I bought a Sears 135mm, f 2.8 on e-bay for 25C$ shipping included & tried it out on my Panasonic G1. I was experimenting with it wide open & found the results disappointing due to soft images. I set up in the living room to see how the sharpness would improve with the lens being stopped down. I shot a high contrast white geranium against a dark background from the minimum focus distance of about five feet. The camera was set to ISO 200 & a WB of shade. Contrast & sharpness was tweaked in Photoscape. 1. F 2.8 (wide open) 2. f 3.5 3. f 4.0 4. f 5.6 The sharpness does improve a bit as the lens is stopped down & I venture to say quite acceptable @ F 5.6. What say you?