Is Mark 4 focus system inferior FOR STREET PHOTOGRAPHY to the Mark 3?

[Streker26]

I have upgraded to the Mark 4 from the Mark 3. I do street photography of people. It seems that the Mark 4 works in a very, very different fashion then the Mark 3 when it comes to autofocus. I have tried every single focus setting or combination of settings but I continue to have problems. I am using exclusively a 50mm 1.4 USM lens as I did on the Mark 3 by the way. So it seems like the Mark 4 takes longer to focus. It sometimes hunts. The shutter button as well is not as responsive. But the biggest problem that is driving me up the wall is very often the camera will focus on the background to the exclusion of foreground subjects. And I don't just mean small figures in the foreground but even when I have a person filling one third of the frame in the center of the field! It is weird because this is not always the case but it is often the case. It is especially bad when I shoot fast. If I am slow and deliberate it is less often a problem. But the thing is that this was NEVER an issue with the Mark 3 for me. So I would love to know what settings people recommend as best to quickly catch in focus a a foreground figure in priority over background subjects. And also if others have had similar issues with this camera in relation to it's predecessor. Thanks

[jrhoffman75]

Single center point or maybe single surround?

[Streker26]

Hi, 

Thanks for responding. I've tried them all. Single point seems to work best.  Expanded AF area and Auto Select AF (which acording to what I have read is supposed to be best for locking focus on fast moving subjects in your foreground) are not as successful. Im generally shooting in AI Focus. 

For what it is worth I shoot very fast so as not to be noticed. I will shoot someone standing in front of a storefront or walking past me in the street. %50 of the time the camera will focus on someone more distant from the subject or even focus on the store behind the subject. Even when the subject is five feet from the frame. I must be doing something wrong but it keeps happening. The other day I had two woman talking and they were three feet from me and the camera focused on the background store behind them although they practically filled the frame. Now if I slowly lift the camera to my eye and press the shutter slowly this will happen less. And it is not the lens as I have two 50mm lenses that this happens with equally.

[Waddizzle]

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@Streker26 wrote:

 Im generally shooting in AI Focus. 

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The use of AI Focus mode is more than likely source of all of your troubles.  I suggest using One Shot mode for street photography, and never use AI Focus mode ever again. 

[Streker26]

But one shot mode is specifically for still subjects. No? That is why I don't use it. I have used Servo and AI because I either shoot people in motion or I am in motion myself or both! 

[Waddizzle]

One Shot mode can be used for anything, even action sports, with a fast enough shutter and the proper depth of field.

Avoid AI Focus because it does not work as well as it was intended.  Not only does the camera have to focus, but it takes a little extra time to decide if it should [use] One Shot mode or AI Servo mode.  Stick to [manually] selecting One Shot or AI Servo mode, instead of letting the camera do it for you.  This is not all that different from selecting your own AF point, instead of letting the camera do it for you.

AI Servo mode is not used for “moving” subjects, per se.  Lenses have a plane of perfect focus.  Depending upon your aperture setting, there is some distance behind and in front of the focus plane where subjects are in “acceptable” focus.  This is called DOF.  

AI Servo mode is [used to] track subjects whose distance to the camera is changing.  As the distance to the subject changes, the subject can move away from the focused plane, and out of the DOF.  AI Servo is used to adjust the focusing distance to the subject, as the subject moves away or towards the camera, to keep the subject within an acceptable DOF, if not in perfect focus.

[Waddizzle]

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@Waddizzle wrote:

One Shot mode can be used for anything, even action sports, with a fast enough shutter and the proper depth of field.

AI Servo mode is not used for “moving” subjects, per se.  Lenses have a plane of perfect focus.  Depending upon your aperture setting, there is some distance behind and in front of the focus plane where subjects are in “acceptable” focus.  This is called DOF.  

AI Servo mode is [used to] track subjects whose distance to the camera is changing.  As the distance to the subject changes, the subject can move away from the focused plane, and out of the DOF.  AI Servo is used to adjust the focusing distance to the subject, as the subject moves away or towards the camera, to keep the subject within an acceptable DOF, if not in perfect focus.

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[Streker26]

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@Waddizzle wrote:

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@Waddizzle wrote:

One Shot mode can be used for anything, even action sports, with a fast enough shutter and the proper depth of field.

AI Servo mode is not used for “moving” subjects, per se.  Lenses have a plane of perfect focus.  Depending upon your aperture setting, there is some distance behind and in front of the focus plane where subjects are in “acceptable” focus.  This is called DOF.  

AI Servo mode is [used to] track subjects whose distance to the camera is changing.  As the distance to the subject changes, the subject can move away from the focused plane, and out of the DOF.  AI Servo is used to adjust the focusing distance to the subject, as the subject moves away or towards the camera, to keep the subject within an acceptable DOF, if not in perfect focus.

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OK... but for my purposes of quickly taking pictures of people in the street I generally am myself moving past them or towards them. I rarely stand still since I will be spotted by my subject. The subject themself can equally well be walking by or standing still but I am nearly always in some sort of motion. I do momentarily pause of course to take the shot but it is only for a second as I move on. So in this manner might not AIServo in fact serve me better or do you still feel One Shot is the way to go? Thanks again for your patience while I try to sort out the pros and cons of this...

[TTMartin]

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@Waddizzle wrote:

One Shot mode can be used for anything, even action sports, with a fast enough shutter and the proper depth of field.

AI Servo mode is not used for “moving” subjects, per se.  Lenses have a plane of perfect focus.  Depending upon your aperture setting, there is some distance behind and in front of the focus plane where subjects are in “acceptable” focus.  This is called DOF.  

AI Servo mode is [used to] track subjects whose distance to the camera is changing.  As the distance to the subject changes, the subject can move away from the focused plane, and out of the DOF.  AI Servo is used to adjust the focusing distance to the subject, as the subject moves away or towards the camera, to keep the subject within an acceptable DOF, if not in perfect focus.

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 And a point and shoot can be used for sports because they have a huge depth of field, but, most people using a dSLR are doing so because of the subject isolation given by a shallow depth of field, or because they need a large aperture to allow enough light to be captured. 



The 50mm set at f/1.4 and a subject distance of 10 feet has a 12 inch depth of field, meaning if the subect moves more than 6 inches front or back they are out of the area of acceptable focus. 

[diverhank]

Everyone who has a 5D Mark IV who had the Mark III basically agrees that the 5D Mark IV Autofocus is improved from the Mark III that was already very good.  The features, however, remain very similar.  That leads me to believe that maybe some of your settings were inadvertently set up wrong.  You might want to reset the camera, just in case.

In case you're not familiar with the 5D Mark IV AF features.  Here's a Canon youtube link that gives you the basics on the AF system:

https://www.youtube.com/watch?v=KY6VHltC-1U