One of the most frequently asked questions that I get from our readers, is what to do with dust inside a lens and whether it is something to worry about. I decided to write an article on this subject, because lens dust and flecks are a very common issue not only for camera sensors, but also for lenses. When I first discovered dust inside my brand new lens that I only used for a couple of days, I was very disappointed and I remember how I started searching for a solution online in panic mode. If you are frustrated with a similar issue and do not know what to do, keep on reading.
1) How to Inspect Lens for Dust
So, how can you find out if you have dust inside your lens? Actually, let me rephrase this question – how can you find out how much dust you have inside your lens? Because even brand new lenses normally do have some foreign particles in between lens elements. A quick visual inspection of the lens front will often reveal large dust particles behind the first lens element, if there are any. Just make sure that the front is thoroughly cleaned beforehand and any protective filters are removed. Look straight and then inspect the lens at an angle and you might see some dust behind the front glass element. Now if you really want to see dust, and I promise you will, here is the best way to do it. First, find a very bright LED flashlight. You can find those pretty much anywhere nowadays, even in a grocery store. Next, you will need to open up the lens aperture (the lens obviously needs to be dismounted from the camera, rear lens cap should be removed). If you have an older lens with an aperture ring, you just need to set the aperture ring to the smallest value (which is the largest aperture) like f/1.4 or f/2.8 and you are ready to go. If you have a modern lens like Nikon “G” type AF-S lenses, then you will need to push up a small metal lever to open the lens aperture as seen below. To keep the lens aperture open, you will need to keep pushing it with one finger: