1. taim sos signal o signal i no wok gut, o taim ol bikpela samting bilong mekim ol wok bilong mekim ol ejensi (olsem ol daiafram, ol spring, ol sil, ol transmisin, na ol narapela) i bagarap, long han bilong operesen otomatik operesen, yusim hanwil i go het long holim strong wok bilong valv long bosim.
2. han wil tu i save yusum olsem wan riten blong valv travel taem zero signal presa regulet valv i open o i klos, sapos proses i nidim smol amaon blong flo kontrol valv, hanwil i save yusum blong kasem objektif.
3. hanwil bilong bekelite inap long kamapim gutpela wok bilong kontrolim valv, stretim valv olsem wanpela moa baipas, invesmen kos, na karamapim wanpela eria bilong, taim aperture i bikpela o taim yusim gutpela metal i dia moa, yusim ol wil mekanisme long ol invesmen kos na i karamapim wanpela eria bilong tingim, em i gutpela baim.
