Hallo all. I conceed that this may be a very silly question but bear with me. I was looking at second hand nikon lenses on ebay recently and I was struck by the various descriptions given by sellers when describing the glass on the lens. In particular, glass which have very minor grazes on the front of the lens. One seller wrote that a certain amount of markings on the glass exterior was acceptable and would not appear on the photo; grazes on the glass exterior at the back of the lens barrel ie opening into the camera body, were more significant and detrimental. The seller's observation started me thinking: is there an acceptable level of marking on the front lens that will not appear on the finished photo? I would be grateful for any wise words. Cheers M.