Focusing and Sports primary reason for missing focus

I have had several members ask me about focusing and fstops and I wanted to share the primary reasons that a photographer might experience focusing problems with their subjects, particularly when tracking action. In my experience it is usually one of these issues but sometimes/often they may overlap.

1. F Stop or Aperture:

Aside from being part of the exposure triangle, when a subject is focused properly this number determines how much of the space in front or behind the subject will be in focus. For example at if you are taking a portrait at f 1.4 with an 85mm most of the background and foreground around your subject will be out of focus. Depending on how close you are ( which I will discuss later) its possible that if you focused on the subjects eyes that their ears could be slightly out of focus. Again the aperture just controls how much of the photo will be in focus in the foreground and the background of where your focus point locked. In the following photo I was shooting with a 400mm 2.8 lens in the backfield. The Quarterback and running back where fairly close to the sidelines where I was positioned. I shot this at 2.8 and notice that the Quarterbacks arm that is handing off the ball is sharply in focus but the running backs face isn't. The focal plane is the line across the quarterbacks arm and the running back was slightly behind it. If I would have taken this at F3.5 or f4 both of the players would have been in focus. If I would have been further away from the subject they also would have been in focus.

Canon 1DX, 400mm lens @ f 2.8

Another example of how narrow the depth of field can be with a telephoto lens. Notice the ball carriers right hand is in focus and his carrying arm is nearly in focus but his face is almost completely out of focus. Also notice the defenders arm is out of the focus plane. 400mm f2.8 @ f3.2

2. Focal Length

The focal length and distance to the subject also determines how much of the subject and background will be in focus. Doing a headshot at 24mm will have a deeper depth of field (more in focus) then the same headshot with a 300mm. Basically the longer the lens the more shallow the depth of field at the same fstops. These are two photos taken at f 2.8. Notice that the first photo of the runner taken at 50mm at f 2.8 has a great deal of the background and foreground in focus while another photo taken at 2.8 with a 400mm lens has a very shallow depth of field.

Canon 1DX, 50mm 1.4 lens @ f2.8.
Canon 1DX, 400mm @f2.8

3. Distance to the subject.

This is similar to the focal length but in short, the farther you are away from your subject the more the more the background and foreground will be in focus. These photos are taken what the same lens and same exact settings on a football field. The only thing that changed was the subjects distance from my camera which was stationary.

Canon 1DX about 60 yards away, 400mm @ f2.8
Canon 1DX, 400mm 2.8 @ f2.8 at 20 yards away.

4. Missed focus

This is the failure for you camera to lock focus on the subject and is not connected to the depth of field but simply the camera and lens not locking onto the subject. This could happen because of camera or operator error. Proper focusing would require a much longer discussion. This article is assuming that people are using camera equipment that is functional and using the right focal points and action tracking features within their cameras. The photos below are examples of missed focus.

Camera failed to lock onto the ball carrier (#3) and instead locked onto the player #1 in the background.
Another example of the camera not locking onto the intended subject.
Another example of a nice action shot that I missed due to the focus not locking onto the subjects.

5. Shutter speed.

The general rule (which doesn’t always apply) for sports is that a shutter speed of 1/1000 is needed to freeze action and that even for still subjects, your shutter speed should at least equal the focal length of the lens you are using. As the focal lengths increase so should the shutter speed increase to often double that amount. So if you are shooting still subjects with an 85mm lens you should be at least over 1/85 on your shutter speed but if you are shooting with a 600mm you might want to be at 1250 shutter etc. A lot of times photos are out of focus for the first 4 reasons and people blame it on shutter speed. Usually motion blur has a bit more distinct of a look than an out of focus photo. The following examples were essentially accidents where I my shutter was being moved down as I was walking from one side of the field to the other. The first photo below was taken at 500 shutter speed (accidentally). Notice the defenders arm and helmet are blurred. The second photo below was taken (accidentally) but is an exaggerated example of what happens with too low of a shutter speed when tracking action. The settings on the last photo were f2.8 on a 400mm lens with a shutter speed of 100.

Too slow of a shutter speed will result in motion blur.

6. Back or front focusing.

This is a phenomena where your lens is locking onto subjects slightly in front of or behind your intended subject of focus despite your focus being precise. This often shows up as the subject in your shot appearing “soft” despite the fact that you focused specifically on the subject and didn’t make any of the mistakes mentioned earlier. This requires the lens and camera to be calibrated properly and is the only solution. The following photo was taken with a lens and camera combination that was routinely back focusing my photos. In this photo the focal point was locked squarely on the players face but the focus is behind the players slightly. This isn't always a problem that is as distinguishable from an ordinary out of focus photo and usually requires careful observation and testing. Fortunately most of the consumer and professional cameras today allow you to calibrate your lens within the camera.


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