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Strange Af Issue With Canon Lens


tdierikx
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OK - so I'm snapping away at some 3 week old puppies with my 18-55mm EF-S IS lens (came with the 450D), and suddenly it decides to stop doing the auto focus thing when I zoom in on a munchkin - and refused to take the photo. Still auto fosused fine and took the photo when not zoomed in though...

Lighting wasn't perfect, but wasn't crap either - and it had been focusing and taking photos fine with or without zoom prior to that point. I had the camera on full Auto mode, but even when I changed modes, it still didn't want to auto focus or take the photo when zoomed in. If I turned off the AF and manually focused when zoomed in, it took the photo just fine.

So - could it be the light/subject/close distance that was the issue - or could this be the start of me looking for a new lens? The 55-250mm lens worked just fine, so I don't think it is the actual camera at fault (and the AF is built into the lens, not the camera)

Any ideas gratefully appreciated...

T.

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Newly charged battery Roova... *grin*

It could have been the distance/subject - I was scrunched up in a puppy playpen taking photos of 3 week old pups...

Here are a couple of photos that worked that worked just fine...

post-23772-0-84601500-1327225713_thumb.jpg

post-23772-0-65587600-1327225766_thumb.jpg

Cute, huh? BT cross Staffy - don't ask - I volunteer with rescue...

T.

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I'll try the lens again today and see if it still plays up - it could have been a distance issue, but I've never had it happen before with the 18-55mm lens in similar conditions...

I can't wait for these little guys to start looking like real dogs - I want to know how their snouts turn out... like mum's BT roman nose, or like the supposed Staffy dad's nose... I'm thinking we may have a few of each and some combos... lol!

There are 7 boys and 1 girl in this litter - the girl is the mostly brindle headed one, with a tiny smudge of white on her nose.

T.

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agree with the others that the main times I have had focus issues with a Canon is either battery running low, too close, or not enough contrast (eg pure black animal, no contrast areas), in which case I would switch to manual and do it myself. Perhaps you got that bit too close, you could easily check on that by looking at the pictures zoomed in at 100% in your photo browser of choice and see how sharp the images were, and whether they were in focus at the point you used to focus. If the battery was not low, first thing I would try was taking a step back. I would also say that sometimes my Canon (5dII), does some weird one off things, but turning it off and turning it on again fixes it - I can be shooting away and all of a sudden it will come up with an error message saying it can't shoot anymore, but this turning off and on gain clears the problem, so it could also have bee nothing to do with you too.

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I've had the distance issue a few times with the longer lens...

Didn't get the pups out today - was mowing around the rescue property instead. Hopefully we will have reasonable weather tomorrow and I can get them out onto the nice short grass for a better photo shoot.

I'm not a big fan of the shorter lens and don't use it all that often, but yesterday I was curled up in a 4 foot square playpen and really couldn't use the longer lens... *grin*

T.

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How close was close?

On my 18-55 Canon (non IS though) AF will only really "sort" things out at a distance of about 30cm? Soounds like that could be your problem as you said it has happened with your bigger lense aswell which would normally show your a little to close for what the lense can handle, my 75-300 is 1.5m at shortest? Once again its not an IS lense, actually it should have the "Macro" distance on the lense? Any help?

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Well - tested the 18-55 lens again today... no joy... the AF appears to be stuffed. Grrr! Wont focus on anything at any distance by itself.

On the upside, I prefer the longer lens anyways so I can photograph puppies/dogs just doing their own thing and not being totally distracted by a camera in their face.

Thank you all so much for your suggestions, they really helped!

T.

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Something else to watch for with Canons. Sometimes they will allow you to compose a shot but when you press the "Shutter Release" they won't capture the photo. In some cases you get an error on screen. Or they turn themselves off altogether. This is caused by the lens not communicating properly with the camera itself. Undo the lense then refit it and it seems to solve the problem.

Have seen it happen with a few canon's of different models. But only canons, hasn't happened with any of the Nikons I also use.

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It seems to be the AF mechanism/motor that is having the issue with my lens.

Seeing as I don't use that lens all that much it may be that it has seized... the manual focus works fine, but I'm not as good at doing it as the AF was... *sigh*

What I'd really like is an 18-200mm lens - that way I can have the best of both worlds without having to switch lenses... something for the wish list I think, as I don't have a job at the moment and money is a finite resource right now.

T.

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Googling leads me to believe that it's not an unknown occurrence for the AF to cark it on this lens... and I've tried every suggestion I found to try to get it working again... AF is definitely dead... *sob*

It's possible that it's seized due to me not using it all that much and it has been exposed to a wide range of conditions (ie. hot and cold, muggy, etc).

What's really scary is the price range to get a new one - anything from around $110 to $404... huh?? This isn't the II (second generation) 18-55mm lens, it's the original one. The II is even more expensive - almost to the point that if I only had the option to buy the 18-55 II lens, it wouldn't be all that more expensive to get an 18-200mm Sigma or Tamron one...

Moot point at the moment about getting a new lens - me has no job and no money right now... *sigh*

T.

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Late to this thread but just wanted to check a few things before you go plonking down some cash as I got a little confused reading.

- does the lens autofocus properly at all?

if no -> yup, there's a problem ;)

if yes -> does it autofocus when you are up close but NOT zoomed in at all?

if no -> are 100% positive that you are not too close? Lenses have a minimum focus distance and if you are too close, the AF will not work. It's not a flaw, it's a limitation of the particular lens and every single lens out there has it. A cm can make all the difference.

if yes -> when you try to zoom from this closest spot, does the autofocus work?

if no -> you are too close. You have effectively moved the lens closer and thus encroached into its minimum focus distance so the AF will not work. Remember, usually when you zoom in you must physically move BACK as minimum focus distance at the widest focal length will be closer to your subject than your minimum focus distance with your longest focal length.

Hope this helps and saves you some bucks. It's an extremely common user error.

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Late to this thread but just wanted to check a few things before you go plonking down some cash as I got a little confused reading.

- does the lens autofocus properly at all?

if no -> yup, there's a problem ;)

Not autofocusing at anything at all - regardless of distance. I've had this lens for a couple of years and am aware of the distance thing - tried taking a wide shot of a tree at longer distance, and nothing... I think it's AF is just dead/seized. MF works fine though. The longer lens AF also works fine, so I don't think it's the camera...

T.

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