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From: keesan@bbnccv.UUCP (Morris M. Keesan)
Newsgroups: net.rec.photo
Subject: Re: My first lens(es) [actually apertures and sharpness]
Message-ID: <624@bbnccv.UUCP>
Date: Wed, 5-Jun-85 18:32:49 EDT
Article-I.D.: bbnccv.624
Posted: Wed Jun  5 18:32:49 1985
Date-Received: Sun, 9-Jun-85 01:29:42 EDT
References: <1015@ihuxb.UUCP> <1366@watdcsu.UUCP> <929@peora.UUCP> <579@sfmag.UUCP>
Reply-To: keesan@bbnccv.UUCP (Morris M. Keesan)
Organization: Bolt Beranek and Newman, Cambridge, MA
Lines: 21

In article <579@sfmag.UUCP> howard@sfmag.UUCP (HowardMoskovitz) writes:
> . . .
>recommend you try the following first before buying a new lens:
> . . .
>	                          . . . Use a very sturdy tripod,
>	stop down your lens as far as possible to maximize depth of 
>	field and edge-to-edge sharpness (the slower shutter speed is
>	okay because you're on a tripod). . .  
> . . .

Wrong.  (ALMOST right).  Stopping down as far as possible will indeed maximize
your depth of field, but it will not optimize sharpness.  Most lenses display
their best sharpness and resolution when stopped about half-way down; check
any of Modern Photo's lens tests, to see this.  When the lens is stopped all
the way down, the smaller aperture causes a deterioration in sharpness due to
refraction effects.  For best sharpness, stop down only far enough to get the
depth of field you want.
-- 
Morris M. Keesan
keesan@bbn-unix.ARPA
{decvax,ihnp4,etc.}!bbncca!keesan