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Why not increase shutter speed? Why use NDs? (Seriously)
  • 120 Replies sorted by
  • I'm planning to shoot stuff to slow down in Twixtor. The slow motion doesn't need to be that much, maybe +50%. And I plan to do it in 1080 30p. Should I use then faster shutter speed like 1/120 instead of "normal" 1/60 ? How far you can go until it looks bad?

    I have GH2, I could also use 720 60p but I don't like the idea of resolution loss.

  • If it works, cool, use it. I would do some quick experiments with what some are noting are the situations where it might be problematic (overly staccato look, and true level of post motion blur achievable, and difficulty doing in post). But if you are getting images you like, rock on. Particularly these days, as audiences are coming to a point where they see and like a variety of different image types. Only time to be wary would be professional setting if you're working with others who expect different end result look or who even just prefer using a more traditional set of camera settings.

  • @Sangye First: You must be young. Two: You must play videogames on a regular basis ;o)

  • I don't think there's much to argue about. You understand why. It's a preference that apparently a lot of people are on board with.

    I certainly don't like the look of 24p with high shutter speeds and no motion blur the vast majority of the time, but if you do then go nuts!

    I also hate the trend to have these shakey zoom in and out shots for talking heads. Not to mention cutting to some off kilter side angle that's colored differently. Apparently a ton of people think this style is aesthetically pleasing, but I think it's junk.


  • @oophus: Yes, as long as your shot contains mostly non-overlapping linear motion, postprocessing for motionblur works sufficient enough.

    As soon as you run into a mixed motion shot, with linear/nonlinear motions overlapping, artifacts will creep in.

    You'll need all those overlapping motions in different image layers, then it'll work. That's why I mostly tell ppl not to rely on 'the fx guys' to fix something in post, if they could get it easily right in the first place.

    1 minute, on set to change a filter, can save a few days of postprocessing hell.

    But that's just me, maybe I got to picky over the years ;)

  • @vicharris Sorry about that, I didn't mean to piss anyone off, just stating that its good to add to convention and try new things. I can see some cool applications of adding your own motion blur in post, Ive done it myself with some interesting results. Sometimes Its nice to have the control when comping in elements. I have used reelsmart motionblur and sometimes it works great sometimes it doesn't. It depends on the complexity of the scene.

  • I would say the obvious reason for using NDs is consistency.

    If you expose with the shutter speed, motion will be rendered in a wide variety of different ways throughout the film. If that's your stylistic intent, then fine, but it definitely calls attention to itself in a way that could throw even the average viewer out of your film.

    It's not really the 180 degree shutter that's sacred, it's maintaining a single fixed shutter speed throughout the film. THAT is why we use NDs.

  • @Sangye - Another con to add to your above list of using shutter speed as your method of exposure is in lighting conditions where you are working with mains supply of either 50hz or 60hz. How on earth could you get the exact exposure you're looking for with shutter speed alone without getting a mismatch between your shutter speed and mains frequency.

  • I was about to post

    it's filming 101

    Then I saw @viicharris had just beaten me to the post, pointing our the elephant in the room.

    Thanks. I thought we'd all suddenly gone to la-la land !

  • @Sangye

    I do, and it is a serious question.

    If you've made some novel discovery, let the world know. Show us your shutter speed trick, your perpetual motion machine or whatever. Honestly, do you get off on wasting others' time?

  • @flablo

    I remember a friend of mine (who is very into movies but knows nothing about film techniques and 180 shutter) who noticed and appreciated very much the "strobing" effect he saw in the movie 23 Days Later

    Probably you meant 4 weeks and 6 days and 23 hours and 59 minutes and 59 seconds and 23.978 frames later :P

  • @cde clearly maintaining a fixed shutter speed throughout a film is not what is necessarily done these days. Action scenes will have the gladiator-saving private ryan- no motion blur action thing happening and then it will change for mellower scenes depending on the effect desired.

    I don't know if motion blur really is something natural to human sight, maybe someone has read that somewhere but I was taught that it's just a convention we have become accustomed to because it was something created by film cameras and technology. It's similar to how people didn't like watching The Hobbit at 48 fps because it looked too much like a soap opera on TV, or how HDTV's can show material that looks really 'fake' to our eyes because the old technology has shaped our expectations.

  • no motion blur action thing happening and then it will change for mellower scenes depending on the effect desired.

    Source for this info, please, @Alienhead ?

  • @Alienhead Yes, but in films where the technique is used, it is usually to call attention to itself for stylistic effect in a few key sequences, usually action. The majority of the film is shot with one fixed shutter speed. If one were to follow Sangye's technique and expose with shutter speed, then the rendering of motion would be wildly different throughout thefful., and not for any stylistically appropriate reason.

