10-1: The resolution is best close up in the foreground
and diminishes progressively with increasing distance of view (towards the top
of the photo). Thus smaller objects can be discerned near the bottom of the
picture but these same objects (no change in size) would likely not be distinguishable
in the hills farther away across the water. This same simple principle holds
as we look out over a landscape: a house nearby would be large, with observable
details, but would be small and generalized at a distance, say, of 5 miles.
BACK
10-2: 1 inch = 100,000 divided by 12 or 8333.3 feet.
In miles that would be 8333/5280 = 1.5783. BACK
10-3: The lake can be found in the last image, an
aerial photo printed at the scale of 1:141,000. Look for it, it shows as a dark
roundish dotlike feature. A 1:4000 scale image yields 1 inch = 333.33 ft (approximately
100 yards or the length of a football field) = 0.063 miles. On the Interstate
(large white road), individual cars are visible. A typical auto is about 15
feet (180 inches) in length. The resolution therefore is at least as good as
about 5 yards (meters) - probably even approaches 2 yards but nothing of that
size is evident. BACK
10-4: Look at the scale expressed this way: 1:30000
= 1/30000, which might be read as 1 inch per 30000 inches. The denominator is
the clue. Small denominators are large scale; large denominators denote small
scale. After all, 1/10 is a larger fraction than 1/1000. BACK
10-5: After loading the film, you first would check
the film's ASA value and, if your camera is so equipped, turn the timer to a
position coincident with, or close to, that value. Then, you would turn (rotate)
the lens along its thread, causing its focal length to change, until the scene
is in focus for the close-up of the person (done visually through a sighting
window and/or by reading distance numbers on the lens barrel). Now, adjust the
F/Stop, probably to something like F/11 or F/16. Next, turn the timer knob to
some exposure time setting, perhaps around 1/250th of a second. If you have
a light meter, look to see that the needle is between two guide marks that indicate
near-optimum settings. If the moving needle does not fall between these marks,
adjust either F/Stop or exposure time until the needle assumes the right position.
You are ready to snap the picture. Then, repeat the process for the distant
scene, changing the focal length to infinity. You probably will need to also
adjust F/Stop and/or exposure time, since the amount of light from a distant
scene will differ. At sunset, the F/Stop will probably be set to F/2 or thereabouts
and the time to something around 1/8th to 1/30th of a second, both to allow
more light to enter (opening up the lens aperture and keeping it open longer);
these settings, too, need to be determined experimentally. (The settings used
in both time of day cases are probably reasonably close to adequate even if
you don't have a light meter.) BACK
10-6: The rule might read like this: an object of
some primary color sends its light onto the negative; the layer that is activated
will be the complementary color composed of the other two primary colors; when
a print is made, the layers activated are the other two complementary colors.
For green, then, the negative will be red + blue = magenta; the positive will
be cyan + yellow. Try this now for a red object. BACK
10-7: RF = photographic distance/map distance = 9"/63,360"
= 1/7040 or 1:7040. Note: the 63,360 is just 5380 feet x 12 inches/foot. BACK
10-8: 1.75 inches x 1/39.36 inches/meter = 0.04 meters.
0.05/1108 = 1/27700 BACK
10-9: 2.2" x 20000/1 = 44000. 6.83/44000 = 1/6442.
BACK
10-10: Scale = f/H* = 0.5/(5000 - 1000) = 1/8000.
10-10: s = f/H*; H* = f/s = 0.152 m/1/2000 = 304 meters. (6 inches x
2.54cm/inch = 15.2 cm = 0.152 m) Note: the photo size does not enter the solution,
the actual size could be much larger, with the area of the photo occupying only
a fraction of the print area, or smaller, in which case only part of the scene
would occupya 9 _ inch print. Thus, the scale remains independent of the size
of the print. BACK
10-12: First convert feet to meters: 12000 ft x
1/3.28 ft/m = 3658. Then convert 9 inches to millimeters: 9 inches x 25.4 mm/in
= 229 mm. Then Rg = 3658/15 x 229 = 1.065 line-pairs/meter. BACK
10-13: Rs = H/f x Rg. Thus: 6000/120 x 4 = 12.5
line-pairs/mm. BACK
Collaborators: Code
935 NASA GSFC, GST,
USAF Academy,
Webmaster: Bill Dickinson Jr.
Primary Author: Nicholas M. Short, Sr.
email: nmshort@epix.net
Contributor Information
Last Updated: July '99
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