People often ask which Pentax film SLR to get. In brief: get an MX with a 50/1.4.
In more but still very partial detail, based only on cameras I have used.
The lens is what really matters. The 50/1.4 is a very fine 50mm lens and if you are a 50mm-lens person it is the lens you want. It’s also relatively cheap because Pentax are mostly not a cult brand. Many of the ‘M’ range cameras came with this lens, as did the LX. Lower-end cameras often came with a slower 50mm which is probably not as good: not because it’s slower but because it’s just not as good.
The MX, and ME / ME Super were part of Pentax’s ‘M’ range. There are others in the range. They are all metal and well-made.
- ME / ME Super. The second is the successor to the first. The ME does not have a manual mode so you definitely want the ME Super. They are pretty common. You select the speed in the ME Super with a pair of buttons, not a dial, which is a bit annoying to use. It is a long time since I used one but I don’t think there is a DoF preview, which is also annoying. The viewfinder is as good as the MX’s I think (again, a long time ago).
- MX. This was Pentax’s professional camera before the LX. It’s a fully-mechanical metered-manual camera, with everything you could want from such a camera. The viefinder is wonderful: with a 50mm lens you can use the camera with both eyes open.
Other Pentaxes to consider.
- Super A / Program A (may have different names in the US). These were the spiritual descendents of the ME Super and were fine I think, the Super A is more serious. I once owned a Program A but I have forgotten what it was like.
- LX. Replaced the MX, and was a very serious professional camera which avoided the bloat which was already afflicting Nikon. They do go wrong (mine has, several times), but they can be repaired. Lovely to use.
Pentaxes to avoid.
- Anything with a Z such as the MZ and so on. Late-film-era plasticy horrid things. Nothing wrong with them for what they are, but what they are is not a good thing to be: why would you buy one?
- K1000. Student camera, lower-spec than the MX and now probably more expensive because it has become one of the cult film cameras. The reason it’s become a cult film camera is because people on photography courses were given it to use and so lots of attractive studenty people used to carry them around, 20 years ago, and the myth has persisted. There’s nothing wrong with it, but why not buy an MX.
Summary: get an MX, with a 50/1.4 if you can. If you want a more interesting camera try and find an LX, also with a 50/1.4 (same lens, same image quality!). If you want something more automatic look at a Super A, an ME Super or, again, an LX. The LX may break down in interesting ways but will be fixable. The MX will never go wrong.