Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
I<br />
PROJECTION<br />
AND SOUND<br />
Continued from page 14<br />
high quality lenses? Better proiection pa\s<br />
at the boxoffice, believe me.<br />
By the way. using short focal lenses<br />
necessitates having a mechanism equipj)ed<br />
m\h a heavy lens mount, so that the lens<br />
will be held very rigid in order to maintain<br />
a satisfactory good overall focus.<br />
Of course, the use of short focal lenses is<br />
olten necessary for 35mm screen projection<br />
in newer and smaller theatres. Short focal<br />
lenses are now available in focal lengths to<br />
meet all requirements, and they will deliver<br />
a very satisfactory picture. When short focal<br />
lenses are employed, they require critical<br />
focusing but the alert projectionist can keep<br />
the picture in good focus if the lenses are<br />
of good quality and arc a well-known brand.<br />
All of the newer projection lenses have<br />
been corrected for practically all types of<br />
.iherration. however, some prove out better<br />
than others in certain uses. The lens to he<br />
used in any given condition is one which<br />
produces the sharpest field over the greatest<br />
area of screen, and which also has a minimimi<br />
amount of astigmatic, spherical and<br />
chromatic abberation.<br />
With the exhibitor having selected the<br />
finest quality projection lenses, and knowing<br />
from screen tests exactly what such<br />
lenses will accomplish, the projectionist<br />
then should be able to easily maintain this<br />
same sharp focus at all times, if he is alert<br />
and takes pride in his profession, unless of<br />
course the film is badlv buckled.<br />
SOUNDFOLD<br />
was specified in more new theatres during 1974 than any<br />
other wallcovering. There is only one SOUNDFOLD. Don't<br />
settle for imitations. Clip the rapid quote below and send it<br />
to us, we'll do the rest.<br />
Rapid Quotation Form<br />
Use this card to obtain tnst pricing on any Soundfold<br />
installation.<br />
Soundfold Inc. installs<br />
Wall height at highest point<br />
Wall length .<br />
Send me a full color brochure<br />
Client installs<br />
Please have your representative call on us_<br />
Or call collect, Art Sickels, President<br />
513-228-3773 or 513-293-267 1.<br />
Soundfold Acoustical Fabric Wallcovering Systeni • P.O. Box 2123 • Dayton, Ohio 45429<br />
U.S. Patent No: 3,185,207<br />
Before we proceed further in<br />
our discussion<br />
on projection optics, let us present<br />
some definitions that are very important to<br />
3 practical understanding of the optics of<br />
motion picture projection.<br />
The speed of a projection lens is the<br />
ratio of its focal length to its aperture,<br />
and it is expressed as its f-number. A 6-in.<br />
lens with a 2-in. aperture has a speed of<br />
f/3. The faster a lens, the lower the f-uLimber<br />
and, in the theatre, the brighter the<br />
projected picture, of course.<br />
One final definition to consider is standard<br />
focal' lengths. Motion picture projection<br />
lenses are manufactured in standard focal<br />
lengths and are carried in stock by leading<br />
manufacturers of theatre lenses and are<br />
generally distributed through local theatre<br />
supply dealers. Dealers carry a stock in<br />
sizes to fit most needs.<br />
Clean Lenses Daily<br />
Projection lenses should be cleaned every<br />
day. It is important to keep all lenses<br />
scrupulously clean and well polished. Lens<br />
cleaning tissue and lens cleaner are both<br />
available at leading theatre supply dealers.<br />
Even a finger mark can mar picture sharpness.<br />
Loss of light is not the only evil effect<br />
of dirty lenses. Deposits of dirt and dust<br />
can disperse, diffuse and misdirect a portion<br />
of light rays. As a result, the lighter shades<br />
in the screen image are made still lighter<br />
and the blacks become a dirty gray. The<br />
picture, instead of being "snappy," is dull.<br />
A satisfactory picture is one that has good<br />
"contrast." The picture should be "pleasing"<br />
to the viewer. A perfectly projected picture<br />
is what every theatre should, and can, have<br />
provided your theatre is equipped with the<br />
right type and size projection lenses.<br />
The best way to improve drive-in theatre<br />
brightness is to use the fastest available<br />
optical system. With a fast lens coupled<br />
to a reversed anamorphic adapter, screen<br />
brightness can be made almost the same<br />
for Cinemascope and widescreen presentations.<br />
There is no excuse for poor screen illumination<br />
in drive-in theatres today with nev\<br />
high-power projection lamps available and<br />
faster and better projection lenses. Also,<br />
there are screen coating materials now obtainable<br />
for refinishing dirty or old screen<br />
surfaces in theatres from leading theatre<br />
supply dealers or screen manufacturers.<br />
Dull and poor picture definition is often<br />
due to dull screen finish and not always<br />
to inadequate light output from lamps. How<br />
long has it been since you had your screen<br />
refinished?<br />
Keep this in your mind if you are interested<br />
in keeping your patrons coming back<br />
to your theatre. Because screen size has<br />
greatly increased over the years, resulting<br />
in the picture being made to cover, or<br />
dominate, the audience's field of view, it<br />
must have better quality and focus than<br />
ever before. Moreover, because picture sizes<br />
are extremely large, the projectors must be<br />
maintained in top running condition. Every<br />
defect in projection will be greatly magnified<br />
now. Keep the intermittent movement<br />
Continued on page 36<br />
16 The MODERN THEATRE SECTION
Change language