I use a Schneider Symmar 210mm/370mm convertible on my RB Auto Graflex 4x5. The 370mm conversion works fine, I've used it down to 15-20ft. I never tried to see how close I could get with it. I suspect your 380mm Tele-Optar will work fine on the RB Auto. I have a 380 Tele-Optar in shutter that I use on my Graflex Super Graphic. Just as an aside, I've also used the 380 Tele-Optar on my Calumet C1 8x10. It will cover, although movement is minimal.