I'll take a look at my Hi-Matic tomorrow and will be back. BTW, aperture on thsese cameras is not like with SLRs, so if you depress the shooter fast it might not have time to close - try by depressing in two steps with a delay of about 1/4 sec, and you'll see if the aperture is indeed set at 1.8. I'll be back tomorrow after trying to see if the aperture ring does not have a screw somewhere. Do not try to open the lens, as the shooters on these cameras are very complex (like the automatic transmission on cars).