Originally posted by stevebrot It depends on the material used for making the screen. Given the number of negative experiences shared on this site and other places on the Web, the risk is probably high enough to suggest avoiding cleaning, soaking or rinsing with IPA (isopropyl alcohol) or other solvents. I have wondered about wetting agents such as photoflo (used as final rinse during film negatives processing) to avoid water spotting, but don't have a ready supply of recent-made screens to test various approaches.
I have asked my friends that do camera repair and they are mum about recommendations, the standard response being to leave the task to the pros.
Steve
I've cleaned my focusing screens a few times without issue.
My process needs plastic tweezers, three
small brand new unused plastic cups with lids, one with purified water and one drop of dishwashing liquid, the second with purified water only, and the third with purified water and one drop of dishwasher rinse aid. ( I can't remember where I learned this but I didn't come up with it)
- Using the plastic tweezers remove the screen by the tab only. NEVER touch the screen itself and DO NOT use metal tweezers. Theres' inexpensive plastic ones made specifically for focus screens. If anyone needs help on this step Stevebrot has explained it before as well as linked the excellent document originally provided by Katzeye. Read it.
-With the screen now out use a rocket blower on the interior with the camera upside down
-Put the screen in the first cup, lid on, and swirl the screen in the first one for a few seconds. Let it sit for a minute of two.
-Empty the liquid, very carefully transfer the screen to the second cup, and gently swirl it around again for several seconds to remove any soap residuals.
-Empty the liquid again, transfer the screen to the third cup with the rinse aid, which is meant to help prevent water spotting. Gently swirl again, dump off the liquid and pick it up with the plastic tweezers you have (you do have them, right?) and let the liquid drip off for several seconds at least maybe a minute.
-Place the screen on a clean lens cloth and cover with another until totally dry. You don't want dust settling on it while drying.
-Blow out the camera with a rocket blower again "just in case", then reinstall the screen.