100mm 2.8 Macro Not focusing

[swanphototx]

My macro lens is constantly hunting for a focal point. It has recently started this and no matter if I'm using it for ring shots or portraits, good lighting or bad, it won't focus.

It's never been dropped or damaged. I've had it for almost 5 years. 

[Danny]

Hi, swanphototx!

So that the Community can help you better, we will need to know exactly which Canon camera model you're using with your macro lens. That, and any other details you'd like to give will help the Community better understand your issue!

If this is a time-sensitive matter, our US-based technical support team is standing by, ready to help 24/7 via Email at http://bit.ly/ContactCanon or by phone at 1-800-OK-CANON (1-800-652-2666) weekdays between 8 AM and midnight ET (5 AM to 9 PM PT) and Saturdays from 10 AM to 8 PM ET (7 AM to 5 PM PT).

Thanks and have a great day!

[swanphototx]

I shoot with the Canon 5D Mark iii

[ScottyP]

Could you have bumped the focus limiter switch?  The "L" version anyway has one, and it lets you use either the FULL focus range or to limit it to close up .3-.5m or to far away .5 to infinity.    

If you didn't bump it accidentally maybe you should start using it on purpose. The macro lens is a slow focuser, and limiting the amount it can hunt is helpful. 

[swanphototx]

I don't believe so. I don't have the "L" series.

[ScottyP]

Funny how often something simple like bumping something is the issue though.  I am constantly bumping my 35mm from AF to MF.  Once I had bumped my flash backwards just a tiny bit in the hotshoe so it was still flashing but not in sync with the camera, so I was seeing the shutter in the shots.

[swanphototx]

It's definitely in auto focus. It hunts and hunts, but can never grab focus.

[Waddizzle]

Would we be correct to assume that your other lenses do focus properly, so that we can rule out the camera?

If you manually focus using LiveView, do you get a focus confirmation when press the shutter halfway?

[FamousEdOwen]

I have a canon rebel xs with the 18-55mm lense and is doing the same thing.  I can manually focus and the red lights show when I push the button half way in.  When I have it on auto focus it just keeps going in and out.  Sporatically it will find focus and stop but most of the time it goes on for as long as I hold the button in.  I have 3 other lenses and these all work fine so i know it is in the lense, not the camera. 

I hope it's okay to jump on someone else's post.  I didn't see any more replies and was hoping for an anserw since I have yet to find any others with the same problem.

[RobertTheFat]

---

@FamousEdOwen wrote:

I have a canon rebel xs with the 18-55mm lense and is doing the same thing.  I can manually focus and the red lights show when I push the button half way in.  When I have it on auto focus it just keeps going in and out.  Sporatically it will find focus and stop but most of the time it goes on for as long as I hold the button in.  I have 3 other lenses and these all work fine so i know it is in the lense, not the camera. 

I hope it's okay to jump on someone else's post.  I didn't see any more replies and was hoping for an anserw since I have yet to find any others with the same problem.

---

Unlike the situation with the OP's macro, this sounds like one of those cases where the autofocus motor got stuck. The usual cause is trying to focus manually while the lens is in AF mode. The cure that often works is to forcibly manhandle it back into position. Obviously this requires a certain degree of finesse, but the procedure has been described several times in the forum. I can't tell you exactly where to look, but I don't doubt that one of the other regulars will be able to help you. (If I'm right about the cause!)