For DSLR I've used the IDAS LPS-2 and the Astronomik CLS-CCD.
Hutech/IDAS filter is better in colour correction IMO.
I keep returning to that filter - just bought the MFA clip in version from Peter Tan in Honkers!
http://www.tan14.com/Dwg/mfa.pdf
I've found the LPS-2 cope with sky glow very nicely too - allows me 15min RGB images when required.
Good Luck
Doug