I couldn't understand what he was saying either. I don't think he was
talking about light loss due to either reflection or absorbtion. He is
trying to make some kind of point about the maximum aperture of a lens
behaving different from stopped down but there didn't seem to be any reasons
given.
A wild guess is that when the lens is wide open it's aperture isn't limited
solely by the aperture blades. Light coming away from the optical axis is
limited by parts of the lens other than the blades. When it is stopped down
the light is limited almost entirely by the blades (including the off axis
light).
His comments about the fresnel lens interacting with the main SLR lens was
interesting but doesn't really seem to have anything to do with maximum f
stop versus stopped down f stop.
I didn't say anything earlier out of hope that someone had a better
understanding. It is an interesting question! Thanks for keeping it alive
Fernando.
-jeff
----- Original Message -----
From: "Fernando Gonzalez Gentile" <fgnzalez@xxxxxxxxxxxxx>
> So, do you think the quoted paragraph from Mr. Hésharu Nozawa doesn't make
> sense? Even after reading the enclosed document on Pen FT uneven f-stop
> marks?
> I do think it doesn't make sense and is contradictory but then, I'm not a
> native English speaker either, nor am I an optical engineer. And, after
all,
> the question/finding remains unsolved.
> >
> > Now, if you followed me this far, don't you feel the same way? There's
> > another piece of your life you could have used for soemthing more fun,
> > better for you, almost anything else, right?
> Mmmmm... no.
>
> Fernando.
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