amfoto1 Loc: San Jose, Calif. USA

On what camera and using what AF methods, AF mode and what AF point selection?

First of all, you might already be aware, with action photography you pretty much need to use the optical viewfinder of a DSLR.... Not Live View. Mirrorless camera electronic viewfinder also may not be up to the task.

With sports you pretty much need to use AI Servo (not One Shot or AI Focus). That's intended for moving subjects, to allow tracking. There's no "focus confirmation" in AI Servo (there's nothing to confirm, since the focus runs continuously). You have to get accustomed to that.

The camera model matters because some have more or less capable AF systems and AF points in their array.

The most accurate way to shoot sports with AF is with Single Point. On all Canon DSLRs it's safe to use the center point, because it's always an enhanced, higher performance type. On some models, peripheral AF points are also high performance.... others, not so much. For example, all 65 points in the 7D Mark II's AF array will give the same level of performance with an f/4 lens/TC combo. But, at the other extreme, an SL2 or original 6D only has a single high performance AF point, at the center. The rest are considerably lower performance and not as usable for moving subjects.

Multi-point focus patterns (Expansion, Zone, All Points) leave it up to the camera to choose where to focus, to some extent. Some camera models have all these focus patterns. Others only limited choice. In part, it's just that the camera might choose something different than you wanted.... But also because it might select a lower performance AF point that's not able to track a moving subject.

Using Single Point (and knowing your camrea's AF system, which AF points to avoid and which to use, if there's a difference) will give the highest percentage of correctly focused shots... But it's more work for you, keeping the AF point right where you want camera and lens to focus. (Might help to use Back Button Focusing, if not already doing so.)

Different cameras have different AF performance, too. For example, both 7D-series and 1D-series cameras have a separate chip running the AF system. (They also have dual image processors, though that doesn't directly effect AF performance.) All other Canon models share a single processor.... which handle both the images and the AF functions. (Well, except for the 50MP 5DS, which use dual processors to handle the exceptionally large size files... but they still use those same processors both for image handling and AF.)

You mention the lens was an EF 70-200mm f/2.8 II.... which is fast focusing with USM focus drive. So the lens itself isn't a problem, in this case.

I use the same Canon 1.4X II teleconverter with various lenses... and see only slight difference in AF performance.

When you add the teleconverter to the lens, it becomes and effective f/4 max aperture. This may not perform quite as well on some cameras, because most Canon have one or more AF points that give extra high performance when used with f/2.8 and faster lenses. So if you compare shooting sports with you lens alone (f/2.8) versus with the 1.4X installed (effective f/4), you may notice a slight slowdown. But it will usually still work very well, depending upon lighting conditions.

I shot a sporting event about a week ago. I didn't use a teleconverter, but two out of three of the lenses I used were f/4 or f/5.6 (one was f/2.8) and all were USM, which should give pretty much the same AF performance as your setup. I took upwards of 1500 images, edited them and had about 600 uploaded into 9 galleries online two days after the event. Part of my workflow is to check focus and be certain it's acceptable. I "black flag" any "missed focus" shots I find, just to keep track of how I'm doing. I just looked and out of a bit more than 1500 images I made that day... using those lenses on a pair of 7DII... I have a total of twelve images marked as "missed focus".

Now... Maybe I didn't catch and mark a few... Or had already decided they weren't "keepers" for other reasons and didn't look closely at the focus accuracy. I culled out a whole heck of a lot more because they were duplicates or for poor composition, bad timing, etc.!

Also, maybe I'm not as critical as you. I evaluate sharpness and focus at 50% magnification.... because I know that's more than "good enough" for high quality prints up to around 16x24". A lot of people look at their images at higher magnification than that... and at some level every image looks bad! Using a modern monitor set to it's native resolution and viewing an image from a 24MP camera "at 100%" is like making a five foot wide print, then viewing it from only 18 or 20" away. Of course it looks like crap! And it has nothing to do with real world uses of the image (unless heavy cropping is planned)... the image that appears soft at100% can look great at more practical magnifications.

Part of the reason my missed focus percentage is low is because I mostly just use Single Point I also use BBF.. And I'm familiar with the type of event.... often don't do quite as well at unfamiliar events, where I'm still learning how the action moves.

