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Documentary in Motion: Basic Slider Techniques

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This post is part of a series called Documentary in Motion.
How to Use a Jib to Add Motion to Your Documentary
Documentary in Motion: Advanced Slider Action

Sometimes a pan gives you a decent camera movement, and other times you want something with a little more flair in your documentary. At its most basic function, the camera slider delivers a side to side movement that is dramatically different than a pan, in that the camera moves through a space, which changes the perspective. Most importantly, the slider reveals something as it moves, which makes it an important tool in your storytelling tool belt.

For example:

 

Establishing Shots

Often you’ll see sliders being used as establishing shots. Perhaps as the camera slides from outside a door frame and into a room, revealing a subject. In this way, the viewer can feel like they’re watching the subject from a distance, like a voyeur (but in a good way). If you want to shoot an establishing shot like this, you don’t always need to be outside a door frame. You can use any foreground, such as a table, or cabinet, or a column. 

A foreground is imperative to the slide, especially when you use a wide lens: otherwise the camera’s movement may be completely lost to the viewer. And if you use a medium to telephoto lens on a slider you’ll need to be a little more strategic with placing the camera if you want there to be a foreground. That may involve adjusting your tripod way below your normal operating height, or simply placing your slider very prominently behind an object that can serve as a blurry foreground. I also recommend shooting the establishing slide with multiple focal lengths, and in both left and right directions. That will give you the most flexibility in the edit. 

Man sitting at work bench

When you choose an establishing shot, you also want to think about the camera perspective in relation to the subject. Are you revealing the subject’s back, while they’re at work on something we can’t see? Or are they facing the camera? A side perspective, or 3/4 profile, can be a great medium between the subject facing away or toward the camera. Just imagine if the camera was a person, looking upon the subject with their face away from you… it kind of feels like you’re sneaking up on them. That can be good, if it makes sense for your documentary story.

Add Motion to Static Objects

Establishing shots are not the only time you’ll want to use a slider on a documentary. In fact, it’s sometimes not essential to add camera motion to scenes where there is already some kind of motion. But when there’s absolutely nothing moving on screen, that’s precisely when a slider can be most effective. 

In many documentaries, a part of a subject’s story is best told with photos and objects, especially if that part of the story takes place in the past. Looking around your subject’s home or workplace, or wherever you’re shooting, you can usually spot a few framed photos, personal objects, posters, refrigerator magnets, books. Take a moment to shoot those pictures and objects at different focal lengths. Now in your edit, you can easily put together a few little sequences of slides that help push the story forward.

Too Fast and Too Long

There are a lot of scenarios where a slider can add style to your documentary shot list, but it’s important not to get too carried away. No matter how long your slider is, or how much action is in the scene, a slider shot that moves too fast or goes on for too long is an instant story killer. It attracts attention to itself and away from the story. 

How do you know when a slide is too fast or too long? It’s an instinctual feeling you get when you watch or edit a film, but trust me, you know it when you see it. To me, anything longer than four or five seconds is too long, and the slower the better.

Slider Choices for Documentary

Just like the decision to bring a jib to a documentary shoot, knowing when to take a slider with you is often based on the portability of the slider you own. Details matter here: the first time it takes you a long, frustrating 20-30 minutes to set up one slider shot, you’ll maybe decide then and there to never bring one along again. 

That’s especially true if you could be shooting so many more shots during the time it takes to setup one slide shot. If your slider takes you only a couple minutes to setup, however, then you may start to get excited by its possibility and want to use it as much as possible. It’s easy to get carried away, so even if you hit upon the world's most perfect, portable slider, try to keep your slide shots in moderation.

Cinevate Duzi slider and Edelkrone pocket slider
Two solid slider options for documentary makers: a Cinevate Duzi slider and an Edelkrone pocket slider.

So what makes a slider more portable for documentary shoots? For one, sliders typically come in at two to three feet, sometimes longer. But honestly if you can find a shorter slider, or modify or build one yourself, you won’t miss the extra track length. Essentially, if you can move a camera slow enough on a slider, you realistically only need about four to six inches of a slide to achieve a four or five second shot. Of course when you use the entire slide track, you have more options in your edit. Still, you don’t need a lot of track. There’s even a slider out there that has six inches of travel, marketed specifically to “carry only the most frequently used part of your slider.”

In addition, the very center of the slider is more useful than the far ends of the slider. That’s because when you place the slider on a tripod, the far left and right side of the slider will have some “flex.” Different components of the tripod, fluid head, and quick release plates all have a little bend to them, and when you slide a camera across the slider track, you’ll often see the horizon shift as the slider bends. So on a 36” slider, if placed on a tripod, you may still only use the center 12 inches for most of your slide shots. 

But it’s not just the size of the slider that makes it more portable and likely that you’ll use it on your documentary. The slider’s ability to provide friction, to introduce some kind of drag that slows your slide down, is the single most important feature that can make or break a slider on a documentary shoot. Without friction, it’s nearly impossible to achieve a consistent speed as you’re pushing your camera down the slider track. 

Cinevate fly wheel on a Duzi slider
The fly wheel on a Cinevate Duzi slider.

If you slide faster, the speed inconsistencies are less noticeable, but as mentioned above, fast slides are quite distracting in most videos (unless you’re shooting in slow mo; more on that in the next tutorial). The one problem with built-in friction pieces is they often make sliders heavy, expensive, and cumbersome. So if you want something relatively lightweight to bring on your documentary, look for sliders that have a “fly wheel” or fluid friction, but at reasonable weights and track lengths. 

Alternatives to Using a Slider on a Tripod

If you have a quick release system, it’s quite easy to click in a slider onto your tripod, your camera onto the slider, and you’re ready to go. But because of the propensity for horizon flex, it’s sometimes better to find an alternative source of support for a slider. That’s where light stands come in. If your slider has the right mounts on the ends, you can simply drop the slider onto light stands, adjust the heights so that the track is relatively level, and you’re ready to go, using equipment you’ll most likely already have with you on a documentary shoot.

Video camera and slider on light stands

Alternatively, you could simply place the slider on whatever flat surface you can find, be it a floor, table, countertop, etc. For uneven surfaces, sliders that have “all terrain” legs are an easy solution for leveling the slider. One thing to remember is if you’re placing the slider directly on a surface, you’ll want to attach a fluid head or ball head on top of the slider so that you can adjust the camera’s tilt and pan angle. 

For me, I prefer to place my slider on top of a tripod/head, which allows me to adjust the framing and not have to carry an additional fluid head around just for the slider. In this way, along with the quick release system, I’ve been able to add slider shots on most of the documentary shoots I’ve been on, without carrying much additional gear. If you are hoping to achieve more advanced slider shots than simple side to side motion, however, you’ll need that extra fluid head or a ball head after all. We go into more details on advanced slider movement in the next tutorial.

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