Farishta 517

The lenses in these beautiful Luxotica glasses have
fairly strong cylinders (-2.50) in what I refer to as
the vertical (v) direction. The high index lens in front
of Farishta's right eye has a Rx of -9.00 (horizontal
direction) and -11.50 (vertical direction). This is an
advantage because the lens is five centimeters wide
and only four centimeters high. Lens thickness is
less than five millimeters. The lenses would be much
thicker if the cylinders were in the horizontal direction.

Technical note: I measure the dioptric strength of the
glasses in my collection with a set of old lenses used by
an optician in the 1960's. I hold the glasses at 30 to 40
centimeters distance, pointing to a square object in the
distance. If the glasses have a minus prescription, I look
for a positive lens of the same dioptric strength and
squeeze this against the negative lens in the glasses.
A minus six lens in the glasses with a plus six lens
pressed on to it produces the effect of a plano lens. The
square object in the background is seen in the right
size (Sph 0) and shape when the cylindric strength is
compensated in the same way by adding yet another
lens. The procedure looks - and may sound - a bit
clumsy but it works fairly well and it does not take much
time. The only thing I can't measure is the exact angle
of the cylinder (in degrees) and therefore I simply give
the information in three categories: v (vertical, say
anything around 0 or 180 degrees), h (horizontal, say
anything between 70 and 110 degrees) and o (other,
or oblique if you wish).
The set of lenses was another buy at the "Waterlooplein"
flea market during the 1980's. The lenses were for sale
at two guilders each and there were some 200 of them.
Far above my budget - but when I explained the seller
that I wanted all the lenses he asked only one hundred
guilders for them. That was more than I had with me
and after some friendly bargaining he sold me the lot for
about sixty guilders, kindly refusing my bus ticket offered
as additional pay. The set turned out to be 99% complete
and I was a happy man. Those were the days....