Since they are a niche piece of equipment, not everyone is familiar with what exactly a tilt-shift lens is and what they are used for. Admittedly, I’ve only used them sparingly in my career. Speaking in simple terms, a tilt-shift lens is a lens that allows the optics to tilt and rotate in relation to the image sensor on your camera.
When you take a photo with a standard lens, your lens and the sensor create planes of the same angle. At a wide aperture, everything in front of and behind your focus point will gradually become more out of focus. Using a tilt-shift lens, you can achieve more control over what is or is not in focus by having greater control of your focusing planes, therefore keeping more of the image both in and out of focus, depending on what you’re looking for. It should be noted that there is no auto-focus available on T/S lenses.
You can use this flexibility to achieve a number of desired outcomes. Although on short notice prior to my trip my Canon rep was unable to get me the lens, I was able to rent the Canon TS-E 135mm f/4L MACRO from borrowlenses.com and use to great effect while photographing a king penguin colony on South Georgia Island. By tilting the lens down, you’re essentially moving the plane of lens to be closer to the angle of the the ground and in effect, widening what falls into the range of focus. This allows you to utilize some of the benefits of a relatively lower aperture while still achieving a great deal of detail.
This is just one use and effect achievable with a tilt-shift lens. Even if you’re not familiar with their use, it’s likely you’ve seen photos or even video utilizing the concept. In portrait photography, where a longer lens is ideal to bring attention to the subject and blur the background, a tilt-shift lens can be used to use such a lens in a tight space. In architecture, having greater control over your image plane can be used to combat the distortion that often happens to parallel lines. If you’ve ever seen a photo of a cityscape that looks more like a scale model than an actual city – that’s a tilt-shift lens in action!