Way out of my depth on this one - except just a thought; I notice in the
OM-1 manual it mentions that certain screens will produce incorrect metering
with certain lenses. There are some that work with standard and w/a lenses
that apparently do not with certain longer ones.
Lee
----Original Message Follows----
From: frieder.faig@xxxxxxxxxxxxxxxxxxxxxxxxx
Subject: Re: [OM] are SC lenses to blame?
On Fri, Jul 19, 2002 at 05:04:10PM -0500, Robert Gries wrote:
> John H. and I have had a frustrating time with a couple OM-1 bodies and
> meter accuracy. He mentioned that others on the list have had problems
> with certain lenses and the accuracy of the OM-1 meter.
>
> With the lenses that I have available, it seems that the SC lenses are
> the ones giving me grief. Using an evenly lit surface, the meter
> inaccuracies are as follows:
>
> 21/3.5 (MC) meter is right on - agrees with hand held meter
> 35 shift (SC) 1.5 stops over - this is after I let the meter "settle"
> 85/2 (MC) meter is right on
> 135/2.8 (SC) meter is about 1 stop over.
>
> I still need to go home and check this with my other lenses, but thus
> far is there anything mechanically different between older and newer
> versions of these lenses that would cause this? I have not had any
> problems with these lenses and the -4Ti, so I am guessing it might be
> more with the OM-1 meter, and not the lenses.
>
> Any and all information is greatly appreciated.
My thougts:
What about backlight in the viewfinder? Is your surface really evenly lit?
Check it with a spot meter, I was shocked how your eye can fool you,
When I compared some lenses.
I´d also check the accurancy of the apperture lever of the lenses?
I have a lens wich is about 1/3 stop too optimistic compared to others.
About transmission: I don`t have a lot of information, and only on MC
lesnses.
The best Transmission I know is 95.50er lens (99.40er surface),
The worst is 83.30er lens (98.70er surface).
The difference would be 83.3/95.5= 0.89 ~ 0.2 stops difference.
Frieder Faig
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