doduce wrote:
Maybe this is dumb question, but were I to buy a FX 35mm lens and use it on my D7100, would it perform the same as a DX 35mm? In other words, would the FX lens still be a "DX nifty fifty?" My gut says YES, but .......
The FX 35mm f/1.8 is designed to produce a good image on a full frame sensor, while the DX 35mm f/1.8 is designed to make a good image only on a DX sensor. Almost all lenses have better image quality at the center, and worse at the edges. With the DX lens, the images at the edges of the DX sensor will be a little weaker than the center. With the FX lens, the DX sensor isn't recording the edges with the weaker part of the image, so the recorded image overall will be better.
The clincher is the prices: the Nikon 35mm f/1.8G DX is $200, while the Nikon 35mm f/1.8G FX is $600. A little more expensive than a "DX nifty-fifty", which is what I would call the first lens.