Nikon's D70s weakness is in noise control and u would see grain when your ISO is above 800. Not recommended. U see luminous noise. Red speckles.
50mm prime would not allow u to shoot wide. Thus, in restaurant setting, u may not be able to frame a group shot due to space. However, your 1.8 lens would allow u to step down your aperture to approx 3.5 in a group shot and u can compensate with your shutter.
What you need is anti-physics and I have yet to see that feature.