Consumer durables

Stuck phenomena on iris blades happens after some use of period of time, so periodical maintenance is indispensable for comfortable use inviting disassembling iris open and closure mechanical system requiring special device, technology and skill as a professional engineer. The reason of stuck and fixed oil, mold and dust pieces and the material should be removed so carefully as not to destroy the original performance of the lens construction. Though almost of the lens would be thrown away when any growth of mold on the lens element inside. It is true that the mold inside of the element means the death of it if recent one piece engineering plastic casting method had been introduced on the lens, because there is no way to disassembling the element in pieces. On the other hand the lens supporting barrel was made of lathed metal case and is possible decomposition, the old lens would be survived as one of consumer durables.