Dear Folk, I'm wondering which Vivitar flash unit would work with my Graflex, wi th 150mm in Copal 0 or 250mm in Copal 3. I've never used a flash before, and so I don't know how they are rated. Is it for distance or broadcast coverage? Somew here I read that Vivitar makes a reliable unit; I can't remember if it was their 383 model or 3700? Any advice which would "illuminate" the subject for me would be much appreaciated. By the way, is there a virus in my computer? or what's wi th the quasi-political stuff that seems to attach itself to the bottom of these discussions? Best, David