I finally got lens number three of the 17-50 f/2.8 lens from B&H. Before I put the lens on I cleaned the contacts very carefully with rubbing alcohol, and made sure it was dry before putting the lens back on. It seemed to work well, except once. I got the no lens attached thing again. This time no amount of turning off/on would work. I had to unseat the lens and reattach. It just happened once. I am going to hope that it is just a D40 issue, or just this D40 and keep it. It is really nice to have a faster lens. I found that I had to swap in my 55-200 often though at the Lantern Lighting event. I didn’t always need the upper end, but 50 was just too short most of the time for an event like this. The 55-200 works fine in the middle of the day. I like it a lot, it is just too slow as evening come on. Oh well. Can’t get everything with one lens.