Instruction manual

20
100: For extra sensitivity with little, if any, reduced image quality
200: For cloudy and overcast days, these settings produce acceptable image
quality with some visible noise
>400: For indoor photography whether or not a flash is used. These settings
are useful for "stop-action" and sports photographs, but produce high to very high
noise.
Note
Many cameras store your last ISO setting, even if you turn it off. Always
check the ISO setting before leaving for a mission!
2.1.2 Shutter Speed
Shutter speed determines how long the camera’s sensor is exposed to light.
The dimmer the light, the longer the camera needs to collect enough light to make
a good photo. Outdoors at night, without a flash, this can stretch into seconds or
minutes.
Digital cameras control shutter speed by switching on the light-sensitive
photo-receptors of the sensor for as long as is required. Some digital cameras
feature both electronic and mechanical shutters.
Shutter speeds are expressed in fractions of seconds, typically as
(approximate) multiples of 1/2, so that each higher shutter speed halves the
exposure by halving the exposure time: 1/2s, 1/4s, 1/8s, 1/15s, 1/30s, 1/60s,
1/125s, 1/250s, 1/500s, etc. Long exposure shutter speeds are expressed in
seconds (e.g., 1s, 2s, 4s, or 8s). If you want to change how motion is rendered
you can use different speeds: 1/30 of a second looks about natural for running
water while 1/500 of a second freezes everything.
In aerial photography you should use the fastest shutter speed you can (no
less than 1/250s) because short shutter speeds mean less jitter. You can also
manipulate the ISO setting to reduce shutter speeds for a given lighting situation.
For example, say you’re taking a picture in the fading light of late afternoon. At
ISO 100 the shutter may need to be open 1/30s to adequately expose the image,
and it is hard to hold the camera steady for 1/30th of a second (a situation made
worse by the vibration of the aircraft). If you increase the sensor’s sensitivity to
light by increasing the ISO to 200 (i.e., roughly twice as light sensitive as ISO
100), the shutter speed may be halved to 1/60s to take the same photo.
Increasing further to ISO 400 will result in a quick 1/125s shutter time.
2.1.3 Aperture
Aperture refers to the size of the opening in the lens (iris) and thus affects the
amount of light falling onto the camera’s sensor. Aperture affects exposure and
depth of field. The size of this opening is controlled by an adjustable diaphragm
of overlapping blades similar to the pupils of our eyes. Indeed, an aperture acts
much like the pupil of an eye. Your pupil opens wider as light decreases, letting in
more of the available light. Conversely, your pupil gets smaller when the amount
of light increases to reduce the amount of light entering your eye.