I have this problem with my close-up flower shots: if flower color is yellow or white, lots of pictures get blurred in the flower area, as if the yellow flower itself radiates a lot more light back (towards the camera) then the rest of the flower and/or landscape. It looks somehow like I would photograph the boiling core of the sun, without a filter.
Even if I step down exposure to, say -1, the brilliance ratio is still unusually high between the actual flower and the rest. The equipment is Canon EF-S 60 Macro and an EOS 50D.
I thought try using a purple filter to cut some yellow back, but the guy at the store said no, this would only give my photos a purplish hue. He said color filters dont work weel with digital cameras (?).
Sorry for the junky photo, but the engine says max. file size is 150k, and this is the best I could do with my original to shrink it to 150k.