Focusing Zoom Lens

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July 12th, 2009 admin Leave a comment Go to comments

Focusing Zoom Lens

Knowing Which Digital Slr Camera Lens is Right for You?

When shopping for a Digital SLR Camera people often overlook or skimp on the cameraâ€™s lenses. Camera Lenses serve as the digital SLR cameras â€œeye,â€ the lens determines what and how your camera will see your subject and how well that view is transmitted to the cameraâ€™s sensor chip for recording. The way I like to look at camera lenses is as painterâ€™s brushes, broad strokes, medium stokes, all purpose brushes, and small detail brushes. There is a lot to learn about digital slr camera lenses and this article will serve as a basic outline to understanding them. The following sections explain the basic types of digital SLR camera lenses, how they work, and how to select them.

Focal Length

On a digital SLR camera the focal length of the lenses measures the distance between the lens and the image sensor, measured in millimeters. Lenses can be classified into subgroups like prime, macro, wide angle, normal, telephoto, and zoom lenses. They are also rated in regards to f-stop or speed an example would be a F2.0 50mm lens or a 1.4F 80 mm lens. We will explain this later in this article.

Prime Lenses:

Prime lenses are fixed focal length lenses like a 50mm 1.4f lens. To zoom with these types of lenses you need to use your feet and to get closer or farther away from the subject. Traditionally prime lenses are sharper and faster then zoom lenses. If youâ€™re on a budget you can pick up some amazing used older prime lenses off eBay or your local camera store.

Macro Lenses:

Marco Lenses are your detail brushes they enable you to get up close and personal with your subject. These types of lenses are used for extreme close ups on small objects like daisies, pennies, and food but not limited to these types of subjects. Examples of macro lenses are 50mm and 100 mm macros. These lenses are also great for selective focus types of photos.

Wide-angle Lenses:

Wide-angle lenses are your broad stroke brushes; these types of lenses have short focal lengths. The short focal length has the visual effect of â€œpushingâ€ the subject away from you and making it appear smaller. The beauty of wide-angle lenses is you can be relatively close to your subject and fit a broad stroke of the background into the scene.

One problem with wide-angle lenses is known as convergence, a distortion that makes vertical structures appear to lean toward the center of the frame. A way to check if the wide-angle lenses you are interested in has convergence is to take test pictures before buying the lens. With high quality wide angles lenses like Canon â€œLâ€ series lenses address this convergence issue well. Examples of wide-angle lenses are 15MM, 17mm, 24mm and 28mm lenses.

Normal Lenses:

Normal Lenses try to mimic how the human eye sees and are some of the most versatile lenses you can use. These are my all purpose brushes, and are somewhere between a wide angle and a telephoto lenses. If you buy just one lens try and buy the fastest normal lenses you can like a 50mm 1.4f lenses. Some examples of normal lenses are 35mm; 50mm, 65mm and some consider a 80mm a normal lens.

Telephoto Lenses:

Lenses with long focal lengths 100mm and higher are called telephoto lenses. A long focal length seems to bring the subject closer to you and increases the subject's size in the frame. Telephoto lenses also give your subjects a graphic look and flatten out your subject. These lenses are my short stroke brushes.

Zoom Lenses:

Zoom lenses are special because they can be very versatile. These types of lenses vary in their focal lengths and come in many in wide-angle, telephoto, and wide-angle to telephoto. In my bag I carry a 17mm to 35mm my wideâ€“angle broad brush, 24mm to 70mm my medium brush, and a 80mm to 200mm my short brush. With these three lenses I get a very board range of focal lengths for any situation. All of my zooms are at least f2.8 through out the lenses range, which means my f-stop can stay constant while I am zooming in and out. These types of lenses are very expensive but so get what you pay for. When shopping for a zoom lenses check out the f-stop range rating. An example is a 24mm to 300mm f3.5-f5.6 lenses meaning the lowest f-stop you can shoot is at the 24mm range of the lenses and when you zoom to 200mm the lowest you can go is f5.6. Zoom lenses can give you flexibility and versatility all in one lenses. When buying a zoom lens try and get one that is made of glass and is the fastest you can afford, you will not regret it.

Understanding what these different groups of lenses can do will help you make more informed decisions on what lenses to purchase and what to put in your camera bag.

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On my 70-200 zoom camera lens when I rotate the focus ring there?

is a "Macro" setting with 1:5, 1:8, etc. How does this work and/or how can I use this feature in taking photos?

So-called 'true' macro is 1:1, which is very close, sometimes referred to as 'life-size'. If you have 1:5, it is one-fifth life-size; if you have 1:8 you have one-eighth life-size,etc. Getting into macro mode is done differently on different zoom lenses. Try taking pictures of flowers; my motto is 'fill the frame'.

Depth of Field - A Visual Guide to the Lens

Canon EF-S 55-250mm f/4.0-5.6 IS Telephoto Zoom Lens for Canon Digital SLR Cameras
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