Autofocus is leisurely so its not. In this roundup well investigate the best cameras under 200 available in 2019. Although tamron pioneered the release of the first 150 600mm lens sigma followed suit by releasing two versions of lenses with exactly the same focal.
Sigma Apo 150 500mm F5 6 3 Dg Os Hsm Photo Jack Hoying Photos At
The sigma 50 500mm is something of a specialty lens.
I say this because while a 10x zoom seems like a good investment you really need to have a reason to pick up.