Sony SAL 50mm f2.8 Macro m42 The Nikon DK7 is an

The Nikon DK7 is an eyepiece adapter that allows classic smaller-thread (19mm) accessories to attach to the larger 22mm "pro" thread found on many modern Nikon cameras (check your manual to be sure)

Originally designed for the Cosina/Vivitar 100mm f3

Compact enough for a field camera

with a big electronic viewfinder and convenient dial-based shutter speed and exposure compensation controls

the glass is clean and mechanical function is good

Sony SAL 50mm f2.8 Macro m42 The Nikon DK7 is anThe Sony SAL 50mm f2. 8 Macro is a compact macro lens for Sony Alpha and Minolta Maxxum SLR cameras it's not compatible with Sony Alpha mirrorless cameras unless you put it on an adapter (not included). But if you have a Sony or Minolta Maxxum SLR, this is a pretty sweet lens: not much larger than a standard 50mm lens, but with life size magnification built in. In excellent condition, with clean glass and good function.