Bars and tone ??

[R. Hewitt]

You can put the coffee on hold!

Bars and tone serve two purposes. The most important being that it gives a reference level for editors/companies using your footage. In the days of analogue recorders the bars and tone were used to setup the VTR to the same levels as were recorded by the original camera or other VTR to tape ensuring they got the best out of the recorded material.

In the digital world this is less of an issue but is good practice AS LONG as you ensure all material following the bars and tone were recorded at the correct levels.

The second purpose is to act as an identifier at the start of the tape and also to lay down the start of timecode. It is normal to start picture recording at 1-minute into the tape in the broadcast world. This also has historical reasons where it was not advisable to record at the beginning or end of a tape as these are the areas most likely to be stretched or damaged, either when the tape was loaded onto the spool, stopping after rewind or fast forward spooling or in the case of 1″ and 2″ tapes where they were laced into the VTRs by hand as they were on spools rather than in cassettes.

It’s always worth recording colour bars and tone from your camera for the first minute as it gives a neat time that makes looking at the duration of your recording very simple at any point on the timeline.

Normalising in its most basic form looks through the entire selected clip and produces an audio level and range that gives the best range between loudest and quietest and within the limits of the audio system being used. It’s a little like adjusting the range of contrast in photo editing applications where you want to ensure that highlights aren’t burned out and the shadow areas aren’t crushed.

[George Socka]

The question has come up in my mind as well. The bars are generated to SMTPE standard by the electronics in a camera or NLE. However, if the white balance of the camera is wrong, then what the camera sees and records onto tape is no way within any spec. If the blacks are crushed by bad exposure, then how does it help for the end user to look at the aforementioned bars and make any kind of decision about tweaking the content based on looking at the PLUGE bar? And why would the VTR operator at a TV station want to align his (her) equipment by something that came in over the transom anyway? Much better to actually shoot something like the Getrag (sp?)Color Checker, and then use that to see that red is red and white is white. Color correcting software could then be used to apply corrections based on that rather than the HSL corrections from the days of analog proc amps.

Another mystery. But the bars do look cool and “pro” on the monitor!

[R. Hewitt]

Unfortunately PAL colour bars do not have a Pluge pattern and few stations will use the bars generated bythe camera precisely, as you point out, they may bear no resemblance to the colour temperature of the scene or camera setting. The point of colour bars on the camera is more of a leader on the tape and to identify there is a recording rather than just black.

A studio environment can more precisely setup the cameras and have much greater control over colour temperature (the camera operator dealing only with visuals and focus). The bars in this case are used to line-up the VTR. Knowing that the bars are from an accurate source, lining-up a subsequent VTR on those bars WILL reproduce, accurately, the source material as originally recorded.

The original point of colour bars was to ensure consistent setup within the broadcast chain. In the digital domain more advanced test patterns are used but colour bars are very simple to produce and as a result have been incorporated into many camera and VTRs.

As long as the users monitor has been correctly set – this is what pluge is for, then any material viewed will show all the flaws as recorded and will enable them to make an accurate assessment of the material and what corrections are needed.

What would be useful is to know the exact colour temperature as recorded – something that should be simple to add to the tape data regions.