Just got this on Thursday and tried it out on an outdoor cat. I'm stuck at home most of the weekend so I wanted to see what it was like with the 1.4X extender. Again all I had to shoot was a cat. I think it work for our purposes.
No reason that I can think of that it was ISO 500
This is an older 400DO, date code UR (2003)
1.4XIII
Full Frame
Crop
Crop and Sharpen
Comments, Suggestions, Slams are all welcome, what ever makes you feel good
The Crop-Sharpen version looks pretty good. Very similar to what I'm seeing with the Sigma EX 120-300/2.8 OS + 1.4x III, but different FL, of course. I expect a 500L would be noticably better (mine is compared to the 120-300 OS), but it's a much smaller, lighter alternative, which provides totally acceptable results for most situations.
I've seen a wide range of reports from 400 DO users with regard to the performance of the lens with a 1.4x. Some have been quite pleased with the results, and others have not.
Over the years since I bought my 400 DO, I've tried using it with 4 different 1.4x converters. Two were Canon 1.4x II converters. One was a Canon 1.4x III, and one was a Tamron SP 1.4x. With one of the Canon 1.4x II converters, loss of image quality was significant. With the other Canon 1.4x II, with the Canon 1.4x III, and with the Tamron SP 1.4x, loss of image quality was minor and somewhere in the same range that I've come to expect from using a 1.4x with my 500/4. Further, the hit on focus speed with the 1.4x is relatively small provided that the lens' focus limiter switch is set to shorten the focus range.
Thus, my conclusion is that variation in image quality of the 400 DO with a 1.4x is likely the result of differences in how well the particular copy of the 400 DO matches up with the particular copy of the 1.4x. I would also guess that a carefully done micro adjustment can minimize any loss in image quality.
I have no issues with or without a 1.4x converter.
As mentioned above, you'll simply need to focus adjust your 400 DO with and without a converter.
Again, the images of your cat are not the best test of your lens with all that harsh lighting. Would be nice to see your exif.
The first three images are without a converter, the last with mark II converter. I can't see any issues when I use my 1.4x
For small birds, you will be challenged unless you can get about 15' away from the target.
Looks great for your settings. I think you are seeing harsh glare.
When the light is strong, I drop in a circular polarizer to mitigate some of the effects. Then as the sun wanes or I am in shadow I put in the standard UV filter so as to not unnecessarily lose precious light. Highly recommend the polarizer if you don't have one yet.
