 David Archibald |
Lense question..... I want to thank everyone for the advice that they have given me. I noticed in my January edition of Popular Photography that there is a NEW BLACK Canon EOS Digital Rebel. I couldn't find a price so I guess that I will have to call. I was going to buy a Canon EOS Rebel (film) but was going to settle for the two-tone colors but I have to buy the Digital Rebel now. Also I have some questions on lenses and specifications (numbering). Let me know if I am right or wrong. A 28mm - 90mm lense will have a range of 1.10236 ft. to 3.5433 ft. ? (based on 1 Milimeter = 0.03937 ft.) A 80mm - 300mm lense will have a range of 3.1496 ft. to 11.811 ft.? Are the price tags on these lenses worth the price for the amount of distances you are able to achieve with these lenses? Also I will look on the internet for more information but what is an f/stop and what is it for? What does it do? Dave
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- Gregory LaGrange Contact Gregory LaGrange Gregory LaGrange's Gallery |
11ft? That's not what the millimeters stand for. Those are the focal lengths of the lenses, not a distance for the range of the lens. The f/stop is the apeture or opening inside the lens. There are apeture blades, also called the diaphram, that adjust to make an opening bigger or smaller to regulate the amount of light going through the lens. Just like the pupil and iris of your eye.
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Jon Close |
1 millimeter = .03937 inches, not feet. Focal length is a measure of the distance from the film plane to a theoretical point in the lens. Modern lens construction with multiple elements results in lenses with a physical size unrelated to focal length. Most xx-300mm zoom lenses are much shorter than 300mm (11.8 inches), while 28mm and shorter lenses sit more than 44mm away from the film plane. More important is that focal length tells us the relative angle of view that the lens will provide. Longer focal lengths give narrower angle views (and hence bring distant objects "closer"), while shorter focal lengths give wider angle views.
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David Archibald |
Ok with all of that information said..... How do you determine how far in distance will the lense be able to shoot to? Maybe I'm not asking the right questions. Hmmm. I would like some lenses that would take some good/great close-ups (not macro) and some that I can get some great close-ups from a distance? Sincerely, Bummed and Bemused
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Jon Close |
There may be some esoteric exceptions, but all camera lenses will focus to infinity (and beyond!). The close focus (macro) ability is given in their specifications. If you want to relate the view of a distance subject to the "power" rating of binoculars/telescopes, then divide the focal length by the film frame diagonal. For 35mm film that's 43mm but 50mm is commonly used, so 300mm focal length is roughtly equivalent to 6x binocular.
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