Recently, I read a photography blog that said that everyone needs to own a filter wrench (a specialized tool to help remove filters from lenses), because sooner or later you will need to remove a filter that has been tightened onto your lens and you can’t remove it without one of these special tools.
A few years ago I had a stuck circular polarizer filter. These are more difficult to remove than the usual filter because the front element rotates freely – it’s the back element that you need to grasp to remove the filter from your lens. For most people it’s a bit difficult to position your finger tips to just grab the back element without also grabbing some of the lens.
I went to the rental department of my local photography store to see if I could borrow a wrench to remove it. They didn’t have a filter wrench in their rental department tools, but instead of trying to sell me something I didn’t need, they showed me how to use an ordinary rubber band as a filter wrench!
The ideal rubber band will stretch some, but not too much, as you place it on the threaded edge of your filter. It provides just enough extra grip to your fingers to grab onto the slippery and thin edge of the filter for you to simply unscrew the filter from your lens. You just need to carefully place the rubber band so that it is only touching the edges of the filter and not the edges of the lens.
Now I keep several rubber bands with my lens filters, and haven’t yet had a filter that I couldn’t remove with a rubber-band wrench.