AF Studio lense for D800, around 50mm

Hi,

I currently own 2 zooms (24-70 and 70-200) bought in the last few months as well as a few old primes from my film days. I am not a pro at all but I started also enjoying taking pics in an 'ok'  equipped home studio. Taking mostly pictures for friends and family.

I would like to buy some 'around 50mm' prime that could make a visible difference in sharpness compared to the 24-70 2.8. Any recommendation for an AF lense?

Thanks in advance

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FTD5