
My grandpa’s Rolleiflex, from the attic.
The easiest way to get more out of black and white film for your darkroom experimenting is to use medium format film. Medium format is sold as “120 Roll Film”. Developing medium format film in the darkroom is the same as 35mm format, but the film is way broader, making it easier to handle. If you have a developing tank big enough to handle two rolls of 35mm film, it can probably handle one roll of 120 film.
Different cameras give you a different size negative, and different format. The classic medium format size is 6x6cm (2 1/4 square inch), which you get with most Rolleiflex and Hasselblad cameras. Or with a Holga. Mamiya makes a bunch of cameras that shoot 6×4.5cm or 6x7cm. There are plenty of others. A Holga is the cheapest way to jump in the game. A few weeks ago I bought a perfectly functional Rolleicord (6x6cm) for 40€ from a shop.
Why medium format? Because the negative is bigger, way bigger. Going from 35mm (2.4×3.6mm) up to 120 (say, 6x6cm) roughly triples the size. If you are thinking digital, it is not at all like going from a smaller sensor to a larger one. It is like tripling the number of megapixels and sensor size at the same time.
I enlarge ISO 400 negatives shot on HP5+ in my darkroom up to 30x30cm all the time and get no grain whatsoever. Perfect resolution. This gives you a lot more room to play. If the exposure is off, or there are a lot of highlights or shadows in your picture, you can get more out of the negative without loosing quality. It like shooting with a state of the art digital camera. Indeed, I find I can get more tonal range on HP5+ film shot at 400 than I can with my Nikon D800 at 400, similar to what I get shooting digitally at 100.
Shooting medium format film is a fifty dollar solution to get a lot more room to play in the darkroom. You could buy hundreds of rolls of medium format film for the price of a digital camera with a similar resolution…