Aperture
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Aperture
means “opening.” The opening inside the camera’s lens is what lets light into
the camera. Photographers refer to the size of this opening as the aperture.
Aperture is adjustable in most cameras. |
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The
aperture is calibrated in f/stops. Common f/stops are f/22, f/16, f/l1, fiS, f5.6, f/4, and f/2.8. Sometimes they are written
with a dash, such as f-22. In spoken language the punctuation is not
mentioned. F/22 would be spoken of as simply f 22. |
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The
aperture is calibrated in f/stops. Common f/stops are f/22, f/16, f/l1, fiS, f5.6, f/4, and f/2.8. Sometimes they are written
with a dash, such as f-22. In spoken language the punctuation is not
mentioned. F/22 would be spoken of as simply f 22. The
confusing part about understanding aperture is that it is written as a
fraction with a letter instead of a number as the numerator (top). Apertures
with a large number in the denominator (bottom number), like f/22, may seem
to be something big but are actually “small.” So when a photographer talks about
using a small aperture, the opening size is small but the f-stop has a large
lower number. When
a photographer has “closed down” the lens, he/she has used an f/stop which
does not let much light in, such as f/22. This is called a “small” f/stop.
When a photographer “opens up” or shoots “wide open” to let in more light,
he/she is using an f/stop such as f/2.8. This is called a “large” f/stop. Aperture
works together with shutter speed and ISO to form an ideal exposure. There is
more than one combination that will produce an image with the same lightness
and darkness. If the photographer starts with a set exposure, he/she could
change the aperture to be more opened up. Then the camera would automatically
choose a faster shutter speed in order to maintain the same amount of light
entering the lens through the now larger opening. When
the ISO is changed, the camera’s sensitivity to light is increased or
decreased. So the combination of aperture/shutter speed will change
accordingly. The photographer may want to change the ISO in order to get the
desired combination. Sometimes there is no shutter speed available for the
chosen aperture. This usually happens in very dark or very bright lighting
situations. Source of
information - from articles from the PSA Journal (Photographic Society of |