It's the Nikon 50mm f/1.8 prime lens. It retails now at $100-$200, but when I purchased it, it was $99.00. It was the best advice I received when I first started getting serious about my photography.

Zeiss Ikon 50mm f/2.0 Makro Planar ZE MF Macro Lens (Canon EOS-Mount)See price on Amazon.com Zeiss 50mm f/2.0 Makro Planar ZF Manual Focus Macro Lens for The Nikon F AI-S Bayonet SLR System.See price ...