Auto vs Single AF point selection

[Big Mike]

I've always favoured single point selection. Mostly, I don't like the idea of the camera choosing where it will focus therefore I like to pick one point and make the camera focus on exactly what I want it to.

I mostly shoot with a 5D mkII, which certainly isn't known for it's AF prowess....I've found that it's really no better than my old 20D cameras (which was disappointing because the 5DII is a lot newer and more expensive).

Anyway, I was shooting a hockey tournament recently and at times I was having trouble with the speed of the AF (single AF point, 70-200mm F2.8 L IS). I wasn't surprised really, it's never been fast but I don't usually shoot sports and I found that I was missing focus a lot more than I thought I would.

On the second day, (after really seeing how often the focus was missed), I switched to Auto Point Selection.....and wow, it was a lot faster to focus. Of course, there were still plenty of issues where the camera chose something that I didn't intend to focus on, but releasing and reactivating the AF, to make the camera choose something else, worked most of the time.

Overall, I ended up with many more tack sharp shots with the auto point selection than with single point.

And for the first time, I was actually happy that the 5DII has the same small cluster of AF points from the crop bodies, because it at least gave me control over where it would focus by keeping the subject in the centre of the viewfinder.

I'm also starting to appreciate why cameras with advanced AF are that much faster. For example, on a model with 49 or 51 AF points, you can choose to use a cluster of points and move the cluster around, thus getting the best of both the control of 'single point' and the speed of 'auto point'.

 

[Overread]

Yep this is why some cameras, like the 7D have two single AF point modes. One uses a single AF point as well as a small cluster of AF detectors around it whilst the other spot AF mode uses the single point only.

And like you've found many like the single with cluster in most situations. More AF points giving a faster reliable lock-on to that area. The very fine AF point being used mostly when you need exact focusing.

 

[TCampbell]

Unfortunately the 5D II's simple 9-point AF isn't known for being strong for fast action focusing. The 1D X, 5D III, and now the 7D II all have Canon's iTR (intelligent Tracking & Recognition system) which can be tuned to follow the action.

I still have my 5D II, but it's mostly just the backup camera. I had considered modifying it for IR photography or perhaps astrophotography, but as I already have an astrophotography camera and I suspect that after taking a handful of IR photos I'd satisfy my interest (I'm not sure I'd get hooked on it), I'm _really_ hesitant to modify the camera. My 5D II was barely used. I waited and waited following the rumors of the 5D III. FINALLY I gave up on any hope for a 5D III release and bought the 5D II... so naturally the 5D III came out within a couple of months of my purchase and I switched. So here I am with a 5D II that has (checking quickly...) 8335 shutter actuations on it.

 

[Big Mike]

The 5DII actually has more than 9 points. There are 6 more 'AF Assist' points that surround the centre point. I knew this, but never gave it much though since I always used single point mode.

And it seemed to me that one of the main flaws of the AF system on this camera, was that it kept the same point pattern/spread that APS-C cameras had, despite the viewfinder/FOV being much larger.

So essentially, it's got 15 AF points, all pretty much in the middle of the frame. Not great for tracking across the frame, but at least now I know that I can get faster AF than when it's using only one point.

 

[Gary A.]

I shoot mirrorless, which doesn't track at all, but if you keep the subject in the focus reticle, it will continue to refocus fast enough for sequential capture of sports action (not as good as a dSLR but certainly workable for the hobbyist). I've always used single point (but a large focus box about the size of the circle in your viewfinder image above). I think I'll try "Multi Point", (equal to Canon's Auto Point Selection), and see what happens.

 

[James Baranski]

I am relatively new to photography but have learned a lot over the past few months. Set your camera to AI Servo for motion photos..

 

[Vtec44]

I've always been using continuous focus with single point AF for moving subjects. I've never had an issue

 

[JacaRanda]

I've always been using continuous focus with single point AF for moving subjects. I've never had an issue

What kind of moving subjects, fairly large and fairly slow?

 

[Vtec44]

I've always been using continuous focus with single point AF for moving subjects. I've never had an issue

What kind of moving subjects, fairly large and fairly slow?

Yeah... larger and slower than normal I usually aim for the head so if I miss, the back ground will be tack sharp and I just call it art

 

[JacaRanda]

I've always been using continuous focus with single point AF for moving subjects. I've never had an issue

What kind of moving subjects, fairly large and fairly slow?

Yeah... larger and slower than normal I usually aim for the head so if I miss, the back ground will be tack sharp and I just call it art

LOL

 

[Big Mike]

I am relatively new to photography but have learned a lot over the past few months. Set your camera to AI Servo for motion photos..

Yes, it's important to know which 'AF mode' you are using. Moving subject mode (AI Servo or AF-C) is typically best for sports/action shooting.

This is a completely different setting than the AF points and the two are mutually exclusive. You can shoot in 'One Shot' with either single or auto point selection, and you can shoot in 'AI Servo' with either single or auto point selection. (and AI Focus, of course)

On my cameras, I have removed the AF function from the shutter button and use 'back button focus', which I believe gives me the best of both AF modes (One shot & AI Servo). I typically keep it in AI Servo so that I can continuously focus, but I can 'lock' the AF by simply releasing the back button. This system works well, except when in low lighting, which is when I need the AF assist light, and that only works in 'One Shot' mode.

 

[lennon33x]

Mike,
I was recently dealing with this same issue. I recently shot a wedding and realized that my 50mm ƒ/1.8ii wasn't wide enough, so I purchased a 35mm ƒ/2. It has a slower focus motor (similar to the 50mm ƒ/2.5 Macro). Was there a specific setting that you changed to make it focus a little faster, or change to where it limited the focus points you selected?