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Author Topic: Lamp too bright
Phil Ranucci
Expert Film Handler

Posts: 236
From: Carpinteria,CA, United States
Registered: May 2006


 - posted 01-27-2019 10:08 PM      Profile for Phil Ranucci   Email Phil Ranucci   Send New Private Message       Edit/Delete Post 
Barco DP19 with a 3000 watt lamp.
Output is way too high >35 ftlamberts.
I can turn the lamp down to the minimum but it's still too hot, over 20ftlm.
Running at minimum also can cause flicker issued in the future, a smaller bulb isn't currently an option.
Will defocusing the lamp do any damage to the mirror or lightpipe?
Thanks

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Dave Macaulay
Film God

Posts: 2321
From: Toronto, Canada
Registered: Apr 2001


 - posted 01-28-2019 06:16 AM      Profile for Dave Macaulay   Email Dave Macaulay   Send New Private Message       Edit/Delete Post 
(Duplicate, please delete)

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Dave Macaulay
Film God

Posts: 2321
From: Toronto, Canada
Registered: Apr 2001


 - posted 01-28-2019 06:21 AM      Profile for Dave Macaulay   Email Dave Macaulay   Send New Private Message       Edit/Delete Post 
I recommend you align the lamp to max then pull the cathode back to defocus, counterclockwise on the Z adjuster. Maybe doesn't matter but I have seen damaged integrator parts apparently due to bad lamp alignment... expanding the beam spot rather than going through its minimum should avoid that.
If the LSC file was calibrated, the brightness reported will be in the ballpark but far from accurate. If calibrated at 35 it won't be very accurate except close to 35, to get a trustworthy 14 it should be recalibrated at 14..
I have tried installing a lamp as a lower power lamp (4kW as 2kW for a new 20C) to allow lower minimum power and brightness. It worked ok, no flicker, but yours may not like that. Barco sends a max size lamp with new projectors and I didn't have a smaller on at hand.
Defocus will shift color a bit, 99.999%+ of people won't notice... but probably out of DCI tolerance. Which no commercial cinema cares about.

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Leo Enticknap
Film God

Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000


 - posted 01-28-2019 01:46 PM      Profile for Leo Enticknap   Author's Homepage   Email Leo Enticknap   Send New Private Message       Edit/Delete Post 
We sometimes encounter this problem installing laser projectors in high end home theaters (for which, obviously, you can't defocus the bulb).

The only solution for that is an ND filter in front of the lens.

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Sean McKinnon
Phenomenal Film Handler

Posts: 1712
From: Peabody Massachusetts
Registered: Sep 2000


 - posted 01-28-2019 03:26 PM      Profile for Sean McKinnon   Author's Homepage   Email Sean McKinnon   Send New Private Message       Edit/Delete Post 
This probably wont help you today but there is a smaller aperture you can install on the integrator rod available.

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Jarod Reddig
Jedi Master Film Handler

Posts: 513
From: Hays, Ks
Registered: Jun 2011


 - posted 01-28-2019 03:34 PM      Profile for Jarod Reddig   Email Jarod Reddig   Send New Private Message       Edit/Delete Post 
Was going to recommend an ND filter but Leo beat me to it.

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Peter Hall
Master Film Handler

Posts: 314
From: London, UK
Registered: Dec 2000


 - posted 01-28-2019 11:53 PM      Profile for Peter Hall   Author's Homepage   Email Peter Hall   Send New Private Message       Edit/Delete Post 
Better to place the ND filter (or I agree, an aperture near the ND filter) in the light engine than after the lens. Contrast suffers horribly otherwise

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German Marin
Expert Film Handler

Posts: 227
From: Verbania (VB), Italy
Registered: Jul 2001


 - posted 01-29-2019 07:17 AM      Profile for German Marin   Email German Marin   Send New Private Message       Edit/Delete Post 
Install a 2000W lamp...

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Monte L Fullmer
Film God

Posts: 8367
From: Nampa, Idaho, USA
Registered: Nov 2004


 - posted 01-29-2019 01:33 PM      Profile for Monte L Fullmer   Email Monte L Fullmer   Send New Private Message       Edit/Delete Post 
Seen DP19 with 1200w lamps installed..

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