The obsession with using Shutter Angle on an electronic video camera.

workshops-275 The obsession with using Shutter Angle on an electronic video camera.

I’m not sure I fully understand the obsession with using the shutter set in degrees on video cameras. For years video cameras have used fractions of a second to display the actual shutter speed. Very simple, tells you exactly how long the shutter is open no matter what your shooting frame rate. Basic film cameras use a fixed rotating shutter. This is a disc that will have half of it cut away to allow light to fall on the film. If a full circle is 360 degrees then half of this is 180 degrees, hence the commonly used 180 degree shutter. As these basic shutters are fixed then if you changed the film cameras frame rate then the shutter speed changes too. The shutter speed will always be half of the frame rate. More advanced film cameras have shutters where you can adjust the amount angle of the shutter opening, sometimes to as much as 270 degrees, but often only to an angle less than 180 degrees.

When you use degree’s your having to continually make a mental calculation of your shutter speed in fractions of a second to ensure that you don’t run into phase issues with your lighting etc. Why do this? With a video camera, if you use fractions of a second you know exactly where you are. I know of many film cameramen, myself included that found degrees to be a nuisance with the shutter speed changing all over the place depending on frame rate and angle. Fractions of a second are far easier to work with. For example, to avoid flicker from artificial lights (in particular florescent office lighting) when shooting in 50hz areas use a shutter speed that is a multiple of 1/50 and in 60hz countries use a fraction of 1/60, no matter what your frame rate. Try figuring out what angle you need to shoot 24p in a 50hz country (the answer is 1/172.8). Degrees is a hangover from film days that is seen as fashionable because it make you sound like a cinematographer, but this is fashion for the sake of fashion, not because it makes sense or is a better way to work. There is no difference in the way the shutter functions within an electronic video camera whether you use degrees or fractions, it’s just a different way of describing the same thing (unless you have a high end camera like the f65 with a mechanical shutter). If you want to mimic a film camera with a 180 degree shutter then all you have to do is halve the frame rate, so 24p = 1/48, 25p = 1/50, 30p = 1/60. Very simple.  Then if you need to match the local mains frequency simply use the next highest mains multiple. So if shooting 24p in a 50hz country use 1/50th or shooting 24p in a 60hz country use 1/60th, much easier to figure out than degrees.

20 thoughts on “The obsession with using Shutter Angle on an electronic video camera.”

  1. It depends on what you are doing. For example (and I can’t comment on the F3, F5 etc as I haven’t used them) on the EX3 in variable framerate mode, using shutter angle rather than degrees ensured that no matter what framerate was chosen that the shutter would automatically sort itself out. Rather than having to set specific fractions of a second based on every framerate that was chosen. At least that was my understanding. I could have been wrong.

    For example if you wanted to record something at and odd framerate like 22fps for example for under cranking (which some Hong Kong guys did for cheap direct to TV/DVD fight sequences). There’s no 1/44 shutter option.

    Of course, as I say I could be wrong, and maybe the EX3 didn’t modify things automatically for such small incremental framerate changes (i.e. maybe it says 180 degrees on the viewfinder, but really keeps the shutter equivalent to 1/48 rather than 1/44 in such an instance. I don’t know for sure). But in general the convenience still stands that you can change the framerate, leave it on 180 degrees, and the camera will sort itself out in general, rather than having to change the framerate and then manually change the shutter speed as well. Using shutter angle just simplifies things a bit in that regard.

    That is a specialist circumstance however, and I do agree with the thrust of the article that the use of degrees is used by many to make themselves sound grander than they really are.

  2. Yes, angle will make the shutter speed track the frame rate, but that’s when the problems start with odd shutter speeds drifting in and out of phase with your lighting leading to flicker, rolling dark bands and gradual colour shifts. Can the end viewer tell the difference between a 1/48th shutter and a 1/50th shutter? I very much doubt it, I know I can’t. The primary benefit of using a 180 degree shutter, or at least a shutter speed around half the frame rate is that it reduces motion blur and image softening due to camera shake etc at low frame rates. A 1/25th or 1/24th shutter is open so long that a little bit of camera shake will soften the image, or when you pan the image will soften. If your shooting at 50/60p then you in most cases you don’t want a 180 degree shutter as when the shutter speed starts getting into the 1/100ths then you can start to run into judder and strobe type artefacts as well as needing twice as much light. This is where a fixed, fraction of a second shutter speed is better. In addition fixing the shutter speed for a shoot will ensure that the portrayal of motion will be constant throughout the project.

    1. I agree on those points, especially with regard to lighting issues. However it depends on the final effect that is desired. With high action sports, shot outside with no lighting frequency considerations, quite often things need to be done very quickly (for example in competitions where I can’t ask the competitors to wait for a shot to be setup), and with the EX3 I used to use a variety of frame rates and was thankful for the ability to be able to set an angle and forget about it.

