We discovered a velour that we call AB velour -- Absolute Black velour. Light projecting on it at normal SMPTE spec brightness levels will simply not be seen, no matter how much overshoot you wind up with. Thus, if you need to mask into the image enough for the fringe to be totally eliminated and to do that means you have 2 or 3 inches of picture spill on the mask, not to worry -- it will not be seen on this AB velour. That solves a host of problems in the practical world.

Steve

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You are always forced to crop a little in at least one direction, unless you have both adjustable top and side masking, and/or use a variable length lens. Most places don't have these.

How do commercial theatres deal with the problem of the masking velour covering the left and right theatre clusters when playing 1.66 or even 1.85 on smaller screens? Is the room equalized with or without the mask in place for the smaller width ratios? If it is eq-ed with the mask at scope, would that make any sense give that there are more flat films released than scope films?

As for Joe's idea....I think it should be submitted as an Academy Award nominee for Technical Achievement....mention that it would be oh so sheek.

The standards don't specify that the area beyond the projectable image areas of SMPTE 195 will be free of distracting elements, but if everyone is doing their job correctly, there shouldn't be anything there that the masking can't absorb. The masking defines the projectable image area on the screen per SMPTE 195, the aperture is cut to place the fuzzy edge onto the masking.

The (IMHO) excessive 10% crop figure came from you: "The only way it can make any sense is to have a safe area (10% crop) and that space is used to hide any of the mechanics of showing the image". The more reasonable 2% crop suggestion for a margin of error was Pat Moore's.

I am more optimistic than your view of "all working within standards yet at the worst of the extremes". Severely cropping the image to deal with an absolute worst case situation seems like overkill.

As to cropping the picture...if it is in the safe action area...there is nothing wrong with it...nothing of interest is supposed to be there.

Steve

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As for the "engineer who installs all his cinemas with the speakers above the screen aimed at the area in front of the audience so that the sound is supposed to be reflected into the auditorium. " I am not an acoustician, but that sounds highly dubious. How does he know what his reflective surface is doing to the sound; no reflecting surface reflect the entire audio spectrum evenly. It will absorb some frequencies and create sharp spike in others -- tying to fix that with 1/3rd or even 1/6th octave equalizers can be a bitch. Plus, if he is reflecting off the front of the audience seating, how does he get even coverage, to say nothing of the affect people and their clothing will have on the reflected sound hitting them? Sounds risky. But then, I never argue with something that someone found to work....if indeed it does work.

You are right, the heavy velour should only be used as a border at the edge of the mask -- china silk, which is acoustically transparent, should be used for the rest of the mask material. Unfortunately because china silk is pretty expensive, a lot of installations don't spring for it, much to the detriment of their eq. One of the places I work has full velour for the mask -- 26lb velour at that. It completely covers Left and Right speakers. Nice goin', designer guys --same theatre with the full glass front wall and a ceiling that dips down in front of the change-over corner of the screen.

I always though you gauged "acoustically transparent" by simply playing your pink noise. looking at your RTA, put the material in front of the speaker and what you see is what you hear. You shouldn't see any difference, or at least nothing significent. Define significent, well, anything that you can hear, say +/- 3db. With china silk I would be surprised if it is any more than +/- 1 db and only in the very high end -- probably not even as much coloration as standard speaker grillcloth.