I havent had any problems yet untill dusk (no light). I didn't have to use the sky screens yet even though it was mostly clear on Sunday. Because the Chronograph sits below the horz board I think the blast and everthig goes over the top of it. I might wind up putting a piece of plexiglass over the top. I have put clear tape over the sensors when it was on a tripod, but Sunday the chronograph stayed pretty clean even with 150 gr charges. I'll try to take a picture tonight with the chronograph in it. That should clear it up better.