Aside from variations in manufacture or camera calibration, lenses do differ in actual light transmission. With today´s glasses and coatings, the differences are far smaller than they used to be, and for "non-extreme" lenses like those three you mention, they *should* be quite small indeed.
In practice, I would be surprised if three different cameras did indeed read the same without extra calibration - even if they used the same lens...
Per
torsdagen den 1 maj 2003 kl 14.53 skrev Charles Dias:
Hi,
Another question a friend asked me and I couldn´t answer perfectly.
Imagine you placed three cameras of the same brand and model side by side, loaded with the same film and with the same function adjustments. It are pointed to the same 18% gray panel and the spot light meter are set. One of the cameras have a 20mm f2.8, other a 35mm f2.8 and the last a 135mm f2.8.
If you set f5.6 in all lenses, will the light meters of the cameras indicate the same speed for all three cameras???
I asked him that it problably would indicate different speeds, in the limite of +/- 1 EV, because the lenses have different optical construction (different kinds, number and arrangement of optical elements), but I´m not sure about this.
Is my conclusion right???
T+
Charles
"It´s no better to be safe than sorry" In "Take on Me" song by A-Ha
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