John, You're right the 135mm has more reach, but it is also a bit slower. The M-100mm f2.8 is a bit smaller and faster, so it's easier to focus and hold steady. There is a bigger K-100mm f2.8 but they are more rare. The M-135/3.5 is an old favorite and dirt cheap for the quality it provides. You won't go wrong with it! Regards, Bob S.
[EMAIL PROTECTED] writes: << After a 30 year absence from photography I'm back and re starting almost where I left off-fully manual.Only this time with Pentax,the K1000. I am having great fun with my two M series lenses,28/3.5 and 50/1.4, my 50/2 will be passed on, I think. My question is,"how different is the M135/3.5 from the 100/2.8 for pulling in ,more distant subjects"? I have no interest in doing portraits at this time-just more reach for candids. Best, John >>