• January 3

180 Degree Shutter – Learn It, Live It, Love It

A Spring-Wound Bolex 16 mm Camera

I’ve received a lot of emails after posting my “How to Setup Your 7D” video tutorial asking what the 180 degree shutter rule is and why it’s so important. To be completely honest, before these Video DSLRs came around I didn’t really understand the principles of the 180 degree shutter rule myself. Video cameras I’ve used in the past always defaulted to a 180 degree shutter automatically so unless I went into the settings to change my shutter speed or frame rate, I was always good to go!  However, this all changes with Video DSLRs hitting the market because they have no preset shutter speeds to rely on and most of the manufacturers of these DSLRs don’t find this rule important enough to make it a primary feature.  Therefore, I figured this would be a great opportunity to consolidate a few articles and resources on the web to answer this question once and for all.

I want to thank Jason Wingrove and Stu Maschwitz for breaking down the 180 degree shutter rule for me. Stu wrote an excellent blog about this topic last year when Reverie first came out describing why it is so critical to shoot at a 180 degree shutter!

I’m also seizing this opportunity to discuss the 360 degree shutter issue, as it’s one that needs airing out. Sure, it may be a creative choice for a filmmaker to use a greater-than-180-degree shutter, but when my mom sees the trailer for Collateral and asks me why it looks like video, we’re talking about a choice that sets back the progress of digital cinema. If you want your 24p HD to look like film, the film we know and love, stick to a 1/48 second shutter speed or faster. -Stu Maschwitz

During RedCentre Episode 25, Jason had a great discussion with Mike Seymour on shutters and keeping the film look.  Check it out, it’s a great resource that dives further into the explanation I am about to give you.

With all that said, lets dive into why the 180 degree shutter rule is so important. With the rise of digital cinema it is critical to maintain the “film look” that we all love so much. We do this with shallow depth of field and low light from large sensors, interchangeable sharp/fast glass, Matte-Boxes, Follow Focus, Stedicam Rigs, Dollies and Jibs, 24P, color correction, vignettes/film grain, and the list goes on and on… However, one thing that is often overlooked and under appreciated is the 180 degree shutter speed rule.

Basic Operation of a Film Camera by Joram van Hartingsveldt

To maintain the “film look,” first we need to examine how a film camera actually works. Take a few minutes to study the animation at the left. As you can see, a physical shutter on a film camera is basically half a circle. The opening defines the shutter angle.  Just like ISO/ASA wasn’t a luxury to instantly adjust on the fly back in the day like it is today, neither was your shutter speed on film cameras. In order to change the shutter speed you had to physically remove the disc and replace it with another disc that had a different sized hole cut out. Likewise, to change the ASA on a film camera you would have to physically remove the film stock and swap it out with another roll. Aren’t we spoiled today?!?

Anyways, let’s quickly review… The physical shutter in a film camera has the shape of a half circle (as you can see in the animation). This is defined as a 180 degree shutter angle, makes perfect sense since a complete circle would be 360 degrees… In order for the film to feed through the gate while properly exposing each frame of film, the disc will have to rotate one complete revolution for every frame. Therefore if you are shooting 1fps, the frame would be exposed to the open part of the disc (allowing light to hit that specific frame of film) for only half of its complete revolution or in other words 1/2 shutter speed. During the other half of the disc revolution (while the closed half of the disc is blocking that frame of film) the next frame of film is being fed into the gate ready for its opportunity to be exposed. So, since we now understand that when shooting at 1fps, the shutter speed would be 1/2, then you basically just carry that math on! 24fps = 1/48, 25fps = 1/50, 30fps = 1/60, 60fps = 1/120, 120fps = 1/240 and so on…

Now very quickly you can see why the 180 degree rule can get dangerous pretty quick once you start filming with higher frame rates. When the 2/3″ Red Scarlet comes out with 120fps (150fps burst) then you will be cutting a HUGE amount of light shooting at shutter speeds up to 1/300th. The same goes for cameras like the Phantom that shoots well over 1000fps. In order to get the proper shutter speed you need to be shooting at least 1/2000 and pouring the light on the subject in order to maintain proper exposure during those extremely high shutter speeds.

So how exactly does the shutter speed affect your image? Well if you come from a photography background you don’t really need to read this explanation. However this is the true magic on the convergence of photo and video today! The same terminology and fundamentals are more important than ever in relation to aperture, ISO, and shutter speed. Therefore, what happens when you take a photo at a slow shutter speed – 1 second exposure? You get a lot of motion blur. What happens when you take a photo at a fast shutter speed – 1/8000 shutter speed? You stop motion.

