Using Grammatical Signals Suitable to Patterns of Idea Development
Photography: 3 - Shutter Speeds
1. Lenses are come in different sizes:
<30mm = wide angle
50mm = what the human eye sees
>70mm = Telephoto
Zoom = Combines all three into one
24mm 50mm 70mm
2. DOF refers to how much of a photo is in focus:
The smaller the f-number,
the smaller the DOF:
3.
4. In your camera – between the lens and the
film/CCD - is the shutter
Video on next
slide…
6. Think of it as a door that opens for a split second
to allow the image of your subject to burn onto the
film/CCD…
7. As the photographer you have control over how
long this ‘door’ is open
Typically this will range from 1/1000th
of a second
(very, very fast) to 1 or 2 seconds (very slow)
8. The longer the
shutter is open,
the more chance
there is that
something in
your subject will
move, for
instance…
…the train appears still
9. But at a slower
shutter speed the
train has
travelled an inch
or so while the
shutter was
open…
…so the train blurs
10. And at a very
slow speed the
train moves so
much that it
barely registers
on the photo…
…and becomes ghost-like
19. If you use a shutter speed slower than 1/60th
of a
second your photos will suffer from camera shake
(your hands can’t hold a camera that still for that
long!):
23. Either:
Set your camera to Shutter Priority mode and take
a series of photos of the same moving subject at
different shutter speeds
Or, if your camera does not have Shutter Priority,
go to www.camerasim.com and experiment with
the shutter speed slider
25. Opening the shutter exposes the film/CCD to light
Too little light causes under-exposure, too much
causes over-exposure:
26. You’ll remember that Aperture gives us Depth of
Field by changing the size of an iris in the lens:
Think of the iris as a curtain that you can open or
close
27. By opening or closing the iris you control the
amount of light getting through it – just like closing
a curtain to block out the sun on a bright day
This can be used to compensate for under or over
exposure, so the iris can be opened (perhaps to
f2.8) to let in more light when using a fast shutter
speed, or the iris can be closed (f16) to let in less
light with a slow shutter speed…