I have a high end Sony digital p&s camera that goes from f/2 to f/8. I'm getting ready to make the switch to digital SLR, but as I'm looking at lenses, I'm concerned that most only go as small as f/5.6.
I use the smallest size ( f/8 ) quite a bit, such as taking shots of moving water with a slow shutter during the day light. In fact, there have been plenty of times when I really wished I could make the aperture even smaller. Is this something I'm going to have to give up if I go to SLR? I'll check out antoni's answer in the other section, but sinec he copped a plea, I'll answer you here in hopes of getting 10 points. (haha!!!)
When you see a zoom lens described as f/3.5-5.6, that means that the largest aperture at the wide angle end of the lens if f/3.5 and the largest aperture at the telephoto end of the lens if f/5.6. This is because the aperture is a ratio of the lens diameter to the focal length. It's not as simplistic as this, but the same size opening for one focal length is going to produce a smaller f-stop value (larger number) for a longer focal length.
If this was NOT a zoom lens, a 50 mm lens set to a 25 mm diameter aperture would be at f/2.0. A 100 mm lens set to a 25 mm diameter aperture would be at f/4.0. Zooms are not so straightforward as this, because of the shifting lens elements and things I don't even understand. I'll have to try to learn some more about this stuff... When they are talking about zoom lenses, they use the term "effective diameter" and I don't know enough about optics to explain that term.
As pjgoros says, the minimum aperture is going to be more like f/22. In fact, I see that the Nikon Zoom Super Wide Angle Nikkor 18-55mm f/3.5-5.6G ED AF-S DX Zoom-Nikkor Autofocus Lens is more accurately described as an f/3.5-22/5.6-38 lens. Get it? At the wider angle lens, the ratio is from f/3.5 to f/22. At the tele end, the ratio is from f/5.6 to f/38. Glad to help. They don't make it easy to understand, do they? ;-) Report It
I think maybe you're confusing that f5.6 with some zoom lens' maximum aperture at the long end. dSLR lenses will stop down to at least f16, some will go to f22, some even to f32. refer my answer to this question in photography
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