if your tamron 28-75 lens is 49mm, the two filteers can work for your lens , Please verify your camera's lens thread size(usually marked somewhere on the lens barrel or printed underneath the lens cap) before ordering.The number is always preceded by a "ø" (diameter) symbol the two lens difference is the stops 

Nikon-NEX you are asking, as long as your lens is a AI mount, then fits. 

EOS-FX,You can use Canon EOS EF / EFS Lens on a Fujifilm FX Mount Camera body,, Your canon ef 75-300 1:4-5.6 is canon EF mount lens and fuji x-a3 is X mount camera body. so the adapter ring fit for your camera and lens. but pls notice, your lens is telephoto lens,we do suggest you could use one telephoto lens bracket that could be attached to the tripod to increase its stability. because the canon lens could not adjust aperture,so suing our adapter ring could not adjust aperture 

K&F have a list of which adapter will work for each lens to camera combination they support 

if your tamron 28-75 lens is 67mm, the two filteers can work for your lens , Please verify your camera's lens thread size(usually marked somewhere on the lens barrel or printed underneath the lens cap) before ordering.The number is always preceded by a "ø" (diameter) symbol the two lens difference is the stops