I gotta say the 70-200mm 2.8L IS is the best lens I've owned in its focal length zoom range. And I have read everyone is always happy with pentax 50-135mm 2.8 SDM. I kinda thought I was one of the few dual system owners:
Pentax & Canon
I hadn't read where the Pentax lens topped the Eos lens in hands on owner's surveys:
50-135mm 2.8 SDM Versus Canon 70-200mm 2.8L IS
Anyways a couple points. I own Canon 1.4x II teleconverter and its an exceptional pairing with the 70-200mm 2.8L IS resulting in a respectable 98-280mm f4 IS on my full frame 5D. Both the lens and teleconverter are weathersealed and even include gaskets at lensmount which surprisingly pentax does not include on their SDM lenses.
Now I don't own a 6.3 frame per second 50D aps-c eos dslr but if I did then what would I have with same lens and then with TC 1.4x combo?
70-200mm 2.8L IS "becomes" 112-320mm 2.8L IS on 50D.
& with 1.4x Teleconverter its 179-512mm f4 Image stabilized supertelephoto zoom.
Sure I paid $265 for my Canon 1.4x II Teleconverter but as I had read on a few canon forums its exceptional with 70-200mm 2.8 and best of all it was available for sale.
I suppose if I wanted faster frame rate and if I believed crop isolated view crop factor gives me more reach then getting a Eos 50D may be a logial step for me. Thesedays 50D is $1069, which I feel is still way too high. I think it should be priced where nikon D90 is at thesedays so $850 tops.
50D
http://www.bhphotovideo.com/c/product/580462-REG/Canon_2807B006_EOS_50D_SLR_Digital.html
D90
http://www.bhphotovideo.com/c/product/580241-REG/Nikon_25446_D90_SLR_Digital_Camera.html Originally posted by dopeytree