I didn't get interested in photography until I was over 30.   I started with a point-and-shoot film camera, but quickly realized its limitations.   I then bought a second-hand Pentax ME Super single-lens reflex (SLR) camera, with a 28-80mm lens.   This was just an historical accident, because the Pentax happened to be in the store, and I hadn't given any thought to what brand of camera I should buy.   After the ME Super, I bought a Super-A, but I've forgotten why I made this change; perhaps the ME Super died on me, or perhaps there was some feature of the Super-A which I wanted.   I had now bought several lens, which meant that I was committed to Pentax equipment.
    My next step was a ZX-5, known in the United States as an MZ-5.   I bought this camera because it has TTL metering for the flash, which means that when you take a flash photo, the camera body turns the flash on and then switches it off when enough light has hit the subject.   This makes life a lot simpler than having to work out what the correct aperture setting is for a subject at a particular distance from the camera.   The birds and insects often don't hang around long enough to allow that type of calculation!   The ZX-5 is also an auto-focus body, but I didn't use that feature at the time, because I didn't have any auto-focus lenses.   Even now that I do have some auto-focus lenses, I still manually focus them, though if I had a long auto-focus lens then I might use it on auto focus.
    The next step was backwards, when I bought a ZX-M, with the "M" standing for manual.   This is a cheap low-end camera which Pentax introduced around 1999 or 2000, with no auto-focus and not even a built-in flash.   I bought it because I enjoyed the "split prism" focussing system of my earlier cameras, which allows very accurate manual focussing.   However I soon realized that the "ground glass" manual focussing system of the ZX-5 was easier for me to use on my faster moving subjects like birds and military aircraft.   Nevertheless, the MZ-M has been a useful back-up body which I've used at airshows so that I don't miss shots when the film is rewinding in the ZX-5.
    At the end of 2001 I bought a Pentax Z-1 camera body, solely because I wanted its 1/250th second flash sync speed to avoid problems when taking long-lens photos of birds and insects when there's a lot of ambient light.   My previous camera bodies only had flash speeds of 1/100th of a second.   This was the top of the line Pentax body for many years, until it was replaced by the MZ-S in 2001.   The controls on the ZX-5 are virtually identical to the MZ-5, and very similar to the ME Super and Super-A, but the Z-1 is a different beast entirely.   The Z-1 is larger, heavier and much less intuitive to use than the other bodies, which have the main controls like the shutter speed on simple dials.   You can see some of the difference by looking at this comparison of the MZ-M, MZ-5 and Z-1.   If you want to investigate the features of the Z-1 further, check out this PZ-1p manual.

    At the end of April 2002 I bought a Canon D60 digital SLR camera, along with a matching 100-400mm image stabilization lens and a 100mm macro lens.   I've  written a page about the pros and cons of digital photography compared to film photography.   I was disappointed with the auto-focus performance of the D60, so in December 2002 I bought a Canon 1Ds digital SLR and a Canon G2 digital point and shoot camera for underwater photography.   Then in April of 2004 I bought a Canon 10D digital SLR so I could enjoy the benefits of good auto-focus for airshows together with the 1.6 times crop factor of the D60, turning my 100-400mm lens back into the 35mm equivalent of a 160-640mm.