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¬