05-06-2011, 07:43 AM
[quote name='Klaus' timestamp='1304663233' post='8091']
Well, so we've got a mediocre lens and then try to make it look better again ?
[/quote]
From a Physics class that I had years ago: when two samples are very far apart, get one more in the middle to get a better idea of how the curve goes.
Mediocre depends on how you use your lens. Many photographers compose their pictures to put the subject according to the rules of thirds and borders/corners only have sky or out-of-focus stuff. So dismal sharpness in the mid-areas is a no-go but can be less important in the borders if the subject (like portraits) allows it.
When the test show good border sharpness, we know it is OK too in the mid-areas. But in the case of the Sigma, we're not sure of how fast the performance drops from your test. Maybe reading MTF curves would be better then.
Well, so we've got a mediocre lens and then try to make it look better again ?
[/quote]
From a Physics class that I had years ago: when two samples are very far apart, get one more in the middle to get a better idea of how the curve goes.
Mediocre depends on how you use your lens. Many photographers compose their pictures to put the subject according to the rules of thirds and borders/corners only have sky or out-of-focus stuff. So dismal sharpness in the mid-areas is a no-go but can be less important in the borders if the subject (like portraits) allows it.
When the test show good border sharpness, we know it is OK too in the mid-areas. But in the case of the Sigma, we're not sure of how fast the performance drops from your test. Maybe reading MTF curves would be better then.