      In general use I will use fractions of a second, but it is good to have the other option there if needed. And that’s what it comes down to, options. It is true that a lot of people use shutter angles etc in an attempt to seem more sophisticated or knowledgable than they really are. However for those who know how to get the best out of a camera and who can use these functions as intended I think that having the option there is useful.

      Depending on the project, such as high action sports, it often isn’t too desirable to have a constant motion portrayal throughout. But of course it depends on the final result that is desired and the creativity of whoever is involved. Most often, consistent motion type is what is needed. But there are a few cases where it isn’t. As I say, good to have options 🙂 Incidentally, 60p at 1/120th for sport can look really good! For slow motion having at least the equivalent of a 180 degree shutter is best for the crispest motion. Going higher, or for example 1/50th at 50p for slow motion looks smeary and very cheap looking for some reason.

      Often for slow motion I have used much shorter shutters than is often recommended. For example in this short promo I often used 1/250th for the slow motion shots precisely because I wanted a more hyper look to it.

  3. I totally agree on this one in fact it’s all about snobbery and further mystification. A bit like talking to a doctor when they start rambling on in doctor speak.
    Shutter Angle is as you say a film camera term and that’s where it should remain we have so many electronic video junkies these days talking in film terms it makes you laugh…if you want the film look and all that goes with it then shoot film.
    This obsession to get a video camera to look like film is becoming a joke worse still those still obsessed with making a DSLR not only into a video camera but pimping it up with so much metal it takes away the compactness of the camera and makes it almost unusable. Rant over.

    1. The film look term has become overused really, and I’m not even sure many people realise what they want from it. Filmlook has, for some reason come to mean 24p in many people’s minds. For me though the film look is about having a nice smooth image, free from hideous, harsh looking digital edge enhancement and over processing. A natural looking image, not a digital looking one. Let’s not forget that all those harsh edge enhancements that cameras often come preset with do not do the compression codecs any favours either. Most of the good professional camcorders can produce a perfectly sharp looking, but natural image, with the edge enhancement turned completely off. Turning such functions off doesn’t affect resolution unless utilising the ability of some cameras to go negative and actually start physically softening things.

      I do agree though Philip, that it is quite amusing to see the way people pimp out their cameras to an almost unusable degree. Like a Mechano set on a tripod! I get constant amusement from Red, who in Jim Jannards words “set out to produce a camera that is free from looking like the Greek God Hydra” and in fact ended up producing exactly what he set out to avoid!

      Incidentally, speaking of snobbery, I use a DSLR for video because, thanks to the recession, kids doing work for free, and the relentless release of new camera gear every five minutes along with the fact that far too many people obsess about the camera that is being used rather than the person using it, it is all I can afford. I don’t choose to use it, and I’d love to have an F5, or and FS700, or even an FS100. So the one thing I have learnt about going from using the disc based XDCAM cameras, DSR’s, HDCAM etc down to using a DSLR is… I really do not care a rats about the camera a person uses any longer. A person who is great with a DSLR will be great with an F5. While a person who is rubbish with an F5 won’t be any good no matter what camera they are given. That’s my rant over 🙂

  4. I use shutter angle not because I like the words, but because putting the camera in that mode assures me that shutter speed will always be twice frame rate, no matter what speed I shoot.

    When you’re working fast, and bouncing between normal and off-speed over and over, having only one parameter to change fast is much better than having two parameters to change quickly via small buttons.

    The frame rates that are flicker-free are embedded in my brain from my AC days. Not because I purposely memorized them, simply because they were the speeds I was repeatedly asked to set the camera to over and over. 24. 36. 48. 72. 96.

    1. I agree Nate, and this is one reason I preferred using it a lot too. Having shutter angle as a hang over from the days of film isn’t such a bad thing. After all, how many of us still say we are “filming” something when we are using a video camera? Shutter angle will just become a parlance in the same way that many terms in film have stuck over the years despite the original use being obsoleted.

  5. Personally I think the shutter angle calculations can be modified to a greater degree (pun intended) within narrative film making as you can have half a degree increments, fractions changes even on most high end cinema cameras are still clunky presets really. I would rather have my millimetre control over inch calculations (if you get my metaphor) but for high speed shooting I find a few things happen, on the cameras I have used in variable frame rate mode, it seems that the degree or synchro scan maintains a 180 degree shutter for the output frame rate I.e. 24p and not the actual frame rate I.e. 60p, it basically plays back with a fair amont of motion blur, as if I had shot 24p at 1/24th as I am sure it is picking 1/48th for the 24p and not 1/120th for the actual 60p. I now use fractions when shooting high speed footage in a variable frame rate modes to ensure I am achieving 180 degrees or more/less to taste.

