A camera without a lens is like macaroni without cheese, a ship without sails, Simon without Garfunkel... you get the point. Your lens is an important, multitasking gadget, allowing you full control over a variety of aspects to your shot. Aperture, focus, and focal length are all dictated by this handy device. But don't take our word for it! Camera guru, Vincent LaForet is here with Blake to show us the basics on what lenses do and how to pick one that is best for your project. Check out the video below!

Aperture
The aperture is the diameter of the lens opening. The larger the diameter of the aperture, the more light reaches the film or image sensor. The aperture also performs a critical function for focus. As the aperture decreases in size, the background and foreground gain sharpness. This zone of sharpness is called the depth of field.

Aperture is expressed as F-stop and will be indicated on your camera in abbreviations that look like this: F2.8 or f/2.8.
The "F" stands for the focal length of your lens, and the number indicates the diameter of the iris opening. (For a more in-depth explanation, head over to this lesson!)

Focus Ring
Located around the barrel of your lens, this helps you focus the image. Some lenses will also have an auto focus switch, which means that your lens can do the focusing for you on those days that your eyes are feeling a little tired.

Prime or Fixed Lens vs Zoom Lens
A prime lens has a fixed focal length, whereas a zoom lens has a handy ring that allows you to switch to different lens equivalents within the single lens. But don't knock prime lenses entirely! They may be less versatile than a zoom, but they often have superior optical quality, are lighter weight, smaller bulk and cheaper.

A Lens for Every Occasion!
Various lenses are suited for specific applications. Lets have a look at some common lenses and what they do.

16mm- An ultra wide lens, this bad boy distorts heavily, emphasizing objects in the foreground by making them look a lot larger than the background. Dynamic, but use with caution!
28mm- Standard for documentary and photojournalism to shoot cowboy shots, otherwise known as medium shots.
35mm- Another standard for documentary filming, also tight enough to shoot portraits.
50mm- Standard for cinema/video, it approximates the human eye's typical focal length.
85mm- A popular portrait, or "beauty" lens. Capable of making everyone look lovely!
200mm- The top of the scale for most people, this is a telephoto lens. Their inherent shallow depth of field makes them useful in eliminating unwanted foreground and background objects by simply throwing them out of focus. Great for sports photography!

Now that we've had a friendly overview, let's take a closer look at the wonders of focal length and what that means for your video. Onward to Episode 2!

Check out the other episodes in this series:

• 
  Behind the Glass Part 1: An Introduction to Lenses

  Join Blake as Vincent Laforet explains the world of lenses. Learn how to distinguish…

• 
  Behind the Glass Part 2: Focal Length

  Focal length is a critical element of lens selection. Watch and learn as Vincent…

• 
  Behind the Glass Part 3: Depth of Field

  What do a barbarian and an astronaut have in common? They both want to teach you…