trouble with autofocus on 70D with Tamron 16-300

[whistler]

I have a relatively new 70D and used it with brand new Tamron 16-300 lens.  Had trouble with autofocus under easy conditions.  Was provided another lens and had less trouble.  Then used with old Canon 70-200 2.8 IS and now notice same issue.  Times that focus should be easy the camera doesn't search, it just does nothing as I push the shutter half way.  I snap a shot or two out of focus and that seems to actuate the focusing. Sometimes I can zoom clear in to 16, and that seems to jar it into action.   I now think the problem is not the lens choice, but the camera.  Has anyone experienced this problem?  Any thoughts?

[RobertTheFat]

There may be a clue in the fact that it happens with your 70-200. My 70-200 f/2.8L IS II exhibits the same behavior if I try to focus on a subject that's too close. That lens has two separate settings, one of which lets you focus closer but with (I believe) slightly lower reliability.

[ScottyP]

That lens has a minimum focal distance of just 0.39 meters, so I'd you are at least a foot and a half from the subject you are ok. Robert mentions the range limiter switch on the 70-200 which is actually for following a far-away subject without the lens periodically hunting around and getting lost if something closer to you gets between you and your subject. You may want to check that switch if you have one.

Autofocus is the hardest thing for 3rd party lens makers to get right. It may just work slower than you'd like. What focus mode are you in? If your subject is moving you should be in AI SERVO and not in ONE SHOT. If it is NOT moving, then ONE SHOT focus may work better because the camera will (hopefully) focus right and then not hunt for focus again unless you press the shutter again.

[whistler]

Thanks Bob and Scott. I've had this trouble with both the Tamron 16-300 and the Canon 70-200 2.8L. At first I thought it was the new Tamron as it happened fairly frequently on an Alaskan trip with that brand new lens. After that lens was replaced, thanks to a new ownership fine camera shop in Davenport, it happened again, but not as often. Then I noticed it with the 70-200 which had never given any such trouble when shooting with my old 40D. At this point I began to suspect the 70D rather than either lens. It happened last when I was shooting butterflies sitting on flowers using the Tamron lens. The camera was set to one shot, not A1 servo, and was not set on the short distance limiter. I would shoot several shots without trouble, then suddenly it would not do anything when the shutter was pressed half way. The butterflies were motionless, and nothing seemed different between the 'good' shots, and the sudden lockup. It did not search; it just did nothing. My 'fix' so far, has been to shoot a couple shots out of focus, and then it seems to 'wake up'. I've also sometimes zoomed in from 200 or 300 to 16 or 70, and that sometimes wakes it up. The fact that it has happened with two different Tamron lenses, and the Canon, lead me to think it is camera rather than a lens problem. My next step is back to the dealer for help. I am sure open to all thoughts. Thanks

Jerry

[MarkTM]

Hello Jerry,

I found this old post by googling the symptoms I just observed on my setup, and found I'm exactly in your same condition!

I own a Canon EOS 70D and a Tamron 16-300mm f/3.5-6.3 Di II VC PZD MACRO lens since exactly 1 year, and during my recent travel I stumbled upon this annoying behavior: sometimes the autofocus gets stuck, and the shutter release button just won't work. I tried to zoom in and out and to refocus on a different point, and to switch the lens from AF to MF and back, and eventually the camera waked up, but I had not clues about what happened or what behavior unjammed the camera.

What I noticed is that even if the shutter release button didn't work, the lens was actually focused: by switching it to MF I was able to take focused pictures.

Did you find a solution? Do you know whether the guilty is the camera or the lens?

Thank you!

Bye,
Marco

[ebiggs1]

The Tamron 16-300mm f/3.5-6.3 Di II VC PZD MACRO lens is a fairly new Tamron lens.  It should work well on a Canon crop cameras like the 70D.  Have the camera checked out.

[jmitsch]

I've been using the Tamron 16-300 with Rebel 5ti exclusively for 2 weeks now to check it out in all ranges and just last night and again this morning, I also experienced the autofocus issue. I tried setting different lengths, switching between manual and autofocus, turning off/on, etc and haven't found anything that seems to work consistently. It isn't swimming -- it just doesn't do anything with shutter half-pressed. I'm using single focus so I can make sure I'm finding a strong contrast area to direct it to and one-shot. Will clean the camera and test with other lenses to see if I've developed AF problems with those to try to narrow down the problem but will keep digging to see if this is a known defect. Lens may be finding its way back to Tamron. 😞

[RobertTheFat]

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@jmitsch wrote:

I've been using the Tamron 16-300 with Rebel 5ti exclusively for 2 weeks now to check it out in all ranges and just last night and again this morning, I also experienced the autofocus issue. I tried setting different lengths, switching between manual and autofocus, turning off/on, etc and haven't found anything that seems to work consistently. It isn't swimming -- it just doesn't do anything with shutter half-pressed. I'm using single focus so I can make sure I'm finding a strong contrast area to direct it to and one-shot. Will clean the camera and test with other lenses to see if I've developed AF problems with those to try to narrow down the problem but will keep digging to see if this is a known defect. Lens may be finding its way back to Tamron. 😞

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As I pointed out to the Original Poster almost two years ago, that symptom is easily explained if the camera is positioned too close to the subject.

[jmitsch]

>that symptom is easily explained if the camera is positioned too close to the subject.

I wish it was that simple. I have been testing at all ranges after having first experienced it when trying to focus at 300mm and thought that maybe it just didn't like being extended that far.

[jmitsch]

Looks like I inadvertently clicked in the wrong place to reply earlier. Thanks for your reminder about distance to subject as that's always a good one to keep in mind. Unfortunately, that hadn't seemed to be the problem as I experienced the problem at various combinations of both range and focal length. Happily, cleaning contacts seems to have fixed my problem for now and perhaps, just removing the lens and putting it back on to reseat contacts will be all the fix I need in the field if this happens again.