On Sun, Dec 31, 2000 at 02:15:27PM -0800, jldasch@xxxxxxxxxxxx wrote:
>>>>> "C.H." == C H Ling <chling@xxxxxxxxxxxx> writes:
Classical optics is an old and well understood area of physics. It is
precisely this that allows the manufacturers to design their optics.
With modern computer codes it is possible to accurately simulate all
characteristics of a lens, including the imaging of out of focus
areas, which you feel ("bokeh") can not be measured.
-John
Yes, but the possiblity to simulate all characteristics of a lens,
does not mean, that
every new lens is perfect. A computer can only calculate the values
of a given design,
and might opimize one or another parameter. But it is still the lens
designer, who has
to decide, which folumla is the best suitable for a new lens, which
is the best compromise.
This decission depends a lot from his personal (or his company`s)
opinion about the
meaningfulness of a lens characteristic.
This is the information I´d like to have about a lens, MTF curves
can only give a rather
hazy idea about this.
I´ll never forget when a professor of optics told us about his
unsucessful trials to improve
old lens design from the 1950/60`s with his new computer programs.
He sad, that is was
really impossible to do this, until he added new elements (more
lenses, new glass type..).
His explanation, was that those guy`s which had to calculate every
single ray of light by
hand got by far a better understandig, of what really happes in the
lens, which enabled them
to find the best possible design, without computer aid.
Frieder Faig
On the other hand new lens design before computers literally took
years to do the calculations. A new lens for Leitz was serious
undertaking and a momentous event when it was completed.
Winsor
--
Winsor Crosby
Long Beach, California, USA
mailto:wincros@xxxxxxxxxxx
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