I am in need of a longer focal length and I can't currently buy a +400mm lens so I have decided to purchase an extender/teleconverter for now. I have two lenses on which I will use the TC. The first lens is the Sigma 120-300mm f2.8 Sport (the latest model) and the teleconverter will probably spend his whole life on this lens. The second lens that I might sometimes use it on is the Canon EF 70-200mm f2.8L IS II. I have been looking at the Sigma and Canon 1.4x and 2x teleconverters and I cant decide which one to get...
My concerns for the Sigma is mainly how it will affect the AF speed and if it would work with the Canon lenses. The second concern is the image quality. I know teleconverters reduce image quality but how much of a difference is in the image quality between the Sigma and Canon TC???
Then there is the issue of what magnification to buy. I'm leaning more towards the 1.4 but there are scenarios that the 2x magnification would be really useful.
What are your thoughts, suggestions and experiences? Help me out here :)
P.S I'm a sports photographer so I need fast AF on my lenses. And the camera I have are Canon 1DX MK II and Canon R6.