I have a 4x5 negative which I would like to contact print onto another sheet of 4x5 film to get a transparancy. I'd like to use HP5+ film, which is fairly fast (box speed 400 ASA). I plan on using my enlarger as the light source. To figure out the exposure of the contact print, can I just use a spot meter on the baseboard of the enlarger and place that in zone IX? Am I better off using an incident meter?