what does this mean?

[DCBarner]

I bought this lens:

Canon EF-S f/ 3.5-5.6 IS DSLR Lens 18-55mm

What does the f/3.5-5.6 mean?

I understand the f stop numbers but does that mean I'll only be able to use fstops between those numbers? I thought the aperture was in camera. This may be a dumb questions, but I would like to get things straight. Thanks

Dane Barner

[RLucas]

It simply means that at the wide end (18mm) will give you a wide open aperture of f3.5. At the narrow end, your maximum open aperture will be 5.6. If you turn on your camera, and look through the viewfinder. Start at the wide end with your max aperture setting, and slowly zoom to the narrow end, you should see your camera stopping itself down to 5.6.
That is all those numbers mean.
Hope this helps!

[DCBarner]

So will I be able to set an aperture opening larger or smaller than the numbers indicated?

[teaking]

when fully zoomed in you will only be able to go as low as F5.6, but when fully zoomed out the lowest F stop will be F3.8 I think there the numbers you used lol.

The hightest F stop is youe guess for that lense but there your lowest at the two ends of the lense. Just turn the dial and see what F stop it goes up to witht he lense on.

[dcclark]

Yes, you can always set an aperture smaller than the numbers indicated. For example, you can always set f/8 or f/16.

The numbers quoted are the largest possible apertures available at 18mm and 55mm (respectively). Most lenses "stop down" very far, usually at least to f/22 or f/32, but the numbers that most people interested in are how far they "open up" (that is, how big the aperture can get, to allow in the maximum amount of light). So, lenses quote the maximum available aperture. As you zoom, that maximum aperture gets smaller due to the inner workings of the lens.

[DCBarner]

I'm sorry forgot to say thank you! THANK YOU! I'm still trying to remember that a larger f stop is a smaller opening. I'll get it.

Dane

[dcclark]

DCBarner -- it might help to think of an f-stop as a fraction -- after all, we do write it f/8 and f/16. Remember that 1/8 is BIGGER than 1/16, which is exactly true for apertures as well.