The Focus issue
Tuesday, December 30th, 2008In digital cameras, there basically is no “focus issue” - other than people not understanding how the AF system works. The manufacturers do not make this easy by using confusing terms and symbols, e.g. the AF point select symbol looks just like the metering mode symbol… then they use terms like “AI”, which few mortals can decode (AI means “Artificial Intelligence”) - I never cease to be amazed at such user-confusing issues.
For beginners, here is a simple (simplified only a bit!) summary:
AF becomes easy once you realise:
- There’s a setting for WHERE you focus, and a setting for HOW you focus.
- WHERE is all about the focus points:
- “All points” means the camera chooses the closest object covered by a point.
- That may not be what you want so it is OK to use just one point, move that over the object you want to have sharp, and then focus.
- As a refinement of that, you can keep your finger on the shutter after the focus beep, then recompose a bit, and then shoot. (we call this “focus-recompose-shoot”).
- HOW is about how the camera behaves when trying to focus (regardless of the ‘where’):
- This can basically be set to “stop when you have achieved focus” (terms like “One Shot” or “AI Focus are used for this) or “keep trying forever” (terms like “AI Servo” are used for this).
- The former is best when you want control, but the latter is usually best when you are shooting moving objects like sports.
Basically, that’s it. Nothing to it - except after understanding, you need to practice. Yes, there are subtleties beyond this of course, but they are subtleties. Using just what you read above, you can achieve focus where you want, when you want.








