Re: The irony of camera lenses
- From: davem@xxxxxxxxx (Dave Martindale)
- Date: Mon, 10 Apr 2006 06:48:08 +0000 (UTC)
"Rich" <rander3127@xxxxxxxxx> writes:
"Reduce resolution while gaining resolution." That is in essence what
"stopping down"
a lens does.
That's an odd way of looking at it. Stopping down a lens generally
reduces aberrations, and always increases the effects of diffraction.
What you're left with determines resolution.
When the lens is wide open, aberrations generally cause far more
blurring than diffraction does. So stopping down decreases aberrations
a lot while diffraction remains insignificant in comparison, and you
gain resolution.
On the other hand, when the lens is almost fully stopped down,
diffraction is the main source of blur, and if you stop down further you
won't decrease aberrations significantly but you will increase
diffraction blur, reducing resolution.
So any lens has an optimum aperture for resolution, and larger *or
smaller* apertures both give lower resolution. Of course, sometimes
there's still a good reason to work at those other apertures.
Dave
.
- Follow-Ups:
- Re: The irony of camera lenses
- From: Don Stauffer
- Re: The irony of camera lenses
- From: Rich
- Re: The irony of camera lenses
- References:
- The irony of camera lenses
- From: Rich
- The irony of camera lenses
- Prev by Date: Aiptek Brand in General
- Next by Date: Re: Wearing phot vest at Europe in June 2006
- Previous by thread: Re: The irony of camera lenses
- Next by thread: Re: The irony of camera lenses
- Index(es):
Relevant Pages
|
Loading
