One thing that lead to my interest in cameras at an early age was seeing old family photographs and learning about the processes used to make those photographs. We have at least one tintype in our possession. We also have some old cameras that belonged to my grandparents. I've started collecting old cameras and fixing them as needed. Some of them still take fairly nice photographs.
Seneca No. 5
One of the oldest cameras I have is an old Seneca No. 5 view camera that belonged to my maternal grandfather. This camera was made ca. 1905. It is still functional. I may try to use it at some point, again, but I'd have to modify the film holder, because it takes glass plates, normally.
Kewpie No. 2
I also have a camera that belonged to my maternal grandmother. It's a Kewpie No. 2 box camera from about 1915, and it also still works. The box camera takes roll film (620 size) and it can be made to take 120 roll film.
These cameras can be found on eBay for about $15. I have a roll of film in my refrigerator ready to use with this camera when the time is right.
Various Kodak Cameras
I have also come into possession of several older Kodak Autographics cameras dating to the early 20th century. Most of these could be used if I could find roll film large enough. They took photographs on negatives that were made to be contact printed on postcard size paper. The film mechanisms are too large for 120 roll size film.
Agfa Plenax PD 16
I bought an Agfa Plenax "pocket" camera off of eBay and have used that a couple of times.
The Agfa Plenax camera will take (with a little work, and the spool that was included with the camera) 120 roll film. One of the most interesting things about this camera was that when I got it in the mail I found that it still had film in it. I had the film developed and there were photographs on it. Here's one:
I'm still using the Agfa Plenax - so far just with black and white film that I develop at home - and believe I can get some nice photographs with it.
Argus Argoflex and Graflex 22 Model 200 Twin Lens Reflex Cameras
When I was in high school one of the cameras that was available to borrow for photography classes was a Graflex 22. I don't recall having used one back then (instead, I used my Canon AE-1, which had just come out), but I've recently acquired two twin lens reflex cameras. The ones I bought were not high end when they were initially made (the Rolleiflex TLRs were very nice and still command very respectable prices on eBay). Still, with some practice and attention to detail, these cameras are still fun to use.
Both of them will use 120 roll film. [Unfortunately, when I cleaned the shutters of both of these, I used a small amount of oil that was too heavy for the lightweight shutter petals. From what I have read online, lighter fluid is a better fluid to use when necessary, but that's a whole discussion in itself. It has taken me a long time to get the oil worked out of the shutter petals, and by now the shutters work about 85% of the time. I do have to still clean the oil residue off of the petals occasionally.]
There are a few things that have been critical to success in using these older cameras. The lenses may need to be disassembled and cleaned; the shutter may need to be cleaned, the inside of the body may need to be blown clear of dust and debris; the take-up reel may need to be modified to work with 120 roll film (the only roll film readily available these days). Exposure is, of course, entirely manual. I have had to refamiliarize myself with Ansel Adams' Zone System, and to compare exposures using live view (with Magic Lantern) on my Canon DSLR with what the GE light meter says. Oftentimes I will use my DSLR to meter on a scene, then adjust that for use with whatever film camera I am using. Most importantly when using these old cameras - particularly the TLRs, I think, is that holding the camera absolutely rock steady is critical. I have bought a cable release and used that with these TLRs and that has been helpful. Another thing that I've done with the Argoflex is to recalibrate the focus using a piece of glass sprayed with a frost spray that I got at Home Depot.
Here are a couple of shots I have made with these TLRs:
The color shot using the Graflex proved to me that if the camera is held rock steady, if the right exposure is made with the right film, a very nice quality photograph can be made.
Old cameras can be fun to tinker with and to use. They can also make you think harder about exposure in these days of DSLRs, when many exposures can be made without cost - a nice feature, to be sure. But, it's still rewarding to get a nice photograph on film, though it often takes considerably more thought when making a shot.