Issues with Autofocus on ES-F 18-55mm Lens

[plumwd]

Hello everyone,

I just purchased a T2i with the ES-F 18-55mm lens kit.

When in autofocus mode, the lens will sometimes (more often than not), be unable to take the photo. It just keeps trying to focus and the flash will blink rapidly. I am able to take photos sometimes in autofocus, but most of the time the above is what happens.

In manual focus I can take photos no problem.

This is my first DSLR although I used to use them at work frequently.

Thanks!

[RichardTaylor]

Are you trying to auto focus in low light?
If so try setting the camera to centre focus point only and see how that goes.

Also see page 202 of your (English user guide) for some tips.

[litenphrame]

Are you in using the camera and lens low light conditions? If that is the case, there is not enough contrast around the focus point for the camera to know if the focus is correct and therefore continues to search for focus and prevents the shot.

[plumwd]

I think that this was likely the issue. I did some playing around with it and setting the focus point seems to have helped.

[RichardTaylor]

Good news and thanks for the update.

[plumwd]

On further testing (now that it's daylight), I think the camera is still having issues.

It's continuing to search even with a focal point sent, and has a really hard time taking a picture at all on fully automatic mode.

I cannot focus when it's in 55mm mode either. The photo either gets shot blurry or the camera keeps hunting. This happens in both auto and MF.

[plumwd]

I think it's also worth nothing that I bought the camera second hand.

[veritasimagery]

Originally Posted by plumwd

On further testing (now that it's daylight), I think the camera is still having issues.

It's continuing to search even with a focal point sent, and has a really hard time taking a picture at all on fully automatic mode.

I cannot focus when it's in 55mm mode either. The photo either gets shot blurry or the camera keeps hunting. This happens in both auto and MF.

The camera shouldn't be "hunting" for focus if the lens is in MF. With the lens in MF it's all up to you if the image is in focus.

The other question is, are you using "Live View" or shooting through the viewfinder? The live view mode is terrible for focusing. I have my T3i hunt around at times if I am using the "Live view". The only time I use it, though, is for shooting images from low angles. Then I use my "flippy screen" (and tripod) so I don't kill my back.

Also, silly question, how clean is the lens glass? A small smudge can really tweak out AF.

[plumwd]

It's possible the lens is faulty right?

I've tried cleaning it and that doesn't change the outcome.

When in AF mode most oft the time, I can just hear it going back and forth, never settling on anything.

[RichardTaylor]

Quote.
"When in AF mode most oft the time, I can just hear it going back and forth, never settling on anything. "
Ends quote

That doesn't sound good, especially at higher light levels.
Do you have any filters on the lens?
If so that may cause problems also.