Today’s post by Joe Farace
One of the basic laws of imaging states that only one part of a three-dimensional object can be truly in focus at the image plane. This means the areas that are located in front of and behind the focus plane will appear more or less in focus or in what some people like to term acceptable focus.
Depth-of-field is that area that your eyes perceive as being in focus and is affected by several things, including the distance from the camera to the subject. Depth-of-field increases as the lens aperture is stopped down and decreases as the lens aperture gets larger and when the camera-to-subject distance decreases. At the point of critical focus, there is a range of acceptable focus that is one-third in front of that point and two-thirds behind it.
As the control of aperture shifted to the camera body, aperture rings have disappeared form most modern lenses. But some older lenses and occasionally some newer ones for mirrorless cameras, especially when adapting those from other formats, have an aperture ring. Most vintage lenses even have a depth-of-field scale, which can be helpful when using hyperfocal focusing.
The Hyperfocal Distance is the specific point of focus where any object that is between that distance and infinity is in focus. Here’s how it works: After you pick an aperture you rotate the lens’ focusing ring for that aperture opposite the infinity mark so that everything from what’s at the opposite end of the focusing mark will be in acceptable focus.
How I Made this Shot: This photograph of the Platte Valley Medical Center in Brighton, Colorado at night was made using a Canon EOS 1D Mark IV with a EF16-35mm f/2.8L USM lens at 24mm. Exposure 1/15 sec at f/8 and ISO 12,800. Yes the image is quite noisy. Heck it’s still noisy even after applying Dfine.
Along with photographer Barry Staver, Joe is co-author of Better Available Light Digital Photograph with new copies available from Amazon for $21.50 with used copies starting at five bucks. For some reason,(not Barry or I) the Kindle price is really high.