Originally posted by ptwist61 [deleted]
I would battle the K-x with DA* lenses versus 5DMII to "L" series lenses to be fair.
[deleted]
Lenses here are not the issue. The differences have to do with the physics of pixel size and density between both product sensors. Your Pentax setup (a nice one) would be the equivalent of f4 on a FF.
Pentax excels in single focal length lenses, but their current zooms are unexceptional. There is nothing in a current K-mount equal to any top-line L zoom, especially the Canon 70-200mm f2.8 IS MkII.
If your heart is set on making a direct comparison, than something more reasonable might be against a Canon 50D using the Tokina 50-135mm sister lens to the DA*. I've done something very similar with my 7D vs. my K20D. In addition to costing two-thirds of what the DA* lens runs, I actually preferred the rendering of the Tokina--better sharpness and color. Plus it's got a tripod mount which the Pentax version sorely lacks. There's some meaning here somewhere.
Comparing a FF sensor with a crop mount is entertaining but only meaningful when the stakes are higher--as in commercial work and larger expensive fine art prints.
M