Sometimes, for storage purposes, two lenses will be designed to fit inside of one another. In the event that they become too tight, though, you may have trouble separating them. Here is what you should do if this unlikely event occurs. First off, find a relatively small towel and dampen it with water, making sure to ring out the excess water. From there, heat it up in the microwave for around a minute and a half. Then, place the heated towel over the lens and let it sit for just under 60 seconds. This should do the trick and if it does not, repeat the above steps until it does.