# Focus issues with 600mm f4 is ii



## rogerd (Oct 26, 2013)

I just received a new canon 600mm f4 is ii lens and am having trouble getting consistent sharp focus. One will be very sharp the next image or two will be soft. When manually focusing same issue. I have tried with is off and on there seems to be no difference. I used a tripod and shutter release. I assume it is my problem but am at a loss as to what I am doing wrong, any suggestions would be appreciated. Thank you.


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## kaihp (Oct 26, 2013)

At the risk of asking an obvious question: did you use mirror lock-up with the shutter release and what was the delay?


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## rogerd (Oct 26, 2013)

No I didn't use mirror lock-up but don't think that should be necessary to get a sharp image. I do get some very sharp images even hand held but there are also soft ones. I'm hoping nothing wrong with the lens just me.


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## RomainF (Oct 26, 2013)

I'm able to get all my shots sharp at 1/125 handheld with the great IS. 
Could you upload some pics to help us understand your issue ?


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## Vossie (Oct 26, 2013)

What camera, what aperture, what shutter speed, which focus mode have you been using? Do you have problems with moving or still objects and are these distant or close?

The 600 f4 has a narrow DoF when used wide open, especially for close objects. Have you selected a specific focus point om the area that needs to be sharp?


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## Mt Spokane Photography (Oct 26, 2013)

You say that some manual focus images are sharp, and the next one isn't. That sounds like movement of the lens. I can understand AF being inconsistent, but manual focus does not change between shots.


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## RomainF (Oct 29, 2013)

I was browsing Youtube when i watched this video. Could be relevant to your case :
Canon 5D III x 70-200 2.8 IS II issue


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## wearle (Nov 4, 2013)

I had a similar problem after receiving mine. After going through extensive testing, I felt it had to be a problem with the lens itself so I sent it to Canon in late April. It was returned a week later, and the difference was phenomenal. I'm finally getting the results I should have gotten in the first place: very sharp images and a significant increase in the number of keepers.

*According to Canon, "It was found that the adjustment of the circuit board was incorrect causing inaccurate auto focus." *

Before the adjustment, I was getting about 10 percent keepers. Now, I'm getting about 70 percent. The 30 percent I end up deleting are mostly repeats and/or poor technique (excitement causing vibration) with probably 30 percent of those due to an actual miss in focus. This is probably more in line with how the lens should perform.

It is possible you got the same initial guy that adjusted the circuit board on my lens. 

Wade


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## RGF (Nov 14, 2013)

wearle said:


> I had a similar problem after receiving mine. After going through extensive testing, I felt it had to be a problem with the lens itself so I sent it to Canon in late April. It was returned a week later, and the difference was phenomenal. I'm finally getting the results I should have gotten in the first place: very sharp images and a significant increase in the number of keepers.
> 
> *According to Canon, "It was found that the adjustment of the circuit board was incorrect causing inaccurate auto focus." *
> 
> ...



I just got mine - have not tested it. Better do it soon.


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