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Old Oct 17, 2006, 1:31 PM   #1
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mayby somebody can set me straight on lens apertures, lets use for example the 70-210.

f 4.5-5.6

f 3.5-4.5

f4

the only decent 1s are the f 3.5-4.5 & 4, but what puzzles me is why a fixed aperture f4.

the way i understand it is if it's fixed then you have no variable depth of field & would be limited to shutter speed depending upon amount of light but yet the f4 is the better 1.

but then there's something about the 3.5-4.5 that when you get all the way out to 4.5 it's no good.

100% confused.
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Old Oct 17, 2006, 2:04 PM   #2
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joee wrote:
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mayby somebody can set me straight on lens apertures, lets use for example the 70-210.

f 4.5-5.6

f 3.5-4.5

f4

the only decent 1s are the f 3.5-4.5 & 4, but what puzzles me is why a fixed aperture f4.

the way i understand it is if it's fixed then you have no variable depth of field & would be limited to shutter speed depending upon amount of light but yet the f4 is the better 1.

but then there's something about the 3.5-4.5 that when you get all the way out to 4.5 it's no good.

100% confused.
Quote:
f4.5 isn't necessarily bad, it's just slower than f4. On the wide end, f3.5 can be better than f4. The f4 beercan is way heavier and longer than the f3.5-4.5, and many who own both say the f4 doesn't produce pictures that are all that much better. Most will admit that they carry the lighter 3.5-4.5 for longer walks. Unless your budget is really tight, don't think about the 4.5-5.6.
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Old Oct 17, 2006, 5:22 PM   #3
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joee wrote:
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the way i understand it is if it's fixed then you have no variable depth of field & would be limited to shutter speed depending upon amount of light but yet the f4 is the better 1.
Lenses are rated by their largest available apertures (smallest f/stop numbers). That does *not* mean that you can't use other aperture settings.

You can still use smaller apertures (higher f/stop numbers).

Most lenses can be set to an aperture of f/22 or smaller (a smallest aperture of around f/32 is relatively common with zooms in this focal range).




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Old Nov 7, 2006, 11:32 PM   #4
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constant apr just means it doesnt change when you zoom in........others get darker the closer you try to get........
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