on 12/01/2005 00:48, Wayne Harridge wrote:
> Thanks for quoting the full contents of your letter from Olympus, interesting
> reading
> though I'm not sure I understand exactly what they are getting at !
Neither do I, ever since I read it for the first time. I get lost at:
"The OM-System lenses are manufactured based on the same concept of this TTL
number system. But the aperture ring of the OM lense engages at each f
number intervals. Therefore, the light passing through the lens is not cut
exactly in half by stepping one stop from full-open aperture to next value.
Because of this, the space between the full-aperture f number and the next f
number is smaller than the distance between other f number."
These paragraph seems to synthesize too many data for me to understand.
I seem to understand F1.4 or F2.8 in the normal and wides in question, would
not be marked "0" as they would in the Pen FT numbering system (that's why
the adapter?). Were they to be marked "0", the space between the
full-aperture f number and the next f number would be larger than the
distance between other f number
Is it not cut by half because of light fall-off compensation, and to correct
for the errors caused by the curvature at the edges of the lens; as in Pen
FT?
Same would apply to the 50mm F1.4 (which I avoided to count on yesterday due
to an error in concept I had), and unexpected results could be accounted by
the nature of the light source (size, colour, constant intensity or not....)
- items I used to discuss offlist with Carlos Santisteban when the thread
'Long exposure capability of OM2n' during May 2004.
I wish I had tested the 50mm @ 1.4 and 2, but only did @ 1.4, 2.8 and 5.6.
Regards,
Fernando.
Fernando.
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