Shutter

Shutter


The shutter not only controls the exact moment when the film is exposed to light but also the duration of the exposure i.e. the amount of light that is admitted . We can use same analogy as we did for the aperture. The length of the time the shutter remains open controls the quantity of light that reaches the film in the same way that the quantity in the container and, equally , doubling the time that the shutter remains open doubles the amount of light admitted to film .

Some shutters generally those on direct vision viewfinder cameras ,fit within or just behind the lens body and use a set of blades which rapidly open or shut. These are called diaphragm , or leaf shutter . the other principal type of shutter the focal plane shutter is found on most single lens reflex cameras and consists two separate blinds positioned just in front of the film . shutter speeds very little between cameras usually the longest time the shutter will automatically remain open for is 1-sec. the briefest exposure may be 1/250 sec. although many single lens reflex cameras have shutter with 1/500 or 1/1000 sec. settings . as well as exposure , shutter speed controls how subject movement records

Using the shutter speed control

Shutter speedring
Shutter speed dial
The positioning and appearance of the shutter speed dial vary according to the two types of shutter . most focal plane shutters have a setting dial on the top of the camera body . the numbers represent fractions of a second “250” is 1/250 sec. most bladed shutter ( direct vision viewfinder ) cameras have a similarly numbered ring around the lens body , near the aperture control.

In both cases the shutter mechanism is tensioned when you wind on the film ready for the next exposure , and fired by pressing the shutter release on the top or front of the camera body . ( simple cameras either have a one speed shutter ,or offer two or three speeds , marked not in times , but say in weather symbols).

Shutter speed settings

B 1 1/2 1/4 1/8 1/15 1/30 1/60 1/125 1/250 1/500 1/100



WATER LEVEL
shutter speeds like “f” numbers decrease in a regular sequence each shutter speed setting is half the previous exposure time . this shared doubling and halving sequence is particularly important when combining aperture and shutter setting .
Set the shutter to ‘B’ (bulb) , and it will remain open for as long as you hold down the shutter release button .



1/250 1/60 1/15

Shutter speed and movement
Shutter speed makes a considerable difference to the way moving subjects record in your pictures. The three pictures above show the same scene taken at , from left to right and right to left , 1/15 sec. 1/60 sec. and 1/250 sec. at the lowest shutter speed ---1/15 sec, -- subject movement has recorded blurred , implying action , but with a loss of detail .the faster times – 1/60 sec. center , and 1/250 sec. right progressively eliminate the blur, revealing detail , but reducing the sense of movement.
At speeds less than 1/60 sec. it is easy to blur the entire image accidentally because you are holding the camera unsteadily . if you want to avoid camera shake and most subject movement blur , keep to speeds of 1/125 sec. and shorter . you can prevent shake at lower speeds by supporting the camera securely , preferably on a tripod.

Bladed and focal plane shutter
Bladed shutter are fitted to direct vision viewfinder cameras and those cameras where the viewing system is such that light need not pass through the lens until exposure . the mechanism is inside the lens body.
On a single lens reflex camera , with through the lens viewing . the shutter is positioned in the camera body , just in front of the film (at the focal plane ) , this means that you can change lenses at any time without exposing the film.
Focal plane shutter have two blinds , which pass in succession in front of the film to give the exposure . the shutter speed dial alters the gap between them – the narrowest gap giving the shortest exposure time .