In <3B2F017D.9010003@ampsc.com>, Arthur Entlich wrote:
> In general, some of the older fixed focus lenses proved to have better
> glass, and if they are well multicoated they can be great.
>
> One of my best lenses is a Nikkor 135 2.8 tele. It is a Q series, which
> was a quality multicoated glass.
>
The main problem is that most SLR cameras these days come with zoom lenses
as standard. Designing zooms always involves more compromises than fixed
lenses, as you have to allow for the changing light paths as the elements
move when zooming. Until computers where used for the design work zooms
tended to be of poor quality or very expensive, because of the vast amount
of calculations needed. Computers enabled designers to do these
calculations in a fraction of the time, so zooms became better and cheaper.
However there are still trade-offs involved.
There are also many more glass elements in a zoom, and the internal
mechanics are much more complicated. A good fixed lens will usually have
6-7 pieces of glass in it, and simple mechanisms for focusing. A zoom can
often have 14 or more glass elements in it, in several different groups,
and these groups have to move backwards and forwards at different rates
when zooming or focusing. It is a wonder that they can get them to work
successfully at all, especially at the prices now charged.
Brian Rumary, England
