Ok, without taking all day to sort out for the perfect photo, I grabbed a couple of reject shots of birds at odd angles when they were young and cropped them in. I try to stay at this range most of the time as I get the best results and do notice as the birds get more size (these about about 8 weeks old) the scales become that nice even slate. If I select chicks with the light slate at this age, they end up too light in the legs for my liking when they get older.

