shutter speed

4 replies to this topic

#1 Jaysingh rajpurohit

Jaysingh rajpurohit

New

• Basic Members
• 8 posts
• Cinematographer

Posted 14 September 2011 - 10:19 AM

what is diffrent in shutter speed and shutter angle..and when we use shutter speed and when we use sutter angle
i know verrywel abput shutter speed but i want know about diffrent ,thnx
• 0

#2 Brian Drysdale

Brian Drysdale
• Basic Members
• 5069 posts
• Cinematographer

Posted 14 September 2011 - 11:28 AM

Usage often depends on how you set up the exposure time on a particular camera. On film cameras you usually adjust the shutter angle (180 degrees commonly being the normal setting), while digital cameras they tend to set up the shutter speed (although some have either option). The principle is explained here:

http://en.wikipedia....ry_disc_shutter

BTW It would be better to ask the technical questions in another part of the forum, since this section is about cinematographers and their work, rather than technical questions.
• 0

#3 dan kessler

dan kessler
• Basic Members
• 172 posts
• Other

Posted 14 September 2011 - 11:42 AM

Okay, I was already typing this up, so I'll go ahead post it:

To put it in simplest terms, in motion picture cameras, the shutter
generally takes the form of a rotating disc with a wedge cut out of it,
like a pie with a missing slice. The open wedge is the part that allows
light to reach the film.

The term "shutter angle" refers to the angular sweep of the open wedge.
So, a 180 degree shutter angle would be half of the total disc.
A 90 degree shutter angle would be one-quarter of the total disc, and so on.

Some cameras have a fixed shutter angle, while others have variable shutter angles.

Shutter angle is one of the factors that determines shutter speed.
The other factor is the speed at which the shutter rotates.

At 24 frames per second, the shutter makes one complete revolution every
24th of a second. If our shutter angle is 180 degrees, then for exactly
one-half of that time the shutter will expose the film, that is, the
shutter speed will be 1/48th of a second.

Here's the formula:

Exposure time (or shutter speed) = (Shutter angle/360) X (1/frames per second)

Wide shutter angles naturally provide longer exposure times, while narrow
shutter angles have shorter exposure times.

Besides controlling the amount of light, the shutter angle will also affect
the amount of blur a moving subject records on the film. Wide angles allow
more blur; narrow angles allow less blur.
• 0

#4 John Sprung

John Sprung
• Sustaining Members
• 4635 posts
• Other

Posted 14 September 2011 - 12:55 PM

Adding to the above, film cameras with variable shutters rarely go wider than 180 degrees because of the reason the shutter is there in the first place: It protects the film from exposure during the mechanical pulldown from one frame to the next. Angles as large as 288 degrees have been used with specially designed film movements (the hot kinescope process of the 1950's). With digital cameras, you can get shutter angles within just a hair of a full 360 degrees. This enables some interesting possibilities. With that much motion blur you're immune from skipping (aka incorrectly "strobing").

-- J.S.
• 0

#5 Jaysingh rajpurohit

Jaysingh rajpurohit

New

• Basic Members
• 8 posts
• Cinematographer

Posted 15 September 2011 - 12:19 AM

Thnx
• 0