Hi everyone: I own a Bronica ETRSi with an AE III viewfinder prism. The AE III prism is equipped with a standard eyepiece correction lens that has a diopter range of between -2.5 and +0.5. Since purchasing my prism, my eyesight has deteriorated requiring me to (ideally) get Bronica's optional Plus Eyepiece Correction Lens that offers a diopter range of between 0 and +3. Unfortunately, despite searching for many months I am unable to locate a Plus Eyepiece Correction Lens; it would seem that they are very rare indeed, and I was, therefore, wondering if anyone had any knowledge or experience with fitting an alternative brand name circular correction lens to the AE III prism viewfinder; and, if so, which brands fit and what worked best. Thanks for your help.