I am so impressed with this lens! My copy is sharp at F/2.8 and I cannot tell the difference when stopped down, unless I really look close at 100% crops. I will show some crops later in this blog.
Also with the 1.4 II tele-converter I cannot tell the difference between F/4.0 and stopped down, inless I put it at 100% and really look hard. That is a hell of an achievement. Just absolutely amazing to me. Especially after using the old 300 IS and the Sigma 300 mm F/2.8 prime.
At this point I am not going to test it with the 2x tele-converter because I do not have the III and my copy does not flatter this lens IMO.
So next time in Bangkok I will pick up a 2x III and run a test.
Something else I think I should mention is. This lens optically is a carbon copy of my 500 II lens as far as I can tell. I have run some pretty intense chart tests and it is clearly up to the 500 II IMO.
The 500 II is also an amazing lens with and without T.C.'s Wide open it is as sharp as it gets and with the 1.4 I can see little to none, drop in sharpness.
I like bird tests. It is my hobby. And what I judge a lens by. So enough talk. Here are a few pics. This bird stayed still for me today and I purposely picked this spot for the rather tame birds. It is a water treatment plant in Thailand. Leam Pak Bia.
All of these shots are hand held except for the 500 mm lens which I used a bean bag on my window in my pickup.
This first one is 300mm II cropped some and sharpened.
With the Mark IV if the birds are very small or very far away. The 500 II just cannot be beat. There is no substitute for size.
The 300mm II lens is light weight, easy to handle, and takes T.C's very good. But it is painfully expensive. If your main target is birds. Then you will be using a T.C. most of the time. To get the focal length you really need, you need to add a 2x T.C. which makes things a little sticky for me.
With the price so ridiculous for these lenses. The 500mm II is the clear winner here IMO. At F/5.6 you have 700mm FF with the 1.4. You retain reasonable AF. With no loss of sharpness. And the weight is very manageable.
Personally I am getting older now. And can see when the 300 II will be my primary birding lens without a doubt. But not now!
Here is a shot with the 500 and a 1.4 T.C. It is tack sharp. Click on it for a larger view.
Birding is a great hobby. Get out and enjoy it.