  • Subject matter depends a lot too. My old boss shot a talking head @ 24p with some ridiculous shutter speed, like 1/250 or 1/500 or something like that.

    I thought it would be trash, but the speaker kept his head pretty static and there was nothing moving in the background, like cars or anything to really give it away. It looked fine.

    On the other hand, I've filmed animals running with insane shutter speeds due to lack of ND, and 60p --> 24p it looks ridiculous. Of course, that might be the desired effect sometimes.

  • @Cde agreed. I think Sangye's idea is interesting and makes me imagine the possibilities that a faster shutter speed may offer, but it's not practical to change it around for most situations, not at this point anyway.

    @goanna check out some films that use the fast shutter technique such as the ones already mentioned.

  • Shutter speed can be a tool a film maker can use, but like any tool, it has to be used for the right job. Conventions aside, at first thought to some people, it might seem more practical, but as mentioned by many: to offset the amount of hours and perhaps days in post production work to achieve an image you could have created in camera on set, is plain crazy talk. If the whole idea is to save time (as mentioned in the OP), this is not the right tool for MOST scenarios. The extra 30 seconds to a minute to drop an ND into the filter tray as apposed to the work needed to get FX blur looking acceptable just makes that plainly obvious. Stylistically speaking: experimenting IS good, but can be a dangerous game to play on the wrong project. Film making isn't an ancient art, but it's old enough that we have learned a few things, hence our accepted conventions.

    As for the point of real life motion blur, just close one eye and wave your hand in front of your face. Does it look like 1/500 to you, or 1/50? Pretty easy to see why we like 180 degree shutter blur.

  • If the convention of shutter angle is required for the job, then stick to it. Otherwise I think @Sangye has a completely valid point. This parameter is like f-stop, sensor characteristics, lighting etc just another tool for chosen aesthetic. Very frequently used in high dynamic scenarios. But also has it's justification in others, if it supports the overall aesthetic of the work.

  • You need ND's to be able to control the shutter speed/angle yourself. You need to be able to control the shutter because of, so to speak, aesthetic aspect and the technical one.

    Let's set "the look" aside for a moment.

    You would be able to use shutter to control exposure - only in natural light, or with flicker free lights with ballasts.

    If you are already setting up the truck of HMI's you probably can rent a better ND, and generally you have time to slide it in before the shot.

    If you do run and gun in natural light than it is probably OK the way you do it. If your narrative, content and characters drive the whole thing and it is interesting and dynamic, than set everything to AUTO, it will do just fine. Vérité.

  • Actually GH2, as well as all the low and middle class camcorders, gives unnatural motion blur no matter what shutter speed is choosen, i.e. it's very far from the motion blur of the cinema cameras and movie productions. I've tried ReelSmart Motion Blur plug-in which in my opinion is the best popular for that purpose. If you adjust its settings right, then the footage becomes completely different, very close to the feel of the movie productions. Even if it's not graded. A really big positive difference!!! The only inconvenience is that this plug-in takes a lot of time for processing... very slow.

  • I've tried ReelSmart Motion Blur plug-in which in my opinion is the best popular for that purpose. If you adjust its settings right, then the footage become completely different, very close to the feel of the movie productions. A really big positive difference!!!

    Can you make some demo video? May be SBS even.

  • When I shot with Lumix 7-14 at day light, I prefer set fast shutter instead close aperture to 16-22, because MFT lenses not sharp at very closed aperture. That lens can't attach filter in front. Otherwise, wide angle make picture with less motion, and the problem with motion blur not really visible. After S 1/100 all shutter numbers look the same, there is not really difference from 1/100 to 1/2000, so if you have no time for instant shot, and you know that the scene will be with restrained motion of objects, you can use highspeed shutter, but if you see any electric lights in frame, maximum possible shutter can be only 1/100 at 50Hz countries and 1/120 at 60Hz of electricity.

    For serious projects I try to avoid it and film at 1/50 with filters, of cause.

  • Check out the RED Motion Mount, interesting technology to improve on the bad motion blur of digital cameras.

    I can only say it again: RSMB only works well with relatively simple movements. If there are several layers of moving objects in your frame crossing over each other, it produces ugly artifacts. I was once asked to fix a daylight shot of dancers that was shot with 1/100 by mistake and it was a nightmare of masking…

  • Yes, let's see the footage. I want to see how to get the jerks out of a shot where the shutter isn't open long enough to get all the movement in, how the codec manages to compress all those sharp frames and how the work in post is able to interpolate objects into the missing positions which never got recorded.