Parts of an SLR (Single Lens Reflex) Camera

Lens & Shutter

The Lens: The lens is a piece of glass or several pieces of glass installed in a barrel that actually bends the light rays that reflect from a subject and focus them on what’s called a focal plane where there is a CCD or a piece of film which can register an image.

The quality of the glass and the sophistication of the way the lens is designed contribute greatly to its effectiveness in making a sharp image. Most lens glass is corrected for aberrations and colors depending on whether it is designed for digital or film use.

Naturally, the better quality of glass and manufacturing process, the more expensive the lens.

The Shutter: The shutter is the mechanism that controls the time that the lens will be open to admit light and therefore make an image. Shutter speed times can vary from one minute or more to a 2000th of a second or shorter. The shorter the time the shutter is open, the more action is “frozen” in the image created. The longer the shutter is open, the more blurry the image.

The Aperture: The aperture is the mechanism that controls how wide the lens is open. It is measured in what is called “f/stops.” An f/stop is a measurement of how wide the lens is open. The numbers usually go from f/2.8, f/3.5, f/4, f/5.6, f/8, f/11, f/16. Each “stop” represents ½ the amount of light that reaches the focal plane. So, if you “stop down” the aperture by one stop, you are letting in half the amount of light.

The Shutter and the Aperture ring control the amount of light that the camera lets in to create the proper exposure. They work together and can be manipulated to achieve various effects.

Don’t forget, if you have questions, leave a reply and I will answer them as quickly as I can.


William Lulow