DSLR Mechanics

In Roald Dahl’s James and the Giant Peach, the young James is given a bag of crystals with the promise that “marvelous things will happen; things even you never dreamt of.” With this gift, a world of endless possibilities and wonder was soon unveiled to James— an experience analogous to the gift of the DSLR camera with video capabilities.

With these cameras, the cinematic world of depth of field is now at the fingertips of photographers and filmmakers alike, and at reasonably affordable prices. Additionally, the film look of aesthetic quality blur aka, bokeh, that consumer level filmmakers admired was now available for their creative vision. But what is the story behind these cameras? How do they work? Let's investigate!

DSLR is an acronym for digital single-lens reflex. What that means is actually pretty simple. With various pieces of glass, a mirror, and a prism, light is guided through the camera and then out the viewfinder for you to see. This is great for composing images since what you end up seeing in the viewfinder is not an approximation, it's the same light as what you'd capture when you press record.

Let's follow the sexy DSLR cross section diagram above for reference. Light enters through the lens, then bounces off a mirror to the pentaprism, which then reflects the light around until it's sent through the viewfinder and finally to you, the viewer!

When you've decided that you're ready to record here's what happens, the mirror swings upwards and the shutter opens for a period of time (depending on the shutter speed) allowing the light to be projected upon the camera’s image sensor. While the mirror is flipped up, the image in the viewfinder is blocked resulting in a viewfinder blackout. Whilst using your camera for video, the mirror is perpetually in this upward position resulting in a constant viewfinder blackout, but don’t worry because you can still check your image with the LCD on the back!

Photo via Wikipedia

When the Nikon D90 and Canon 5D MarkII were released in 2008 as the first video capable DSLRs, filmmakers were gifted with the power to obtain incredible control over how they captured images, leading to a reawakening of aesthetic beauty in low budget films. Hopefully now that you understand the basic principles of how light is captured with these cameras you'll be inspired to try them out.