Category Archives: cinematography

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.


Setting Exposure with Standard Gammas – Use your judgement!

grey-boxes Setting Exposure with Standard Gammas - Use your judgement!First take a long look at the image to the left. look at the 3 small grey boxes. What do you see?
Is the middle of the three grey boxes brighter than the others? Does the bottom small grey box look about the same brightness as the top one?

This post comes as the result of a discussion going on elsewhere about how to correctly expose when using standard gammas. Basically discussing how to expose when your not going to do anything to your footage in post,  for what I would call “direct to air”.
There are many ways of setting exposure. You could use a light meter, you could use zebras,  you could use a waveform monitor or histogram.

Lets imagine that grey box is a face. If you were using zebras you would normally set them to between 65% and 70% and then expose the shot so the face exhibited the zebra pattern over any parts of the face not overly highlighted or in shadow. This is the textbook way to expose using zebras. Another way to expose might be to use a mid grey card (also known as an 18% grey card). With standard and cinegammas you would normally expose this at 50% using the cameras histogram, waveform monitor or spot meter. Again this is a textbook, technically correct exposure. But this is the real world and the real world is very different to the theoretical world because light plays tricks with our eyes and the overall brightness of a scene can change the mood of the shot.

Lets say you have a room with dark coloured walls.  At one end is a window and you have an actor standing at each end of the room, one against the dark wall, one against the window. We have two shots in our scene, one looking at the actor against the dark wall, one looking at the actor against the window. What happens if we expose both faces using zebras to exactly the same textbook 65% level? Well the face against the window will look darker than the face against the black wall. Look back at the grey boxes on the left. The top and middle grey boxes are exactly the same brightness but because the middle box is against black, to our eye’s it appears brighter than the top one. Now if we were to use a histogram or waveform monitor to expose these two shots, all the extra white in the window shot might tempt you to reduce the exposure, this would make the problem even worse. In fact to expose these two shots so that the faces match as you cut between them you need to reduce the exposure on the darker shot. Looking at the grey boxes again the lowest box is actually at 45% while the other two are at 65%, yet the lower box appears to be about as bright as the top box.
So what am I trying to say? Well exposure isn’t all about setting object “X” at exposure “Y”. You must use your judgement and a known monitor or viewfinder to asses your pictures. Learn to interpret what your monitor is telling you, learn to recognise scenes that may need to be exposed away from the text book values and methods. Above all else don’t be afraid to expose for what looks right, as opposed to object “X” at value “Y”.
I suppose to follow up on this I should tell you how to calibrate your viewfinder or monitor… I’ll do that soon in a later article. Did you find this useful? let me know, I’m planning on writing more about dealing with light and lighting.