I am willing to bet that a lot of us have not thought about cleaning our camera viewfinder before, and I am also willing to bet that if those of us who have not thought about it looked at our viewfinders right now, we would be a bit grossed out. Take five minutes and watch this helpful video to learn how to clean yours so it is bright, clear, and clean.
Coming to you from Mike Smith, this great video tutorial will show you how to properly and effectively clean your camera viewfinder. We spend a ton of time worrying about keeping our lenses in tip-top shape, but it can be easy to forget about the viewfinder. You might be surprised by just how much gunk and random debris can build up in one over time, and this can make the image you see through it blurry or cause a loss of contrast, making it more difficult to get the shot you want. Beyond that, having a bunch of dirt, debris, and who knows what else that close to your eye for extended periods of times is never a good thing, but thankfully, it isn't hard or time-consuming to clean off. Check out the video above for the full rundown from Smith.
Please clean the viewfinder cover, too. It's where your eye makes contact and the one in the video looked like it needed a good wipe.
NEVER start cleaning with a circular motion with the cloth because you might slosh around sand or dirt and scratch the viewfinder! Gently poke or dapple the viewfinder with a q-tip soaked in alcohol or lens-cleaner until all visible particles are gone, then use a new one to wipe it . Some sand residue made it on my EOS 80D viewfinder and I made the mistake of using an alcohol wipe over it which ultimately scratched the viewfinder and required repair. Not sure why viewfinder magnifiers or eyepiece protectors aren't more widely available.