sfx filter

[mic warmington]

I have recently come into possession of an sfx filter, to use with sfx film. Will the TTL facility on my EOS30 cope with it, or will i have to stop down, and if so by how much?
mic warmington

 

[Leon]

i think its about 4 stops - although when I had an eos 300, the ttl coped with the filter fine.