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Pete01's picture
Submitted By: Pete01
Joined: Apr 5 2006
Posts:
Sigma 100-300mm f4 EX IF HSM
Posted: April 5, 2006 - 2:57pm

Hiya,
I was wondering can someone tell me what the "f4" stands for in the lens title and how it relates to the camera?
Is it like the best stop to use the lens with or something?

Cheers peeps!

Pete

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ronk's picture
Submitted By: ronk
Location: Quensbury, NY
Joined: Mar 15 2005
Posts:
#1
Re: Sigma 100-300mm f4 EX IF HSM
Posted: April 5, 2006 - 4:04pm

F4 means that largest aperture that the lens offers is F4.The aperture is the size that the blades of the lens make when they close down to make the picture. The F number is always expresed as a percentage of the focal length of the lens, so that f4 on any lens will allow the same amount of light on the recording media regardless of the length of the lens.
You ight wish to pick up a copy of Kodak's "Joy of Photography" that will explain camera terminology in detail.

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