In a message dated 9/4/98 11:34:53 PM Central Daylight Time,
svtbrad@xxxxxxxxxx writes:
<< And one odd observation- I was getting a higher shutter speed through the
Zuiko 300 (f 4.5) than I was the Vivitar (f 4.0 at 210). A stop and a half
difference. Strange. also, had no problems with the OM4 on manual,but it
froze up every time on auto (4th and 8th secs w/viv lens). Is it that the
different metering can't read that low of light? curious to hear input on
either of these. >>
Back in the early 80's there was a lot of noise in the photo mags about
transmisson ratings vs. published maximum apertures. As you probably know, the
maximum aperture of a lens - as rated by the manufactor - is a mathmatical
calculaton. The actual amount of light transmitted through a lens, however,
varies considerably with the number of elements, coatings, etc. The more
complex the lens, the more light is lost on its way through the lens.
Fortunately, with through the lens metering cameras, the loss is compensated
for by the metering; but, as you found out, an f 4.0 is necessarily an f 4.0.
Jim
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