I use a Nikon D300 DSLR it has a DX (½ frame) sensor. I'm thinking of buying a used 50mm prime lens to use as a portrait (short telephoto) lens. I'm figuring the crop factor will give it that field of view. My question, will using a lens designed for an FX sensor on a camera fitted with a DX sensor effect the aperture (F stop)? Will I need to compensate when the camera is set to manual, using a hand held flash meter in a studio?