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adam dewhirst
shutterspeed/image quality
on Feb 24, 2011 at 11:29:48 pm

this is very basic. i just wanted to know the relationship between image quality and shutter speed. does increasing or decreasing the shutter speed effect the image quality in a negative way?


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Rick Wise
Re: shutterspeed/image quality
on Feb 24, 2011 at 11:50:12 pm

If your camera allows you to increase the shutter speed, shoot some tests of people or things in motion. You will see that with a higher shutter speed each frame will be crisper. That does not mean the action will look "better". Sometimes we need blur for the illusion of continuous motion.

You can achieve a similar effect by reducing the shutter angle on cameras that allow you to do that.

Rick Wise
director of photography
San Francisco Bay Area
part-time instructor lighting/camera
Academy of Art University/Film and Video (grad school)
http://www.RickWiseDP.com


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adam dewhirst
Re: shutterspeed/image quality
on Feb 25, 2011 at 12:04:18 am

thanks rick,

i have a hdrfx1 sony. shutter speed can go up or down. i was going to experiment with using the pp4 setting that sets the shutter speed at 25 and seems to bump up the iris function to compensate for the brightness. this is supposed to give a film look.

so is there a difference between shutter speed and shutter angle, if so, what does it entail?

adam


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Todd Terry
Re: shutterspeed/image quality
on Feb 25, 2011 at 1:56:33 am

If you are shooting electronically (with a video camera) you don't really have to think about shutter angle. That's more pertinent to real film cameras that have adjustable shutters. In a film camera, the shutter is basically a semi-circle shape that rotates 24 times a second (assuming you are shooting 24fps) and exposing the film. If the shutter is an exact semi-circle... that is a 180° shutter... thus each frame is exposed for 1/48th of a second at 24fps. Film cameras that have an adjustable shutter can basically vary this size/shape of the shutter... and while a 180° shutter might be considered "normal," you can adjust and narrow that shape so the "opening" is smaller (say, 90° rather than 180°) which in that case would give you an exposure (or shutter speed) of 1/96th a second. I.e., the more narrow the shutter, the higher the shutter speed.

That was just some background... you can more or less forget that part unless you are shooting real film, and just think in terms of shutter speeds. With a video camera... a "normal" shutter yields an exposure roughly equivalent to what a 180° shutter would be, if it were a film camera. Therefore, if you are shooting 24p with your video camera, a "normal" shutter speed would be 1/48th of a second.

For easy math, just think of doubling your frame rate and stick a "1" over it to see what a "normal" shutter would be. So, for 24fps, a "normal" shutter speed is 1/48th. For 30fps, it would be 1/60th.

That "normal" exposure gives you the motion blur on each frame that we are all used to seeing with motion... which your brain interprets as fluid-looking action. You could lower your shutter speed (say, down to 1/24th) and each frame would have more blur. You could crank up the shutter speed (the equivalent of a more narrow shutter) to, say, 1/192nd of a second, and the faster exposure would "freeze" the action more in each frame, making each frame much sharper. That might sound "better" (sharper is better, right?)...but that's not necessarily the case. Without the motion blur, the images in motion will look choppy and juddery. This "narrow shutter" effect is sometimes used in action films to make them look, well, more "actiony."

You would also want to shoot a higher shutter speed if you were shooting footage to be slow-mo'd later.... because when you overcrank real film for slow motion footage the faster fps naturally results in a much higher shutter speed... and the lack of motion blur makes the action look more fluid and realistic in that case.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



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Mark D'Agostino
Re: shutterspeed/image quality
on Feb 25, 2011 at 3:49:53 pm

Great answers from Rick and Todd. This is the best example in a while of how people answering questions in forums should do it...clear, concise, not condescending, subjective.

Mark D'Agostino
http://www.synergeticproductions.com


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adam dewhirst
Re: shutterspeed/image quality
on Mar 22, 2011 at 9:51:09 pm

yep, thanks a lot for that.


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