Lens whacking – it's not as destructive as it sounds. So before you go slamming that expensive piece of glass into a hard surface, listen up close.

Lens whacking, also called free lensing, is a method of shooting with the lens detached from the camera body. It allows light leaks, creates a tilt shift focus effect, and adds a dreamlike, vintage quality to your footage.

Watch this video to see lens whacking in action:

That entire video was shot with the lens detached from the camera. The following lesson is written based on my own lens whacking experiences along with this blog post written by lens whacking virtuoso James Miller. James has been whacking lenses for years and does some pretty incredible stuff with the technique. Check it out:

Normally the only light that hits your camera's sensor is filtered through the lens. When you remove the lens, light can hit the sensor from many different angles. If too much light is let in your image will be over-exposed and hard to make out – but if you let just a bit in, you'll get some lovely lens flares and light leaks.

Removing the lens from the camera will also affect your focusing. Depending on how you tilt and move the lens away from and toward the body of the camera, you’ll notice that all of the frame, none of the frame, or only a portion of the frame will be in focus. This is similar to the effect achieved by tilt shift lenses.

This is what you can expect to see, but the beauty of lens whacking is that the results are largely unpredictable. It's possible (and actually quite popular right now) to add light leaks and lens flares after shooting (in post) using overlays. However, I personally find it more fun and fulfilling to create the effect myself, organically and spontaneously, in real time. It's a dynamic form of shooting in which you find yourself moving around, experimenting, and engaging more deeply with your subject.

Equipment

Since you'll be shooting with your lens detached from your camera body, the first thing you'll obviously need is a camera with a detachable lens! A DSLR is a good choice. For this lesson I'll explain the process using Canon cameras with Nikon lenses. But if you have a different setup, you should just experiment and see what works. You can use a camera with a full frame sensor—like the 5D Mark II or III—or one with a cropped sensor like the 7D.

When shooting with a Canon DSLR, it's best to use old Nikon glass (without a Nikon adapter!). Using Canon lenses won't work, as the distance between the rear element and the sensor is too small. The vignetting is too extreme, and the lens just doesn't fit correctly. Nikon lenses are just slightly smaller than Canon ones, so they fit perfectly into the lens mount. Prime lenses are great, as you won't need to zoom.

You can find some pretty nice older Nikon lenses online for around $50-100. James Miller recommends the Nikon E series 50mm 1.8 as a good place to start, for the price of only $50-75. A 50mm lens is great for the full frame sensor, but on a crop sensor that ends up more like a 70 or 80mm. Because you’ll typically want to shoot handheld when lens whacking (in order to move around and experiment more freely), stabilization is a concern. With a longer focal length you can run into issues with wobble and rolling shutter. Therefore, a 35mm lens is a better choice for a crop sensor. However, I did shoot on my 7D with a 50mm lens and didn't find it too difficult.

You may also want to use an eyepiece like the Zacuto Z-finder to add extra stabilization and free up your hands to manage the lens and filter out light.

Method

First, turn your camera to video mode and turn live view on. Make sure you move the lens out of the way when the mirror flips up for video mode.

Open the aperture on the lens as wide as possible, and set the focus to infinity. If the lens is too soft when it’s open all the way, you should close the aperture a step or two. However, it's best to keep the lens open as this will let in a good amount of light. The smaller your aperture, the closer you'll need to bring the lens to the body in order to achieve focus; if the aperture is set too high, you won't be able to whack. In a similar vein, it's best to set the focus to infinity because the smaller your focus distance, the closer you'll need to bring the lens to the camera in order to focus. If you're focusing on something close and find that you have to move the lens too far out from the camera body to achieve focus, turn the focus ring away from infinity.

With shutter speed set to twice your frame rate, and your aperture open, tweaking ISO will be the main way to adjust your exposure.

Using your fingers and wrist, tilt the lens right to left, up and down to achieve the desired look.

If you have an eye piece, hold the lens and camera body with your left hand, hold it up to your eye to stabilize, then use your right hand to filter the light at the top or sides if necessary.

Tips and Tricks

+ Light leaks and flares will appear on the side of the frame that you tilt the lens on. So if you want more action on the right, tilt out on the right. For more fun on the left, tilt out to the left.

+ Sometimes you can rack focus by moving the lens towards and away from the camera body, especially when shooting closeups.

+ When focusing, if your subject moves further away, bring your lens closer to the body. If your subject moves closer to the camera, pull your lens further from the body.

+ Because you're shooting handheld, try to focus on one element and be sure to get long shots. It's fun to experiment, but once you get the right focus or light leak, hold it a while. Don't just capture a few seconds here or there.

+ Use this technique sparingly. You don’t need a huge lens flare in every shot. Simply holding the lens out from the body to the point where the image is in focus will add a nice, subtle wash of light to your composition.

+ Try using light leaks as a transition. In the field, shoot light leaks at the beginning and end of your shots. When editing, start with a properly exposed and in focus shot that ends with a blast of light leak, then cut to a light leak that is slowly brought back in focus and to the correct exposure.

+ If you're worried about dust and dirt getting on your sensor, James suggest cutting a piece of optical quality polyester film like Melinex, or ND filter film, and fitting it into the lens mount hole under the outside ring and above the contact pins.

Now that you know the basics, it’s time to liberate those lenses from the constraints of your camera body and whack away, my friends! We'd love to see what you do with the technique, so when you're finished, add your lens whacking videos to the Lens Whacking Group! To get your creative juices flowing, I'll leave you with a gorgeous video shot by James Miller, the lens whacking master: