Zoom Lens
How do I work the magnification of a zoom lens for a DSLR camera?
I recently got a Canon EOS 400D digital SLR camera, and I am me more time to upgrade to the lens with a zoom. However, separate lenses are new to me, so I am struggling to find out to which lenses are more than any other figure. I was hoping someone can tell me how you can work either from the strength of the optical zoom on Canon lenses, or give me suggestions of lenses, to . consider Any help is greatly appreciated. Thank you, Martin.
You already have two good answers, but I have it in the box at all times, so here you go. My answer adds a little visual aid. There is no lens-to-distance equation. When we talk of a "35-mm-equivalent", a 50 mm focal length is approximately "normal" View without magnification. For most DSLR's, the lens factor of 1.5-1.6 means a "normal" focal length would be about 31-33 mm. If we return go on a 50 mm "normal" lens then would be a 100-mm lens, a "2 power" lens, 200 mm would be 4X, and so on. Just divide the smaller number In the greater number and you get the "X" power of the lens. For example, a 35-80 mm zoom lens is 2.3x. Divide 80 by 35 and you will be the result preserved. 35-80 mm zoom lens is 2.3x. Divide 80 by 35, and you will get the result. Normally it is better to know what the focal length of a lens in "35 mm equivalent" and judge that, rather than relying on the "X" power of the lens. Thus, most point and shoot cameras start at 35 mm and have either a 3x or 4x zoom. This makes it would be an 35-105 or 35-140. I have some that start times at 28 mm, though. A 3-fold from 28 mm 28-84 and a 4X 28-112. Neither is a particularly strong telephoto lens and the 4X is about the same as the 3X that was initially at 35 mm. It is also important to recognize that the tradition prescribes that lens focal lengths, usually in the form of "35 mm are equivalent to the expression, "where" 35 mm "refers to a 35-mm film camera. This is because of the relationship between the sensor and the actual size Focal length of the lens and the resulting angle of the lens. I have a Point & Shoot which is actually a 5.8-24 mm zoom. This is a 4X zoom. The 35 mm equivalent 28-116 mm. The sensor is 7.2×5.3 mm. (1/1.8 ") (And I wish I knew someone who could explain the how the hell they are with sensor size terminology!) I, another point & shoot that is actually a 5.7-17.1 mm zoom. This is a 3x zoom. The 35 mm equivalent 34-102 mm. "How could a shorter focal length give a longer 35 mm equivalent? "you might ask. It is because the sensor is only 5×4 mm. (1/2.5") I have a few Nikon DSLR, and – luckily – they all have the same size sensor. They all have a "lens factor" 1.5. This means that you frequently represents only the actual focal length of the lens to the 35 mm and then you can get accurate comparisons of the camera make-to-camera. Most of Canon, for example, have a lens factor of 1.6. On a Nikon DSLR, a 28-mm lens "35-mm equivalent" of a 42-mm lens. On most Canon DSLR's, the same 28-mm lens is the equivalent of a 45-mm lens. This example is only to show how freaking confusing it can all be when you try to mind the "X" power to make a zoom lens. Bottom line … Check the 35 mm equivalent specifications for the lens. In this way you will be leveling the field and compare apples to apples. More or less. I Here is a mini-tutorial I compare myself to focal lengths. This is NOT a lens test or test a camera! It is just to show the difference between various focal lengths. The lens was the Nikon 18-200 VR lens, which (by definition) an 11X lens, is that to say, but not 11X, which will look like the final image. I added a frame with a 300-mm lens taken. The camera was a Nikon D200, so there is a 1.5X "crop factor", "lens factor" or "focal length multiplier." There is further explanation on the image itself. It would help if you click "All sizes" above the picture. http://www.flickr.com/photos/7189769 @ N04/476181737 / This was done with two different lenses: the Nikon 17-55 and 70-300: http://www.flickr.com/photos/samfeinstein/1245831147/
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