Step down filter ring for Sigma 24-70mm f/2.8
I'm having my T3i modified for full spectrum astrophotography. I'm also interested in IR. Just wondering if I'd experience any vignetting using an 82-77mm step down ring on a Sigma 24-70mm f/2.8 IF EX DG HSM with a Hoya 77mm R72 IR filter given the APS-C chip size? Big price difference between the 82 and 77mm filter and I can use the 77 on a few of my other lenses.