Film-Tech Forum ARCHIVE: How often do you guys calibrate your cinema projector

This is topic How often do you guys calibrate your cinema projector in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Anhtu Vu (Member # 7689) on 12-07-2014, 04:43 PM:

I'm just curious as how often you guys calibrate your cinema projector for optimal quality/performance.

I calibrate our cinema projector and sound system once a month.

Posted by Marco Giustini (Member # 4544) on 12-07-2014, 05:11 PM:

I feel that once a month is not necessary.

Sound-wise, I feel that a proper EQ takes time and several listening sessions. Once you have achieved what you want you may want to do a periodic CHECK to confirm all channels are still there and everything sounds as expected. There is no "quick EQ" acceptable, unless I am really really familiar with the system and I know what to do with it.

Picture-wise, again unless you have a 515 it may not make sense to check the colours every month. Xenon lamps are pretty much stable. You're welcome to check the focus, frame and make sure all works.

It is not down to the engineer how often you want a projector or a sound system calibrated. Ideally I feel there should be a projectionist/technician on site capable of running some basic checks (channel ID, framing charts). Then you may want an engineer to run maintenance and further checks/calibrations every 12 months.

Posted by Justin Hamaker (Member # 2165) on 12-07-2014, 05:32 PM:

Focus is checked on a daily basis and adjusted as necessary - especially after changing to titles of a different format. Lens files are tweaked only when something appears to have changed. We have one projector with an inVision lens which is much more prone to issues and has to be monitored more closely than the others.

We have someone come out to check the sound periodically, but usually there is nothing to change unless we have had some kind of equipment issue.

Aside from equipment issues, I have found the digital projectors to be pretty stable. Even after software updates I have not had any issues with lens files being messed up.

Probably the one bit of maintenance that should be done periodically is to "exercise" the lens. Especially if you have a string of weeks where the same format is used. This may not even be necessary, but if there is any gunk on the lens motor or gears, it could cause things to stick if left in the same position for too long.

Posted by Gavin Lewarne (Member # 5397) on 12-07-2014, 05:49 PM:

I check and adjust Framing, focus, lens settings and run all the built in test patterns once a month.

Luckily for us we have a very high end recording studio next door, so they come in with some serious sound analysis equipment and check the EQ every 6 months or when I feel it is a bit off. Otherwise basic sound checks are again once a month when I do the projector.

Filters are cleaned every 2 weeks (reusable barco metal mesh ones)

I monitor lamp brightness every week and check that against the CLO sensor in the projector, ours seems to drift quite frequently.

Other than that it pretty much never gives us any serious show stopping issues.

Posted by Harold Hallikainen (Member # 5405) on 12-07-2014, 11:17 PM:

I think that current electronics is very stable, so drift is minimal. But, failures can happen at any time. USL makes the LSS-100P to do automatic daily measurements of luminance, color, and SPL. Information on it is available here.

Data collected from a local theater can be seen at https://lss.hallikainen.org/index.php . I use a self-signed certificate, so you'll have to accept that to see the data. Next year, free SSL certificates are supposed to be available!

As stated in the recent report on luminance measurement, luminance should be measured "as often as necessary."

Harold

Posted by Annli Com (Member # 8266) on 12-08-2014, 12:14 AM:

Dear All

We are daily morning check all screen with self created TEST Content the cpl include pattern files flat and scope and 5.1 and 7.1 sound track with auro test content
Also Check every audio channels,amp,Speaker and screen 2D and 3D withe 3d passive filter before First shows

The Test Content Scheduled At All Screens morning before first Show

Shibupaul

Posted by Carsten Kurz (Member # 5396) on 12-08-2014, 04:31 AM:

Anhtu - what do you mean with 'calibrating' in detail? Which steps do you perform monthly? Do you have your own color meter?

- Carsten

Posted by Marco Giustini (Member # 4544) on 12-08-2014, 04:44 PM:

Harold,

I'm curious: why the front channels are so inconsistent? What happens to the HF?

The graph capability is very interesting.

Posted by Marcel Birgelen (Member # 6801) on 12-08-2014, 05:57 PM:

Harold, you've created this PHP script yourself and hooked it up to the Google Chart js library?

It's a pity this LSS-100P doesn't support simple SNMP, you could otherwise use a whole bunch of out-of-the-box monitoring, alerting and graphing tools for it.

Posted by Harold Hallikainen (Member # 5405) on 12-08-2014, 06:28 PM:

Thanks for the comments! As noted, the left and right HF sometimes drop a couple dB while the center does not. It turned out this is masking being brought in for flat and partially covering the speakers. There is a bit of bad data on 11/10/14. On that date the script skipped ahead due to a timer overflow. That has been fixed.

The variation between left and right is also interesting. This MAY have something to do with the multiplexed microphone positions being set for a specific SPL for each speaker during calibration while the LSS is at a single microphone position at the center of the back wall of the auditorium.

On the UI, the LSS includes an internal web server with graphing (using chart.js). For lss.hallikainen.org, the LSS is posting XML to the server. As it is received, it's dumped into a MySQL database. The report (and this is just a weekend project on my own) uses data for the last month from the MySQL and, as noticed, Google Charts to draw the graphs. I MAY add SNMP in the future. From my experience, though, the S (Simple) in SNMP is misleading. It's a PAIN to code in a microcontroller. I managed to get it working in the JSD-100 and JSD-60, but it's a lot of work. The post XML to a web server turned out to be a lot easier, and, I think, report generation from MySQL should be easier (though my experience with SNMP is a bit limited).

THANKS!

Harold