Home of Professional Cinematography since 1996

class="Paragraph" Calibrating Monitors In The Field

Published :  26th January 2004


I recently encountered the following problem whilst shooting on location with the P+S mini35 with the Canon XL1-s. The spot was then transferred to film and then played in a local theatre.

The main problem then being because it was going to be digitally transferred to film, we weren’t really able to do too much correction in post. The director edited the spot and then sent it uncompressed in Tiff format to the Transfer house.

The first print was terrible, nothing even close to what I had seen from the directors edit. The discussion started 'Are you sure you have (or had, when shooting ) a correctly adjusted monitor'.

My assistant had performed a complete check the day before, including having the monitor (Sony 9041) professionally calibrated (with a vectrascope ...I think). As always, during the course of the day, the client (or agency) adjusted the Contrast, Brightness and Colour of the monitor. The knobs had been taped, but I guess someone didn’t realise the importance or the reason why they were taped. I didn’t have the luxury of having a monitor with a preset button to reset to the original values.

At some point on the first day it became apparent that the monitor had indeed been 'Played with'. I realise there is a given procedure how someone should configure the monitor. I am very familiar with this process, but it still remains a very subjective interpretation of what is right and wrong.

After the shoot was over, the next day I then went to a professional Video business who calibrate the majority of the monitors in the area where I live. Before going I had filmed an 18% grey card (using the same camera). To check exposure I used a waveform monitor. I recorded 60 seconds of the grey card full frame.

At the Video place I viewed the recorded grey card on a Class 1 monitor that was 100% correctly adjusted and took spot meter readings off the monitor, because the monitor continuously rescans it is quite difficult to get an accurate reading.

My thinking was if the monitor was calibrated correctly (one would normally assume so) then all I would have to do is set my location monitor to the same spot metered level, (having placed the same tape with the grey card in the camera at let in play for the 60 seconds) I should then be fairly close if not exact to obtaining a correctly adjusted monitor whilst on location.

The problem is that obviously a class 1 Ultrablack monitor has a much different exposure and contrast range to a commercial available Sony 9042 9" inch monitor.

So, the question is....How can I, make sure that the monitor that I have somehow is calibrated to show the same colours, brightness and contrast as what the editor will see and to what the transfer house will receive as uncompressed data.

Adrian Cranage
Director of Photography
www.cranage-dop.com



What about the monitors used to edit the material on? It seems like the wrong color/brightness/contrast would have been picked up on in that point of the process. I see how it could slip through the cracks, but I don’t see why it should have done that.

Chad Simcox
www.sonofsimon.com



I think you have to give us a better description of what the problem was with the footage ...too dark ...weird color ..black levels wrong...?

I can't seem to sense where in the production the problem is occurring. If client played with the monitor shouldn't the DP see that immediately? Why did the camera operator not realize something was miss set?

Here's one possibility that I witnessed the results of when a crew came back with BetaCam Sp footage that was way, way under exposed. And as soon as I saw it I knew what the mistake was....someone setting the camera by looking at a monitor and not a waveform, and the perfect way to screw up the monitor, especially the Sony PVM 8045 and their like, is to plug the BNC cable into the wrong input. Lot's of times its done by reaching over the top of the monitor (especially when it's in a Porta-Brace case) and feeling for the input plug....trouble is, the top of the case flap covers the top input plug and by feel and by eye sometimes the cables goes into the looping output of the monitor. The result is the auto termination does not sense or terminate the signal, resulting a high contrast bright picture.

So of course the crew fed SMPTE bars and adjusted the picture. Contrast way down, Blacks set ,blue gun on and, bingo, looks nice. Except when they got home whites were recorded around 40 IRE.

Don't laugh, when you're moving fast, this is a great way to screw up. I haven't done it yet, but I'm waiting in line to take my turn.

I don't think the grey card idea will work. The monitor contrast levels are set to the ambient light in which the monitor is observed and the spot meter is going to be fooled. Nothing beats an 11 step gray scale chart and a waveform monitor for knowing exactly what is going on with the signal being recorded. Set it up for the camera and set your light meter to what you rate the camera for and you'll be in range all the time. It's also a great idea to shoot the chip chart right after recording color bars in both 3200k light and show light so the editor or colorist has a good calibrated reference of what is recorded.

My son has an XL1S and trying to get a good exposure thru the lcd color viewfinder is a real challenge. Just moving your eye up or down a little in the eyepiece really changes the contrast/brightness levels a huge amount. It's real easy to get fooled.

Setting up the monitor properly with SMPTE Bars and blue gun is the first thing that should be done in both production and post...as for the waveform ...never leave home without it.

I'm sure lots of us here would like the hear about the P+S adapter you used on the shoot. I'm still trying to talk producers into using one and I'd love to hear reports from the field from those who have shot with it.

Best regards,

Al Emer
Lighting Cameraman
Holmdel, NJ



>And the perfect way to screw up the monitor, especially the Sony PVM >8045 and their like, is to plug the BNC cable into the wrong input.

I've seen this, but I've learned that if the monitor sets up a bit strangely (for example, I've got the "blue only" on and I have to twist the knobs dramatically in order to get the bars to line up correctly) I need to check where the BNC is plugged in.

Art Adams, DP
Mountain View, California - "Silicon Valley"
http://www.artadams.net



>So, the question is....How can I, make sure that the monitor that I have >somehow is calibrated to show the same colours, brightness and >contrast…

This may not solve your problem. Unless your TIFF files had the photometric parameters specified, which is very unlikely, the problem is probably in putting the TIFF files on film. There is no standard way of converting computer image data to film. Try to find out from the folks who did the film recording which film densities correspond to the
computer code values and get examples of files from them and the corresponding film frames. I have had problems in the past with the film recorder house refusing to do this claiming they spent a lot of time figuring out how to get the film to look like a monitor.

I was then forced to reverse engineer their mapping in order to get my film the way I wanted it.

Charles P. Lamb



When shooting Mini-DV, probably the best way to keep yourself out of any danger zones is to always check the LCD and the zebras as a rough reference. There's just no way for the LCD to fall as radically out of calibration as an unterminated monitor can, and the zebras, as far as I know, are 100% reliable.

(I recently did three weeks of highly mobile doc shooting with, unavoidably, *nothing but* the LCD and zebras on a VX2000 and a PD150, and -- to my own surprise -- have no complaints about the results, other than two instances of soft focus in 20 hrs of tape. But oh boy, would I love to have a REALLY decent built-in LCD that's detachable/remoteable)

Dan Drasin
Producer/DP
Marin County, CA



That's what this sounded like to me too. Overall I think it's good practice to always use a terminator plug, instead of the auto termination. This helps prevent accidentally plugging the in into the out. But be careful, I recently got burned, somehow a 50 ohm terminator (used in computer networks) got into my kit, and really confused me for awhile because the difference wasn't nearly as extreme as no termination or double termination.

Steven Bradford- DP and Vidiot.
Seattle,
http://www.seanet.com/~bradford/



>Overall I think it's good practice to always use a terminator plug, instead >of the auto termination.

Using the 8044 - 8045 series monitors, one thing you should especially watch out for is intermittent problems with the auto-termination. A lot of these monitors develop this problem sooner or later, and of course the worst thing is that (at least in my experience) it's always intermittent!

You may set up the monitor fine, but with an intermittent problem, it's easy to be fooled later in the day...

George Hupka
Director/DP
Downstream Pictures
Saskatoon, Canada