Hi: I just got a D7000 and 17-55 2.8 (after deciding that a 2.8 was worth the extra $$ over the 16-85ED, my 2nd choice). I have about 5 days to decide if this lens is sharp enough across the board to keep, or try a different one. I really wanted the 24-70 but with the crop factor it isn't wide enough. For me, the lens need to be acceptably sharp at 2.8. If not, and I have to use it at f4 then I've spent a lot of extra $$ for 2.8 only to not have confidence in it.
About me: I was a staff photog at the LA Times for 20 years, but left just before digital took over. I've shot 35, 2-1/4, 4x5 for nearly 30 years, but I've never been a lens tester per se. If I got the results I wanted, the gear was fine (oh, I miss the Mamiya 6 and 7 and chrome...so freaking razor sharp it's almost freaky). If not, lenses got replaced. I have had a Canon 20D for about 5 years and have been just shooting that for fun, easing into digital. I am not (so far) a pixel peeper, but I am now interested in getting the max from my files, and lenses, and may start freelancing again. I know I know...FX is the way to go but I am awaiting the D800 and more money!
QUESTION: It seems like the sharpness and focus is inconsistent cross the various focal lengths. I have been testing it mainly at 2.8 and 4 and 5.6. Why? Any theories? (I am shooting mainly at ISO400 and both RAW and JPEG/highest files). I am looking at them using Picasa...haven't upgraded to PS or Lightroom/Aperture just yet.
Details: I have been informally testing the sharpness around the house, in/outside, and went to Walmart and shot some shelf displays...items with fine print on the packages. I just shot some cereal boxes on the counter at 24 and 35mm, my CD rack, and other items with detail at 2.8 and 5.6 (camera resting on counter). All seem very sharp to the corners of the frame, and show excellent detail. Then, I shot some frames at 24mm outside at 2.8 and 5.6 and at 24mm the sharpness seems inconsistent. At 18 and 55mm it's good, or seems so though I don't have a reference standard to compare it to except for some of my old prime lenses like the 55 macro and 105/2.5 which is good. I just shot some things in the house using flash, at 24mm, and they all seemed too soft but the other day I shot the exact same thing and they were sharp! Grrrrr.
Does anyone have a good lens test protocol? Should I just put a sheet of the newspaper on the wall, camera on tripod, and shoot at various focal lengths and f-stops? If I go from 17mm to 24mm for example, should I move the camera so that I am filling the frame the same at all focal lengths?
I would gladly post some images to my public Dropbox folder if anyone wants to take a look and let me know what they think? JPEG Fine or Raw?
All suggestions welcome....the clock is ticking.