What is meant by a lens being faster???

So I have read that a lens that is xx-xxxmm f2.8 is faster then a lens that is say xx-xxxmm f4.6. Now I understand that on your camera you can set the focal length to control the depth of field f4.1 is a shallower DOF then f8.0 would be. But when the focal length is being talked about on a lens and people are saying its faster or slower im confused.

Could anyone clarify this for me? Thanks

It means you have a larger maximum aperture, allowing you to use a faster shutter speed in given circumstances than one with a smaller max aperture.

"Faster" means "larger maximum aperture" (smaller minimum f-number) which means it lets in more light when opened up to its lowest-numbered f-stop.

Faster means more expensive..

Todd Lambert wrote in post #13575106
Faster means more expensive..

this.

RTPVid wrote in post #13575099
"Faster" means "larger maximum aperture" (smaller minimum f-number) which means it lets in more light when opened up to its lowest-numbered f-stop.

This...

Todd Lambert wrote in post #13575106
Faster means more expensive..

Inexorably followed by this...

Hahaha spot on with that Jay!

removes bank funds faster (as mentioned, more expensive)

There was an old saying when I raced cars, "speed costs money, how fast you want to go......" well seems it applies to camera lenses as well.

Thanks guys, this seemed to be one of those situations where I have all the peaces but just missed the obvious.

i wonder
Why they dont make all the lenses at f 1.2 or f1.4 and even f1.8 ?
All of us we need to make a photos in low light at night , indoors
Why they made mixes of lenses hahahaha
I will become crazy
For only 6 months i spent 12000 $ on lenses
Buy and sell buy and sell buy and sell
Sure i am crazy

moltengold wrote in post #13575276
i wonder
Why they dont make all the lenses at f 1.2 or f1.4 and even f1.8 ?
All of us we need to make a photos in low light at night , indoors
Why they made mixes of lenses hahahaha
I will become crazy
For only 6 months i spent 12000 $ on lenses
Buy and sell buy and sell buy and sell
Sure i am crazy

cost
weight/size

look how big is a 70-200 2.8. look at the size and price difference in the 85 1.8 vs 1.2

picture a 70-200 1.2.....lol

When I get asked this question, I break it down like this (and I'll credit Bryan Peterson's "Understanding Exposure" book for this logic)...

The aperture of a camera lens is measured in f-stops - the smaller the f-stop number, the *larger" the opening for light to pass through.
That was the confusing part for me...

So, if the sensor of a camera needs a certain number of units of light in order to create/expose a photo, then a lens with a larger opening (the f/1.8 above) can let in more units of light per unit of time to develop a picture than the f/4.6 lens.

Take it a step further and consider ISO, which is the sensitivity of the camera's sensor to light. The higher the ISO, the more sensitive to light the sensor will be to that incoming light, but a higher ISO can also result in more pixel noise (aka picture graininess).

What a slow lens typically means to the people I talk to is that that they will likely be very unhappy trying to snap their indoor sports photos because their slow lens cannot let in enough light to allow for a faster shutter speed (to stop action) and lower ISO (to minimize noise).

faster all has to do with shutter speed. If you have a fast lens it will give you the same exposure with a faster shutter speed. That gives you shallower DOF and less blurr from subject or lens movement while the shutter is open.

Faster = Simply able to gather more light.