When I was exposing film, I noticed that, regardless of the format, I’d expose about the same number of square inches of film for a given type of subject. Said another way, after a day’s work, I’d have the same number of contact sheets to deal with, no matter which camera I used.
I once did a three-or-four-year project on the relationship between technological artifacts and nature in the hills behind Stanford University. I’d either take a 4×5 or a roll film camera with a 12-exposure 120 back. I’d go out for two or three hours a day, and the next day in the darkroom I’d make two or three contact sheets, which meant that I made three times as many images with the smaller camera.I did a series of studio portraits to get test images for a color management research project. I used medium-format and 35mm SLRs, usually using both in a single session. When it came time to examine the proofs, I’d have an equal number of 12-exposure and 36-exposure sheets. I did a series of studio flower still-lifes with 4×5 and 8×10 cameras. Sure enough, I made about four times as many images with the “little” view camera.
I always wondered why this happened, surmising that it was probably equal parts of how fast and easy the camera was to handle, the photographic style each camera encouraged, and the cost of materials (I was pretty parsimonious with my 8×10, knowing that every time I tripped the shutter, it would cost me more than ten bucks).
Now that the photons are falling on silicon, in most cases I’m making more exposures. One big difference is economic: it doesn’t cost anything to get those extra “insurance” shots or to explore some wildly experimental approach. Another is convenience: except when making images of static subjects, changing film was an intrusion on the creative process, and, since Murphy’s Law applies to photography, the things you were trying to photograph tended to happen when you had the camera back open. There is an exception: the job that can be done in six shots I do that way, where with film, I’d usually make it take a whole roll. Digital capture also makes it practical to do low-percentage projects that would be appallingly expensive with film, and would also produce a big pile of negatives and contact sheets to deal with. It’s also great underwater, where, thanks to Murphy, with film the best subjects tend to show up at the end of a dive when you’ve got two exposures left.
I recently had an assignment to do some studio portraits. I used two digital cameras, one based on a 35mm film camera, and the other using a digital back on a medium-format body. I was surprised to find I made about three times the number of exposures with the smaller camera. Why was that, since in both cases, it cost nothing to release the shutter? I wasn’t thinking about it when I was making the pictures, but the little camera is lighter (actually, the bodies weigh about the same, but the lenses are much lighter), gets ready for the next picture faster, focuses faster and more reliably, and has a brighter finder because the lenses are faster. I think those are the reasons I used it more. I’d tend to use the small camera to try things out and experiment with lighting, and pull out the big camera when I found something that worked.