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Video:Camera: Lens Overview

with Chris Davis

DSLR cameras can be used with a variety of camera lenses that can greatly change how a seemingly similar photo will appear. Watch this About.com video to learn more about digital camera lenses.See Transcript

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Transcript:Camera: Lens Overview

Hi I'm Chris Davis for About.com.   Camera lenses come in a variety of sizes and options.  Let's review some of the most common options of camera lenses.

Understanding your lens will help you take better photographs. Although each lens may be designed differently, there are many elements that are universal effecting image quality, focal length, perspective and so on.  The easiest way to start is to look at your lens.  Most of the information you will need will be listed right on the side.  A couple of key numbers you should understand will represent focal length and aperture.  

Camera Lens Focal Length

On your lens the number or numbers followed by mm tell you your focal length.  If it is a single number than you are using a fixed lens which it doesn't have any zoom capabilities.  Where as two numbers will represent the range in which the lens is capable of zooming.  This lens for example has a range of 18 to 135.  As you rotate the zoom ring your focal length is changing, zooming you closer to your subject.  Wide angle lenses have short focal lengths, while telephoto lenses have longer ones.    

One advantage of a zoom lens is that you can get a variety of compositions without lens changes.  Some advantages of prime lenses are cost, weight and speed.  And a good prime lenses will provide a better light-gathering ability which is great for low light situations and a greater depth of field.

Camera Lens Aperture

The aperture controls the amount the lens can open up or close to let in more or less light.  The aperture will be printed on the lens usually as a ratio 1 to 2.8 for example on this fixed lens or as a range of numbers such as this zoom lens, 1 to 4 -5.6.  The reason for the range is that as the lens is being zoomed less light is capable of entering the lens thus changing the aperture capabilities.

Another feature you may see on a lens is the AF/MF switch.  This will allow you to change between auto focus and manual focus in which case you will use the focus ring.

Stabilization on Camera Lenses

Additionally you may have a lens with stabilization capabilities.  This is a feature that you can turn on or off. Stabilization in a lens provides optical stabilization by adjusting elements in the lens to assist in eliminating camera shake.  Optical stabilization is superior to digital stabilization offered in many cameras which adjusts the image on the actual sensor which can degrade the image.

If you are just starting out It's recommended to equip your DSLR with a reasonable zoom lens.  Something like this 18 to 135 lens will allow the capability to shoot both wide angle and zoomed shots.  Furthermore you will still be able to adjust your depth of field and potentially shoot some macro shots.  As you progress in your photography you will want to add a fixed lens such as a 50 to 60 mm lens that are great for shooting portraits.


To learn more check us out on the web at About.com.  Thanks for watching

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