On Wed, Jul 13, 2005 at 11:50:12PM -0400, Tom Reese wrote: > > Exactly. The 18mm lens focused at 7 feet will have substantially more > depth of field than the 28mm lens focused at 7 feet if the aperture is > the same.
That depends on what you mean by aperture. If you mean "f stop" (relative aperture), then you are correct. But if the absolute aperture is the same, the DOF will be identical. With the 1.5 crop factor of the *ist-D, the difference in f-stop to get the same DOF is one stop for all practical purposes.
