I purchased my D5100 in July, 2012, and, so far, I have been disappointed with the results I have been getting.
I originally purchased just the body, since I couldn’t afford the whole kit (with the 18-55 mm and 55-200 mm lenses) at the time. Also, many of the reviews I read were lukewarm about the kit lenses’ sharpness and quality, so I wanted to wait until I could buy a better lens.. In addition, I had an old Nikon AF Nikkor 28-85mm f 3.5 – 4.5 lens I was told could be used (although I couldn’t use Auto Focus, of course).
Since my main interest is to take close-up pictures—mainly of flowers and insects—after a lot of research, I decided to purchase the AF-S Micro Nikkor 60mm f 2.8 G ED lens. During the interim, I took a lot of pictures with the old AF Nikkor 28-85mm lens. The focus and sharpness on these pictures was not very good, even when I used a tripod, but I attributed this lack of sharpness to my inability to focus the lens properly in the manual mode. I anticipated a much better result when I received my new AF-S lens.
Unfortunately, I have been disappointed with my results using the new lens, too. Even when using a tripod and a remote shutter release, and even when shooting at f11 and higher, and even when using the LCD screen and manual focus rather than auto focus and the viewfinder, nearly all of my pictures have a “soft” focus—not sharp at all.
I have read a number of similar descriptions (Kuripakk’s June 30, 2012 post “D5100 + Nikon AF-S 35/1.8G autofocus problems,” for example) about other Nikon lenses from others’ posts. There have been suggestions to “tweak” the picture controls and “sharpness” or to use flash, and I have attempted to utilize these suggestions, but nothing seems to help. I don’t know whether there is a problem with the camera, the lens, or both. I know there can be many variables to taking “sharp” pictures, but I sure could use some insight or opinion as to whether I have a problem with the camera or lens, or both.