Some images to illustrate the difference the Sony 1.4TC makes.
A7riii
A1/200-600 comparison with 600 f/4 and 100-500 (with and without TC)
Not possible to get the same detail from a cropped 600mm image - a cropped 600 f/4 image might come close if lighting is poor.
A9 Swallows.
A1 Swallow
