 Louis Fedele |
wide angle telephoto lense on a 18-200mm lense dose the wide angle stay the same all the way to 200
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Pete H |
Hello Louis; No. As you "zoom" in, the (FOV) "field of view" decreases.
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BetterPhoto Member |
Hi Louis; On the wide angle to telephoto zoom question, the answer is no. On a zoom lense, the barrel length may not change, but the movement of the glass elements compensates for the lack ov length. The field of view will be wider at shorter focal lengths, and narrower at longer lengths. A zoom lense set at 28mm will have roughly the same field of view as a 28mm wide angle prime lense. a 200mm prime lense will have the same field of view, roughly, as a 200mm zoom. Well, I hope I've answered your question. Have a great night and keep shooting.
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robert G. Fately |
Louis, I get the feeling you are not asking so much about the "wide angle-ness" of the lens but the aperture - that is, its speed. A zoom lens is simply one designed to have variable focal lengths (that's what the 18-200 stands for). Each focal length relates to what's called the "angle of view" (what Pete has called FOV - the same thing). TO understand this, get a piece of paper and draw a 1 inch tall line on the left side. Then get a ruler and measure to points to the right of the center of that line - one that's 1 inch away and another that's 4 inches away. Now draw lines from the top and bottom of that line through those two points. The lines drawn through the dot 1 inch away will have an angle between them that's bigger than the two lines passing through the dot 4 inches away - this is their "angle of view". Longer lenses (4" is about 200MM) have a narrower angle of view than shorter lenses. The zoom is a lens that can effectively move that point closer to or further from the film (or chip, whatever). When you change from 18MM to 200M you are, by definition, changing the angle of view. Now the other aspect of a lens is it's light-gathering ability, or f-stop (or aperture). Some zoom lenses are made to have a constant maximum aperture - like an 80-200 f2.8. This lens will remain at f2.8 throught its zoom range. Other zooms, for reasons of cost or portability, have variable apertures - when you set them to their wider angle (shorter #MM) setting they my have an f4 maximum aperture, but at their longest setting it drops to f5.6. I hope that wasn't too confusing, and that one of us managed to answer your question.
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Louis Fedele |
Thanks you guys were a great help
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