Help! I bought a 14" Goerz Apochromat Artar off eBay, Glass is clear, but it will not focus! It looks like it is starting to focus on infinity at about 5", but my 8x10 will not go any smaller. My guess is the glass was cleaned and assembled incorrectly - but I have tried variations and still no luck. Any ideas? Does anyone have a picture of the lens formula so that I can check to see if I am missing an element?