The numbers in this post are a snapshot of where my hybrid film workflow is today. I am still taking most of my film pictures with my old Leicas but, increasingly, they are on a tripod with the Visoflex. Shaking hands and failing vision have reduced my percentage of “keepers” when shooting hand held to nearly zero. So marginal costs are of more than academic interest these days as I think about my future in photography.
Using a Watson 100 bulk loader and Leica FILCA cassettes a 12-exposure roll uses 30” of 35mm film, so a 100’ bulk roll is good for 40 loads. That works out to about $1.50 for a roll of HP5+.
I use a one-shot developer of 5 ml of Rodinal (about $0.10) and 245 ml of distilled water (about $0.08) for a total of $0.18 for a roll.
I make a liter of working fixer solution with 200 ml of Ilford Rapid Fixer (about $2.00) and 800 ml of distilled water (about $0.25). The liter of working solution costs $2.25 and is reused for 20 rolls of film. For a single roll the fixer costs just under $0.12.
I use another liter of distilled water for a plain water stop bath and three changes of wash water. That’s another $0.30.
So the total material cost for a developed 12-exposure roll of HP5+ is $1.50 + $0.18 + $0.12 + $0.30 = $2.10. Each additional frame on a longer roll would add seven and a half cents. For example, a developed 24-exposure roll of HP5+ would be about $3.00.
Medium format costs more. The best price I’ve found for a 120 roll of HP5+ is $4.99 and it takes twice the volume of chemicals to develop that roll. A quick back of the envelope calculation looks like $4.99 + $0.36 + $0.24 + $0.60 = $6.19 for a 12-exposure roll of HP5+. Ouch!
Mere Film Photography 
35mm is the most economic way to go, and of course, as you say, developing at home. So you can get the best of both worlds. Smaller costs and total control about your work… and total responsibility if you mess up.
Thanks for this series!
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