LTI Lamp resistance to repeated cold-striking

[Caleb Williams]

At our theaters we're slowly transitioning to LTI xenon lamps because they are manufactured domestically and thus not subject to tariffs.

LTI have told us that they have reached roughly equivalent light output and life expectancy targest as the CDXL lamps from Christie. So far, our tests have reached the same conclusions. However, we're also implementing a system to turn lamps off when a theater no-shows. That system will of course will not hot-strike lamps, but are LTI lamps generally as robust as the Christie's when cold-striking? The hundreds of Christie's we've used during my tenure did not seem to care how many times they were cold-struck. All except one performed exceptionally for their full expected life. (We had to warranty one due to the xenon leaking out).

At one location for several months we had an error in automation that would hot-strike a CDXL-45SP at the end of the evening. Even that lamp, normally more susceptible to issues because of it's size and power usage, performed as expected for the duration of it's usefull life.

I've read on this forum that the old rule-of-thumb was to avoid striking a lamp as much as possible, but it doesn't seem like the Christie lamps have that limitation anymore, and I'm hoping that the LTI's are the same.

[Leo Enticknap]

As a trainee projectionist in the film days (late 1980s) I was taught that if there is to be at least a 30 minute gap between shows, power the lamp off; if shorter, leave the lamp on during the turnaround, as each cold strike costs around half an hour of reliable service life. In the absence of anyone or any documentation telling me otherwise, I have continued to apply that rule of thumb with digital xenon lamps, and to advise projectionists and customers to program TMS and automation systems accordingly.

I have very little experience with LTI lamps (we supply Ushio unless a customer specifically asks for something else or an Ushio of the required specification is not immediately available), which we generally only sell for film projector lamphouses under normal circumstances. But that rule of thumb has continued to work reliably, as far as I'm aware, with lamps operated according to it (both Ushio and Osram) lasting to warranty hours without any flickering or other malfunctions.

[Steve Guttag]

We have been using Ushio/Christie lamps for quite some time and for the entirety of Digital Cinema (for film cinema, we did have a greater spread in the lamps we used though Ushio was our preferred lamp too...we had successes from the likes of ASL).

LTI has made deals with some of our independents via NATO/Cinema United so I've seen their lamps in theatres we service. Without a doubt, they don't last as long nor put out as much light at any given hour (those two facts play off each other...if the light output isn't as much, you turn it up, which shortens the lamp's life). With Ushio, I get a very predictable lamp that often looks as good on the day it comes out as the day it went in. I don't fear a Ushio lamp that has gone over on hours as I can't remember ever having one explode nor go flickery/problematic near warranty hours.

The only Ushio/Christie lamps I haven't been the most satisfied with are the CDXL-20SD and the DXL-12BAF. The CDXL-20SD often doesn't hit its hours and the coating on the anode stem flakes off. I suspect that the projector (CP22210/CP2215) just don't have the cooling for that lamp. The DXL-12BAF has a decay curve that can be a bit steep. If you can keep the lamp in the bottom of its range will last. But once you start creeping up...its decay accelerates faster than I would consider typical. Conversely, the DXL-16BAF is about 85-90% of the brightness of the DXL-20BAF/L and a popular one in the size range, for us and has a good decay rate.

If people are having good results with LTI, more power to you. I'm just not seeing it, at this point.

As for hot-striking. Ushio (and Christie) policy is that if a lamp can be left off for 10-minutes or more, than turn the lamp off. Furthermore, they've recommended a 10-minute cooling period between shows, which is contrary to the leave-it-on-all-day philosophy.

Their exact verbiage is:

Operational Note for Digital Cinema Xenon Lamps: Based upon our internal research experiments,

operation cycles with “On/Off” mode every 2 hours (10 minutes off), delays the generation of lamp

flicker by up to 30% when compared to the operation cycle of 11 hours continuous mode.

[Ryan Gallagher]

As for hot-striking. Ushio (and Christie) policy is that if a lamp can be left off for 10-minutes or more, than turn the lamp off. Furthermore, they've recommended a 10-minute cooling period between shows, which is contrary to the leave-it-on-all-day philosophy.

Their exact verbiage is:

Thanks for digging up that direct quote, I remember reading that somewhere too but never seem to have it at my fingertips. Definitely counter intuitive to the "old-school" approaches of avoiding the restrikes entirely.

[Caleb Williams]

Thank you all for your input. After we've run these for a bit without shutting them off for no-show's I'll report back on how they do