Quote Originally Posted by Doremus Scudder View Post

If this is a recurrent problem then:

Develop more to start with
Check your magenta filter to see if it has faded; replacing it with a new/good used filter may help


It is rare that I would consider disagreeing with Doremus, but ...

If the filter is a dichroic filter, it is an interference filter that won't fade.

They do, however, become less effective if they become dirty.