PHOTOGRAMMETRIC ENGINEERING 
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Society oi Motion 1 icture and Television Engineers Committee on T-stop 
calibration. 
One of the new Air Force night lenses, a 24 inch f/3.5 for 9 inch by 18 inch 
coverage is illustrated in higure 11. I his lens resolves 40 lines/mm. on-axis with 
high speed panchromatic film, and 
I nm | has an AWAR of 23 lines/mm. The 
focusing dial is located near the body 
mating surface, and incorporates a 
slide rule type of computer to cor 
rect for focus effects due to target 
distance, pressure, temperature, and 
also for whether the film is I.R. or 
panchromatic. This lens, designed 
by Dr. James E. Baker, is only one 
of about 20 lenses designed for the 
USAF by him and others; on these 
all reproduction rights are the prop 
erty of the government. The Bureau 
of Standards checks the formulas for 
these lenses by ray tracing on I.B.M. 
card programmed digital computers. 
Much valuable design information 
is obtained. It is hoped that it will 
be possible to present this ray trace 
data in the form of curves showing 
expected photographic performance 
integrating all aberrations instead 
of the usual 3rd order and 5th order aberration curves. The Bureau of Standards 
is not alone in exploring the possibilities of the electronic computers. Dr. 
Baker is making extensive use of these computers, as are Mr. Cox of Bell & 
Howell and Dr. Pestrecov of Bausch & Bomb. It is amazing how much faster 
these machines do ray tracing. Lens 
designs can be obtained in a matter of 
days rather than months, and the 
work is more thorough. Detail toler 
ance analysis of a lens formula is also 
possible, and this is being done on 
USAF lenses now going into produc 
tion. 
Figure 12 is a picture of the fa 
mous Planigon or Cartogon lens. It 
is the result of a discovery by Russell 
Bean of the American Society of 
Photogrammetry while in Germany 
after V.E. Day. Bausch & Lomb 
under contract to the U.S.A.F. made 
the first American prototypes using 
American glasses. More recently, two 
other companies—C. P. Goerz Ameri 
can Optical Company and Curtis Color 
Laboratories—have started manufacturing this lens. The most remark 
able thing about this lens is its extremely small distortion, this being less 
Fig. 8. A histogram of a group of 
36 inch f/8 lenses. 
Fig. 9. The large T-stop calibrator.