# Canon 5d Mark II auto-focus issue with fast lenses



## kevinkt

I've heard from a few photographers that their 5d Mark II has issues with auto-focus with fast lenses, around between f/1.2 and f/1.8

What are the validity of their claims? Is it really the 5d Mark II's fault or is it just because of the nature of the fast lens/shaky hands, etc?


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## unpopular

I know that with my much inferior a350 I have problems with my 50/1.8. it is possible that when wide open, the AF is missed.


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## kevinkt

Here's a blog post with more information: Karel Donk's Blog » Canon EOS 5D Mark II &#8211; A Piece of ****

Anyone else care to shed light on this topic?


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## Derrel

Focusing with wide-aperture lenses at close focusing distances has been a problem for decades. There can be many factors at play. Karel Donk has a MAJOR hard-on for Canon and their many problems and issues.


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## MLeeK

Derrel said:


> Focusing with wide-aperture lenses at close focusing distances has been a problem for decades. There can be many factors at play. Karel Donk has a MAJOR hard-on for Canon and their many problems and issues.


And focusing on any other focus point than the center is weak at best in low light on the 5d2.


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## Derrel

MLeeK said:


> Derrel said:
> 
> 
> 
> Focusing with wide-aperture lenses at close focusing distances has been a problem for decades. There can be many factors at play. Karel Donk has a MAJOR hard-on for Canon and their many problems and issues.
> 
> 
> 
> And focusing on any other focus point than the center is weak at best in low light on the 5d2.
Click to expand...


YES...and on the original 5D...same issue...it basically has NO peripheral AF points...the 5D and 5D-II used the AF system from the old EOS 20D, WHICH MEANT that the AF points were all quite centrally-located, in a tight diamond shape (with some hidden "assist" points added to the 5D Mark II body, but still, all of the AF points were within the tiny, centrally-located diamond shape in the middle portion of a 24x36mm field...).

A crop-body AF system SLAPPED INTO a full-frame camera....Canon 5tD CLassic and Canon 5D Mark II. The new 5D-III has got a SEXY, powerful, all-new AF and metering system!!! it's a humdinger of a camera!

Focus-and-recompose does NOT WORK as reliably as using a peripheral AF point on many fast lenses, used at close distances, and ESPECIALLY on cameras with weaker AF SYSTEMS, like the 5D and 5D Mark II cameras had. Add an ultra-speed lens like a 50/1.2-L or 85/1.2-L, and then add in moving subjects, poor light,m and widely varying degrees of user experience and skill...yeah, it's a lot like *newbies complaining that ,"It's hard to reach the summit of Mt. Everest."
* 
I am most decidedly *not* implying that the OP is a newbie, but the world wide web is filled with people carping about longstanding problems that some people have when using high-end, exotic equipment on pedestrian cameras under demanding conditions and withgout absolutely impeccable technique and adequate practice and preparation.

Uh, YEAH--*it IS difficult!!!!!* "Doah!"


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## morganza

Thanks for hte blog ling. I posted here because i want to see the updates.


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## fenrirGrey

I'm probably being really stupid, but how do you auto focus? 

I'm moving from the 7D to the 5D Mk II and cannot seem to get it to focus. I'm using the Canon 24-105 L F4 lens

I am in auto servo, auto focus on the lens. 

Please help.


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## MLeeK

fenrirGrey said:


> I'm probably being really stupid, but how do you auto focus?
> 
> I'm moving from the 7D to the 5D Mk II and cannot seem to get it to focus. I'm using the Canon 24-105 L F4 lens
> 
> I am in auto servo, auto focus on the lens.
> 
> Please help.


Is your camera set to back button focus?
I believe it's Custom Function IV, #1 on the 5d2


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