>>4491043It won't affect sharpness much per se, usually it would cause artefacts or flaring, or cast shadows on your sensor/film. A good way to test is to put it on a digital camera, shoot RAW in the middle of the day and just take some pictures of the sky at f/8, f/11 or f16, something like that. Maybe take some with direct light coming into the lens and see if you can see anything in the photos. If theres any dark areas or spots or anything you should see them at f/16. Otherwise it doesn't matter. Fungus won't spread once its dead, and any sunlight at all kills it pretty much instantly.
