[Tig] Measuring a DCI-theatre projector - new vs old lamp

Graham Collett grahamcollett at visible-sprockets.co.uk
Fri Mar 1 15:41:59 GMT 2013


strange, i have done tests with a classic a long time ago, because i was nervous of just that scenario, and an almost dead lamp, (back in the day when you got 5-6000 hours per lamp), compared with a new fpn'd lamp. It impossible to tell the difference. 
One impressive feature of the Spirit's i thought.
Graham Collett
www.visible-sprockets.co.uk

________________________________________
From: Carl Skaff [carl at stopp.se]
Sent: 01 March 2013 08:49
To: tig at colorist.org
Subject: [Tig] Measuring a DCI-theatre projector - new vs old lamp

Hi all

Got a question. Has anyone out there done any measurements on a theatre
projector with a new vs old lamp?


Reason for asking is that we recently finished a movie. All was graded in
rec709, then the DCP was created in a 'DCI-mastering suite' to convert to
P3.

We did some short selects for testing and all locked perfect and we gave ok
to produce the DCP.

Now a few months later they had the 'Red carpet premiere' (don't know if
that's the right english name for it, I ment the premiere before the
premiere for cast/crew/celebs/press).
And now the entire film looked about a stop or two overexposed!!!

This of coarse caused havoc and the DoP and Colorist went around different
cinemas to check the DCP.

In the end we found out that the DCP was ok. Looking at it in an calibrated
theatre it was beautiful.
But the theatre where they had the pre-premiere we found out that they just
put in a brand new lamp the week before.
Yesterday when the DoP and Colorist was in the same theatre to look at it
again it was better (but not ok).
Apparently they had only showed a few films between the lamp change and the
pre-premiere. And by yesterday it has been running a few more hours.
And to top it of...
They said they just did a full calibration... But that was just BEFORE they
changed lamps!!!

So this is how it was:

1) Calibrate
2) change lamp
3) run the lamp for  maybe 6hrs
4) have a premiere


To me that just sounds idiotic. But what do I know. I'm just a colorist.


So have anyone done any measurement on a brand new lamp, 10hrs old lamp,
50hrs old lamp, 100hrs old lamp, 500hrs old lamp, 1000hrs old lamp and
finally an almost dead lamp?

Would be very interesting to see how the gamma/gamut/ftL change over time.

I just know from working on a spirit classic.... If the lamp died in the
middle of a grade it wasn't fun. A brand new lamp vs an almost dead lamp
had a very different temperature. Although that could usually easily be
adjusted with the sprit primaries.




/Carl










(Sent from mobile device)
____________________________
*Carl Skaff*
*Colorist*
Stopp Stockholm
Office +46 8 50 70 35 00

*Stockholm | Los Angeles | Linz*
www.stopp.se





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