Dptips :. Digital Photography Tips, Tricks, and Techniques

Being an avid user of the focus/recompose technique, I am glad I learned about its possible drawbacks early on as the distance of the focus point upon recomposing is no longer the same as the original pre-focused distance. Hence, the focus distance is incorrect and can make for some soft photos.

For those who don’t know what I mean about the focus/recompose technique, it’s a way of focusing on an object and then recomposing/repositioning your camera to properly frame the object. This is also a common technique in sports photography when the action is too quick for the cameras auto-focus and the photographer needs to resort to focusing on an area where he/she anticipates the athlete and then recomposing the shot. I attached a rough diagram below of two scenarios (first time Wacom user, be nice!  )

Example: Portrait – the camera is focused on the subject’s eye (usually the focus point you want). Then the camera is recomposed.
Mountain Biker Jumping – the camera is focused on an area where the photographer anticipates taking the shot of the rider. Then the camera is recomposed.
In both of these examples, the focusing point is skewed once the camera is recomposed as the focus distance has shifted. Just think about planes in geometry and parallel planes.

When the camera is tilted and focused on the eye of the subject, the camera focus distance is on parallel plane A with a distance 6.3ft. When the camera is recomposed the focus distance is now on a different plane say B with distance 6.25ft. The difference between the focus distance and actual shot distance can be the difference between tack sharp, fairly sharp, or horribly soft images. Typically, the further the subject is from the camera the less you have to worry about the focus/recompose issue. However, if you always want to get tack sharp photos plan on spending some time with the AF selection points and taking to account the focus distance shift when using the focus / recompose technique.

Cheers,

Ivan
www.ibwphoto.com