If you used the K1000, then I would suggest you try the Pentax MX as it is not only the smallest manual 35mm but it also happens to have the largest viewfinder with 0.97 magnification and 95% coverage. Compare this to the FM3A's 0.83 and 93% or the F3's 0.75 and 100% viewfinder spec and you can understand why it can be much easier to get critical manual focus with even the fast f1.2 lenses.