Rich, for a long time that manufacturers of exposure meters know that you can change a reflective meter into an incident meter when you add a diffusor dome on the reflective meter's lens. So they produce exposure meteres in this way. Gossen Luna Pro is just one example of the technique. It works. How come they didn't put the same diffusing dome on a spot meter? Well, they have a good reason not to do so. Read my posts in this tread again and maybe, maybe you will understand the reasons.