Section III Model 196A
Paragraphs 3-13 to 3-19
3-13. FILM TYPES. a. When a very slow sweep speed is used. In this
case the shutter must remain open to record one com-
rl
3- 14. Polaroid@ Corporation makes several types of plete sweep and preferably five to ten sweeps if no
film for use with the 196A Oscilloscope Camera. Film drift or jitter is apparent.
is available from any photographic supply store. The
film types especially recommended for the 196A are b. When the signal contains drift or jitter. High
listed below: shutter speed must be used here to reduce blurring.
a. Type 42 -- A good film for steady state traces.
c. When the signal is a non-repetitive transient
This is the most economical film for oscilloscope
(controlled or random) the camera shutter must be
photography, but it is not recommended for high speed
held open until the transient occurs.
transients.
b. Type 46L.-- This is a transparency film, pro-
3-18. APERTURE SETTINGS. The aperture setting,
ducing a transparency which can be directly mounted
like shutter speed, is not critical except when the shut-
for use as a 3-1/4 x 4 in. lantern slide. Be sure to
ter speed is dictated by one of the conditions listed
follow all directions supplied with the film roll.
under paragraph 3-17. In that case, some specific
aperture setting will be necessary in order to main-
c. Type 47 -- Type 47 is exceptionally fast film,
tain the correct ratio between shutter speed and aper-
highly recommended for photographing both high speed
ture setting. If the aperture is set between f/l. 9 and
transients and stationary traces.
f/5.6, the graticule should be exposed separately
(paragraph 3-22).
3-15. EXPOSURE SETTINGS.
3- 16. GENERAL. There are several variables (e. g., 3-19. Table 3-1 and figure 3-3 can be used to deter-
the intensity setting of the oscilloscope, spot speed, mine the approximate exposure settings required under
etc.) that affect the exposure setting of the camera. varying conditions with repetitive traces. When only
The exposure instructions given here are general, but one sweep of a slow sweep presentation (over 5 sec-
in most cases will be sufficient to produce good re- onds) is to be photographed, use an aperture setting of
sults. A good way to determine the ideal aperture f/8 for type 47 film, and f/5.6 for type 42 film. Set
setting and shutter speed without undue waste of film the oscilloscope intensity for a sharp spot with no halo.
is to take several test pictures using the multiple ex- Anypoint along any one diagonal line in figure 3-3 will
posure control. Table 3-1 and figure 3-3 are given give exactly the same exposure. Moving to any adjac-
ent diagonal line will double or halve the exposure 4
as a rough guide to obtain nearly correct settings for
different film types, sweep speeds and oscilloscope depending on whether you go to the right or left. To
phosphors. Table 3-1 and figure 3-3 are for repetitive use table 3-1 and figure 3-3, proceed as follows:
traces only. For slow sweeps (more than 5 seconds
total sweep time, see paragraph 3- 19). a. Decide which film type will be used (para.3- 13).
3-17. SHUTTER SPEED. In most cases shutter speed b. Determine the type of phosphor and filter on the
is not particularly critical. It is important, however, oscilloscope.
that the correct relationship be maintained between
aperture setting and shutter speed. There are times, c. Using table 3-1, determine the basic shutter
however, when shutter speed setting does become cri- speed/aperture setting.
tical. The following situations dictate the shutter
speed to be used: d. Find the necessary oscilloscope sweep speed/cm.
Table 3-1. Basic Exposure Guide
Film I ASA* I Cathode Tube 1 Shutter I Aperture1
42 200 P1 Green 1 f/5.6
P7 Orange 1 f/8
P11 Blue 1 f/ll
Green
Green
Blue
SECO N D S
0-S-181
SHUTTER SPEED
*ASA equivalent daylight exposure index
Figure 3-3. Exposure Adjustment Guide
3-6 01038- 1 |
ACEC
