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Occasional Contributor
Posts: 5
Registered: ‎05-18-2016

Re: trouble with autofocus on 70D with Tamron 16-300

Thanks for the extra idea. I am just now back in from firing off over 100 shots at all lengths and various light/shade conditions; only had AF refuse me once -- that was in dense shade shooting green on green but a slight movement of my focus point prompted the focus/shutter. All I've changed from the earlier morning shoot when it seemed the camera ignored me more often than not, is cleaning the contacts. It could be that all I needed to do was take the lens off and put it back on again. 

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Occasional Contributor
Posts: 5
Registered: ‎05-18-2016

Re: trouble with autofocus on 70D with Tamron 16-300

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.

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Posts: 9,920
Registered: ‎08-13-2015

Re: trouble with autofocus on 70D with Tamron 16-300


@jmitsch wrote:

Thanks for the extra idea. I am just now back in from firing off over 100 shots at all lengths and various light/shade conditions; only had AF refuse me once -- that was in dense shade shooting green on green but a slight movement of my focus point prompted the focus/shutter. All I've changed from the earlier morning shoot when it seemed the camera ignored me more often than not, is cleaning the contacts. It could be that all I needed to do was take the lens off and put it back on again. 


I hope this means that you're back in the saddle, on the road again.

 

A caution about cleaning electronic contacts.  Never use anything even remotely abrasive to wipe the contacts, which pretty much rules out just about everything I can think off.  Maybe, a micro fiber cloth is okay, because it is relatively safe on delicate glass surfaces?  I dunno.

 

The last thing you want to do is create micro-grooves in the surfaces.  Grooves in the surfaces, means less surface area to make contact.  If you look at a cross section, instead of making contact between flat surfaces, now you have a situation where two sets of mountain ranges are coming face to face, and only the peaks of the mountaintops will make contact.

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"Doctor told me to get out and walk, so I bought a Canon."
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Occasional Contributor
Posts: 5
Registered: ‎05-18-2016

Re: trouble with autofocus on 70D with Tamron 16-300

>A caution about cleaning electronic contacts.

 

Thanks for the warning. Wanting to use the gentlest thing I could think of, I had opted for gently swiping with a sensor swab. Am I taking my camera's life in my hands? :-/

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Posts: 9,920
Registered: ‎08-13-2015

Re: trouble with autofocus on 70D with Tamron 16-300


@jmitsch wrote:

>A caution about cleaning electronic contacts.

 

Thanks for the warning. Wanting to use the gentlest thing I could think of, I had opted for gently swiping with a sensor swab. Am I taking my camera's life in my hands? :-/


I come from the school of thought that says if you haven't been properly trained to do it, then you're taking a risk. 

 

Maybe a sensor swab is okay, although I have never heard of such a thing.  Everything I read says use a blower on the image sensors, and to never touch it.  Leave touching the sensor to the camera technical experts.

 

Back to that swab.  Contacts are not as delicate as an image sensor.  But, would you use that swab of yours to clean a lens?

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"Doctor told me to get out and walk, so I bought a Canon."
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Posts: 12,708
Registered: ‎12-07-2012

Re: trouble with autofocus on 70D with Tamron 16-300

"A caution about cleaning electronic contacts."

 

Actually cleaning the contacts rarely works or does anything.  It basically only helps people that don't or hardly ever remove their lens.  Mounting and removing the lens is all they is usually needed.

EOS 1DX and 1D Mk IV and several lenses!
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