Continuing the series on focusing the G9, knowledge of the hyperfocal distance is extremely useful when focusing any camera. Previous postings have included observations about the G9’s use of hyperfocal focusing and depth of field for closeups.
Somewhat loosely speaking, but easy to remember, is that if a camera is set for the hyperfocal distance then everything from that distance to infinity is acceptably in focus. In fact, everything from half that distance to infinity is in focus. For more details, check Wikipedia .
A most useful reference for both hyperfocal distance and depth of field is DOFMaster . Since both hyperfocal distance and depth of field vary with digital sensor size and focal length, here’s a chart of hyperfocal focusing distance specifically for the Canon G9 that was made by using the DOFMaster online calculations.
In addition to the hyperfocal distance, the table includes the near/far distance that is in focus when the G9 is focused at 10 feet. Why 10 feet? When the G9 is first turned on and switched to manual focus, it is set for (roughly) 10 feet.
Here’s an example of how the chart can be used. With your G9 turned off, set the Av mode at f5.6. Now turn the G9 on. The default focal length is the wide angle (7.4mm focal length) when the G9 comes on in Av mode. Immediately, switch to manual focus. You’ll see that the default focus distance is about 10 feet. Referring to the chart above for the 7.4mm lens, the hyperfocal length at an aperture of f5.6 is 5.3 feet. This means that, if the focus distance had been set for 5.3 feet then every distance from 2.65 feet (=5.3/2) to infinity would have been in focus. However, the default distance is 10 feet so everything from 3.5 feet (near focus) to infinity is in focus.
The G9 almost does not require focusing at the wide angle setting! But this happy situation changes dramatically at the longer focal lengths as shown in the chart.
Since aperture, focal length and manual focus distance can be saved as a custom setting (page 109 in the manual), the G9 can be preset for special situations -- including hyperfocal focusing.