Category Archives: Shooting Tips

Calibrating your viewfinder or LCD.

smpte-arib-bars-sample Calibrating your viewfinder or LCD.One of the most important things to do before you shoot anything is to make sure that any monitors, viewfinders or LCD panels are accurately calibrated. The majority of modern HD cameras have built in colour bars and these are ideal for checking your monitor. On most Sony cameras you have SMPTE ARIB colour bars like the ones in the image here. Note that I have raised the black level in the image so that you can see some of the key features more clearly. If your using a LCD or OLED monitor connected via HDSDI or HDMI then the main adjustments you will have are for Contrast, Brightness and Saturation.

First set up the monitor or viewfinder so that the 100% white square is shown as peak white on the monitor. This is done by increasing the contrast control until the white box stops getting brighter on the screen. Once it reaches maximum brightness, back the contrast level down until you can just perceive the tiniest of brightness changes on the screen.

Once this is set you now use the pluge bars to set up the black level. The pluge bars are the narrow near black bars that I’ve marked as -2% +2% and +4% in the picture they are each separated by black. The -2% bar is blacker than black so we should not be able to see this. Using the brightness control adjust the screen so that you can’t see the -2% bar but can just see the +2% bar. The 4% bar should also be visible separated from the 2% bar by black.

Color is harder to set accurately. Looking at the bars, the main upper bars are 75% bars so these are fully saturated, but only at 75% luma. The 4 coloured boxes, 2 on each side, two thirds of the way down the pattern are 100% fully saturated boxes. Using the outer 100% boxes increase the saturation or colour level until the color vibrance of the outer boxes stops increasing, then back the level down again until you just perceive the color decreasing. I find this easiest to see with the blue box.

Now you should have good, well saturated looking bars on you monitor or LCD and provided it is of reasonable quality it should be calibrated adequately well for judging exposure.

I find that on an EX or F3 the LCD panel ends up with the contrast at zero, colour at zero and brightness at about +28 on most cameras.

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When should I use a Cinegamma or Hypergamma?

Cinegammas are designed to be graded. The shape of the curve with steadily increasing compression from around 65-70% upwards tends to lead to a flat looking image, but maximises the cameras latitude (although similar can be achieved with a standard gamma and careful knee setting). The beauty of the cinegammas is that the gentle onset of the highlight compression means that grading will be able to extract a more natural image from the highlights. Note than Cinegamma 2 is broadcast safe and has slightly reduced recording range than CG 1,3 and 4.

Standard gammas will give a more natural looking picture right up to the point where the knee kicks in. From there up the signal is heavily compressed, so trying to extract subtle textures from highlights in post is difficult. The issue with standard gammas and the knee is that the image is either heavily compressed or not, there’s no middle ground.

In a perfect world you would control your lighting (turning down the sun if necessary ;-o) so that you could use standard gamma 3 (ITU 709 standard HD gamma) with no knee. Everything would be linear and nothing blown out. This would equate to a roughly 7 stop range. This nice linear signal would grade very well and give you a fantastic result. Careful use of graduated filters or studio lighting might still allow you to do this, but the real world is rarely restricted to a 7 stop brightness range. So we must use the knee or Cinegamma to prevent our highlights from looking ugly.

If you are committed to a workflow that will include grading, then Cinegammas are best. If you use them be very careful with your exposure, you don’t want to overexpose, especially where faces are involved. getting the exposure just right with cinegammas is harder than with standard gammas. If anything err on the side of caution and come down 1/2 a stop.

If your workflow might not include grading then stick to the standard gammas. They are a little more tolerant of slight over exposure because skin and foliage won’t get compressed until it gets up to the 80% mark (depending on your knee setting). Plus the image looks nicer straight out of the camera as the cameras gamma should be a close match to the monitors gamma.