I was shooting at a party last week and at one point was having trouble getting my D5000 to recognise the D series lens on it (what it does when the aperture is not locked, even though it was). Another guest who was an experienced photographer noticed me having problems and suggested that it might help if I took the lens cap off. Of course, that was not the issue, but somehow trying to explain that with a couple of other people standing around just came across as really pathetic and embarrassing.