3 Tips for Dealing With Rolling Shutter
DSLR video has improved dramatically over the last few years, but rolling shutter is still an issue. Deal with it using these three tips.
No one likes the look of rolling shutter artifacts. They’re a pesky side effect of shooting on DSLRs (or other cameras using CMOS sensors) and have the potential to ruin otherwise fantastic footage. Rolling shutter issues can plague footage in any number of ways, but most often by causing a horizontal skew when whip panning, or the “jello effect” when shooting on long lenses (or handheld). Here’s an example of the jello effect:
Rolling shutter skew is simply a result of the speed at which a frame is scanned and captured on a CMOS sensor. Unlike global shutters, which capture an entire frame all at once, a rolling shutter will scan the frame from top to bottom, leaving room for visual artifacting in the frame.
In other words, the top and bottom points of any given frame are not captured at the exact same moment, which is why images can appear skewed under certain circumstances.This can be seen in the image below.
Image from Engadget
You might wonder why more manufacturers don’t use global shutter sensors on their cameras, and there are a number of reasons for this. In a nutshell, there is usually a tradeoff in terms of performance between rolling and global shutters. A rolling shutter has issues with skew and distortion (as touched on above), but can have better low light performance and dynamic range.
On the other hand, the global shutter may never be able to achieve the same DR as its rolling shutter counterpart, but it would perform much better for handheld work, action scenes, and visual effects work.
Image from DSLR Video College
VFX shots in particular can be very challenging to deal with when working with footage suffering from rolling shutter artifacts. For a VFX artist to do their work best, they need to be able to accurately track footage and match 2D/3D elements to the source footage – which can be a huge challenge when the source material isn’t stable enough.
But even if you aren’t doing VFX work or shooting action sequences, you still need to be careful when shooting on a camera that is prone to rolling shutter problems. A handheld shot using a long lens can turn into complete jello under the wrong conditions, and the skew associated with any number of shooting situations can be a huge distraction in the editing room.
The good news is that there are ways to offset the rolling shutter issues associated with many CMOS sensors. Here are three of the simplest ways to work around it:
Use a Rig
Image from 2355 Productions
This first point applies most specifically to micro-jitters, which can be an issue with nearly any camera, but can be exaggerated by rolling shutter.
Using any sort of stabilizer or rig will always be your best bet when it comes to minimizing micro-jitters. Obviously a tripod or monopod can work perfectly in most instances, but for handheld work things get a bit trickier. As you might imagine, using a shoulder rig is one of the best ways to eliminate rolling shutter (or at least reduce it significantly), but it needs to be set up just right.
I have used some DSLR rigs that didn’t have enough counter weight or just weren’t built well enough to absorb some of the shock that would cause micro-jitters, and ultimately they weren’t much better than actually holding the camera. Rigs that are heavier but still well balanced are an absolute must for even the most basic handheld work.
Alternatively, you might want to consider a small gimbal-based stabilizer like the Movi M5 (pictured above) or a device like the Nebula 4000. Or, if you are unable to use a rig for any reason, the next best thing would be to use a stabilized lens. Any lens with built-in image stabilization will decrease rolling shutter artifacts substantially, but a well-balanced rig is always going to give better results.
Know Your Angles
Image from GSI Engineering
Sometimes knowing how not to use a tool is just as valuable as knowing how to use it. Every camera has its limitations, whether in the areas of dynamic range, sharpness, detail, color accuracy, or otherwise. If your particular camera struggles with rolling shutter, then sometimes the best option is to work around its limitations and avoid shooting in situations where the camera is going to have issues.
One example of this might involve shooting a moving train. If you were to point your camera at a train that is moving horizontally from screen left to screen right, the image would be very skewed, even if you weren’t moving the camera at all. Just like a whip pan, the sensor would be unable to read the entire image at once and would therefore cause a horizontal skew in the image.
While you’re on set, the only option you have (other than shooting on a different camera) is to change your angle. Instead of shooting head on, you could opt to shoot from a 3/4 angle or any number of other positions that would help you avoid the skew entirely. It may feel frustrating that your creative choices are limited, but knowing your limitations will always help you get the best results and avoid issues down the road.
Fix It in Post
Image from the Connecticut School of Broadcasting
The term “Fix It In Post” has become a cliche at this point, but when it comes to rolling shutter, sometimes it actually is the best option. Depending on the severity of the rolling shutter artifacts, you may be able to fix the image during post-production by using any number of different plug ins for various NLE systems or compositing software. There are dozens of options out there, so I would recommend doing a quick google search to see which tools work best for your camera and software combination. Here’s a video tutorial from TheHowToMac that demonstrates how to reduce rolling shutter in Final Cut Pro X.
With all of that said, I would never rely on fixing your rolling shutter in post. The best results will always be achieved by avoiding rolling shutter artifacts in the first place. But if you are in a sticky situation, it’s great to know that there are some editing tools that can help you deal with these problem shots. If you’re interested in more info on shutters, rolling or otherwise, check out these articles from the PremiumBeat Blog.
- FCPX Video Tutorial: How to Fix Rolling Shutter
- How to Repair Rolling Shutter in Adobe Premiere Pro
- How Do Camera Shutters Work?
How do you deal with rolling shutter issues? Got any tips for your fellow filmmakers and videographers? Share your thoughts in the comments below.