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.

[Anonymous]

Is it only this lens, or does it happen with other lenses? 

Try removing and re-installing the lens to wipe the lens contacts.

[Bankesmom1]

This is the only lens that it happens with.  It is the only Telephoto that I have.  It is a Tamron18-270mm F/3.5-6.3.  My other lens is a Canon EFS 18-55mm and I never take it to sporting events because things are just too far away.  And I've never had an issue with the Canon lens. 

[deebatman316]

Do you have any Canon lenses. If so do they fail to AF in warm weather too or just the Tamron lens. Also what is the full model name of your Tamron lens. Also the Full model name of the Canon lens if you have one.

[Bankesmom1]

I do have a Canon lens and it is an EFS 18-55.  It has never failed to auto-focus.  I never take it to sporting events though.  Just inside mainly when things are relatively close.  The Tamron is a 18-270 mm F/3.5-6.3  Thanks for your questions and trying to help me solve this issue.

[deebatman316]

What are the lighting conditions like when this happens. If its dark and lacks contrast the camera will struggle to lock focus. What mode are you shooting in on the top mode dial. Are you shooting in A+/ Green Square Mode. Your camera has 2 main focus modes there's also a 3rd. Your main focus modes are One Shot and AI Servo. One Shot is focus priority. The camera won't take a picture unless its in focus. AI Servo is release priority. The camera will take pictures regardless if the pictures are in focus or not. The 3rd is AI Focus its a hybrid mode. The camera will start out in One Shot then switches to AI Servo if it detects subject movement. This mode IS NOT recommended because camera shake can cause the camera to switch to AI Servo. The lens has a variable aperture F/3.5-6.3 which is slow. At 18mm F/3.5 is wide open. But at 270mm F/6.3 is wide open. The bigger the number the less light enters the camera. Also please post some pictures in the forum too. So forum members can better assist you.

[Bankesmom1]

The lighting conditions are always good.  Outdoor baseball games either daylight, or lighted fields, football the same, and basketball in gymnasiums.  Basketball pictures aren't nearly as good, I need to invest in a different lens because of the low light situations in there.  And I shoot in sports mode to catch the action, and I believe that in sports mode, the default setting is continuous shooting.

[Bankesmom1]

Thanks so much!!!!

[deebatman316]

I would suggest learning about the exposure triangle. Then discontinue the use of Sports Mode or any other Fully Automated shooting mode. Your camera uses an older AF system. Your camera has 7 AF Points. So the sensitivity of the AF system will have limits. All camera gear has limits.

[Bankesmom1]

Thank you for this explanation.  It makes sense.  I'll try these things and just work around the issue.  I'm still baffled why it has worked for years, and all of a sudden does not.  I'm thinking that it is getting to be time to upgrade.