Effect of Different Shutter Speeds (Fast Shutter to Slow Shutter from Left to Right) on Photograph by Nevit Dilmen

Well the difference is when you’re dealing with digital cinema, filming at a greater than 180 degree shutter (which you should NEVER EVER do), allows each frame to contain too much motion blur which results in a “smeary” look… Besides, this is a look that would be mechanically impossible to achieve using a film camera since you need that extra time for the physical shutter to block each frame so the next frame can slide into place… Therefore, a greater than 180 degree rule looks unnatural so PLEASE don’t do it! I know, sometimes breaking this rule is so very tempting when it’s dark out, you have your aperture wide open, and are pushing your ISO to the max… You think to yourself, “I can open up my shutter speed a little more.” Just because the camera lets you do something doesn’t mean you should because before you know it, you’ll be shooting 24fps at 1/24th shutter… Don’t give into the temptation, stay strong because you’ll kick yourself in post when reviewing your footage wondering why your digital cinema looks like nasty smeary video. Yes, all rules are meant to be broken but this is one rule that if you don’t know exactly what you’re doing, you can really ruin your work.

So when is it alright to break the 180 degree rule? Well, if you are going after a certain effect like they used in “Saving Private Ryan” to get a staccato feeling then breaking the rule is acceptable.  On the cameras they used for this film, they adjusted the standard half open/half closed disc with a disc that had a 90 degree opening for the majority of the film except for the high action combat scenes which were shot at a 45 degree shutter angle (to be more accurate, the shutters in these film cameras are electronically adjusted but the same fundamentals apply). Remember, those are LESS THAN 180 degree shutter angles so it’s alright. A 90 degree shutter angle would equate 1fps to 1/4 shutter speed or at 24fps they were technically shooting at a 1/96 shutter speed. That means they had to use a lot more light in their scenes to make this effect work…

What is an easy way to figure out how to convert from shutter speed to shutter angle and back again? Here is a very handy guide written up by Stuart English. My good friend Matt Jeppsen posted an excellent article titled “Shutter Speed vs. Shutter Angle” about this same topic which you can read about in more detail.

Article by Stuart English via Matt Jeppsen @ FreshDV

Now if you are using a Canon Video DSLR, then you will have to make a few minor modifications when choosing your shutter speed for your desired frame rate. If you are shooting at 24fps, the closest shutter speed you can select is 1/50th and if you are shooting at 60fps, the closest shutter speed you can select is 1/125th.  This minor adjustment won’t affect your footage but it’s the principle that counts so Canon if you’re listening, please fix this in the future…  Thanks!

Yeah I know, this is a very long blog about a very simple topic however if you are anything like me, you don’t just want to be told to do something without understanding why you should do it. This 180 degree shutter rule is something I never learned in college and there are tons of cinematographers out there who either don’t know about this rule or don’t obey it. Moreover, there are a lot of photographers starting to shoot video with these new Video DSLRs that need to start out on the right foot and use good habit and proper fundamentals!

UPDATE: Alain Pilon filmed this awesome visual example of 7 common shutter speeds captured at equivalent exposures and merged together in one clip. You can very easily see and understand the effect shutter speed has on water. The camera used was a 5DMKII which shoots at 30fps. Just look at how “smeary” the water looks at 1/30th (360 degree shutter) on the left hand side. Right next to it at 1/60th or 180 degree shutter the water is flowing naturally and it is pleasing to our eyes. For creative effects on the far right you can see that shutter speed begins to stop the motion of the water which gives a really cool look under certain conditions. Make sure you head over to Vimeo so you can watch it in HD. Thanks Alain for this great example!

Effect of shutter speed on fast moving objects from Alain Pilon on Vimeo.

As always, please let me know if you have any questions, comments, or concerns!

-Tyler
“To give anything less than your best is to sacrifice the gift.” -Steve Prefontaine




Comments

  1. David Kruta January 3rd

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    One thing to note: on high-speed cameras, the higher the framerate, the less important 180 degree shutter becomes. For example, when shooting Phantom, lets say you’re shooting 500fps. A 180 degree shutter would mean 1/1000sec speed, but using a 1/500sec (as in a 360 degree) shutter would mean you have a lot more light to work with, and with shutter speeds that high, the impact on the “film look” is next to none. This can also be used in certain situations at around 100fps, something that is pretty typical for RED shooters.


  2. T Roberts January 3rd

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    Thanks for putting this together! Really nice Write up! A great review. I was looking for this information recently. Nice timing…no put intended


  3. Maggie January 3rd

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    Great post, Tyler. Thanks for sharing! :)


  4. John January 6th

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    I’ve been looking for an explanation like this for a while. My background is in stills photojournalism and I was at a loss trying to understand how shutter speeds apply to video. Thanks so much!


