The Sunpak Auto 16R Pro is a genuine pro ringflash with a fully circular tube & a large guide number of 16 (m at ISO100). It is compatible with digital SLR & 35mm film cameras (excluding Sony Alpha & Minolta cameras) & fits lenses with filter diameter up to 77mm. Sunpak Auto 16R Pro Ringflash produces a wide range of effects, from extreme close-up shots, such as oral close-ups or medical-use shots to portrait shots.