Adapting APS-frame lens to full-frame camera may generate vignetting, which is not caused by adapters (some cameras could correct it by adjust APSC). On the other side, Adapting full-frame lens to APS-frame camera provides excellent edge-to-edge sharpness. The smaller image field helps minimize the effects of lens distortion and aberration by using the 'sweet spot' or center of the larger lens image circle. And it will magnify the focal length by 1.6 on Canon, 1.5 on Nikon and Sony, 2.0 on M4/3 camera. 

No, it's a manual adapter without electronic contacts, doesn't support autofocus/auto diaphragm/aperture control 

Don’t forget that it’s a manual lens adapter. Works with full manual lenses. If your lens has no physical aperture ring, you cannot control it from your camera 

No Allen wrench comes with the unit and I did not need one. Mine did not require any adjustments and fit like a glove. 

Hi, this adapter is for Canon EOS mount lens to Sony E NEX mount camera, we checked the sony a 7iii camera mount is E mount , this adapter can fit it , but you can reconfirme it , thanks. 

Yes, it is indeed Nikon f mount. 

Hi, this adapter is for Canon EOS mount lens to Sony E NEX mount camera, we checked the sony a 7iii camera mount is E mount , this adapter can fit it , but you can reconfirme it , thanks.