For my use, the Sony 100-400 mm GM is ideal
It is not my intention to be right or to try to influence others in their decision making. I am simply showing images based on my subjective experience with this lens. Maybe it will help some people to make the right decision when choosing a telephoto zoom lens.
I have to mention that "birding" is not a priority for me at all. When I have the opportunity I try to get some good pictures of it, but I never go out with the intention of taking bird pictures. For die-hard birders, the 200-600 seems to me to be a better compromise, as long as size and weight aren't a big issue.
I bought my 100-400 in 2018, long before the 200-600 was released. Later, a colleague lent me the 200-600 for a test drive. But I didn't really test it, because as soon as I got my hands on the 200-600, I decided that the much lighter and more compact 100-400 was the best compromise for me, regardless of any quality differences. You also have to bear in mind that I live in the mountains, in steep to very steep terrain, and at 72 I am no longer the youngest of men. In other words, weight and size are important in my particular case!
Also, I am still very happy with the 100-400 and the TC1.4 has not disappointed me. Of course, it's possible that I'm just very lucky with my combination and that the two work so well together.
Here is a series of test shots I took with the 100-400mm GM lens and the TC1.4 teleconverter. All but one were taken with the aperture wide open. And all but one were taken with the TC1.4. See the EXIF data for details. All images were handheld and all of them are 1:1 crops. I'll let the photos speak for themselves.
I have to mention that "birding" is not a priority for me at all. When I have the opportunity I try to get some good pictures of it, but I never go out with the intention of taking bird pictures. For die-hard birders, the 200-600 seems to me to be a better compromise, as long as size and weight aren't a big issue.
I bought my 100-400 in 2018, long before the 200-600 was released. Later, a colleague lent me the 200-600 for a test drive. But I didn't really test it, because as soon as I got my hands on the 200-600, I decided that the much lighter and more compact 100-400 was the best compromise for me, regardless of any quality differences. You also have to bear in mind that I live in the mountains, in steep to very steep terrain, and at 72 I am no longer the youngest of men. In other words, weight and size are important in my particular case!
Also, I am still very happy with the 100-400 and the TC1.4 has not disappointed me. Of course, it's possible that I'm just very lucky with my combination and that the two work so well together.
Here is a series of test shots I took with the 100-400mm GM lens and the TC1.4 teleconverter. All but one were taken with the aperture wide open. And all but one were taken with the TC1.4. See the EXIF data for details. All images were handheld and all of them are 1:1 crops. I'll let the photos speak for themselves.
Very short minimal focus distance
We should also consider the possibility of quasi macro shots due to the extremely short minimum focus distance.
The bearded vulture
If a bearded vulture suddenly appears... you'd better act fast!
The two latest test pictures
More Examples
Most of these were taken without the TC. For general nature photography I don't need the TC most of the time.