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Author Topic: dealing with soundtrack damage Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 02-14-2013 11:46 PM                     quote: Sam D. Chavez As to the tape, it works but it lowers the Dolby reference. You need to re-do the level to get back up to Dolby level. It has nothing to do with cutting high or low end frequency response. Sam is 100% correct here. There is no HF loss if the A-chain is calibrated after the tape is applied to the led. (We aren't applying it to the lens.)  |  IP: Logged Randy Stankey Film God Posts: 6539 From: Erie, Pennsylvania Registered: Jun 99 posted 02-15-2013 08:39 AM                     I bet the tape changes the acutance of the optical system in the reader. http://en.wikipedia.org/wiki/Acutance Much the same as the difference between a diffusion-type photographic enlarger and a condenser-type. There is little difference between the two in terms of being able to produce a measurably sharp, clear image but the perceived sharpness is different. (Acutance.) Because of the way a diffuse light "bends" (diffracts) around the edges of the dark/light areas on the film, a diffusion-type enlarger tends to hide the appearance of tiny bits of dust or fine scratches on the film. My guess is that the same thing is happening inside the projector.  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 02-15-2013 10:22 AM                       Randy is spot on here.  |  IP: Logged Randy Stankey Film God Posts: 6539 From: Erie, Pennsylvania Registered: Jun 99 posted 02-15-2013 12:48 PM                     Here's an idea: I have a Beseler 23C enlarger controlled by an Analyser Pro timer/densitometer. If I have a problem negative with excessive dust that I can't get rid of, I would replace the clear glass heat filter with a piece of milk glass then recalibrate the densitometer to account for the difference in exposure and contrast. The Analyser Pro has saveable settings that I can recall when I need them. I would just recall the settings that I calibrated for when the diffusing glass is in place. The diffuser costs me about a half stop of exposure and a half grade of contrast but the Analyser's settings compensate for it. So... What if you got a small pice of frosted glass, about a half or a quarter inch square then created a small bracket to hold it in place when needed. You could make it from heavy, coat hanger wire and an alligator clip. Then, since I can use a computer and software to store and recall settings on my Dolby CP650 processor, I would have one set of parameters saved for regular use and another set of parameters for use when the milk glass diffuser is in place. Whenever I have a problem print, it would take about five minutes for me to make the switch. In these days, when finding good, clean prints of a given movie might be difficult to impossible, this idea might come in handy.  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 02-15-2013 01:31 PM                     Another solution along the lines of Randy's excellent suggestion would be theatrical diffusion gels. Roscoe makes them, and if you request one of the swatch samples from them you'll get one big enough for two projectors' worth of diffusers.  |  IP: Logged Randy Stankey Film God Posts: 6539 From: Erie, Pennsylvania Registered: Jun 99 posted 02-15-2013 01:58 PM                     Considering the confined space inside many projector sound heads, a piece of glass and a bracket to support it might be a tight fit. A piece of glass in there could pose a risk of damage to the film. Theatrical gel sounds like a good, low cost solution that gives repeatable results. If the processor is recalibrated when the gel is in place, it ought to be easy to recall those settings in your CP650 when needed yet still have "normal" settings available when the diffuser isn't needed.  |  IP: Logged

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