On 9 Feb 2001, at 18:16, Bill D. Casselberry wrote:
> Rob brings up the "other half" of the DOF phenomenon, here.
> Most folks are familiar w/ the effect of aperture on DOF, as
> it is easily seen and rather obvious. Many fail to realize
> the significance of the focus distance in the overall scheme,
> though. Basicly - as the focus distance diminishes, so does
> the DOF - which is the base cause of such extremely thin fields
> of focus in macro photography, even at tightest apertures.
Absolutely, the SMCPA*200f4 macro at minimum focus distance and f32
provides a startling 10mm (assuming 200mm FL which we know it is not at
minimum focus distance which is 55mm corresponding with 1:1 which
actually works out to an effective 275mm FL?)
Another factor re DOF which is most often overlooked is that the overall lens
sharpness at the plane of focus will effect the viewers perception of DOF ie if
the lens is strikingly sharp at the FP then the blurred areas will be so much
more apparent whereas a soft lens will be soft a the FP too.
Cheers,
Rob Studdert
HURSTVILLE AUSTRALIA
Tel +61-2-9554-4110
Fax +61-2-9554-9259
UTC(GMT) +10 Hours
[EMAIL PROTECTED]
http://www.ozemail.com.au/~distudio/publications.html
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