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A Review?
One of my old zoom lenses had f = 28mm - 80mm. When the lens was set
at 50mm and I looked through the lens at an owl with one eye,
and kept the other eye open, both eyes saw the same size owl. There
was no magnification. The ratio was simple - 1:1. Any setting
above 50mm, brought the owl closer or zoomed in. Anything above 50mm
is called telephoto. Any setting below 50mm allows you to see more
through the lens and is called wide angle. If you had a 200mm zoom
lens it provided 4 times (4x) telephoto, or the same as walking 4 time
closer to the owl. |
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| Why the confusion? I hope this is easy. f : The lower case "f " stands for focal length, and is the distance between the lens and the 35mm film in the camera or the electronic digital chip in your digital camera. Zoom lenses can vary this distances by physically moving the lens. It is used to define the amount of wide angle or telephoto of a lens. Because digital cameras use a variety of sizes and types of electronic chips, the focal lengths need to be converted to the old 35mm equivalent numbers, if we want to talk about and compare wide angle and zoom. |
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| f = 7.2 - 28.8 ? These are the numbers on one of my FujiFilm digital cameras. It's advertised as a 4x zoom camera. The user's manual provides the 35mm equivalent to approx. 32.5mm - 130mm. Simple math shows that 7.2 x 4 = 28.8. But that's not 4x telephoto as understood in 35mm photography terms. It's only 2.6 times telephoto (130mm divide by 50mm = 2.6). A Minolta DiMage 7,
advertised as 7.1x zoom (28mm- 200mm) gives less telephoto than a Fuji
FinePix 6900 with 6x zoom (35mm - 210mm). True the Minolta
provides more wide angle; but if telephoto was what you were concerned
about... |
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| Digital zoom? When I bought my first couple of digital cameras, I used to say that digital zoom was a useless feature, and should be turned off if your camera allowed it. You could do a better job on your computer if you wanted to crop a photo and make some portion larger. Now, having more mega pixels to work with, digital zoom may be a useful function if you understand when to use it. I also tell those considering their first digital camera that you don't even need a computer today. Some may not even want to use a computer; but just want the ease and fun of using a digital camera. I've taken and printed digital zoom photos and have been quite pleased with the results.
When and where?
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