Jerry, If it was an Infra Red filter it would be almost black (very dark red)so as to only pass infra red light. The inscription would have been "Infrarot" . I suspect it is a Rollei warm-up (colour conversion for colour film) filter "R1" also available in strengths R1.5, R2, R5, R11. These had a female bayonet fitting on the front so that an additional filter could be attached as required. Similar filters in Blue were available and as a cased set. John -----Original Message----- From: rollei_list-bounce@xxxxxxxxxxxxx [mailto:rollei_list-bounce@xxxxxxxxxxxxx] On Behalf Of Jerry Friedman Sent: 22 June 2006 13:31 To: rollei_list@xxxxxxxxxxxxx Subject: [rollei_list] Re: Filter identification question Hi! I hope someone can help me identify a Rollei Bay III filter that I have with the letters I R on it. It is clear and has bay III fittings on both sides (male on onme end, female on the other). Should I assume this is an infra-red filter? How is it used and what effect would it have being used with black and white film? Many thanks, Jerry F. --- Rollei List - Post to rollei_list@xxxxxxxxxxxxx - Subscribe at rollei_list-request@xxxxxxxxxxxxx with 'subscribe' in the subject field OR by logging into www.freelists.org - Unsubscribe at rollei_list-request@xxxxxxxxxxxxx with 'unsubscribe' in the subject field OR by logging into www.freelists.org - Online, searchable archives are available at //www.freelists.org/archives/rollei_list