  5. Thad Beier January 6th

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    A good reason for 180 degree shutter on film is that every frame in the movie theater is double-flashed — the shutter in a projector has two 90-degree holes cut out of it. Because your eye tracks a moving object, a 180-degree shutter with a double-flash blends the motion blur into a continuous smear
    — — — — — — (180 degree shutter) projected is
    —___—-___—___—___ (where the underscores are the second flash)

    If you have continuous projection (digital cinema projectors don’t go dark half the time) then 180 degree motion blur makes much less sense.


  6. Ben January 7th

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    I do a lot of docu and EFP stuff, probably nothing as hardcore as you ;) and I struggle with this issue all the time. Unfortunately, at the end of the day the client pays for a picture so a picture with motion blur is better than something that’s so underexposed they can’t use it. It’s my last resort but sometimes there’s no choice but to kill the shutter. I recently attended a seminar where a well known documentary cameraman spoke to this and he does it all the time. He doesn’t like it, but you gotta do what you gotta do. It’s in the second half of this article: http://negativespaces.squarespace.com/blog/2009/12/11/shutter-gain-and-a-brand-new-camera.html

    great blog btw

    cheers,


  7. Alain January 9th

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    While you have gathered a lot of info to explain what is the 180 degree rule, I think you are too much thinking about ‘getting film look’. Saying using 1/24 shutter or 1/1000 is bad isnt true. Lots of creative effects can be done using these speeds, it just wont look like what we see in movies.

    It is good to know the rules, but it is even better to know when to respect them or not. I tried once to shoot sport (soccer) at 1/1000sec and while it looked weird, once color corrected and a sound track was added, it gave it a distinctive ‘violent’ style that I liked.

    Also, using high shutter speed is preferable when you plan to extract stills from the clip.

    As a rule of thumb, I stay within 1/50 to 1/125 and most people dont notice anything.

    You can see a test clip shot at various speed here:

    http://www.vimeo.com/5249682


  8. Tyler January 9th

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    Alain – I made it clear in my article that there is nothing wrong with faster shutter speeds for creative effects if you know when to use them to enhance the story.

    “So when is it alright to break the 180 degree rule? Well, if you are going after a certain effect like they used in “Saving Private Ryan” to get a staccato feeling then breaking the rule is acceptable.”

    However, I also made it clear that we should NEVER shoot at a greater than 180 degree shutter (1/24th at 24fps for example)… That was the whole point of the article! This is one rule I, along with many others, strongly believe you should never break unless you want your motion to look “smeary” and ugly!


  9. Tyler January 9th

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    Alain – I hope you don’t mind but I am using your clip as an example of filming with different shutter speeds! Great job and putting that together, will definitely help people understand :)


  10. peter January 10th

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    hey,
    you don’t have to replace the actual shutter in a motion picture camera to change shutterspeed. most cameras have an adjustable shutter since the 1960’s.
    and the “180 degree rule” is a rule in editing/framing to keep the eye-lines and movement orientaion right, so it’s a little confusing.
    (…just as a trivia, panavison cameras actually use a 200 degree shutter, wich will give you a little extra light. i think they achieved this by having a faster film advance system.)
    really nice articel though!


  11. Tyler January 10th

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    Hey Tyler, great post, this is something I was always wondering about!

    By the way, I sent you an email to your Mac.com email on your Mac.com site (I think thats where I found it). Anyways, I didn’t know if it ended up in your spam box or something as I have not seen a reply in several weeks.

    My email should show up on this post. The email was from me (Tyler).


  12. T. Delerme January 10th

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    Very good article Tyler. I have been trying to figure this out for some time now. I mainly shoot films and music videos and it will work out perfect for me.


  13. Erik Huber January 11th

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    David Kruta is absolutely right regarding shutter speeds with high frame rates, and in the interest of having an accurate article you should address this.
    As an experienced Phantom tech, I can say that there is absolutely no reason to adhere to any “180 degree shutter rule”. For example, when shooting at 1000fps the difference in terms of motion blur between 180 and 360 degrees (or 1/2000 & ~1/1000) is usually indiscernible, however you can gain a full stop by “breaking” the rule.
    As a result, the new Weisscam defaults at the highest possible degree shutter speed to ensure you’re working with as much light as possible.

    Rules are nice for film school students who are jumping into this for the first time, but anyone with experience will be choosing a shutter based on the needs of the project and not based on rules.


