From: Frank Ernens <fgernens@xxxxxxxxxxxxxxx>
Reply-To: olympus@xxxxxxxxxxxxxxx
To: olympus@xxxxxxxxxxxxxxx
Subject: Re: [OM] Depth of field questions
Date: Sat, 06 May 2000 23:34:53 +1000
Gary Reese wrote
> Olympus designers were first to
> market with a combined close and far focus aberration correction system
> (using floating elements) in the 50mm f/3.5, then later in the 50mm f/2
> and 90mm f/2. In contrast, the f/2 ultra wide angles only offer close
> focus aberration correction.
Are you saying that the slower ultra wides perform better
at infinity? That would make sense - the f/2's for journalism
and the slower ones for landscape. And where does "ultra"
start - 24mm?
Photographer and author, Joseph Meehan, breaks the wide angle lenses into
three classes: moderate (35mm), where the distinction from the normal lens
(45mm-60mm) is fine; medium (28mm-24mm), where apparent distortion is
readily visible but easily controlled; and ultra (21/20mm-8mm), the apparent
distortion is so overwhelming that strict attention to compositional detail
is necessary for successful framing. With ultras, even if one wants to use
"distortion," one still has to tweak the framing to ensure that one doesn't
over- or underdo affairs.
This makes sense since 24mm is about the widest focal length where
relatively easy composition is possible without paying undue attention to
converging lines. With 21/20mm and below, the apparent distortion simply
has to be accounted for.
Similarly, Meehan dissects the telephoto/long lenses into three distinct
classes: moderate (70mm-105mm), which represents a telephoto refinement of
the normal lens; medium (135mm-210mm), where the flattening effects of
tele/long "distortion" are easily noticeable; and super (250mm-1200mm),
where flattening effects become so extreme that three dimensional scenes
appear literally compressed into a two dimensional frame.
John A. Prosper
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