Aperture Question II

[Dolby]

Now that I've read a ton of lens reviews (after getting my lens ...), I have a question regarding fast lenses.

Most reviews say a lens is sharper stopped down - so F4 or F5.6 is sharper than F2.8. What is the point if an F2.8 lens if F4 is sharper?

Relating to the above, would getting the F4 version be sharpest at F4 - or would it again need to be stopped down to be sharper?

 

[hilton]

What they mean is that a lens is sharpest when stopped down from the maximum aperture. All manufacturers will try to maximise the aperture designation on the lens they're trying to sell to you. So whilst it may technically go as large as f/2.8 it will possibly be sharpest (best PQ) at f/4 and similar a f/4 lens (like the 24-105mm) may be sharper at f/5.6 but only slightly.

I think this generalisation is less prevalent on the more expensive lenses (Canon L etc).

So to answer your last question, it all depends on the lens and the quality thereof.

 

[Quantum Theory]

Small apertures are for low light and shallow DOF. That is the point...

Makes shots like this possible:

by Philipp Klinger

If you do not need the shallow DOF and have sufficient light, stop it down for sharpness.

 

[Dolby]

Thanks for the replies.

I thought the small aperture was DOF, light AND sharpness - and all 3 would be best at 2.8.

But now I understand