On Dec 2, 5:02 am, Matthew Winn <*...@[EMAIL PROTECTED]
> wrote:
> On Fri, 30 Nov 2007 22:17:15 -0500, "rwalker" <rwal...@[EMAIL PROTECTED]
>
> wrote:
>
> > I am new to medium format photography. I've just gotten a Yashica D
TLR.
> > Using the focusing screen with the magnifier is taking some
adaptation.
> > First of all, I am 50 years old and wear bifocals. When I look into
the
> > magnifier to focus, the line between my bifocal and the normal part of
my
> > glasses lens hits just about the center of the magnifier. If I lower
my
> > head slightly, I am then looking through the top part of my glasses,
and
> > focusing becomes much easier. I guess my question, bottom line, is
should I
> > be looking through my bifocal at the magnifier, or should I be looking
> > through the upper part of my glasses lens?
>
> Through the upper part. The magnifier is set to give an effective
> image distance of two or three metres so you should use the part
> of your glasses that gives you comfortable vision at that distance.
> (At least, that's how my own Yashica TLR is set up.)
>
There is a subtle point here. You need to be able to focus your
vision sharply on the underside / matte side of the focusing screen.
If your screen has lines or focusing aids like a split or microprism
then those lines or edges or even dust on the matte surface must be
perfectly sharp. Then focus the reflected image through the lens.
If you cannot focus your eyes on the screen, the image cannot be
brought into sharp focus at the correct place. So use whatever
correction combination that allows you to focus on the screen. This
is the whole point of diopter correction lenses for viewfinders and
the reason I'm saving up for a PM45.
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