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Re: Infinity and F-stop RE: [OM] Monopod & ball head

Subject: Re: Infinity and F-stop RE: [OM] Monopod & ball head
From: "George M. Anderson" <george@xxxxxxxxxxxxxxxxxx>
Date: Tue, 04 May 1999 16:50:26 -0700
They're just approximations. How accurate can you really read the thing
anyway?  Course, you can always see the effect by slowly stopping down
the depth of field button.  When in doubt, I always focus on the nearest
object I want in focus, note the distance on the scale, then focus on
the farthest, note that distance and see what f stop is needed to
include both.  Sometimes, you'll find you're asking too much of the lens
and will have to settle for less (or switch to a wider lens).  Lastly,
note that I said 'acceptable' focus.  As objects approach the near and
far limits, they will go slightly soft. The acceptableness is determined
by circles of confusion, print size and viewing distance, etc etc. Too
much for here.

George

"Barry B. Bean" wrote:
> 
> On Tue, 04 May 1999 11:09:15 -0700, George M. Anderson wrote:
> 
> >Look at the focus ring and the lens flange. The flange has F/#s on it,
> >focus ring distances.  If you focus on infinity, there will be some
> >distance in the foregroud after which objects out to infinity will be in
> >focus.  Eg:  Zuiko 50/1.8: when focussed to infinity with lens aperture
> >set at F/8, acceptable focus is from 10m to infinity. But if aperture is
> >set to F/16, the close limit moves to 5m. But, look what happens if you
> >set the focus to 10m and aper to F/8.  Now the flange marks indicate
> >acceptable focus from 5m to infinity, same as F/16 above!  Very useful
> >to use this method for max depthe of field. Method is called
> >'hyperfocal.'
> 
> Just how accurate are lens markings? I notice that on my 200/5 that
> the hyperfocal distance  at f16 looks to be 150yds judging by the
> lens markings. But according to the hyperfocal calculator at
> http://www.frii.com/~mbaltuch/HyperFocal.html, the hyperfocal
> distance for f16 should be 83.33 yards. Which should I trust?
> 
> BB
> -
> B.B. Bean - Have horn, will travel                              
> bbbean@xxxxxxxxxxxxxx
> Peach Orchard, MO                                       
> http://www.beancotton.com/bbbean.shtml
> 
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