>> I think that these questions are off-topic, but I will try to explain.
>You're right. No mention of EOS :-)
>
>> In order to focus to infinite, the rear principal point of the lens must
>be
>> at one focal length from the film plane.
>
>Does it mean that 14mm lens' rear element should be 14mm away from the film?
Not the rear element, but the rear principal point. It depends on the lens
design, but in easy to design lenses, this point is somewere inside the lens.
>If so, what is the height of SLR's mirror? I guess it's more than 24 mm. Am
>I right to assume that good SLR lens design can be achieved at focal lengths
>above this figure?
The important figure is the distance from the film plane to the limit of
the mirror when it's up. It's very close to the film-plane to lens-mount
distance which is 44mm in EOS (on topic :-).
So, in a EOS system, a lens with focal lenght of 44mm or more is easier to
design than a lens below that number. That includes all normal and tele
lenses, but no wide angles.
The more outside the lens the rear point must be, the more dificult to
design, so a 14mm is more difficult than a 35mm, and you will see more
diferences in quality on a rangefinder 14mm vs a SLR 14mm than in 35mm.
You can also consider the fact that a wide-angle is always more difficult
to design than a normal lens both in rangefinders and SLRs.
>Innoyen
Best regards
Vicente
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