    1. I doubt anyone watching would be able to tell whether your shutter speed was 1/48, 1/50th or 1/60th at normal frame rates. Of course ECS offers 0.5 degree steps if you want super fine steps.

      Not sure I understand the bit about high speed. You can’t shoot 60fps with a 1/48th shutter, the shutter would still be open when the next frame starts and that’s not how electronic cameras normally work.

  6. Hi Alistair,

    Just wondering what shutter you would use for 30p in the UK? The footage would be slowed down to 25p in post for a slight slow mo effect.

    Cheers
    Jon

    1. Your best using a multiple of the local mains frequency no matter what the actual frame rate, so 1/50, 1/100 etc.

  7. Exactly. On my GH4 I much prefer to read the shutter in degrees to fractions of a second. If I glance at the shutter speed, and it says “180 deg” I know I have the correct shutter for any frame rate. As the GH4 can go up to 96fps, leaving the shutter at 180 means one less thing I have to worry about when moving fast.

    For instance, I was shooting a volleyball game and wanted to move into 96fps. Quick: what’s the proper shutter speed for 96fps? Now you switch back to 24fps. Did you remember to change the shutter speed back to 1/48? Or was that 1/50?

    If the shutter is at 180, it’s always right, no matter the frame rate.

    Further, the GH4 allows me to switch the shutter speed and f/stop controls between front and back selection wheels. Now, the shutter is on the seldom-used front wheel and the often-used f/stop wheel is under my thumb. This way, the shutter never changes.

    1. Sorry but I totally disagree.

      There is no such thing as one proper shutter speed for any given frame rate. How do you ensure the correct phase between the shutter and artificial lights when using degrees? 180 degree’s is a throw back to film cameras and projectors where the shutter could not be adjusted. Having a 180 degree shutter in the camera matched the projector so the captured footage had the amount of motion blur appropriate to the projection system. This is no longer the case.
      Who say’s you should always use a shutter that is half of the frame rate? What is the benefit that this always brings? For example if shooting a mix of speeds, using 180 degrees means the motion blur will be different for every frame rate, that isn’t always desirable, especially if doing post production speed ramps as the viewer will have to put up with a shorter than necessary shutter speed during the normalised parts of the speed ramp, this completely spoils the effect. And as for the need to switch between 1/48 and 1/50 or even 1/60? Can anybody really tell the difference between 1/48 and 1/50 anyway? In this scenario you’re just more likely to end up with rolling color bands if shooting under lighting of the incorrect frequency. No one has yet to show me evidence that people can tell the difference between 1/50 and 1/48. I have never seen a compelling example of what, once you go above 1/48th and the reduction of excessive motion blur that a constant 180 degree shutter brings, why MUST you use a shutter speed that is half of the frame rate, what is the visual benefit the magical 180 degree shutter brings exactly? What problem, defect, image issue would shooting at 1/96 at 96fps introduce, would the viewer even know if you’d use 1/100 or 1/120 instead of 1/192 to ensure no lighting issues? Could your shot not have benefited from the extra light at 1/96 compared to 1/192? Not saying you can’t or shouldn’t shoot at 1/192, but I’d love to know what the benefit was.
      I think people forget that the way an image is projected with a modern projector or shown on a TV is different to the way it was in the early days of film. Early projectors used to also have a 180 degree shutter. Modern projectors now use double flash or have little to no delay between the presentation of each frame so there is no need to add artificial “gaps” in your motion blur to compensate for the gaps between frames introduced by the old projector shutters.

  8. Hi Alister,

    For an upcoming project we want to shoot at 50P with my F5. The shots wil be combined with CGI, and the computerguys wants us to shoot at 50P. What shutter speed is best to use. In some shots there will also people talking.

    Thanks and cheers,
    Rick David

      1. Hi Alister,
        I shoot to 50p, shutter angle 360 with an Atomos Ninja assassin then encode to 25p. Don’t record from interlace to pulldown because is lost details.. Shutter is not mechanical. At post proccesing from 50p to 25p shutter angle will be 180? Dont know why on camera If I set to 50p, 180 shutter angle, IRE waveform is 40% and to 25p, 180 shutter angle, IRE is 80%. To 80% IRE 50p must set 360 shutter.

        1. A prime example of why not to use shutter angle. You are confusing yourself.

          If you shoot at 50p with a 180 degree shutter your shutter speed is 1/100.
          If you convert this to 25fps, your shutter speed is still 1/100 (you have not changed the camera setting), so in effect the shutter angle becomes 1/90.

          If you want to shoot 50p but have the equivalent of a 180 degree shutter at 25p you have to shoot with a 360 degree shutter. 360 degrees at 50p = 1/50.
          Convert 50p to 25p in post and the shutter is still 1/50.

          It really, really would be far simpler just to set the shutter speed at 1/50 if that’s the shutter speed you want.

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