In photography, the size of the stream of the water is analogous to the f/stop, the length of time you pour is analogous to the shutter speed, and the size of the bucket is analogous to the ISO. Either way, you end up with the same amount of water. To fill a bucket, you can pour a small stream of water for a long time or a fast stream of water for a short time. A bucket is of fixed size and needs a certain amount of water to fill it, just like the sensor in your camera, which is of a set sensitivity (the ISO) and needs a certain amount of light to optimally capture an image. My favorite analogy for exposure is filling a bucket with water. Well, too much explanation is what this page is all about, and I'll go over the f/stop and especially its initially-confusing numbering at some length. Maybe it just takes too much explanation. What they don't have is a set of photos showing depth of field, or a scene shot at a range of exposure combinations where the f/stop's effects are shown. All that is assumed to be of interest and comprehension to the customers. The local camera shop has pictures under glass on the counter showing a scene using a range of focal lengths (for a good example of this, see my friend Dave Dahms' Lens Focal Length Chart), photos showing the same scene printed at different sizes and photos showing an action scene shot at different shutter speeds. This has some interesting implications I'll address further along on this page.ĭespite being one of the exposure controls in photography, the f/stop (or aperture, the terms are interchangeable) remains a source of confusion and mystery to many photographers, even to some who use it all the time.
#F STOP PHOTOGRAPHY ISO#
Now you can switch your ISO from shot to shot, changing the amount of light needed to correctly expose your photo. This amount of light can be achieved with many different combinations of f/stops and shutter speeds.īack in the days of film, that was pretty much it for exposure because your ISO (and white balance too) was set by your film choice and you couldn't vary it within the roll. For any given film speed (ISO) and lighting combination there is one correct amount of light to properly expose the image. The f/stop regulates how much light is allowed through the lens by varying the size of the hole the light comes through. The shutter speed regulates how long the sensor is exposed to light coming through the lens. In fact, the opposite applies.į-numbers typically range from f/1.4 to f/22 depending on your lens, with smaller numbers representing a wider aperture and larger numbers signifying a smaller, or more narrow, aperture.Photographers set their exposure using a combination of shutter speeds and f/stops to get the correct amount of light on the sensor (or film). However, the way that f-stops are written can be confusing as a smaller f-number does not equal a smaller aperture. Are aperture and f-stop the same thing?Īperture and f-stops are essentially the same thing, with the aperture being how wide the lens opening is and the f-stop being the value that controls it. To avoid over or under-exposing an image, you’ll want to adjust the other aspects of the exposure triangle to compensate.
This makes narrow apertures a popular choice for taking photos on sunny days when there’s already plenty of light.
However, images taken with a narrow aperture will be less bright as they are not as exposed. For this reason, f-numbers around f/16 and above are useful in these instances. Photos shot with a wide aperture are also brighter, or more exposed.Ī narrow aperture, on the other hand, keeps both the subject and background sharp and is a common choice for landscapes and group photos. This makes wider apertures signified by f-numbers around f/2.8 or below ideal for portraits. This is also what creates a bokeh effect when shooting in front of fairy lights and street lamps. The f-stop affects how your final image looks by controlling the aperture, and thus both the exposure and depth of field of the photo.Ī wider aperture equals a more shallow depth of field with a blurred effect behind the subject. This can be done by either opening up the lens to allow more light to reach the sensor or narrowing the opening to limit the amount of light that enters the camera.
Increasing or decreasing the f-stop allows photographers to adjust the aperture.
The “f” in f-stop refers to the focal length of the lens.Īperture controls how much light is able to enter a camera, which affects both the exposure of an image as well as the depth of field achieved. The f-stop (or f-number) is the way in which photographers measure aperture on a camera.
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