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  #33  
Old September 29th 05, 10:15 AM
Tony Polson
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Eugene wrote:

Perhaps my comments were a bit harsh. I just took offense to the
suggestion that it was ignorant to use the widely accepted and
understood term "prime lens".



But "prime lens" is NOT a "widely accepted and understood term".

Because of the history of its use, it is essentially ambiguous. It
has only been used as a descriptor for all fixed focal length lenses
in recent times, and only by people who are unaware of its prior
usage, which was as a descriptor for a "high quality" subset of fixed
focal length lenses. You might be too young to recall this.

There was no accepted definition of which fixed focal length lenses
were "prime" and which were not. It was merely an attempt by
marketing people to promote some lenses as being "better" than others,
the implication being that one brand was "better" than another because
of the "high quality" of their "prime" lenses.

The terms "high quality", "better" and "prime" are all essentially
meaningless unless backed up with something more objective, repeatable
and reliable. As we all (should) know, comparisons between lenses are
qualitative at best.

The most commonly used "objective" comparator - MTF - was never
intended for making such comparisons. It was intended as an aid to
lens designers and nothing more. As a result it misleads far more
than it ever informs, and those who claim it is of any real value when
comparing photographic lenses are suffering from delusions.