----- Original Message -----
From: "Mark Roberts" <[email protected]>
To: "Pentax-Discuss Mail List" <[email protected]>
Sent: Friday, April 17, 2015 8:59:54 AM
Subject: Re: Depth of field at infinity
Stanley Halpin wrote:
You will get more diffraction at f/22 on a wide angle lens than you will at
f/22 on a mid-range lens than you will get at f/22 on a longer focal length.
That's not true. Although the physical diameter of the aperture at any
given f-stop is greater on longer focal lengths, the increase in
magnification is *exactly* proportional, thus magnifying the
diffraction effects of f/22 on a 300mm lens so they're exactly equal
to the diffraction effects on a 24mm lens, for example.
Ansel Adams and his f64 group actually made photos that lost quite a
bit of sharpness due to diffraction. They made up for it by using
large format view cameras that required little or no enlargement for
printing. When I've looked genuine Ansel Adams prints close up aI've
often been surprised at how sharp they aren't.
I had a signed Moonrise in my hands in a gallery in Santa Fe. I could
have bought it, but I passed.
The foreground was quite unsharp, but I think that was more depth of
field. We are quite spoiled by modern lenses and digital printing for
sharpness.
bill
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