ITPete

I keep looking at lenses in hopes I'll find something not too expensive in order to expand the range of lenses. I currently have the Canon XTi with the 18-55 kit lens. I have been looking at some of the telephoto lenses and am confused aboout the aperture setting that lenses have. If I remember right, aperture is the size of the opening in the lens to allow light in, but I don't know what to look for in this setting when shopping for a lens. Do I look for something with the widest range in this number or do I look for a lens with the lowest/highest number? Anyone able to school me on this please?

Also, has anyone here baught used lenses from B&H? I found a couple Tamrons I might be interested in, but don't know what kind of questions to ask when calling about the condition.

.:Chris:.

As far as aperture goes, you generally want something that opens wide (ie. F/1.8, F/2, F/2. if you can afford it. If you see F/4-5.6 (common in telephotos) then that means at the widest focal length (ie. 70mm on a 70-200mm lens) the lens will open to F/4, but at the longest focal length it will only open to F/5.6.

Hope that gives you a bit of insight. If you're still confused, lmk and I'll explain further when I have time.

HoosierDaddy

You confused me.

Mars_302

the lower the number the more light is let in. Its due to physical limitations of the lens barrel. thats why you really only see 2.8 or even 1.8 in the higher end models and you will pay for it.

The number represents the minimum opening the aperture will do at its shortest and longest focal length. If you read the specs on the websites they will lit the maximum and minimum. A lot of the times it wil be list like f4-f22 or f32

HoosierDaddy

I was thinking the higher the F# the more light is allowed in.