lens sweet point

[derrycity]

a silly question
people talk about the sweet point on thier len's how do they determine this point.

 

[Nawty]

You take photo's and have a look

If you want to be tediously anal about it you could mount the camera on a tripod and take pictures of a wall at different apertures, you then analyse the pictures for corner sharpness etc...

 

[HoppyUK]

Have a look at the lens tests on places like http://www.the-digital-picture.com/ and www.dpreview.com

You will invariably find that images are sharper in the centre of the frame, and at mid-range f/numbers like f/5.6 or f/8.