Fast lens .... What What?

[Sheiky]

I'm confused.

Don't worry, you'll be fine []


First of all, ALL lenses are slightly/heavily sharper once stopped down. Not only big expensive ones.

Dont we pay more for those low numbers??

Yes we do! But it's not only the low numbers but other factors play a big role as well. Colors, contrast, build quality. Sharpness is not the main factor in a lens...thank God []

I'm understanding, lately, that most lens are best around f8 .... give or take a couple of stops either way.

Depends on what you think is best! Maybe most lenses are sharpest at this aperture, buy it doesn't mean that a portrait shot at f8 is at it's best []

Somebody explain why we would pay nearly two thousand dollars for a low f stop lens when, if we get a better pic around f8, we couldnt be better off with a bottomed out f4?[img]/emoticons/emotion-7.gif[/img]

You're right and wrong here. First of all, most people don't spend nearly 2k on a fast lens, but when we do, we get better pictures at lower apertures like f4 f5.6 etc.


You must also keep in mind, that you are talking about overall sharpness. For a lot of photographers center sharpness is more important. And those guys/girls don't need to stop down to get a better picture. The fast lenses you mention are most of the time very sharp in the center and only improving sharpness at the edges when stopped down.


Oh and I can promise you that a canon 17-55 f2.8 gives you a better picture at f8 than a canon 18-55 kit lens at f8. If you don't count sharpness as the main reason of a good picture.


Hope you're less confused about now. Otherwise good luck! []


Jan