I have a carousel 4200 projector with an Ecktagraph 100-150mm zoom\nff3.5 lens. The only way to get a slide in focus is to hold the lens\nabount 3-4 inches away from the projector, so the light goes thru it\nonto the wall. When I put the lens in the projecotr, it doesn't focus\nat all (I've tried from distance of 10 to 20 feet away from the wall).\nI get no image other than different color lights until I take the lens\nout of the projector - and then I get a clear picture. What could\ncause this? Before I spend money on a new lens (shorter and wide\nangle) or take the projector in to be fixed, I could use any\nsuggestions. Thanks for your help!