  14. Stu January 11th

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    Tyler’s article is accurate — but it’s also an opinion. Erik, you and David might have a different opinion, that the 180º shutter rule matters less for high-speed work — but that’s not an issue of accuracy.

    A high-speed film camera must adhere to the 180º shutter rule, so a high-speed digital camera should also if one desires a film-like motion rendering.

    If high-speed footage is shot with a 360º shutter and played back frame-for-frame at 24fps, it will have that same too-smooth look as 24fps footage shot with a 1/24th shutter.

    So from a perspective of pure “accuracy,” Tyler’s article is correct.

    The truth is that most extremely high-speed footage is sped up somewhat in post, which means that it often has a narrower perceived shutter.

    For example, if you shot 500fps at 1/500, and the editor ran the clip at double speed, it’s as if you shot 250 fps with a 180º shutter. This happens more often than folks tend to think.

    So the opinion that high-speed work need not follow the 180º shutter rule has some basis in experience and reality, but it is not a fact.

    Personally, I always observe the 180º shutter rule regardless of frame rate, and am always happy with the results. I advise folks to do the same.

    But everyone’s entitled to their own opinion.


  15. Jason Wingrove Dir/DP January 11th

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    Yes yes Phantom / Weisscam is one very specialised area where i’ve too seen plenty of ultra high speed work at greater than 180 degrees and had it look quite filmic so yes in this niche area the ‘rule’ can be happily bent.

    However this post is intended to explain the mechanical concepts it’s based on so you can choose to use it as you wish and not to dictate some immovable barrier for all to obey.

    I know plenty of seasoned professionals from the film side, many of whom are neither film students nor first timers. As they all move away from film based acquisition and the mechanical givens those cameras have always controlled for them, all of them subconsciously apply the rule or use it as part of calculations to create effects on either side of it. So suggesting that it’s just a guideline for film students and first timers could be considered insulting, particularly to tyler who took the time to write it.

    Perhaps it shouldnt be called a ‘rule’ as that suggests something to be obeyed at all costs. Regardless, knowing its origins, what makes a film image look how it does and what happens when you bend it is what this post is all about. Thanks for taking the time to post it Tyler


  16. Lalith January 15th

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    Thanks for the information…
    As I concern, If somebody knows, electronics.. its easy to understand this blog…


  17. StreetCar January 17th

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    The bolex doesn’t have a 180 degree shutter, its smaller…just a quick note


  18. Nancy S. January 17th

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    Tyler, your blog is so fraught with inaccuracies it is actually impossible to explain them all in the space provided.

    I wish you had done a fact check on some of the more important details in your comparisons of electronic and mechanical shuttered cameras.

    Any ideal what the maximum shutter angles is on Panavision 35mm film cameras? It’s not 180.

    I can shoot the same shot at 45, 90, 180 and 300 degree shutter angles and get exactly the same temporal motion blur. How is this possible? It’s simple, and when you understand it everything else in regards to shutter angle and motion blur should fall into plac.

    Telling people to only do one thing to never use anything else is the height of ignorance, you should really remove or at least consult an actual expert and greatly revise this blog post before any more harm is done.


  19. Mike Seymour January 17th

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    Nancy – sorry… but you are incorrect. Reducing shutter angle on a film camera will NOT get the same temporal motion blur. Hence the very sharp look in Saving Private Ryan on the beach battle sequences at the start of the film.
    I have shot with a lot of film – as have many of the other great DP and Directors that have posted supporting this post. In fact the comment section of this post reads like a who’s who of film and digital experts.
    But if you would like to offer some further explain your thinking – perhaps we have some confusion of terms? You see quite certain…but as far as the industry standard use of the terms goes… temporal motion blur is VERY much affected by reduced shutter angles in film cameras (and digital for that matter).


  20. Jason w January 17th

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    Nancy. Perhaps your current anti aggresion medication (I recommend respiradone) is in need of a dosage review. Also just checking .. Does EVERYTHING look blurry or just the shutter test footage you mentioned, as this of course could also be a result of poor dosage mismanagement.