Also, I usually stop my lenses down a little, when lighting allows, to f/5.6 or f/7.1... That can "hide" minor focus errors.

If your camera has the feature, Micro Focus Adjustment of the lens + teleconverter might help.

It also sometimes helps to remove any filters from the lens. For sports photography, I usually avoid filters (it varies from lens to lens, but filters can soften images.... or might even interfere with AF).

I don't have the same 70-200mm as you and also tend not to use teleconverters on zooms.... But the following were shot with the 1.4X II on 300mm f/4L (no problem and hardly ever a missed focus issue):




Here's a cropped detail from the above (and I'm pretty happy when I can count eyelashes!)



And these were done using the same 1.4X on 300mm f/2.8 and 500mm f/4:



Those may or may not help, since it's hard to see image sharpness... let along focus accuracy... at Internet sizes and resolution.

Finally, it might have helped to clean the lens and teleconverter electronic contacts. Those are what the camera uses to communicate with them, using low voltage signals which might be interrupted by any oil or whatever on the contacts. They are gold plated (to prevent oxidization), so be careful cleaning them. I recommend using a couple drops of isopropyl alcohol (rubbing alcohol works fine) to dampen a clean cloth, then carefully wiping the contacts with that.

amfoto1 Loc: San Jose, Calif. USA

Just looked again at your sample image and that's a real MESS! It really doesn't appear to be an AF problem.

It looks like a de-centered element (either in the lens or in the teleconverter... hopefully the TC, since it's a rental... and NOT your lens).

It also could be a "tweaked" bayonet mount. Or, possibly, a badly worn out mount ... so much so that the lens wasn't fully and properly seated.

Those are the only way you can get partial focus like in that image.... Sharper on the left (tho still not all that sharp), but the rest of the image, including other subjects on roughly the same plane of focus, badly out of focus.

Look at other problem images and see if they are similarly sharper on one side than the other. If so, that would confirm de-centered element or tweaked/worn mount causing an improperly seated lens.

You mention "focus notification" in the viewfinder... Do you mean that the camera indicated AF was running (which it will do in any focus mode)? Or do you mean you were seeing "Focus Confirmation", which can only be given in One Shot mode (which is not usable with moving subjects.... i.e., cannot be used for most sports photography)?

Just curious, because in this case I'm not sure it matters. I don't think we're seeing an AF problem... With "missed focus" you would have had all subjects on or close to the same plane of focus equally out of focus!

It's a de-centered element or a tweaked/loose/misaligned lens mount. If it were me, I'd be shooting some tests with my lens alone... Just to be sure it's the rental TC at fault, and not my lens.

It's unrelated, but if I'd seen I was getting 1/4000 shutter speed, I'd have either lowered my ISO or stopped down my lens a bit. That's faster shutter speed than necessary for all but the fastest action. You might need 1/4000 or 1/8000 to photograph 300 MPH dragsters.... but 1/1000 to 1/2000 should be plenty fast to handle soccer players! Stopping down the lens would make for sharper shots in some cases... but mostly would be forgiving of minor focus error.

However, this aint' that. What I see in your image is far from "minor focus error" and stopping down won't help.

rthompson10

SOLVED!!

The issue was a mechanical issue with the lens- There are 4 screws holding the back to the lens at the back of the lens where it connects to the camera- 2 of these screws were loose, not seated, and not allowing the TC to mate with the lens, making itangle slightly to one side- Tightened screws and TC fits great

Thanks ALL

RT

rthompson10

Alan,

To answer your earlier questions as I appreciated the time and pix in the response

New to me but used Canon 1DX (Other camera is 7DII
Use expansion points- 8 around center point
Use AI Servo- the AF notification does come up in my viewfinder when I press it
Use BBF- Don't get as great a focus rate usually as I miss the subject sometimes primarily because I have a bad right hand and don't release and repress BBF to follow subjects so sometimes wrong thing will be in focus*Trying to shoot high school sports
Yes realize some of my settings are wrong- getting used to the camera plus my hand sometimes tends to move wheels accidentally
THX

RT

Grahame Loc: Fiji

Thank you for the update, it's always good to hear when a problem cause has been found.

dsmeltz Loc: Philadelphia