"Bob Kirkpatrick" <bob.kirkpatrick@[EMAIL PROTECTED]
> wrote in message
news:5be1562b-109a-40a5-a91c-2983909ca333@[EMAIL PROTECTED]
> 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.
>
True, but if a waist level finder is being used (as I suspect) then there
is
no possiblilty if using a diopter correction lens on the viewfinder.
Rob.
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