    If the recommended dose is still not effective some of the stronger canine varieties have been also known to help
    best
    Jason
    Jason


  21. Michael January 17th

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    ok i heard quit a lot about this 180 degree shutter rule for DIGITAL CAMERAS !!! ;) … and you can see this “effect” notably in all the “new” michael mann films (since ALI) and these michael mann movies use this in kinda artistic way (IMO) but in lot of movies this “look” doesn’t work that good… it looks like it was shot on a 3000 DOLLAR XH-A1 instead of an 200.000 DOLLAR Genesis … ;) (for example) … anyway its a creative and “sometimes” a technical choice you have to make … BUT if you want a film-look you should stick to this rule as well as the choice of lenses, lighting and so on …

    the other side … we shoot a lot of corporate stuff with DVX100 or EX1 or XH-A1 and so on and in the end we don’t care as much about the shutter speed … ok we use mostly 1/50 (germany=PAL=50i or 25p) that is right but if we have to use higher shutter speed (sport stuff / low light situations … and so on) we do – because it’s ok … we don’t need that cinematic look that much … and it’s technically better to use 1/125 or something at that moment. but i wouldn’t too that shooting … lets see …mmmhmm … 2012 ?! ;)

    but in the end it’s a matter of taste and the circumstances … there is no harm for the equipment ore the user … maybe for the viewer;)

    so thanks tyler for that great blogpost …

    oh and all my thoughts are all about the DIGITAL POINT OF VIEW … i have no 35mm experience .. and i’m more in post-production … just sayin ;)

    greetings from germany
    Michael


  22. Tom Dobbie January 17th

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    Nancy,Interesting post,but Tyler,Mike,Stu and Jason are absolutely right.
    Clearly what you see,isn’t what I see,but hey,I’m only a novice,I’ve only been doing it for just short of 30 years,so I’ve obviously missed something.Perhaps you would like to offer some further clarification of the position your taking.
    Regards,
    Tom.


  23. Art Guglielmo January 18th

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    Jeez Tyler. I shot all my home movies at a 180 shutter angle, and now Nancy tells me that was all wrong. All those Christmas mornings of my kids….gone. I knew I should have kept my uncles Super-8.

    Keep up the good work.


  24. Calvin Hey January 20th

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    Interesting read. The thing is, to my eye, the “staccato” effect in Saving Private Ryan, or any other place where a high shutter speed is used, looks like video to me. The first place I ever saw it was with my Sony Handycam in the 1980’s, and you frequently see it in video news footage.

    And that’s one thing I hated about SPR, because it imposed a modern look on something that took place decades before. I’d rather they have gone for a look that was more fitting to the equipment available in 1944.

    In the comparison you linked us to on Vimeo, the leftmost footage looks the most natural. Perhaps it’s just not what you’re used to looking at, because of the limitations of mechanical movie cameras. But when it comes to looking like real life, it doesn’t stutter like footage shot with shutter speeds faster than the frame rate.


  25. Philipp von Kap-herr January 22nd

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    Excellent work, Tyler !

    another ‘Big Respect’ from Germany
    Take care

    Philipp


  26. Captain Obvious January 31st

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    Either call it the “24p/180-degree rule” or it’s Rong(tm)!

    1/60s frames displayed at 24p are EXACTLY as blurry, as frames, as 1/60s frames are at 60p
    ( you just have a lot more of them, a lot less gap between ‘em, and a lot fewer people leaving due to flicker-induced migraines, like me ).

    The *stream* of frames looks smoother at 60p/360, than the horrid 24p/180 does, and gives the same amount of light to the sensor.

    If degrading the view of what was in front of the camera, for archaism, matters to you, you’re probably someone who finds that the Model A ford is better than a modern Jaguar, in all respects, prefer washing your clothes on a washing-board, coal heating your bedroom, prefer dip-nib steel pens, and white-lead makeup, etc.

    24p was the result of technology’s *inability* to work better, not a result of it being visually ideal.
    ( Edison had at least 1 camera running at 48p, iirc, but they couldn’t do sound on it, or something, at that speed, so they crippled it to make it pragmatically functional )

    Someday, the “religion” will fade, and objective quality ( that happens to fit the content .. *sometimes* a migraine-inducing flicker is contextually-correct for the content ) will prevail.


  27. Al February 5th

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    I like your post. Very educational. I myself is coming from a photo background and using the 5D MII. My camera doesn’t allow to shoot below 1/30s anyway. Usually I shoot between 1/40 to 1/60. I still haven’t tried out high speed shooting but I found this article very helpful if you don’t mind me posting.

    http://www.mophojo.com/2009/06/using-the-5d-mark-ii-at-high-shutter-speeds/


  28. enricox March 30th

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    On thing I’m not quite sure for video and somebody could confirm if it is: when using high shutter speed you get more contrast in the shadows, this because the camera has less time to get the light and therefore a simple shadow is darker then at low shutter speeds.


  29. BUY VIAGRA ONLINE VISA MASTERCARD April 1st

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    nice design! :)


  30. Marios Weiss April 20th

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    Wow this is a lot of information thanks you for the post


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Tyler Ginter

I am a Combat Camera Platoon Leader in charge of a team of videographers and photographers who travel the world gathering historical footage for the U.S. Army.