Why does my T3i take a pic when I change lens but then won't take anymore pics?

[colonelplum]

Last year while on vacation the camera wouldn't take any pictures. It tries to focus but never does. If I switch to the larger lens it will take one picture then starts the trying to focus stuff again. Any ideas?  I have tried to clean the sensor and all that with no luck.  One other thing is it started while we were trying to take family pictures on the beach but there was so much condensation that we couldn't.  Appreciate any help!

[ScottyP]

Hi,

A few questions.

How did you clean the sensor? Yourself? Was it the sensor or the mirror? Not necessarily related to your problem, but that is not something for every average user to attempt.

This focus issue happened in bright daylight? If it were less bright it could be the camera struggling to focus in low light. My T3i would struggle in scenes that were not at all dim to the human eye, and it needed pretty good light to focus.

What do you mean "too much condensation"? Was there a lot of fog/moisture on the lens itself, or was it just foggy?

Are you using all the AF points or are you selecting one point to be active? If you selected one AF point, perhaps even inadvertently, you might not be placing your active red point over the subject.

What are you trying to take photos of? A feature-less view like a solid color wall, or a uniform sand scape/seascape can give the camera nothing to grab focus on. Try focusing on an object or a sharp contrast point that stands out from the background.

What autofocus mode? AI Focus is probably the best one to leave the camera on if your subject is not moving a whole lot and not super fast. AI Servo can make the camera hunt for focus when it is not really needed for fast motion.

[colonelplum]

The focus issue happens in all kinds of light and I could be trying to take pictures of my cat, husband, kids, flowers, or a tree and it won't focus.  As far as the condensation, all I know is every glass on the camera fogged up.  I have tried the AI mode, the portrait mode and the manual mode. I can take a picture in manual mode but it is blurry - nothing will come in to focus. I reset everything according to the manual.  I cleaned the mirror - not the sensor.  I had only had the camera for about six month when this happened.

[ScottyP]

Happens on both lenses so not a lens issue.

Shooting looking through the eyecup/viewfinder, or in live view looking at the LCD screen on the back?

Could the focus screen have shifted or fallen out?

I don't suppose it is possible you have both switches on both lenses clicked into MF (manual focus) instead of AF (auto focus)? That happens sometimes to my lenses when I slide them in and out of the bag, but both at the same time seems like a long shot, though that definitely would do it.