Railroad Track Photoshoot

I use a Nikon D80 for most of my work if not all.  I have a nice nikkor 18-138mm lens that does the job well but doesnt get the sharpness that I really want.  I also have a speedlight that I use to light up certain things.

I was using my friends 50mm 1.8 lens today and got some decent result.  This is urging me to buy a nikon 50mm 1.4 lens for my camera.