Last week I talked about the first of two “180 degree” filmmaking rules: the 180 degree line. Today I’m going to write about perhaps the most commonly broken rule that I’ve noticed among professional videographers, in particular DSLR filmmakers: the 180 degree shutter angle rule. I think most people break this rule because frankly, they just don’t know about it. I have to admit, until I started shooting with DSLRs and educating myself on how to properly shoot with it, I didn’t know it. I knew what was considered the “normal” shutter speed setting for my camera (1/60 sec), but I didn’t know why. I hope this post will give you some insight into this rule, and help give you a better idea of when it’s a good time to break it, and when it’s not. [Note: if you want to read an excellent article on the history and math behind the 180 degree shutter angle rule, read Tyler Ginter’s post.]

THE WHY: PROPER MOTION BLUR

Plain and simple, the reason for the 180 degree shutter angle rule is to have proper motion blur. The rule states what your shutter speed should be set to relative to the frame rate of your camera. It’s very simple to figure out. Just double your frame rate. If you’re shooting at 30 fps, you shutter speed should be set to 60. [Note: this really represents the fraction 1/60th of second, NOT 60. But camera settings normally just use the denominator. Also, as a side note, this 60 should NOT be confused with the 60i reference to a media format. When someone says they’re shooting in 60i, the “60” here actually refers to the number of interlaced fields. For every frame in a 30 fps shot, there are two interlaced fields, one odd and one even. So, for 30 frames, there are 60 interlaced frames, thus 60i. But that’s a blog post for another time.] If you’re shooting at 24 fps, your shutter speed should be set to 48. However, as far as I can tell, most DSLRs don’t have an actual 48 shutter speed setting for video. So, use the closest one: 50. If you’re shooting at 60 fps, your shutter speed should be 120. And so on.

If your shutter speed is too fast or too slow, your won’t have proper motion blur. If it’s too fast, you get that staccato look popular in Ridley Scott battle scenes in “Gladiator.” If it’s too slow, the footage will look very soft and dreamy. Most DSLRs can’t go below a setting of 30 in video mode; but if you have a traditional video camcorder, you can probably go as low as 1/15 or or even 1/8. At shutter speeds that low you get that dreamy streaking look.

RULES ARE MEANT TO BE BROKEN – SOMETIMES, NOT ALL THE TIME

Okay, here’s where I may ruffle some feathers. I cannot believe how many DSLR videos I’ve seen that totally throw the 180 shutter degree angle out the window. Where it seems like every single shot is at a super high shutter speed. I see it a lot in the wedding cinematography industry, and I’m not sure why it’s so popular. Now, having shot weddings for a number of years, I know there are times when artistically a high shutter speed works great. It’s popular to use on fountains to make the droplets of water look like diamonds falling. Or if the guests are throwing rose petals in the air or something, that high shutter speed staccato look can be kind of cool. But, I see it used for people just walking across the street, or hanging out in a bridal suite. For my taste anyway, it seems a bit over done.

Now, to be fair, I know that in many circumstances, a high shutter speed is used when it’s super bright outside and the filmmaker is using a high shutter speed to compensate. A high shutter speed means less light is coming into the camera, and thus it’s a “trick” you can use if it’s too bright outside and you don’t have a neutral density filter to cut down the brightness. (Traditional camcorders have them built in, but for DSLRs you have to physically attach a filter). If you don’t have an ND filter, then ideally you should just stop down and adjust your aperture (i.e. instead of shooting at f5.6, shoot at f8, f10, or even–”gasp”–f16 or higher).

Now, I know precisely why DSLR shooters DON’T want to do this. The smaller your aperture (i.e. the bigger the “f” number), the deeper the depth of field, and heaven forbid if you shoot a DSLR with a deep depth of field. Here’s a newsflash people: not every single shot HAS to be a shallow depth of field. Look at classic, timeless movies like “Citizen Kane” or “It’s A Wonderful Life.” They aren’t filled with a bunch of hyper-shallow DoF shots. In fact, many classic and contemporary films don’t use that hyper-shallow look. I know lots of DSLR filmmakers are just ga-ga over the shallow DoF you get with these cameras, but IMHO it’s way over used. There are other aspects of the visuals that will give it that “film” like look besides DoF (e.g. the color grading, composition, frame rate, etc.)

Here are some tips when I think it makes sense to break the 180 degree shutter angle rule.

Depth of Field: as I just mentioned, sometimes you’ll want to increase the shutter speed to help you attain a shallow depth of field. If it’s super bright outside, stopping up to f2.8 or or f1.4 will totally blow out the visuals. Increasing the shutter speed will reduce the light and compensate for the brightness. There are times when you really do need that shallow DoF and this is a good way to do it. Just don’t go crazy.

Low Light: sometimes you may be in a setting where the light is pretty low and so using a slower shutter speed will let more light in, helping out. Depending on your camera, this will give your image more of a “dreamy” look. When I shot with traditional camcorders, I’d often shoot at 1/15 or slower because I wanted to get those dreamy streaks. I also used to shoot regularly at 1/30 at 30 fps instead of 1/60 because it gives a softer, more film-like look to traditional video. 1/60th is very “video” looking.

Epic battle scenes: if you’re shooting epic battle scenes, you may want to use faster shutter speeds to get that staccato look. (I don’t know how many times this may actually come in handy, but at least have it in your arsenal of knowledge.)

If you have other examples of how you break this rule purposefully, and why, please share in the comments.

VIDEO EXAMPLE – “TARANTELLA”

Below is an example of where I used a high shutter speed for a very specific purpose. I’m producing a promo video for an amazing concert pianist in San Francisco, CA by the name of Heidi Hau. For her promo she played the frenetic piece “Tarantella” by German composer Franz Liszt. The story behind the piece is that if you’re ever bitten by a tarantula, you have to do a crazy and hectic dance to rid yourself of the poison. I used a high shutter speed when recording part of Heidi’s fingers to 1) emphasize the frenetic nature of the piece, and 2) to make her fingers look like crazy tarantulas dancing on the keys.