Kevin J. Sperl

 photography

 

Photo Column 009 - And now for the answers - Part I

Shots such as this present interesting exposure decisions. High overcast, bright back lit sky with a collection of flowers in the foreground. How would you meter for this? What happens if you leave your camera on automatic.

 

 

OK, class. Pencils down!! I've given you two weeks to finish this take home test and now it is the moment of truth. Take out your answers and read along.

Q1: Describe the function of aperture in determining exposure. Answer: The aperture controls the amount of light that strikes the film plane, or digital sensor. The aperture value, for example f4.0 yields a circle whose area is relative to the focal length of the lens. The smaller the aperture value, the larger the opening, the larger the aperture value, the smaller the opening. Each aperture value yields one stop more, or less light, than its neighboring value. That is, f/4.0 yields twice as much light as f/5.6.

Q2: Describe the function of shutter speed in determining exposure. Answer: Shutter speed controls the amount of time the shutter is open, letting in the amount of light controlled by the aperture value. The faster the shutter speed, the less time light is allowed to pass, the longer the shutter speed, the more light is allowed to pass.

Q3: A camera meter attempts to expose a metered object as Answer: A middle tonal value, or 18% gray, or Zone V on the Ansel Adams Zone System.

Q4: Assume the camera meter suggests an exposure of f/5.6 at 1/500s. You wish to overexpose the object by 2 stops. Provide three different exposure settings (aperture and shutter) for doing so. Answer: Overexposing means more light. One exposure would be: f/2.8 at 1/500s which opens the aperture only by 2 stops (from 5.6 to 4.0 to 2.8). Another exposure would be: f/5.6 at 1/125s which allows light to strike the film plane for a longer amount of time (1/500 to 1/250 to 1/125) and the last would be f/4.0 at 1/250s, this opens up the aperture by 1 stop and then slows the shutter by 1 stop, effectively yielding a 2 stop increase in exposure.

Q5: BY adjusting the aperture only, provide an exposure that underexposes by 1 stop a suggested exposure of f/8 at 1/60s. Answer: Underexposing means less light, so adjust the aperture to f/11 and leave the shutter alone.

Q6: By adjusting the shutter speed only, provide an exposure that underexposes by1 stop a suggested exposure f f/8 at 1/60s. Answer: underexposing means less light, so adjust the shutter to 1/125s and leave the aperture alone.

Q7:When metering a part of a scene, the camera meter reading shows f11 at 1/250, indicate the adjusted exposure (by adjusting the shutter speed ONLY) to give a proper exposure of that part of the scene on the specified “zone” (referring to the Zone System).

  1. Zone V: f __/11_____ at ___1/250_____ of a second Answer: Camera meters at Zone V!

  2. Zone III: f __/11_____ at __1/1000______ of a second Answer: Z III is 2 stops less light

  3. Zone VI: f __/11_____ at __1/125______ of a second Answer: Zone VI is 1 stop more light

Q8: When metering a part of a scene, the camera meter reading shows f11 at 1/250, indicate the adjusted exposure (by adjusting the aperture ONLY) to give a proper exposure of that part of the scene on the specified “zone” (referring to the Zone System).

  1. Zone V: f ___f/11____ at __1/250______ of a second Answer: Camera meters at Zone V

  2. Zone IV: f ___f/16___ at ___1/250_____ of a second Answer: Z IV is 1 stop less light

  3. Zone VI: f ___f/8____ at ___1/250_____ of a second Answer: Z VI is 1 stop more light

How did you do so far? If you did well, you are well on your way to being a better photographer. Having an inate understanding of aperture, shutter and their effect on exposure is an important tool in your camera bag. Never again take pictures on the green idiot icon. Take control and make photographs. Feels good, doesn't it?

Answers for the remaining test questions appear next time. Until then, keep shooting.