A much better option for a slim filter ring is B+W's flagship XS-Pro Nano line. As mentioned above, this filter line includes B+W's best 8-layer MRC Nano coating and is Kasemann by default. The XS-Pro rings are slimmer than the standard ring thickness and lens caps can be attached to them. I have standardized on the XS-Pro filters for all of my wide angle needs. tradutore