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Old Jun 13, 2008, 4:58 AM   #1
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hi

1. If a lens name doesnt contain IS does that mean it definately isnt Image Stabilised?

2. USM? some say non USM or USM what is it and does it really make a difference?

3. The f stop of a lens, does this basically mean the higher the number the more light it lets in? more always being better i assume.


thanks trying to hammer in that camera technology
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Old Jun 13, 2008, 5:49 AM   #2
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1. If a lens name doesnt contain IS does that mean it definately isnt Image Stabilised?
Correct - No IS definitely means no Image Stabilization in the lens

2. USM? some say non USM or USM what is it and does it really make a difference?
USM: UltraSonic Motor
This feature allow the AF to be faster, but not always depending on the lens construction. It is also silent although how quiet this is also depends on which lens. The most useful feature from USM is this feature allows full-time manual overide of the AF in single-shot mode without having to flip the manual/AF switch on the lens first which makes it more convenient and fast...

3. The f stop of a lens, does this basically mean the higher the number the more light it lets in? more always being better i assume.
Nope - It's the otherway around less is better
Lower number mean more light as this number is a ratio express in fraction, i.e. f/x where x the denominator is the aperture: http://en.wikipedia.org/wiki/F-number
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Old Jun 13, 2008, 6:24 AM   #3
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thanks NHL for that
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