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Exploring ISO settings, f stops and exposure times

September 17th, 2011 by kimly

Since I purchased a fancy new dSLR camera (NIKON D5100; 18-55mm f/3.5-5.6 Lens) I figured I should learn a bit about the manual settings and not spend my life in AUTO or PROGRAM.

So… what did I find out? Like anything, entering the settings gets easier and quicker the more you do it. When I talk specifics on where to find settings, I am talking about the Nikon d5100 – but I would think other modern dSLRs function in a similar manner.

Check out an album of Manual Setting Examples. I’ve grouped the pictures in various ways in order to easily see differences between the setting. After taking all the shots, I came to conclusion that the lighting in my living room is sub-par. I need to do this experiment again, possibly outside, in order to get visible differences in the high end of shutter speeds, ISO and aperture settings.

These settings all control the amount of light that is allowed to hit, traditionally, film or with today’s digital cameras, a sensor.

Aperture, also denoted as f stop, is how wide the lens is open. The wider the lens is open, the shorter the shutter speeds that can be used and still have the sensor collect sufficient light to obtain the shot. It’s counter-intuitive (to me anyway), but the larger the f stop, the smaller the aperture.

Nikon’s Symbolic Representation of Aperture
large aperture
f5.6 – large aperture
mid aperture
f11 – mid aperture
small aperture
f22 – small aperture

Aperture also controls ‘depth of field’ focusing. {Wikipedia has an extremely detailed explanation (including the formulas need to do the calculations) for those looking for more than this simple description.} The larger the aperture, the more the items not focused on, blur. Typically this would be the background of the object being photographed. But the artist could focus on an object at a distance and blur the foreground by using a larger aperture setting. The three shots below all were taken at ISO400 and a half second shutter speed. Notice the wall behind the blue pot; as the aperture is reduced the background becomes sharper. The photos also become darker as there is less light is able to get through the smaller opening and hit the sensor, since shutter speed was kept constant.

f5.6, ISO400, 0.5s
f11, ISO400, 0.5s
f22, ISO 400, 0.5s

I shot in six ISO settings. With traditional 35mm film, ISO is noted as film speed. The higher the value, the better the film is at taking low light pictures with faster shutter speeds and smaller apertures (larger f stops). The trade off being a noisier (grainier) result and/or over-exposure if the other two attributes aren’t also adjusted. ISO100 and ISO200 are typical settings for well lit areas, especially sunny days outside. ISO400 and ISO800 are typically used to take photos of moving objects (sports, kids.) ISOs above 800 are still used for sports shots and may also allow photography in museum settings were flashes aren’t permitted.

f11, ISO100, 0.5s
f11, ISO400, 0.5s
f11, ISO 1600, 0.5s

Shutter Speed is perhaps the easiest of the three concepts to understand; how long is the shutter kept open. Measured in seconds (slow speeds) or parts of seconds (fast speeds). Shutter speed for the shots below was set to a half second. Notice how when combined with aperture and ISO settings the quality of individual pictures varies drastically.

mid aperture

On the Nikon d5100 shutter speed is controlled with the right thumb via a dial. Aperture uses the same dial in conjunction with a button on the top of the camera body.

camera options

The swiveling view finder can be used to frame shots or see all the current setting in a concise format.

camera options

Posted in Photos

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