Fast lenses?

[Morag2]

Hey all, at first when I heard the term fast lens I assumed it meant shutter speed. However, I have now learned that shutter speed is based on the body, not the lens.

So I have gathered that a fast lens has a wide aperature... why is this considered fast where as narrow aperatures are slow? Does it still refer to shutter speed because you can use faster speeds with a wide aperature.

[hoodsa]

youre pretty much right:-).I think a wide aperture is called a fast one because it lets in more light therefore resulting in a faster shutter spped:lol:.

[Hawgwild]

Morag2,

I have been using slr cameras since 1971, and have a number of prime lenses of between f1.4 and f2, and although I have always referred to them as fast lenses, I suppose you could also refer to them as bright, as opposed to a lens with a max aperture of,say f4. When looking through the viewfinder, the bright lens will give you a brighter view than the f4 lens at wide open aperture.

Back before open- aperture metering came along, all metering had to be done at the working aoerture. Imagine trying to focus on something at f16. We have truly come a long way...

Cheers,

Robert