Quote Originally Posted by RalphLambrecht View Post

That is not my understanding. The under-the-lens filters, I'm referring to, are stationary and kept in a filter holder, which is typically clipped onto the lens. What kind are you talking about?
I have a set of kodak filters that clip on also, mainly used by me for its strong #5.
But I was really referring to using using the red swing in filter for contrast filters. If the filters are bent or damaged in the process of exchanging these frequently they might affect the optical path if they are not in motion thoughout the exposure.