Originally posted by Mirton I was going to suggest to keep the 50-135mm and buy an older F/Fa 135mm f2.8, but i know you going to catch the telephoto bug very soon after and wish you bought a DA* 200 instead or something longer. So my recommendation for you is to keep what you have and buy a DA* 300mm f4.
The Pentax-F 135mm f2.8 (its very sharp)
Ahaha that's very possible ! Thing is thoses 200 & 300mm lenses are quite long range and also quite big and heavy (not so compared to telezooms) but still. The day I decide to go to Kenya, I might very well buy a 60-250 or DA300 + the 1.4TC. Until then I have found that for now that 50-135 is very sharp at 135mm stopped down. Cropped it can give you very usable 270mm while staying I think overall better quality than 55-300...
I'am finding that I care of having small & light lenses. For now I like my 50-135 too much to get rid of it to replace with a smaller and not as good 18-135 or whatever. But it remains big...
I would not have said that I would not use my 17-70 when I started with primes. That why I'am willing to try prime for the long range too. See how it goes.