HOYA | Reviews - Infrared photography with the HOYA R72 filter
Zomei Original 77mm IR Filter 680NM 720NM 760NM 850NM 950NM X Ray Glass Infrared Filter For Canon Nikon Sony Pentax Hoya lens|filter for canon|77mm ir filterinfrared filter - AliExpress
For Sale - Sold Two Hoya R72 Infrared Filters - 52mm & 58mm (with 49-58mm step-up ring) (US/CA - PentaxForums.com