Grainy images and nikon d80?

I use a nikon d80 and for some time now all my images have been super grainy. it doesnt matter what i do with my ISO. so NO it is not set to any number above 800.. that was the first thing i checked. its really bugging me does anyone have any suggestions? could it be something to do with my lens? the lens it seems... show more I use a nikon d80 and for some time now all my images have been super grainy. it doesnt matter what i do with my ISO. so NO it is not set to any number above 800.. that was the first thing i checked. its really bugging me does anyone have any suggestions?
could it be something to do with my lens? the lens it seems to do it on is my kit lens, the nikon 18-135 mm...

please help!
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