XA10 - How to get the correct exposure?

[Mike Costantini]

I thought I'd start a new post because I'm sure someone else will have the same question sooner or later.

What is the actual process to get the correct exposure (aperture, shutter speed and gain) on the Canon XA10?

How does one use the Waveform Monitor (WFM)?

I have an 18% gray card if that can be of any benefit, as seen here:
Sample: How to Get a Good Exposure | Izzy Video but cannot figure out how to "lock the exposure" on the XA10

[Andree Markefors]

As a starting point I would suggest:

Set the camcorder to M (not cinema and not the green auto mode) and then shoot using the P mode.

This way the camera is mostly automatic, but you can still lock down certain things that you can't in auto mode.

Enable zebras and set the clip to 100 IRE.

Now when you shoot outside you are likely to see some zebras showing up in overexposed areas. Press the little button above the scroll wheel on the back left of the camera. A +/- symbol shows up. You have now locked the exposure.

By scrolling the little wheel up or down you can increase or decrease exposure in steps. It will still be locked down to what ever you set it to.

If you reduce exposure to the point where there are no zebras, then you know that you are not clipping any highlights.

But the thing is that these cameras record to something that is called 'super white' that correlates to 125 IRE. So even if you see some zebras you might not have clipped the highlights. But anything over 100 IRE is not broadcast safe, but should be fine for computer distribution.

Unfortunately, the dynamic range of these type of cameras is not that great, so you might not be able to expose for highlights correctly and at the same time achieve good exposure for mids and shadows. It's your call how you want to distribute the DR for each shot.

Once you get a grip on these basic things, you can move to more manual settings. You should be aware that if you let the camera set aperture and shutter for you, you might end up with shutter speeds that are "unconventional", i.e. not 180 degree shutter.

[Jeff Harper]

Very nice mini-tutorial Andree, thanks for posting. Your suggestions are a great way to begin with using more manual settings on the XA10.

[Mike Costantini]

Hi Andree,
Yes, thank you very much for the step by step as that is exactly what I was looking for. One thing I'm a little confused about is where you said "A +/- symbol shows up. You have now locked the exposure." The little button you're referring to is the custom button, correct? I haven't played with the camera for a few days, so I will try your suggestions hopefully later today.

[Mike Costantini]

Hi Andree,
Ok, I did a little test last night using the P mode you suggested. I also used the color depth feature which made the picture much more rich. I enabled the Zebra at 100 as you instructed. I then set the custom button so that the wheel would adjust the exposure too. One thing I noticed is that I can turn the exposure up quite high before the zebra pattern shows up, so my question is, how do I know how high to set the exposure in the P mode? At first I thought I'd turn it up until just before the zebra lines show up, but that's way too much. Is there another way to gauge how far to go with it?

[Don Palomaki]

Zebra at 100%, indicates what areas of the image have reach or exceeded the broadcast legal limit.

Zebra at 70% - used by some as the desired brightness for faces, but will not apply to all faces or situations

Zebra - says nothing about shadows or mid tones, gamma, knee, etc.

Zebra is a guide to help you - it is not an absolute. You need to gain experience with the tools and techniques so you can judge what the zebra setting means with respect to the rest of the scene, and your intent for capturing that as a video image, for a given shooting situation including the contrast and brightess range of the scene and the artistic effect you want to achieve.

There is no instant short cut to gaining this, it takes time, experience, and some talent. That is why many people (who generally are not professional shooters) trust to auto expsoure and make and necessary adjustments in post as best they can.

[Mark Goodsell]

I personally prefer to set my zebras at 70 rather than 100.

[Colin Rowe]

Zebras are only a guide to exposure, allbeit a reasonably accurate guide, when set up properly. You need to know your camera, and use your own eyesight to get it right, never trust to the zebra display as the be all and end all, rather, an indication that you are pretty close, (again, provided that you have them set properly)

[Don Palomaki]

The best way to get the correct exposure is to have a good, accurate monitor connected to the camcorder while shooting, and use the monitor to judge the overall exposure to ensure the items of interest in the scene are correctly exposed. (The LCD panel is a poor substitute for a good monitor but better than nothing.)

The benefit of a waveform monitor, if you know how to read it, is that it gives a graphic indication of overall expsoure and brightness range, and whether or not you have blown out highlights and/or crushed blacks. (More information than zebra, but arguabloy less that what you see on a good monitor.)

As to how to use it, not enough time or space to cover that here. Reasearch on line, do somereading on the subject (maybe a lot), and practice witha good monitor connected so you can do correlationbetweenwhat is ont he screen and onthe WFM.

The 18% gray card was developed for film, and is often used in conjunction with bracketed exposures, because you have no instant feedback with film. You have to wait for it to be processed. And the 18% was good choice based on the light response of film. The gray card result may or may not be appropriate for a given video shoot and in any case with video you can have instant feedback on a monitor so there is litle benefit to having a gray card, except maybe for setting mid tone white balance in post.

[Mike Costantini]

I finally had a chance for a test run of the XA-10. I used the P mode and used the custom dial for the exposure. However, something weird happened. After I recorded the first clip, I switched over to the playback mode to make sure the clip that I recorded was there. When I switched back, the exposure setting changed. So I rolled the wheel back to where it was (I remembered) and the picture looked way too dark this time. How did this happen? I read in the book that the camera saves the white balance, so that shouldn't have had anything to do with it (I did set the white balance)

[Andree Markefors]

Kind of a late follow up:

First: what I suggested above was simply a reliable method not to clip any information beyond repair. But as I also suggested, this might not always be possible, since the dynamic range is limited.

Often you will have to decide how much you are willing to clip in order to prioritize shadows or good mid tones. Or add light...

As long as you haven't clipped highlights, a somewhat bright exposure is trivial to correct in any editor. A general rule for shooting video or film is "expose to the right", meaning: expose as bright as you can without clipping, in order to minimize shadow noise. And then dial in the desired exposure in your NLE by adjusting black and white level and or the gamma curve.

That said, it should work fairly well to simply gauge the monitor...

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The little click wheel on the back left has no fixed values. It simply increases or decreases exposure relative to the locked in value you get by clicking the button to lock exposure in the first place.

If you lock exposure and then roll the wheel two notches down you are slightly under exposed. If you then release the exposure lock and point your camera somewhere else and then re-lock, you might very well be slightly overexposed. You then have to readjust exposure with the wheel.

Locking your white balance to a preset such as daylight is always a good idea to avoid WB drift.

[Noam Osband]

I like using a wave form monitor to check my light levels. It seems there is no way to access the WFM monitor in the XA-10 while I'm shooting, that I can only do it while it's paused. Am I right about this? I hope I'm not but I think I am.