So we're staying in this awesome flat in Bridgeport Chicago and I notice that the ceiling light is rather neat. So I tip my camera onto its back and take the above picture.
And a huge lump of dust drops off the back of the lens onto the camera sensor.
So now every photograph has a grey dot on it (you can see it on the shot above to the right of the centre).
Now, the rational part of me knows that this doesn't matter at all in the great scheme of things. Really. But the other, stupid, part of me will focus and obsess on this little grey mark, panic that the camera is now broken and it will never be right again.
Eventually I did the right thing. We wandered down to Central Cameras in Chicago (an amazing camera shop) and I bought a rocket.
I don't know who's idea it was to shape this dust blower like a rocket, but it works for me. The good news is that a couple of puffs at the sensor from this wonder machine and the dust has gone completely. I held the camera upside down while I did this, so hopefully the dust has dropped off completely. At least I've managed to convince myself that this has happened.
I've now formed the habit of dusting the base of a lens before I attach it to the camera. And the word on the street is that the sensor in a digital camera is actually quite well protected, certainly not just a naked piece of silicon, and cleaning it is reasonable (and not particularly dangerous) thing to do.