Originally posted by JinDesu I have a k-x and the 70-200, and used to have the 90 macro.
The Tamron 70-200 performs fantastically from 70-135, soso at 135, fantastic from 135 to 180, and soso at 180-200. It's focus speed is quite good (screwdrive lens), and should be better on a k-5 than my k-x. It is the lightest of the 70-200 2.8s, but it feels well built. Manual focus switch is by shifting the focus ring forward/back, which isn't that great.
The Tamron 90mm macro is a very nice macro lens. It is moderately sharp at 2.8 with some CA. It is fantastic once stopped down to F4. The Sigma 105 and the Pentax DFA 100 are sharper, but the Tamron is no slouch. In addition, it renders very nicely and has very pleasing bokeh. AF performance is good when limiter switch is engaged. Manual focusing is pretty comfortable on this lens. It does feel a bit plastic, but not cheap.
I had the Tamron 180 back in my Canon days and for
tripod work the AF/MF switch actually works pretty well. Start with AF with your hand on the ring...if the AF needs a tweak, snap the ring down and focus without removing your hand. I can see though how it would not be the best thing handheld.
I'll have to check out the Pentax 100 options. I've just had such good luck with Tamron macros in the past (let's see...original 90 on film, first gen 90 AF on Canon, second gen 90 AF on Canon, 180 on Canon, hahaha) it's hard to consider anything else
Funny you mention it, when I adapted a last generation Adaptall 90 to my E-5, yeah, exactly what you describe, little CA at2.8, gone by f4. Sharpest f4-f16, little diffraction at f22...worse at f32.
Thanks for the replies all!