On Sat, 12 Nov 2005 23:30:49 GMT, "Deane Judd"
wrote in : :


I use trifocals. Got them because I wanted to see the instrument panel for
IFR without having to twist my head from side-to-side (vertigo inducing) and
also see approach plates up close. I also spend a lot of time in front of a
large computer screen.

Two things make them work for me: 1) The middle lens is set to focus at
about 18" (~instrument panel and/or CRT distance), which I believe is a bit
non-standard, and 2) the middle lens is 10mm high, which is very
non-standard. They'll try to tell you that 7mm is all that is available, but
this is not true. Settle for nothing less than the 10mm height. That plus
insisting that the frames are adjusted perfectly so the left and right eyes
are always looking through the same near/middle/far lens makes them easy for
me to use and adjust to. The top of the middle lens appears about 10 degrees
below my horizon, which I find about right.

I agree completely. During instrument training, I found trifocals
necessary to deal with my nearsighted and farsightedness. I had the
optician make the middle segment 12mm high and position it so that the
top of it is higher than normal, positioned where the windshield and
control panel meet while I'm looking out the windshield normally. The
bottom segment is only used for reading the finest print on the chart
in dim illumination.