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The hottest thing in the digital camera market is undoubtedly the digital
SLR Nike St. Louis
Rams Jersey , which is better known as a dSLR. While dSLRs are flying off
dealer shelves, many new users are confused about the terminology. Most people
know that SLR stands for single lens reflex. Since nearly all SLRs accept
interchangeable lenses, it would appear they should be known as multiple lens
reflex (MLR) cameras. If you want to understand how the SLR received it s name,
you have to dip into the history of the camera. Early cameras were similar to
the view cameras used today. The photographer looked through the lens, focused,
composed and then inserted a single film plate behind the optics to make an
image. While the entire process was crude by modern standards, the photographer
enjoyed great
control Men's St. Louis
Rams Jerseys , since he looked directly through the actual imaging lens to
compose the shot. While this was fine for still life, portraits and landscapes,
this process did not lend itself to action photography. These early cameras
could only record a single image at a time. Which is why you have never seen a
motor driven view camera. Realizing the need to offer sequences of exposures,
camera makers begin to experiment with various roll film designs. With a roll of
film in the camera, the photographer could fire off numerous images without
reloading. Although this improved throughput dramatically, it caused another
problem. The roll of film had to pass closely behind the camera s optics, which
meant that the photographer could no longer look through the camera lens to
compose and focus. Rangefinder cameras appear to keep things in focus The lower
end Youth St. Louis
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fixed focus lens, so a simple viewfinder was sufficient. Better quality optics,
however, require the lens to be focused, and since the photographer could not
look through the lens with a roll film camera, this was a major problem. One of
the first solutions to this problem was the Rangefinder a type of camera that
offered a distance measuring scale in the viewfinder. By determining the range
from the viewfinder, the photographer could then adjust the focus to match
usually with very good results. Twin Lens Reflex cameras offer another solution
While the rangefinder type cameras worked
well Women's St. Louis
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allowing the photographer to focus and compose appeared in the Twin Lens Reflex
cameras. These cameras used two identical lenses, arranged one on top of the
other in the manner of an over and under shotgun. The film winds past the lower
lens, while the photographer can focus through the upper lens. The twin lens
cameras were fairly bulky, so designers added a mirror and ground glass to the
top of the camera, hence the term reflex. Now the user could hold the camera at
waist level and look down at the ground glass which previewed the image via the
mirror located behind the upper lens. As the user adjusted the focus on the
upper lens, a gear mechanism moved the lower taking lens to match. While both
rangefinders and twin lens reflex cameras offered a credible way to focus and
preview a shot, neither allowed the photographer to actually look through the
actual lens. This sometimes made exact composition difficult. SLRs take cameras
another step forward In their quest to allow users to see through the actual
taking lens Customized St.
Louis Rams Jerseys , camera makers turned to the periscope a simple device
using two mirrors placed at opposite angles to bend the light path. Periscopes
are easy to understand any kid can construct one from a couple of mirrors and
some scrap wood. In a camera, the lower mirror is placed at a 45 degree angle
directly behind the lens. Light striking the mirror is projected upwards to a
ground glass. While a second mirror would show the image on the ground glass to
the user, it would not appear right, because mirrors tend to reverse things. So
camera designers added a prism arrangement that corrects the reversed image.
When you peer through the viewfinder on a SLR, you look through a prism, which
displays the image on a ground glass, which displays the projected image from
the mirror located behind the lens. There is just one problem. If you have been
paying attention St. Louis
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the light path to the film (or digital sensor as the case may be.) Now the
photographer can look though the lens, but the image cannot be projected on to
the filmplane. So the camera designers had to add another wrinkle. They had to
move that mirror. Just long enough to make an exposure, since when the mirror
moved, the photographer could no longer see anything through the lens. So they
designed the instant return mirror. At the instant of exposure, the mirror flies
upward, the shutter fires and the mirror snaps back down. It is a incredible
feat, when you consider that instant return mirrors have to flip up and back in
a heartbeat St. Louis Rams
Hats , over and over for the life of the camera. Once the instant return
mirror was perfected, photographers could once again design their images by
looking through the lens. Unlike the twin lens reflex, this new breed of camera
needed only one lens to focus and shoot with. So they became known as... you
guessed it...Single Lens Reflex cameras. Author's Resource Box This article
originally appeared in Alphatracks; the weblog for Sony and Minolta enthusiasts.