Dumb Lens Question

Why make a lens that's soft wide open?
What's the point, asks this noob?
If stopping down is required for sharpness, why not just make that the widest aperture?

scantron wrote in post #9546519
Why make a lens that's soft wide open?
What's the point, asks this noob?
If stopping down is required for sharpness, why not just make that the widest aperture?

they don't do it on purpose. someone i am sure will come in and give the technical reasons why.

the last questions is easy. people need the larger apertures.

btw - your username gave me flashbacks to HS.

CosmoKid wrote in post #9546665
btw - your username gave me flashbacks to HS.

Totally! Those tests seemed so futuristic back then.

But I guess my question is what good is the large aperture if it's soft? I had a Canon EF 28 1.8 that was totally soft at 1.8.

scantron wrote in post #9546519
Why make a lens that's soft wide open?
What's the point, asks this noob? If stopping down is required for sharpness, why not just make that the widest aperture?

A. There is soft and there is soft. All lenses are softer at their widest aperture than when stopped down a little, but that doesn't mean they are not delivering acceptable images.

B. A softer image is better than no image.

C. Even if you stop the lens down while taking the shots, the camera doesn't actually stop down until the moment the photo being taken. That means that even if you never actually take a photo with the aperture wide open you (and the camera's auto-focus system) still get the advantage of a brighter view of the scene.

D. All of the above.

Because sometimes a slightly soft optics are sharper than a slightly motion blurred picture.

Ah, yes. It's making sense.

It is hard to make a piece of glass that is as good at the edges as it is in the center. Wide open you are using all of the glass. Stopped down you are mostly using the "sweet" center, better parts.

And one of the main differences between an expensive lens and a cheaper one is how sharp they are wide open. More expensive lens may be out of the reach of some. Plus some people new to photography may not know the diff.

It's because 1.4 just SOUNDS better than 2.2, in the case of the 50 1.4 at least. LOL

But really, sharpness is only one of very many components of an image.