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Author Topic: LED readers John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 02-26-2003 11:19 AM                        Do you have specifications for the spectral output of the Kinoton readers that use the red dichroics? Hopefully a peak output near 660nm and a relatively narrow bandwidth with no IR-bleedthrough.  |  IP: Logged Steve Kraus Film God Posts: 4094 From: Chicago, IL, USA Registered: May 2000 posted 02-26-2003 07:36 PM                    John, I meant only that existence of recent developments like white and UV LED's suggests that a visible red + IR LED is possible. That's what I was suggesting might be optimum, not a white LED.  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 02-26-2003 09:27 PM                        If the track is dye only (no silver), you do NOT want any infrared energy, since film image dyes are relatively transparent to infrared. A 660nm red LED is optimum for a cyan dye track. A 550nm green LED would be optimum for a magenta dye track.  |  IP: Logged Steve Kraus Film God Posts: 4094 From: Chicago, IL, USA Registered: May 2000 posted 02-26-2003 09:30 PM                    Yes but not all of us are convinced that silver is going away as fast as some may suggest it is. Besides, why is it so bad to have energy in a wavelength that is not be modulated? If the pickup device is still a solar cell it's just going to create a DC offset which presumably is eliminated at the pre-preamp stage, no?  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 02-26-2003 09:39 PM                        Having unmodulated energy hitting the cell can use up its dynamic range.  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 02-26-2003 09:45 PM                        So if I understand John's comments correctly, it would be possible to play a cyan dye track in a conventional soundhead by inserting a red gel (of the appropriate color) between the exciter and the solar cell, but that sound reproduction would be sub-optimal and the gel would need to be replaced as it fades. Is this correct? Does anyone see a market for red gel kits for theatres which haven't done the conversion by the time when (if) dye tracks become widely used?  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 02-26-2003 10:11 PM                        Most red gel filters (e.g., Wratten 25 or Wratten 29) still transmit infrared energy. You would need to use an IR blocking filter as well. Red LEDs put all their energy in a very narrow bandwidth, which matches the peak of the cyan dye's spectral density.  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 02-27-2003 06:16 AM                        So the combination of a red gel and IR filter would work, then? If so, that sounds like a cheap and effective temporary solution for theatres that might receive dye-track prints. Even if the gel had to be replaced every few days, the cost would be far less than the reader conversion. Is there any way of getting a short loop of a dye-track print to do some testing? Of the places where I have worked, only the newer (post mid-'90s) installations have LED readers; the rest are using exciters and haven't converted. Most are independents which are operating on shoestring budgets and won't be converting until it is necessary. It would be helpful for them to have a workable temporary solution if they happen to receive a dye-track print someday.  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 02-27-2003 08:28 AM                        Yes, a red gel filter and an IR-blocking filter could work, but the available red light level would likely be very low, so you may not be able to get sufficient level, and the noise will be high. Unlikely to be a good solution. Cyan dye track demos were made in the UK, titled "Red Alert": UK Dye Tracks Meeting 2001 UK Dye Tracks Meeting 2002  |  IP: Logged Jim Alexander Film Handler Posts: 71 From: Greenwood, Nova Scotia, Canada Registered: Nov 1999 posted 05-08-2003 09:57 PM                        Thought I'd bring this topic back to the front again. Word has come down the line, here in Atlantic Canda, that the role out of Cyan tracks will be this fall. When? I'm not sure. Has anyone else heard anything or is this just another attempt to send a panic through the industry and make more sales for LED readers? There are still a number of independants in Newfoundland, Nova Scotia and New Brunswick that haven't upgraded yet and are wait word as to when they will need to. Seems to me, that almost like clock work, about every six months someone starts saying cyan is coming in "shortly" only to find out that no, they've decided to wait until more are converted. Is there a date or isn't there?  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 05-08-2003 10:07 PM                        At the Dye Track Committee Meeting held at ShoWest, distributors attending were pleased with the coversion rate to red LED readers in the developed countries, but expressed concern that many areas of the world that still used tungsten light readers would not be able to play "rejuvenated" prints unless they had silver+dye tracks. Making special dual inventory silver+dye track prints for these areas would be unacceptable. The committee recognized the need to promote the advantages of reverse-scan LED readers to improve the conversion rate. BTW, Canada has one of the highest rates of conversion to red LED readers in the world.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 05-08-2003 10:15 PM                     In short...yet another scare. Steve  |  IP: Logged Jack Ondracek Film God Posts: 2348 From: Port Orchard, WA, USA Registered: Oct 2002 posted 05-09-2003 12:23 AM                        Right, but we're still at the same question. They were going to start rolling these things out in earnest this Summer, weren't they? Is that still on or not?  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 05-09-2003 05:48 AM                        The July 3, 2003 date was set by NATO for conversion of their member theatres to red LED readers. It's for the distributors to decide when they want to convert the prints to cyan dye tracks only. Dual-inventory is generally unacceptable to them, so they want to be sure the vast majority of theatres are equipped to play cyan dye prints. quote: In short...yet another scare. Steve Steve -- you were at the meeting too. I summarized the meeting accurately, and am not using "scare" tactics, as you imply.  |  IP: Logged Todd Pettigrew Film Handler Posts: 2 From: Montgomery, AL, USA Registered: Feb 2003 posted 05-09-2003 08:00 AM                     I have been hearing about the Cyan change for years also. Reverse scan is a whole lot easier to keep aligned focused, a whole lot easier than the old vacuum tube photocells or photocell systems. As for the change, It took between 10 and 15 years to change over to 1.85 from the academy ratio 1.37, with many of the prints in the 50's not being hard matted. I think the studios will have to wait till everyone installs modern vitaphone, DTS, or Dolby Digital before the real change comes. My bet is on Dolby Digital becoming the standard. I reciently talked with an editor for columbia motion pictures who was surprised that anyone still had a change over booth. The editors were talking about removing cue marks from prints. How in the world will we wever truly find the end of reels any more, provided the 24 guys before us were not too lazy to peel the tape splice in lieu of the sacraficial refrence frame. Keep the picture sharp!  |  IP: Logged

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