Originally posted by StevenVH I'm in a similar situation, I have the 50-135 and need/want longer reach, and am searching for definitive info on using a 1.5x tele-converter. I think it's a good option as long as the IQ stays acceptable for publication and the AF works well for sports action. I've searched this forum and don't find the definite answer yet.
If I was making more $$ from my photo work I'd have 2 bodies with 50-135 on one and 60-250 on the other and maybe the DA*300 in the bag as well. In the meantime a fully functional tele-converter seems like the best option for me.
cheers
This is where the design of a lens system is important at the onset.
When I look at the options, I consider that if you don't do wildlife or perhaps sports, then the 50-135 makes sence, but if you are into something that needs a sound and fast approach to 300 or 400mm, you are limited to really 2 options,
option 1, within the pentax line up get the da300F4, and if you need more reach with that lens get a TC that will work with the lens, or add the 1.7x AF TC as many forum members have done.
option 2 forego the 50-135 F2.8 in favour of a heavier 70-200F2.8 and add 1.4 and 3x TCs.
I have option 2 using the sigma 70-200F2.8EX (non DG non macro) which is excellent alone or when used with sigma's 1.4x and 2x TCs.
I think adding a TC to the 50-135 will still leave you short in many occasions, and slower than what you can do with a 70-200. Just my $0.02