<p>Greetings,<br /> I realize this is an older thread but wanted to add the following information in case is is helpful to anyone researching the topic of Petri EE lenses.<br /> <br /> The first Petri shutter-priority SLR to use EE lenses, the Petri FT EE, has two small levers behind the lens mount: one (at the lower right corner of the mirror) which pushed against the aperture control pin of the lens to set the proper aperture in EE mode, and one on the right side of the mirror box. This second lever, when pushed in by the aforementioned tab on back of the EE lens, adjusts the red exposure warning flag in the viewfinder to match the maximum aperture of the lens.<br /> <br /> Unfortunately, this tab may prevent mounting on some earlier Petri SLRs. On the manual Petri FT II (which came out after the FT EE) there is a slot cutout behind the lens mount, presumably to accommodate this tab. The standard 55mm EE lens does not have a tab and should mount fine on the earlier breech-mount SLRs.<br /><br /><br /></p>