EOS SL1 auto focus doesn't work. Seems to happen on hot days

[Bankesmom1]

My Rebel SL1 with a Tamron telephoto lens won't auto focus on warm days.  It will sometimes work at close focus, but when zooming in, it won't auto focus. Does anyone have an answer to this.  Same thing happened last year, but my local camera shop could give me no answers.  It was the shop where I purchased the camera, and I was disappointed with their response.  The weather has warmed up, I wanted to take pictures at a grandson's baseball game and no autofocus.  Frustrating.

[amfoto1]

You are shooting sports...

Previous response that you should "never use AI Servo" is terrible advice. With action photography you MUST use AI Servo! If you use One Shot, as that response advises, you will miss focus on A LOT of shots. This is because when you half-press the shutter release button One Shot acquires focus, then stops and "locks" until you release pressure off the button. A moving subject will frequently move away from the point of focus before you get take the shot.

AI Servo is the mode to use for moving subjects. It never stops and locks. It keeps detecting the moving subject and updating as long as you maintain pressure on the button, so will be correctly focused when you take the shot.

It is POSSIBLE that AI Servo actually is working, but you aren't aware of it.

In One Shot mode when focus is achieved you get "Focus Confirmation". Depending upon the camera it may light up a green LED, or it may flash one or more of the red AF points, and if it's enabled will give an audible "beep".

In AI Servo the focus happens silently, without any Focus Confirmation. That's because confirmation simply isn't possible. The focus operates continuously, so there's nothing to confirm! Sometimes people think the camera isn't focusing when they don't hear the beep or see the LED light up.

The focusing mode you should never use is AI Focus. That's not really a focus mode at all. It is automation where the camera is supposed to detect whether or not the subject is moving, then switch to use the correct mode. To be honest, it's probably been 15 or 20 years since I last tried it. But when I tested AI Focus I found it less than ideal. Sometimes it worked fine. Other times it chose the wrong mode or didn't switch modes if a subject stopped or started moving. It also seemed to cause a bit of a delay that caused missed shots.

I switched to AI Servo with Single Point (most of the time) and  Back Button Focusing and my "keeper" rate got  MUCH better. Now I think the only thing that would be better is the new mirrorless R-series that detect people, animals, vehicles, faces and even eyes.

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Alan Myers
San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7DII (x2), 7D(x2), EOS M5, some other cameras, various lenses & accessories
FLICKR

[ebiggs1]

"Previous response that you should "never use AI Servo" is terrible advice. With action photography you MUST use AI Servo!"

No its not. That is what she is using and if you read more carefully you would have known that. It is why she is missing focus. You guys are tying to confuse a beginning photographer with all the advanced advice. Baby steps, my friend.