What do you do when there are several planes of focus and the autofocus mechanism can’t distinguish what the subject is? Or, more specifically, it can’t determine what the correct point of focus should be. In situations like this cheetah in tall grass where the correct focus points are obviously the eyes and not the foreground grasses, the only way to take a correctly focused picture is to switch the camera off autofocus and focus manually. Otherwise the focus mechanism will probably lock onto the grass and throw the cheetah out of focus. Even using a small lens aperture to increase depth of field won’t solve the problem. Fast changing photographic subjects like wildlife can be great for only seconds, or fractions of a second, and manual focus takes time. That’s why it’s important to identify problematic focus scenarios and make quick decisions as to whether AF will work as it should or whether the manual approach is required. My settings for this picture were 1/1000, f/2.8, 320 ISO, and I used a Canon 300mm f/2.8 telephoto.
2 Comments
Nov 27, 2017, 8:16:01 AM
Jim - Hi Bryan, On the Canon, I don't have the kind of mode you're referring to. I have to switch from one mode to another. The new generation of mirrorless cameras have a number of functions that are new.
Nov 26, 2017, 3:01:24 PM
Bryan - I leave my camera, Olympus E-M5ii, in the S-AF +MF mode, which lets me adjust focus manually with the focus ring after I've locked AF with the half press of the shutter button. Is this not a feature on other cameras or is there a disadvantage to that I haven't thought of? Much quicker that switching to AF, even though it's one press of a button, because the half press gets you close and it is usually a minor adjustment from there.