I had a similar telephoto and also a WA lens and used it for a time. I never altered the exposure setting and it did not seem to affect exposure . After a while, I saw no significant mm difference to justify using these lens. I also wondered it these attachements corrupted the Rollei lens. I ultimately sold them. These lens attachments have not been discussed in this group but I am sure that others are more knowledgeable than I. Roger ----- Original Message ----- From: SandyF To: rollei_list@xxxxxxxxxxxxx Cc: cvug@xxxxxxxxxxxxxxx ; camera-fix@xxxxxxxxxxxxxxx ; idcc@xxxxxxxxxxxxxx Sent: Saturday, February 25, 2006 3:09 PM Subject: [rollei_list] "Kaligar" Telephoto Accessory lens for Rollei Automat A while back, I bought a "Kaligar" Telephoto Accessory lens for my Rollei Automat. I haven't used it for months, and now can't remember if this Accessory lens changes the effective speed of the f/3.5 75mm Tessar, thereby requiring changes in the exposure settings. If anyone can help, it would be greatly appreciated. TIA Sandy F. Ö¿Ö¬