I made a (to me) baffling experience recently. I discovered a Fuji Press 800 roll which had expired for several years (I found only the roll, so I don't know how long it was beyond expiry) and decided to shoot it for some street photography. It was a really overcast, dark day and since expired high speed films quickly lose speed I shot it as ISO 400. However, when I got the roll back from the lab it was blank! Do such high speed films have such a narrow exposure latitude that overexposure by one stop burns them? Or is it a lab error? The markings on the side were ok... Thanks for your advice