail in your print (shadow detail). Since your meter measures everything in zone 5 (middle of the scale) you will need to stop down 2 full stops to get your shadows on zone 3. You can do this by increasing your shutter speed by two stops (e.g., 1/15 meter value to 1/60th new shutter speed) or if it fits your creative vision you could change your aperture from let’s say f/5.6 to f/11. In photography lingo you may have heard this referred to as “stopping down”. It doesn’t matter if you are using an internal meter on your camera or an exposure meter, you should have it set to spot metering mode.
This is also why when you photograph snow you have to go the other direction. For example, if you have some beautiful snow in your scene that has been untouched by foot prints I would probably expose at + 1 1/2 or + 2 stops. As a general rule I try and keep everything with detail between zones 3 and 8. When I shoot flowers against a black backdrop I don’t want or need detail so zone 0 is my target.
If you refer to the zone system scale below all of this will make sense.
Now What?
So far you have cut your film speed in half and you have stopped down two stops from your shadow detail meter reading. Now all this is left is to release the shutter and take the picture. That is all there is to it! Since you are printing in the darkroom you will want to develop for your highlights first and then work on your shadows. This is where the old phrase “expose for your shadow detail and develop for your highlights” comes from. This is beyond the scope of this specific article, but this is why variable contrast papers and filters were such a success with black and white photographers. It is like having several grades of paper at your disposal all on the same print. You can refer to an article that I wrote on how to make an enlarged black and white print that will give you additional information on this topic.
When you self-develop your film just decrease the time of your development a little and you should be set. For example if your film data sheet says to develop for 6 minutes then something in the range of 5 minutes would work nicely or use the rule I stated above and decrease by about 15%. If you are interested in my opinion about black and white developers then you may want to read that article as well.
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Tim, I think you should explain things a little more. If you’re not developing and printing your own, how should people communicate with their lab?
Changing your film rating 1 stop moves the exposure +1 stop and most film will tolerate this, sometimes two stops, and this is to minimize the grain…, like digital mantra, exposing to the right…, correct?
Stopping down / decreasing exposure -2 stops moves the needle back an overall -1 and doesn’t look right to me. If you want shadow detail, exposure should be increased, if you mean to limit shadow detail to zone 3, then stopping down or decreasing exposure by 2 stops will move zone 1 to zone 3, right.
Most people these days are recommending color film be over exposed 1-2 stops to minimize grain and give a good tonality / color to the image [portrait, wedding]. Chromes / reversal color has to be within about 1/3 of a stop, as it has about 5 stops of good dynamic range, negative film is normally around 7 stops.
Am I not seeing something? I’ve done a +1 rating and then pushing development 2 stops [over developing], but +1 then -2 exposure doesn’t make sense right now to me.
Thanks for bringing this up.
I made a mistake, decreasing exposure moves zone 3 to zone 1. Damn you iPhone autocheck
James, thanks for reading and commenting. I appreciate it. As an experienced photographer yourself you know it is a dangerous balance when providing short tips for new photographers. I try and find the distill the key points in as few words as possible and hopefully point people in the right direction. I have updated the article to make myself more clear on who the target audience is and the intended purpose of the tip I provided: black and white film photographers that print in the darkroom. You mention a lot about color films and I don’t address color in my article and as you know color films are a completely different approach. I went and checked out your website and really enjoyed your work, especially the architectural photos. I look forward to future comments and if you have any ideas for topics send them over. Thanks again.
Okay, sorry I read this too quickly. You were talking about the meter seeing everything as 18% middle gray [zone 4 or 5 depending on who you talk too, Bruce Barnbaum, Art of Photography] and I missed the turn, my fault. It’s really about translating the meter readings properly to get either the whites or shadows instead of middle gray. When printing for yourself the added density, gives some exposure time to work with at the enlarger.
The talk on color was off topic, sorry, but the discussion is similar when rating the film for desired result and the dynamic range of the media as well as the use of meter to get white whites and blocking up the shadows to properly reflect the scene. I’ll slow down reading, thanks for the compliment. Good stuff.
Tim, I have two questions about your explanation: 1. Why not make the math a little easier by rating the film as recommended by the manufacturer: ASA100 = EI100? Then when you meter you only have to stop down one stop: Meter reads 1/15, expose at 1/30. Is this the same thing or is there a reason for rating down the film? 2. If the idea is to develop for the shadow detail, then why would you shorten development time? Thanks for putting together an interesting website.
Stephen, thanks for the comment. I will try and answer your question without writing a book…
First, we have found with many years of history that manufacturer ratings of film speeds (ASA/ISO) is typically never correct and typically always faster than when we properly test our films. The other variable in the mix here is the developer, the time, temp and agitation of your specific development process. For the reasons I have just stated is why professional photographers always test their films for a personal EI rating. We have also found by using the manufacturer ratings for ASA and development time we are not giving our film enough light. The article is directed at film photographers that have not properly tested their film and developer combinations. Sort of like the old “Sunny 16″ rule sort of thing. When cutting your film speed in half you are doubling the light and it is important to keep that ratio in sync and not use another method. The other thing that might not be obvious is that when I say to meter for shadow detail that is a zone system reference. Zone 3 is the last zone where we can see shadow details in our prints. Our meters take readings in zone 5 and therefore we have to stop down two stops (-2 exp. comp) in order to place the shadow detail in the proper zone. Even though you are stopping down the two stops for your shadow detail you are still doubling the light to the film by cutting the film speed in half. If I am ever in a situation where I would have to use a film that I have not properly tested I would follow my own advice in this article, however that should not technically happen because I have tested all of my variables. By following my advice you can get very good results without have to do all of the testing. In other words it is a good starting place and will ensure good results when you haven’t tested. The other thing to note is about cutting back on the development time a little based on the manufacturer rating. When you develop film the shadows develop first and quickly and then the longer you develop the film the more contrast you have and the highlights continue to develop, hence the reason we test for n-1, etc and n+1 dev times. In effect we are contracting or expanding our contrast. Roll film users find this more difficult than large format sheet film users since we deal with one exposure at a time. You need to look at the curves for each film from the manufacturer and you can see different curves for toe and shoulders. For example many people talk about the steep curve of tmax 100 and their highlights get blown out. This is because they haven’t properly tested their film and processes. I hope my explanation was helpful and if you have any more questions don’t hesitate to ask.
Tim