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Archive 2012 · Canon 300mm f/2.8 L IS II not focusing?
  
 
nctemper
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p.1 #1 · p.1 #1 · Canon 300mm f/2.8 L IS II not focusing?


I have had this lens for 2 weeks and every so often this lens will not auto focus. I turn the manual ring a few times and it will work again. I called CPS and they claim they have never heard of it. BUT my lens serial number is on the service firmware update list.

Has any body run into this problem besides me??

any sharing would be appreciated



Dec 19, 2012 at 10:15 PM
mitesh
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p.1 #2 · p.1 #2 · Canon 300mm f/2.8 L IS II not focusing?


Check the autofocus settings on your camera body. On my 5D3/1DX, there is a setting called "Lens drive when AF impossible"- or something close to that. Basically, it is designed to prevent excessive lens drive as the lens hunts for focus. If this setting is enabled, you might have to manually turn the focus ring to a point that's almost in focus before the lens will attempt to AF.

That's the first thing I'd check- assuming the lens switch is set to AF, of course. Also wouldn't hurt to make sure you haven't set the focus limiter to a range that's outside of the subject you're trying to acquire.



Dec 19, 2012 at 10:24 PM
gvg45
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p.1 #3 · p.1 #3 · Canon 300mm f/2.8 L IS II not focusing?


For the very limited use its had, my 300mm II has been working flawless so far. The heavy work starts next month so I'm hoping it will continue working that way. FWIW, my serial number is not on the service firmware list.

I did have a Nikon lens that had the symptoms you described. It turned out the focusing motor was going out & needed to be replaced.



Dec 19, 2012 at 10:28 PM
Andrew J
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p.1 #4 · p.1 #4 · Canon 300mm f/2.8 L IS II not focusing?


mitesh wrote:
Check the autofocus settings on your camera body. On my 5D3/1DX, there is a setting called "Lens drive when AF impossible"- or something close to that. Basically, it is designed to prevent excessive lens drive as the lens hunts for focus. If this setting is enabled, you might have to manually turn the focus ring to a point that's almost in focus before the lens will attempt to AF.

That's the first thing I'd check- assuming the lens switch is set to AF, of course. Also wouldn't hurt to make sure you haven't set the focus limiter to a range that's
...Show more

+1
My thoughts exactly.



Dec 19, 2012 at 11:08 PM
nctemper
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p.1 #5 · p.1 #5 · Canon 300mm f/2.8 L IS II not focusing?


Lens was set to AF
I'll test it on the Mark4 & 5d3 in the next few days. I set "Lens drive when AF impossible" to off. But the lens will not hunt nor focus.



Dec 19, 2012 at 11:32 PM
mitesh
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p.1 #6 · p.1 #6 · Canon 300mm f/2.8 L IS II not focusing?


Which camera body are you using it on now? Since you noticed this issue, have you tried AF with any other lenses (preferably another supertele) to rule out a problem with the camera body?


Dec 20, 2012 at 12:02 AM
nctemper
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p.1 #7 · p.1 #7 · Canon 300mm f/2.8 L IS II not focusing?


The lens problem is the same on both the Mark4 & the 5d3. Today the combo was 5d3 & 300 and when I turned it on the first time for the day...no focus...I turned the manual focus ring and it auto focused finally about 1 hour of BIF shooting it stop again.


Dec 20, 2012 at 12:23 AM
 

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mitesh
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p.1 #8 · p.1 #8 · Canon 300mm f/2.8 L IS II not focusing?


That's really strange. I wish I could offer more assistance, but I have no other ideas. Might need to be sent in to Canon.


Dec 20, 2012 at 12:32 AM
scalesusa
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p.1 #9 · p.1 #9 · Canon 300mm f/2.8 L IS II not focusing?


nctemper wrote:
Lens was set to AF
I'll test it on the Mark4 & 5d3 in the next few days. I set "Lens drive when AF impossible" to off. But the lens will not hunt nor focus.


Set the "Lens drive when AF impossible" to ON, not off if you want it to hunt for focus. If it doesn't, I'd send it in for service.



Dec 20, 2012 at 12:40 AM
Russ Isabella
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p.1 #10 · p.1 #10 · Canon 300mm f/2.8 L IS II not focusing?


I also would check the switch on the lens itself that allows you to set a range for focusing distance. I know on the Mark I version this certainly can affect AF.


Dec 20, 2012 at 12:56 AM
OwlsEyes
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p.1 #11 · p.1 #11 · Canon 300mm f/2.8 L IS II not focusing?


Not intended to be insulting, but check the AF/MF switch on the lens. I have accidentally switched this in a position that was between mf & af and freaked when the lens would not AF reliably... alternatively, you might have a bad switch on the lens.
good luck
bruce



Dec 20, 2012 at 02:07 AM
JimboCin
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p.1 #12 · p.1 #12 · Canon 300mm f/2.8 L IS II not focusing?


OwlsEyes wrote:
... check the AF/MF switch on the lens. I have accidentally switched this in a position that was between mf & af and freaked when the lens would not AF reliably...


I did this once too. Called CPS about my lens not being able to AF. Felt like a total idiot when I found out what the problem was. (not insinuating this is your problem)



Dec 20, 2012 at 02:52 AM
convergent
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p.1 #13 · p.1 #13 · Canon 300mm f/2.8 L IS II not focusing?


JimboCin wrote:
I did this once too. Called CPS about my lens not being able to AF. Felt like a total idiot when I found out what the problem was. (not insinuating this is your problem)


That "in between" thing can be a problem. I had an issue with my 5D3 this weekend where I couldn't adjust some settings. Turned out the thumbwheel on the grip was "in between" positions and causing the dial on the body to also not work.

It may be worth putting all the switches on the lens through all their positions a couple of times just to assure that nothing is askew there.



Dec 20, 2012 at 01:58 PM





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