August 17th, 2010
I am a photojournalist who has evolved into a multimedia journalist and producer. When I work in the field I have a minimal footprint, often trying to do the work of an entire production crew on my own.
Being a one-person-band isn’t preferable and, having spent time working with MediaStorm I am an advocate of working as a team. But, sometimes the budget, location, or story don’t allow for more than one, maybe two people.
Part of a series, this post is intended for others journalists who are shooting, or starting to shoot, video with the HDSLR Canon 5D Mark II. I’m posting because I’ve spent a lot of time researching blogs, forums, and testing through trial and error.
I hope this becomes the one-stop-shop I wish I’d stumbled upon and, as such, I would like to encourage reader comments. What tips do you have? What links, videos, or content pertinent to the post would you like to share? Help us grow in this new world of media production.
However, please note the date of the post. HDSLR videography is a rapidly changing field and this information may soon be old.
Click through the jump to learn more about the 180 degree shutter rule, shutter speed, ND filters, and the “rolling shutter” of CMOS sensors.
(Many thanks to my sweetie for her iPhone picture of me wandering around home figuring out gear).
THE CAMERA SHUTTER
Digital cameras today allow for incredible latitude in image capture, but generally digital cinematographers are trying to mimic the ‘film look’ which is why it’s super cool that Canon released the firmware 2.0.4 for the 5D MKII, enabling 24p. Which is…what exactly?
24p means that an entire ‘frame’ is displayed to the viewer 24 times per second. That’s analogous to a film-based movie camera projecting film at 24 frames/second. For video capture on the HDLSR, your playback speed–or frames per second–is what will determine the shutter speed. This is because of the 180 Degree Shutter Rule, another factor you must now consider when shooting.
As a still photographer, what I know is this: given a set aperture and ISO, the slower the shutter speed, the less light I need, but the more motion-blur I can expect. Also, if I want a given aperture, say f2.8 for a shallow depth of field, but it is bright out, I can decrease ISO and increase shutter speed.
When capturing digital video on the 5D MK II, I can still do all of these things but I don’t want to. If I go too low in shutter speed, I will have visible blur; it’s video that looks like a non-stop, blurry and out of focus still. Having done it, I’ve decided it doesn’t look very good.
If I set the shutter too fast, it looks stuttery, especially with any sudden motion by the subject. A variant of this was used in the film Saving Private Ryan and others, adding to the style and “atmosphere” of the scenes, but is generally unwanted.
The shutter is a semicircle plate, or a half-moon. When film is fed through the gate, the shutter is closed (the solid part of the plate is the shutter, closing the film gate). As the half-moon plate turns to ‘open’ the film is exposed. One revolution is 360 degrees, but only 180 degrees is open for exposure so, if you’re shooting at 1 frame per second, the shutter will only be open 1/2 second. With digital video, the mechanics are no longer necessary, but the rule still applies.
When shooting digitally, if you’re exposing 24fps, 1/48s shutter speed will sync things up right under the 180 degree shutter rule. Any slower, you get motion blur, any faster and things get too crisp and stuttery.
Take a look at Khalid Mohtaseb’s Haiti piece at 01:20. He notes that he increased the shutter speed to ‘crystalize’ the water.
If you can’t push your ISO and you’re already at your widest aperture, you simply need more light. Period. If you’re shooting in bright sunlight but you want a shallower depth of field, you need to invest in some neutral density filters. All of this is so you can keep your shutter speed properly set and obey the 180 degree shutter rule. Think about it like this: you’re in shutter priority mode and it’s constantly fixed at 1/60 or 1/50; the only variables for exposure compensation become aperture, ISO, or a neutral density filter.
The Shutter Speed Cheat Sheet:
For 24p, set the shutter at 1/48 or as close as possible (1/50)
For 30p, set the shutter at 1/60
Which “p” to shoot at? If you like the look of hollywood film, consider shooting at 24p. If you’re working with video from other cameras (point and shoot, helmet cams, HDV cameras) shoot at 30p so your video will play nice with the other camera’s. And if you’re shooting for European PAL then shoot at 25p.
Neutral Density filters
Neutral density (ND) filters block light so, on a bright day, you can shoot at lower shutter speeds and/or lower apertures. For HDSLR video they are essential for daylight outdoor video when you want to control depth of field. Because the shutter speed is set at 1/50 or 1/60, unless you want to shoot at f22 on a bright day, ND filters will be necessary.
Professional video cameras have a switch the operator can flip that applies a neutral density filter to the image capture. For the documentary or reportage shooter with an HDSLR, a variable ND filter will become invaluable.
Tiffen ND Filter Set – you will need to change these out for each change in lighting conditions.
Lightcraft Workshop Variable ND Filter – a cost effective solution. I have never used them, but they state their step-up ring size eliminates vignetting on wider angle lenses. Reported drawback is you cannot fit a Canon lens hood over the ring nor can you adjust the ring very well if you left the hood in place when you installed the ring.
Singh Ray Variable ND Filter – expensive and will vignette on wider-angles (depending on the lens) due to the thickness of the the rings.
CCD vs CMOS sensors and the “rolling shutter”
Something else to know about is the difference between CCD and CMOS sensors. Since this is about HDSLR’s which use CMOS sensors I’m not terribly concerned with CCD’s except to say this: CCD’s capture the entire image at one moment while CMOS sensors “scan” the image; it happens really fast, but the sensor records the light hitting the pixels in the same way you are reading this text ie. top to bottom, left to right.
In a practical sense, what that means is if the camera (or subject) is in one position at the start of the image capture and another position at the end of the image capture, the subject will have a bending distortion. This is most notable when taking a picture of, say, an airplane propeller with the iPhone. If you have one, take a picture of the door frame and move the phone with a little twist as you do so. See a warped image? This is known as “rolling shutter.”
There’s not much you can do about this except to keep your shots as steady as possible, don’t whip the camera around when panning, and be careful with fast-moving subjects. You can also buy some plugins for Final Cut which can smooth things out. Below are some links with further background (note the dates of the discussions as this is ever-changing technology) and note I am not endorsing any one of these products yet as I’ve never used them.
Check out the example of rolling shutter on a helicopter rotor in this piece by Travis Fox at 5:01.
Also, for a more in-depth shutter degree to shutter speed conversion cheat sheet, visit the Pro Video Coalition
Or watch this piece from the 5DFilmSchool on Shutter Degree.
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