Posted 05 February 2013 - 04:15 PM
Always hard to tell from a photo, but I have had deposits like this before and have removed them. When you apply a solvent, like alcohol, for stains like these where they have been in place for a while you need to let the solvent sit on them for a while, 60 seconds or more, so it has time to dissolve them so they can be cleaned off. Since it looks like some of them have a spot of grit in the center, you don't want to press when you wipe as sliding these across the surface may scratch depending on their hardness. So put a generous amount of alcohol on the surface and let it sit a minute, then dab it dry and see if any of these have budged or dissolved. Repeat 2 or 3 times. If there is no grit on a particular spot it is fine to use some rubbing pressure with a clean Q-Tip. So if no grit on the spot then wet the Q-Tip and place on one of the spots and gently rub to see if it comes off.
Now not all things are dissolved by alcohol or other spirit solvents. Sometimes, if the sopt is organic in nature like tree sap, then saliva will usually get it off as your saliva obviousely has enzymes in it designed to dissolved (digest) organic material. So if the alcohol does not work, then wet a Q-Tip with some spit and dab it on a spot and let it sit a minute then rub it off with the wet Q-Tip. Your saliva rarely cleans completely off so then follow that with an alcohol application to get any stains left from your saliva drying on the lens.
With a combination of either alcohol or saliva or both, over the years I have gotten every stain off my optics. So no stain or other gunk has ever survived the alcohol and/or saliva treatment.