Jippy11 wrote in post #16755067
I had all but convinced myself that the Canon 400mm f5.6 was the lens I wanted and needed for my photography, (Wildlife, mainly birds) then I see a few reports on the Tammy 150-600mm, which are quite good, so now I am thinking again, is there that much of a diffence in IQ, I understand the different apetures and AF differences, my main query is with IQ.
It is to be used with a 7D.
Two different tools.
A prime 400L is sharper, faster, autofocus is faster, it will be a superior image from a technical stand point. But it's only 400mm.
The 600mm Tamron will be less sharp (but not soft), not as fast, autofocus not as fast, so it's overall technical image quality might be a touch less. But this is from a pixel peeping stand point. If you look at the images of the birds people are doing with the Tamron, it's quite superb for it's cost and the images are great. You have to consider the 200mm difference, which is a BIG difference.
Bottom line: If you want 600mm, wait for the Tamron, order it and wait a few months.
If you want to get the in-between, and not wait, then look to the Sigma 50-500.