In a message dated 7/8/01 1:47:43 PM Pacific Daylight Time, parz@xxxxxxxx
writes:
> So, can anyone explain this behavior? Does it happen on other
> OM4T's vs other bodies?
>
>
I have an OM-2 and OM-4t. I put a 35/70 f/4 lens on the OM-2 and set it at
f/8th focused on infinity, ASA set to 200. The Auto Setting shows 1/8th SEC
and as one rotates the zoom ring from 70 mm to 35 mm the needle just barely
moves.
On the OM-4t, everything else being equal, on Auto Setting the needle moves
from just slightly less than 1/8th at 70 mm to just slightly more than 1/8th
at 35 mm.
So, the OM-4t detects slightly less than 1 stop change. The OM-2 shows not
quite so much variation. I suspect the difference may be in the metering
circuitry on the OM-4t Vs that on the older OM-2.
Both bodies I have matched exactly with a friend's high end Sekonic meter
last month. However this test was done using two prime lenses. The OM-2 had
a Camtech CLA in the past year and both bodies have SR44 Silver Oxide
batteries in them.
While I don't have the exact same combination as in the previous situation it
does appear that the OM-4t is more sensitive to the change in focal length as
one zooms. Some of the more technically astute members of the list can
better address this, but it seems to me it must stem from the changes in
light transmitted through the lens as it zooms and the OM-4t is more
sensitive to the change.
I don't think the variation between the two setups that I tried would make a
qualitative difference in most photo situations. Just my two cents worth.
Dave D
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