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Archive 2013 · Focusing With the Canon 16-35mm f/2.8L II
  
 
Rudy Rudolph
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p.1 #1 · Focusing With the Canon 16-35mm f/2.8L II


Hi,
I recently purchased a Canon 16-35mm f/2.8L II and I have a question about its autofocus. I generally shoot with only the center autofocus point on my 60D. When I want the sharpest part of the photograph on one of the rule of thirds cross lines, I usually point the center autofocus point at the subject I want and then move the camera so that the subject is on the cross lines to follow the rule of thirds. Should I continue this approach, or should I change my autofocus point and try to line up the composition before focusing?

Thanks,
Rudy Rudolph



Jan 19, 2013 at 10:00 PM
rabbitmountain
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p.1 #2 · Focusing With the Canon 16-35mm f/2.8L II


Hi Rudy,
Your "focus-and-recompose" technique is widely used, especially with lesser AF camera bodies. You should be fine at apertures of f/4 and smaller. At f/2.8 I never noticed focus problems either.
Only some special lenses like the 50L and 85L show disappointing focus-and-recompose results when shot wide open, because the focal plane is so thin that it shows when you sway the camera even a bit.
I'd say just take some sample images of both techniques and examine the images on your computer. You will be able to decide what works best for you.



Jan 19, 2013 at 10:44 PM
Gunzorro
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p.1 #3 · Focusing With the Canon 16-35mm f/2.8L II


Rudy -- I agree. That's exactly what I do. I might use alternate AF points on a 1D-series mounted on a tripod. Otherwise, with hand held work, I focus and recompose with wider focal lengths.


Jan 19, 2013 at 11:12 PM
rabbitmountain
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p.1 #4 · Focusing With the Canon 16-35mm f/2.8L II


Actually the wider the FL, the larger the OOF effect will be because your camera will rotate more degrees. Also, with WA you have a larger DoF so it compensates.
Basically you're OK at f/4.0 or smaller.



Jan 20, 2013 at 09:21 AM
AmbientMike
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p.1 #5 · Focusing With the Canon 16-35mm f/2.8L II


Its what works for you I usually use center point.


Jan 24, 2013 at 12:01 AM
 

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carnac
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p.1 #6 · Focusing With the Canon 16-35mm f/2.8L II


I use the joy-stick to move to the closest focusing point with all my lenses (unless it is very low light).

I find it only takes a little practice and I get better results (and this is with a 5D mk II). I still may recompose, but I don't have to move as far since I use the nearest AF point. I have also started using the back button focus option.

For quick snap shots of family and friends, I find having the top (portrait or landscape) AF point selected helps me not get the dreaded "heads in the center of the frame, feet cut off, and way too much sky" syndrome.

Jim



Jan 24, 2013 at 08:19 AM
Daan B
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p.1 #7 · Focusing With the Canon 16-35mm f/2.8L II


I find outer AF points unreliable with this lens wide open because of the heavy field curvature. I use only the center AF point (no focus recompose) and just crop in PP to compensate for composition.


Jan 25, 2013 at 11:55 AM
scottam10
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p.1 #8 · Focusing With the Canon 16-35mm f/2.8L II


I'm with rabbitmountain, you should be able to use focus and recompose as a wide lens gives you a large depth of field; I never notice focus problems even at f/2.8

I'm always a little confused when people buy full-frame UWA lenses like the 16-35 or 17-40 for use on crop. I prefer the 17-55 f/2.8 IS, which is cheaper, has a bigger zoom range, sharper image quality and has IS.
I guess the 16-35 offers weather sealing and better build quality. It's all personal preference I guess



Jan 25, 2013 at 12:29 PM
eosfun
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p.1 #9 · Focusing With the Canon 16-35mm f/2.8L II


A lot depends from the composition of the picture you make. With wide angles it's easy to have a subject at 1/3 of the image at a distance below a meter while at center point the image is at infinity for example. Imagine you shoot an urban scene where you take a wall at 30 cm in the left 1/3rd part of your image, while the rest of the image is at infinity. Than a slight move of the AF sensor over the image subject can make the camera focus wrong, because the focus point shifts from 30 cm by a slight move over a great range to infinity. Even though depth of field compensates for a part, and even though field curvature can be both helpful and counterproductive, one always has to carefully compose and keep the simple rules for DOF control and the AF points in mind. In general, unless you are mainly shooting landscapes at infinity, I find the wider a lens, the more precisely you have to set your focus point. That is a pitfall many wide angle photographers seem to overlook. This is also true for the wide angle zoom the 16-35mm is. For everything else I have never noticed this lens has a better or worse AF than other great L lenses. It's just a matter of carefully composing the picture and set the AF point where you want the main point of sharpness.

Have EOSfun



Jan 25, 2013 at 12:58 PM
scalesusa
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p.1 #10 · Focusing With the Canon 16-35mm f/2.8L II


The focus and recompose will likely only be a problem at very close distances with wide apertures. In that situation, it can be a issue with the center point as well, since the 60D has no AFMA, and there may be some AF error.


Jan 26, 2013 at 02:03 AM





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