The 1.4x TV is a well build product. Works great with the 70-200mm and 200-600mm lens.

I don't do a lot of Wildlife Photography, but when I do the 1.4 TC provides 40% extra reach to the 100-400 GM and 200-600 G lenses. It's not cheap but it is well constructed and performs well for a TC.

I bought this 1.4 teleconverter about a month ago and the magnification and light loss are what I was expecting. I use it with my 7RIII and 200-600mm zoom for birding. All three are new to me. So, I am still experimenting with camera settings.

Amazing for birding with the 100-400 and the A7RV. Found that the focus grabs quickly, and tracks well.