No Lens Attached?
I've recently had a strange problem a couple of times with my A200. Suddenly, it has stopped shooting, with the message "No lens attached, shutter locked." a few times. Even though there was a lens attached.
It doesn't appear to be a lens issue, because it has happened with a couple of different lens.
It first happened about a month ago, after working much of the day on an outdoor shoot. I thought it might be dirt on the contacts, and did some cleaning, noting a little greasy dirt on the cleaning cloth. After that, it worked again for a while.
Today, part way thru another outdoor shoot, it happened again. I swapped lens back and forth a couple of times, and had some intermittent problems. Then, it cleared up, only to come back a few shots later.
I switched batteries, thinking it might be a power problem, coupled with a 60% depleted battery, even though I've run batteries down to 10% with no problems in the past. After a couple of intermittent mis-fires, it was fine the rest of the day.
I'm a little spooked now, since I don't know when it might be unreliable again at the worst possible time, and I can't determine if it is a dirty contact issue (doubtful), a power issue, a firmware problem, or an actual hardware problem.
A couple of times, just powering the camera off and on has fixed it. Other times, it seems re-seating the lens, maybe more than once, solves it. Or maybe, it gets better without doing anything specific.
The 70-300 did a good job the rest of the time, though.
is it an af lens...does it work in 'M' mode?
As the fault occurs with two lenses It's a camera issue.
Are the contact pins on the camera straight and do they depress and return easily?
The pins do appear straight and clean, and seem to be depressing and rebounding normally and equally. One of the first things I suspected.
When this happens, the lens wont work in manual mode either, so it seems a camera sensing issue, whether or not it is mechanical or logical/electrical.
It does seem plausible that it could be a contact issue with the pins, but inside the body, and not with the tips of the pins themselves.
I hope you're still in the Warranty period.