COMM 242, Advanced News Photography (Photojournalism)
Exercise: exposure combinations
Keep in mind that f/stops, shutter speeds and film/digital sensor speeds are nearly always related
by precisely half or double. That is, changing your f/stop from, say, 4 to 5.6
(one stop) is the same as changing your shutter speed from 125 to 250. Each lets in half as much light. ISO numbers too are measured in comparably: 100 is half as sensitive to light as 200; 400 is
twice as sensitive as 200, etc. So if you want to change f/stops, shutter speeds
or ISO numbers while maintaining the same exposure, you need to also adjust the
other variables.
Standard f/stops: 1.4 (widest opening), 1.8 (or 2), 2.8, 4, 5.6, 8, 11, 16, 22,
32, 45. Most cameras can set half stops.
Standard shutter speeds: 1 (one second, slow shutter speed), 2 (half second),
4, (1/4 second, etc.) 8, 15, 30, 60, 125, 250, 500, 1000, 2000. Many digital cameras can set half shutter speeds.
Standard ISO speeds: 100, 200, 400, 800, 1600, 3200.
Try using these for the exercises below.
Your camera is set to manual mode. Your light meter shows you a combination of f/stop and shutter speed as indicated. Assuming you wish to maintain the same amount of light striking the film for proper exposure, calculate the comparable numbers for each alternative.
Example:
Your indicated f/stop is 11. Shutter speed is 125. You want a more shallow depth of field, so change your f/stop to 5.6. That lets in two stops more light. To compensate, your shutter speed will be____? Answer: 500. (Two stops less light, to compensate for two stops more light based on change in f/stop.)
But you also want a still faster shutter speed than 500. To achieve this, you must change your ISO number. It's currently set at 400. To obtain a shutter speed of 1000, you must set your ISO number at____? Answer: 800, equivalent of one stop more light (more sensitive).
1. Indicated f/stop: 5.6. Indicated shutter speed: 125.
You wish to change your f/stop to 4. Your shutter speed will be____?
2, Indicated f/stop: 5.6. Indicated shutter speed: 125.
You wish to change your f/stop to 8. Your shutter speed will be____?
3. Indicated f/stop: 5.6. Indicated shutter speed: 125.
You wish to change your f/stop to 11. Your shutter speed will be____?
4. Indicated f/stop: 16. Indicated shutter speed: 60.
You wish to change your f/stop to 5.6. Your shutter speed will be____?
5. Indicated shutter speed: 30. Indicated f/stop: 5.6.
You wish to change your shutter speed to 60. Your f/stop will be____?
6. Indicated shutter speed: 30. Indicated f/stop: 5.6.
You wish to change your shutter speed to 250. Your f/stop will be____?
7. Indicated shutter speed: 125. Indicated f/stop: 16
You wish to change your shutter speed to 500. Your f/stop will be____?
8. You have a variable focal length (zoom) lens marked 1:4. You know this means the widest the aperture
can open is f/4.
Indicated shutter speed: 30. Indicated f/stop: 4. Your ISO number: 200.
You know this is too slow a shutter speed for sharp pictures ot a volleyball game.
You need to gain faster
ISO speed, at least three stops. The ISO speed you would choose to obtain that:____.
9. Choosing the ISO number you indicated above, what will be your new shutter speed at f/4?
F/stop_____. Shutter speed_____.
10. You have a zoom lens marked 1:5.6.
Your light meter indicates a shutter speed of 250, f/stop 8. Your ISO: 800. You wish to lower your shutter speed to 30, to add a swirl of colored movement in a Zumba class. Describe two things you can do.
11. You want to photograph people on the street, and know that you have to work quickly. Focus may be a problem, so you need to set your camera for maximum depth of field. Which setting would be best?
a. Aperture f/4.
b. Aperture f/11.
c. Aperture f/5.6
d. Shutter speed 60.
12. You want to photograph a basketball game, and need to stop fast action. Which setting would work best?
a. Shutter speed 60.
b. Shutter speed 15.
c. Shutter speed 500.
d. Aperture f/16.