Like watches, bicycles and especially clean handkerchiefs, I can barely remember when I didn’t own a camera. People with cameras on their smartphones will find it difficult to believe that the first widely available camera, the Kodak box brownie, was a rectangular black wooden box about 12 cm by 12 cm by 9 cm. The viewfinder was a small glass prism in one corner which one peered down into while holding the camera at waist level. There was no focusing. The film inside was on a roll and had to be wound-on by hand after every ‘shot’. There were perhaps 12 or so photos on a roll. The roll had to be removed carefully, to prevent light entering and taken to the local Chemist (Pharmacy) to be ‘developed’. The result was a series of transparent (black and white) negatives and paper-backed prints of exactly the same size. My grandfather processed his own ‘contact’ prints as I did later and went on to build my own enlarger to magnify the size of the finished print.
Seaside towns sported a breed of street photographers who would pretend to take your photo, then if you showed interest, really took your picture which you could collect at the end of the day from their temporary premises. Of course if you go on modern rides in amusement parks you may well be offered the same service.
The production of plastics led to cheap smaller cameras and eventually, the improved chemistry allowed smaller film sizes and hence smaller cameras with coloured film. The final film size, which produced a camera mirrored in the cameras of today i.e. small, but convenient to hold and with a diagonal size of 35 mm.
Now of course only the devoted few use film, as the digital age has produced sensors so small that they are actually smaller than the crystals of silver-nitrate that they have replaced and lenses so complex, accurate and cheap that could not have been imagined even 20 years ago.