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Re: [OM] focusing using ground glass vs. micro/split prism

Subject: Re: [OM] focusing using ground glass vs. micro/split prism
From: "C.H.Ling" <chling@xxxxxxxxxxxxx>
Date: Fri, 03 Jan 2003 10:35:22 +0800
I think most people will found focus with split image is easier but if
you need accurate focusing you have to use the matte area. The split
has limited resolution, as I remember Pop photo performed some tests
on the AF systems, they said the AF sensor is working like split image
focusing and hence the max. resolution you can get is around 50lp/mm
only. Since I have changed to matte area focusing the sharpness of my
shots improved a lot especially with wide angle lens wide open. With
matte focusing you need to adjust the lens by turning
left-right-center, you cannot just turn in one way and determine the
sharpness unless you are aid with a high magnification tool.

C.H.Ling

Donald Shedrick wrote:
> 
> With the 2X converter, you are at f5.6, and at that lens speed the
> micro/split prism is unreliable and the focus seems to shift as you
> shift your eyeball.  At lower f values (4 and below) I find the
> split, if used on a straight verticle line, is a little more accurate
> - meaning you will get the focus spot on with less guess work.  At
> least that is the way my eyes work - others may be different.
> 
> --- "Richard F. Man" <richard@xxxxxxxxxxxxxx> wrote:
> > I have almost always relied only on the micro/split prism for
> > focusing.
> > However, recently I am getting to like to use the ground glass
> > portion
> > better. It's really cool when the image just snaps into place, as
> > by magic.
> > One question, is it possible for the two focusing mechanism to
> > "disagree?"
> > I was taking pictures using the Zuiko 180/2.8 coupled with the 2x
> > converter
> > and I thought there are times that the focus point is slightly
> > different. I
> > don't have 20/20 vision, but I can do without glasses, if this
> > matters.
> >
> > Thanks!
> >
> 
> =====
> 
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