Originally posted by stevebrot You are absolutely correct. If a person needs a 20, a 28 would be a poor substitute. However, I don't know that anybody said the OP was looking for a 20mm lens. A 28 is a good recommendation for a wide-angle on 35mm film and is sufficiently wide to satisfy most subjects. Most available 28s are relatively fast, quite sharp, and have low distortion. They are also dirt cheap.
I personally like wide-angles and own several 28mm lenses. Every once in a while I have wanted a 24. Never, have I had a need for a 20. Given my personal experience, I don't know that I would point a noob in the direction of an expensive specialty lens and a 20mm is very definitely a specialty lens.
The M35/2 is a decent lens and would be my first choice for street photography using a 35mm camera like the MX. Again, what is an appropriate advice for a noob? I like my 35s (I have several in three different mounts), but would not point someone in that direction unless they already owned a 28 or a 50 and wanted something in-between. Traditionally, the classic kit is a 28mm, a 50mm, and a 135mm. All three are usually good, readily available, and dirt cheap.
Steve
I think that's a sensible approach. Oddly enough, the set of lenses I bought for my first MX was M 28/2.8, M 50/1.4, M 135/3.5. Still have them all, worn paint but in excellent working order.
While the first version M 28/2.8 is not as well-regarded as other Pentax 28s, it is very decent, affordable, and easy to find. Same for the 135/3.5. A 50/1.7 is a fine affordable alternative to the 50/1.4.
The three lenses make a very compact outfit. I often put two of the three in jacket pockets and go without a camera case.