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.
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.