Hopefully someone can provide some advice. I have just got a new Optoma HD87, upgrading from a HD65. I am having an issue with the dynamic iris, or at least I think I am. It makes a pretty harsh mechanical type noise when there is a dark scene shift and there is a brightness pulse along with a bit of a colour flash. I was wondering if anyone has ever had a similar issue. My paranoia imagines the iris impacting on the colour wheel some how. I have dropped to iris level - 3 and changed to dynamic black - off. But I still get noise when there is a change of res, as if the settings don't apply for everything. What kind of noise level should I be expecting from an optoma iris? It is beyond a hard drive click? Pointers appreciated. Thanks, Paul.