Wave Form Monitor - understanding

[Ian Chapman]

Hi All...your help, experience and advice would be most welcome on the following:

In different light, particularly outdoors, we all know how tricky it can be to see the LCD screens (I have both XF300 and XF100) in order to make an accurate exposure. The XF100 is particularly tricky to see compared to XF300.

My judgement is usually accurate after 18 months with the cameras, but not always. So I have recently tried to master the Wave Form Monitor.

Excluding the top and bottom of the bounding frame of the WFM area, there are six thick white lines and five intermediate fainter lines.

It seems to me, after much experimentation, that if the green 'blob' which represents the 'whites' is allowed to just touch the faint line next to the top thick white line (that's the one next to the top of the whole frame) then the exposure is pretty much spot-on and allows the highlights to be retained (i.e. not burn out) and the main exposure to be as accurate as I could hope for.

Would this observation be consistent with your own findings?

If not, then can anyone reveal a more accurate way to interpret the WFM and it's mushy green output?

many thanks...look forward to your replies

Ian

[Mike Kujbida]

Ian, see if the following tutorial from Sony helps at all.
Using the Vegas Pro color scopes

[Seth Bloombaum]

Not owning these cams I can't confirm where white is in the WF displays, so these comments are about WF and exposure in cameras in general..

Exposing for whites is a typical approach. Nothing screams "poor quality video" like blown-out whites. When they blow, all detail is lost, it is unrecoverable in post, and it has a look all its own, doesn't it?

Exceptions are specular reflections, that is bright light sources reflecting off shiny objects. For example, the bright highlights on chrome bumpers at an outdoors antique auto show on a sunny day.

However, faces that don't look like faces tend to be a much worse result that whites that are blown out. We all know what faces are supposed to look like. For most of our work, it is the human face that is the most important object in the frame. For caucasian faces, that means about 75 to 80ire or % of full scale white on facial highlights. This is where Zebras are so useful, Sony usually gives you 75 (faces) and 100% (whites) zebras, Canon a range of choices from 80 to 100. If you have 75 or 80% zebras touching facial highlights, those faces should look just right without CC in post.

What to do when the latitude of the scene is so broad that you can't both put whites at or near 100 and facial highlights at or near 75 or 80? If you're running and gunning for the news, you expose for the face, or, you turn on your on-camera light and then expose for the face.

For other sorts of field production, you might light or relight, or change locations, or just reposition your camera and subject in relation to the light source and available shade. Indoors, and the window in the shot is so bright and blown out? Reframe so it isn't in the shot. Shoot at night. Get a flag out there. Shoot in front of a different window, on the shaded side of the building.

I am excited to own a camera with WF, but the WF is so small... still, very handy for some tasks. On a day-to-day basis I still use Zebras as the primary exposure indicator.

In general, it's better to err on the side of underexposure and later color correction. With the limited scene latitudes that today's video and dSLR cameras can represent, it's well worth looking at various flattening techniques. These are different for every camera... and I'm not familiar with what you can do with yours. Perhaps black-stretch and underexpose will flatten things out for later stretch in post color correction?