Chris Burke Posted October 1, 2007 Share Posted October 1, 2007 .....of a 15 degree shutter angle in Super 16? I would think it is a pretty quick shutter, good for capturing fast motion with sharp images. Link to comment Share on other sites More sharing options...
Nick Mulder Posted October 1, 2007 Share Posted October 1, 2007 Either I am bout to get a lesson or you are - I think there is something wrong with your understanding of shutter angles ... Your shutter speed or exposure time (which is a more accurate term prone to less confusion) is dependent on both the shutter speed and shutter angle ... To calculate your exposure time per frame find the % the shutter is open per frame - ie. in your case 15/360 = 0.04166666667 ~ %4.2 So for whatever fps you shoot at the shutter will be open for %4.2 of one frame cycle - for eg. 24fps: one frame = 1/24sec = 0.04166666 ~ 42ms (the same answer as before that for some reason may become clear with some more input from other posters?) so anyway, the exposure is %4.2 of 0.04166666 = ie. 0.04166666 * 0.04166666 = 1/576 of a sec - which is as you say "a pretty quick shutter, good for capturing fast motion with sharp images." I'm not sure what 'equivalent' you are after though ... super16 or any other aspect/format has nothing to do with it Maybe you mean in lieu of an adjustable shutter, what fps would give me a relative shutter angle of 15deg in a 180deg shutter camera ???? (along with all the extra redundant frames) - the mafamatatics are as follows ... (2*(1/576))^-1 = 288 fps (of which you'd have 12 'streams' of 24fps each with a 15deg shutter angle a 1/12 of a cycle phase apart to choose from, to put it simply you'd be shooting 12x as much film as you needed) Link to comment Share on other sites More sharing options...
Dominic Case Posted October 1, 2007 Share Posted October 1, 2007 I think Nick's first answer is what you are looking for. At 24 fps, the shutter angle, as a proportion of 360deg, gives you the exposure time as a proportion of 1/24th sec. So a conventional 180deg shutter is open for 180/360 = 1/2 the time, that is 1/2 x 1/24th = 1/48th sec A 15deg shutter would be open for 15/360 = 1/24th of the time, that is 1/24 x 1/24th = 1/576th sec. From a still camera perspective that's only moderately fast, but it's still much shorter than the conventional motion picture 1/48th sec. But while each individual frame might render fast-moving action a lot sharper, you will now have a longer gap in between them. Instead of a gap of 1/48th sec between each frame, you now have a gap of 23/24 x 1/24th - very nearly 1/25th sec, nearly twice as long as if you were running at the conventional 24fps speed. If the action you are shooting is fast action, then objectes will have moved even further in that time. This results in a jerky, stroboscopic effect. Filmmakers often go to considerable troulbe to re-introduce motion blur if it's missing for this or any other reason, so as to produce a more satisfactory result. Link to comment Share on other sites More sharing options...
Premium Member David Mullen ASC Posted October 1, 2007 Premium Member Share Posted October 1, 2007 A good example of the jerky, strobey motion of a 45 degree shutter at 24 fps, check out "Saving Private Ryan" and parts of "Gladiator". So 15 degrees would look quite bizarre... Since 24 fps is a fairly low frame rate in order to create the illusion of continuous motion, a certain amount of motion blur in each frame is actually needed or else you sense just how few frames there are sampling the motion. Link to comment Share on other sites More sharing options...
Nick Mulder Posted October 1, 2007 Share Posted October 1, 2007 I have some test footage here that was shot 15fps with the shutter synced to a photographic flash - although i dont know the exact flash duration wikipedia tells me a typical photographic flash duration is around 1/3000sec mafamatatics: (X/360)*(1/15) = 1/3000 X = ~ 0.6 deg It was a test for a music vid I plan to do with dance strobes in place of the photoflash so i can get a proper 25fps without the capacitor/timing pooping itself ... Its pretty choppy - but hard to really tell because of A. the 15fps speed factor on playback at 24fps in projection and B. the short duration of the takes as the photoflash would deplete itself within 20 frames or so Link to comment Share on other sites More sharing options...
Stephen Whitehead Posted October 15, 2007 Share Posted October 15, 2007 A good example of the jerky, strobey motion of a 45 degree shutter at 24 fps, check out "Saving Private Ryan" and parts of "Gladiator". So 15 degrees would look quite bizarre... Since 24 fps is a fairly low frame rate in order to create the illusion of continuous motion, a certain amount of motion blur in each frame is actually needed or else you sense just how few frames there are sampling the motion. Was all of "Saving Private Ryan" shot at 45 degrees? or just the battle scenes? Steve Link to comment Share on other sites More sharing options...
Premium Member David Mullen ASC Posted October 15, 2007 Premium Member Share Posted October 15, 2007 Was all of "Saving Private Ryan" shot at 45 degrees? or just the battle scenes? Steve Just where you see the effect of it. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now