on 6/11/02 1:20 PM, ll.clark@xxxxxxxxxxx at ll.clark@xxxxxxxxxxx wrote:
> In <3D0612F3.15432.3F3583C@localhost>, on 06/11/02 at 03:10 PM,
> Tom@xxxxxxxxxxxxx said:
>
>> I think that would be better. Mirror lenses lose almost a stop of light
>> from the central 2nd mirror, so that f/8 becomes an f/11, slower than
>> a 300/9.
>
> Are you sure that this is true of the Zuiko?
>
> ---------------------------------------------
> les clark / edgewater, nj / usa
> ---------------------------------------------
Most of the mirror lenses I've checked have corresponded to the meter
reading of a regular lens pretty closely i.e. the manufacturer must
compensate for the central obstruction by sizeing the overall opening to
account for the blockage. Metering a blank evenly lit wall from up close,
with both lenses focused on infinity I found the same meter reading with my
500/8.0 and the 300/4.5 -- both metered at f8.0. My Celestron 300/5.6 and
the 600/8.0 Vivitar 'solid cat' were the same. I haven't tried this with the
Celestron C90 1000/11.0 yet...
--
Jim Brokaw
OM-1's, -2's, -4's, (no -3's yet) and no OM-oney...
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