It's a clip-on iris diaphragm, equidistant divisions allowed the juxtaposition of speed and aperture scales, this made the conversion table superfluous, it was useful as DOF Preview and like Optical exposure meter, I could find the instructions if you are interested about it really, it was manufactured from 1933 up to 1941 and there were several versions, the last one B I too.- All the best Carlos --- ERoustom <eroustom@xxxxxxxxxxx> escribió: > eBay item: 290194743940 > > What is it? > > E. > --- > Rollei List > > - Post to rollei_list@xxxxxxxxxxxxx > > - Subscribe at rollei_list-request@xxxxxxxxxxxxx > with 'subscribe' > in the subject field OR by logging into > www.freelists.org > > - Unsubscribe at rollei_list-request@xxxxxxxxxxxxx > with > 'unsubscribe' in the subject field OR by logging > into www.freelists.org > > - Online, searchable archives are available at > //www.freelists.org/archives/rollei_list > > Los referentes más importantes en compra/ venta de autos se juntaron: Demotores y Yahoo! Ahora comprar o vender tu auto es más fácil. Vistá ar.autos.yahoo.com/ --- Rollei List - Post to rollei_list@xxxxxxxxxxxxx - Subscribe at rollei_list-request@xxxxxxxxxxxxx with 'subscribe' in the subject field OR by logging into www.freelists.org - Unsubscribe at rollei_list-request@xxxxxxxxxxxxx with 'unsubscribe' in the subject field OR by logging into www.freelists.org - Online, searchable archives are available at //www.freelists.org/archives/rollei_list