I know we're all different, but I'm going to venture that you're probably better at taking pictures than you are at maintaining your finely tuned, very expensive equipment. Let's talk about that.
Are you exactly like me? Probably not, but I'll bet there are similarities (yes, I put my pants on one leg at a time. I sleep from time to time, I go to the bathroom, even the Queen of England passes gas from time to time [mind picture!]). We're all different but here's what I'm talking about:
I take my camera out every day. Rain or shine. Snow and wind and temperatures of -40°C. When I do, I shoot anywhere from a few frames up to a maximum of 500 or so. I come home, grab the CF-card(s), stick them in the card reader and upload them to the computer, being sure to make a second copy on another external drive at the same time (OK, that was nagging. Help me out: I'm trying to pretend I'm your mother here. Don't run with scissors and if you keep making that face it will stay like that).
Then I spend 'way too much time editing and sorting and printing and emailing and reading blogs and forums and newsgroups... and somehow I never get around to looking after my equipment. Until something overt goes wrong.
I'm not very good at maintaining my stuff. Some people are, but not me. I'm a really bad mechanic (I break things. Trust me - all I have to do is look at stuff and it breaks) so I don't try to fix things any more. Especially when they're little tiny precision things like you find inside cameras and lenses.
I spent all that money on Nikon gear because I knew it was rugged, war correspondents bang them around in combat zones, Scott Kelby gets them knocked over by NFL quarterbacks, they just keep on going and going and going... but sometimes they do break.
The focus sensor on my D300 broke. Well Nikon won't say "it broke", they said they 'adjusted and cleaned it'. Same thing with my 70-200 lens. They 'adjusted' it. They charged me $300. You know what? A fair price. Someone else I know dropped his D2X on some concrete steps and he paid $450 to have it fixed. Probably also fair.
Here's the thing: when Nikon (or Canon, or Sony or...) services your gear, they make it like new again. When I got it back, they had changed every soft part on the outside of the camera (those little rubber doors, the grip), they even replaced the escutcheon plate on the 70-200 lens where my fingers had worn out the white screened markings, because that's fresh and new.
They inspected everything. They even mounted the big lens on a projector and looked at every inch of a target. Then they tuned it so that it was factory perfect.
And they CLEANED it. I swear, it wasn't that clean when I bought it!
We all clean our stuff. You learn really early that spotless glass takes better pictures than ones with freckles. We've all learned how to carefully clean the sensor in our cameras. But not like the factory does it.
If you're going to Africa like Ron is, or you're going into wedding season like some of the pro's I know, or you just want everything to be perfect when the opportunity for that killer shot arises, think about sending your gear in for a tuneup*.I spent $300 and got peace of mind in exchange. No excuses now: if something is out of focus or otherwise not correct, it wasn't the camera, it was ME. And every time that happens, I try to learn what I did wrong and not repeat it.
Pick a time when you can spare your camera for a couple of weeks, then, "just do it". And don't forget to floss, and sneeze into your arm. And it won't kill you to call your mother just to say 'hi'.
* I called Nikon to ask them what they charge. They (can't speak for the others) will inspect your gear and do an external cleaning for free, whether it's in warranty or not. Then if something is wrong, they'll give you an estimate for the repair (or adjustment, they call it. I think they don't want to admit anything can break!). Minimum charge for a tuneup for a body is $50, and they told me they charge $86 per hour for general repairs. They also have some flat rate charges.