Hi, I want to purchase a fast lens. What makes a lens fast? Is it the number of photos you can take per second? Or that it focuses more quickly?

Can anyone recommend any fast lenses as well? Thanks.

I think that the number of photos you take per second will be more determined by the camera body itself (given that everything is in focus and right conditions and all that )

So I guess you'd be looking for a lens with a large aperture, that way you can have faster shutter speeds,and hence take pictures faster!
On the canon zoom lenses, the largest you can get (mostly on the L series lenses) is f/2.8... and they are quite expensive!


I think that what makes a lens fast is how fast it focusses and the maximum aperture you can obtain.

Heh as Adam said a "fast lens" is one with a large maximum aperture, the majority of the pro lenses have the fastest aperture in their class with most being f2.8 the lower the aperture number the more light it lets in making it faster. Focusing speed is in part the job of the lens but also partly your camera body.

What make of Camera are you buying for? Do you want a zoom lens ie 24-70, 70-200 etc or a prime fixed focal lens like a 24, 28, 35, 50 etc?

Jamie

Technically you can't make a lens fast, unless you attach a rocket on it or something .

If you want a fast focusing lens you could try the USM lenses, or if you have more money to spend you can go for the L series like how Adam mentioned above. Also Prime lenses tend to focus faster than zoom lenses. This is all in with respect to the auto focus function. Maybe you can practice to focus faster on manual??

If you're looking for fast shutter speeds, then naturally choose a lense with large apertures like f/1.8 or f/2.8. These will allow you to take photos at high shutter speeds without under exposure to a degree, depending on lighting and shutter speed.

If you're looking for a lense that can take alot of photos in a short period of time, then the main factor is not the lens itself, but your actual camera. The lens will allow you to take high shutter speeds without under exposure, while your body will be caching the photos taken. So it all depends on what camera you have if you want a rapid firing camera.

Question for mop39: if you don't know what a fast lens is, then how do you know that you want to purchase one?

http://www.shuttertalk.com/forums/viewtopic.php?id=666

Thanks everyone for helping mop39 out..

I think, as adam StudioJ said -- people often refer to"fast" lenses as those with a large maximum aperture, which gives them better low light performance.

If you're after focusing speed, some manufacters (e.g. Canon) make lenses that have faster/quieter motors. For Canon, look for the USM (Ultra Sonic Motor) lenses.