camera lense Q
Out of context: Reply #10
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- vaxorcist0
The practical meaning is this, an F3.5 to 5.6 lens means you will use a flash more in low light than an f2 or F1.8 lens, because the lens lets in less light at it's most open aperture setting.
Most cheaper zoom lenses make a compromise, they are F3.5-4.5 or 3.5 - 5.6 lenses, whereas non-zoom lenses are often F1.8, and expensive zoom lenses are often F2.8.
In bright light, on a sunny day, you can shoot at F16 and 250th at 100 ISO, in the shade, F8 to F11... any lens will do....
BUT in the shade, or indoors, you may want a faster (i.e. smaller F number, but "larger" aperture)
At F5.6, a lens lets in less light than a lens set to F4 or F2.8 or F2.
At 400 ISO, indoors, you may shoot F2 at 125th shutter, or F2.8 at 60th, or F4 at 30th or F5.6 at 15th. Therefore, your F5.6 lens has a shutter speed that may be too slow, even slow-ish with an image stabilizer.
The other Aperture issue is depth of field. If you want very little depth of field, to get a certain nicely out of focus background look, an F1.8 lens will do this more elegantly than a F5.6 lens, where the background will be less nicely blurry. Depth of field depends on distance and focal length too... if you get as close as possible, and shoot at your longest zoom setting, you will get as little depth of field as your lens can offer if you shoot at the widest (lowest F number) aperture....
A 28-135 lens, if you shoot at 4 feet, F5.6 at 135 zoom, say, for a headshot, the background will be mostly out of focus if it's 10 feet or so away from the subject. If you're using an 85mm F1.8 lens, the background is more easily and beautifully out of focus, even if it's closer to the subject....
sorry for the long note, ... geeky but cool....