Guys and Girls Can people have a final look over my calculations before I buy the wrong screen. I think I know what I want but felt it prudent to double check the thinking. Stewart's are expensive and I therefore don't want to make a mistake. The projector coming is a CRT based unit. It is quoted as 1000 lumens with new tubes. Mine is a good second hand unit. Gordon's excellent screen article on the site describes what to look for in screens and the calculations necessary for the right brightness. If I was going for a panel projector then the ANSI lumens figure and the Lumens figure would be similar. This is because these projectors use a high intensity lamp that burns at a constant brightness. A CRT projector works differently. It has two brightness specs. ANSI and Peak. Light in my projector comes from a beam of electrons hitting a phosphor coating. The primary limitation of the brightness is the current that this ‘beam' can pull. A full white screen will have a much lower brightness that a 10% white block on a black background. Hence the difference between the two figures. The ANSI (lower figure) is based on the whole screen and the Peak is based on a 10% of the face of the CRT having the bright area. There seems to be 5:1 or 6:1 ratio between the two figures for most projectors. This would make a 1000 lumens CRT projector have a 167 to 200 ANSI Lumens figure. I have used a 185 average. I therefore do the calculations based on: (screen gain) x (Projector output in ANSI Lumens)/ Sqft of screen This gives a ftL figure. Foot Lamberts. TVs are normally 32-35, a cinema 11-12 and a room where you can control all light it needs to be at least 8ftL. (Like the projectors proposed location). Well I have done the calculations using 185 ANSI, 1.3 screen on the two screen sizes I am interested in and get: 72 inch wide 8.9 ftL<br />80 inch wide 7.2 ftL this looks boarder line re the recommended 8 ftL min. I have however seen this projector on a 100 inch screen (from memory) and that would give 4.6 ftL. It looked great and far from dull. In fact I thought it looked great. I think my calculations are fine re ‘the letter of the law' but I am questioning the wisdom of using the ANSI figure for CRT calculations. With films, surely the Lumens figure is far more accurate re brightness and the ANSI figure would only be for ‘Power Point presentation' stuff. If so and I put a 1000 Lumens figure into the calculations instead of 185 I get 72 inch wide 48.1 ftL<br />80 inch wide 39.0 ftL and at 100 inch 100 inch wide 25.0 ftL Now everyone at the Event saw the Cine7 (a 1000 lumens projector (185 ANSI)) on the same 100 inch wide screen and I can't ever remember anyone commenting on it was too dull. In fact everyone loved it. I think I will be going for a 80 inch wide 16:9 screen and I am not too worried that it will be too dull, I just can't make the calculations tally with what I have seen! What figure should I use for calculations?