Using a Light Meter for DV shoots

[Seth Bloombaum]

Originally Posted by Larry Vaughn

...I could use Zebras, but I shot a bike race outside last weekend and no matter what I did I couldn't make the zebras go away when someone with a white t-shirt was in the photo. It was an overcast day and the images didn't look overexposed in the lcd or through the viewfinder on playback. The zebra setting was default so maybe it never will go away at the lower numerical setting.

So, my next question is what software to use as a vectorscope? I don't want to pay $600 for the Canon software at this point, anyways.

Learn more about Zebras. Zebras do not indicate overexposure. In outside shooting with available light a meter isn't going to do more for you than Zebras will, and a light meter is one more piece of equipment to futz with. OTOH, a meter is a handy way to rough-in lighting setups.

1. What reference was your Zebra set to? Depending on the camera, this could be anywhere from 70 to 100 (percent of full white). If you want white jerseys to be white, set Zebra to 100 and expose such that all highlight areas of the jersey show Zebras.

2. "...no matter what I did I couldn't make the zebras go away..." What did you try? Does your camera have ND (Neuteral Density) filters, shutter speed controls, and iris controls? Is it possible that the camera was on auto exposure, or, that one of the above controls was on auto?

So, my next question is what software to use as a vectorscope? I don't want to pay $600 for the Canon software at this point, anyways.

Your NLE may have a vectorscope. Usually, you'd want to check exposure with a waveform monitor, a vectorscope is rarely used in the field, but is handy for matching & correcting colors.

For field, I use DVRack on a PC, but there are some other choices out there if all you need is waveform/vector scopes (DVRack does quite a bit more, but there is a less expensive "Express" version as well). scopebox.com on a mac, and others.

[Larry Vaughn]

I set the camera on manual and stopped down the iris manually. I did this at several shutter speeds and nd filter settings. I do need to optimize my knowledge in this area, which is why I asked. Canon doesn't supply much info here.

So, if I understand this correctly, at 100% when the zebras are only on white, you get a good detail in the whites without overexposure. If they show up in darker areas, then those areas are going white and the actual white will burn out.

What happens at the lesser settings like 70%?

Scopebox doesn't support HDV yet, are there other Mac solutions similar to DV Rack? I have a Mac and a PC, I let them fight each other late at night.

[Seth Bloombaum]

I set the camera on manual and stopped down the iris manually. I did this at several shutter speeds and nd filter settings.

Something's not right here. I think you must be missing something - on full manual you should be able to get down to no picture at all using shutter speed, iris and ND. Is it possible that gain is still on auto?

Sorry, don't know much about other mac solutions. Depending on the camera you can downconvert on the fly to scopebox or whatever - this is fine if you just want to see exposure.

So, if I understand this correctly, at 100% when the zebras are only on white, you get a good detail in the whites without overexposure.

Almost. White is white, no detail. A "white" t-shirt with any sort of directional lighting will show greys, shadows, and highlights. These are meaningful details. The eye sees all this range, the brain says "white". You need the camera to see all this range, too. If there are 100% zebras across the entire shirt, there won't be grey, there won't be shadows, there won't be much detail. So, what you want is 100% detail in the truely white areas of the "white" shirt, the brighter areas and highlights.

If (100% Zebras) show up in darker areas, then those areas are going white and the actual white will burn out.

Right.

70% & other settings on Zebras are usually used to check skin tones.

(Arguably) a caucasian face should be about 75 or 80 units. Some Canon cameras have settings for 70-75-80-etc., up to 100. In this case you might roll through the different settings to see what they tell you about a scene.

Some practices have wide acceptance... but there are still people who say "I do it this way and it works for me". More power to them.

Caucasian faces 75-80. Whites to 100 (note that your camera may show some detail in recordings above 100). The tendency when working without Zebras seems to be to underexpose, but this is generally better than overexposing.

Oh, one more thing... when I'm shooting I let specular highlights burn out if needed. These are, for example, the reflection of the sun off a chrome bumper. If they're small, I say let 'em burn and don't worry. See how it looks to you.

Mostly, do a bunch of shooting, paying attention to what the zebras tell you, take it in to edit, look at your scopes on the editor, try to develop a sense of how the chain of exposure works on your systems from shoot to edit to distribution.

[Larry Vaughn]

That's what was happening, manual iris stopped down until black-no picture. It's been a week and I don't remember all the settings. I'll fool around with this some more; your info is real helpful.

Can you recommend any book that covers this topic? Maybe I should keep asking questions here.

Most of the TV guys I worked with in the era of 3/4" tape with were just point and shoot. One of them was amazed the I actually disassembled the camera and cleaned everything, or set the camera on manual and stopped down a bit to intensify colors.

[Andy Harding]

Hi John,
As a starting point I use a ISO on the lightmeter of 320 for mini DV in my Xl1s and XL2.
If I set the meter to fps thought (running at 25fps (PAL) it usually reads a stop over E.G
At ISO 320 lightmeter could read f5.6 at 1/60
At 25 fps lightmeter would read f4.0 at 1/60
(these could be the wrong way around i'm away from the meter at present).

Basically on a normal meter use ISO 320 as a starting point. Works for me anyway and I only shoot the XL2 on manual settings, with a manual lens.

[Heiko Saele]

Learn more about Zebras. Zebras do not indicate overexposure. In outside shooting with available light a meter isn't going to do more for you than Zebras will, and a light meter is one more piece of equipment to futz with. OTOH, a meter is a handy way to rough-in lighting setups.

1. What reference was your Zebra set to? Depending on the camera, this could be anywhere from 70 to 100 (percent of full white).

If you're lucky your camcorder can show you two zebras at once, like 70 to 90% and 100%
I love to use the two zebra display with 70% and 100% - when you're used to it it's giving you so much information you won't need a lightmeter at all. Skin tones at 70% is stripes, everything blown out at above 100% is dots - what more do you need?

[Paul Steinberg]

Originally Posted by John Astad

Hi,

I was wondering if anyone in the forum has used a light meter when setting up their manual shots. I've been using the zebra pattern with success but what about a light meter for getting a general f-stop/shutter speed reading?

I have a hand held http://www.bowerusa.com/SP-lightmeters.html light meter that I used with my 35 mm camera and was thinking about putting it to use for DV cam shoots.

Question is, what do you set the ASA at on the light meter dial? Anyone have any ideas?

Regards,

John

Hey John, to find the ASA rating of your camera...

Point your camera at an evenly lit 18% grey card and set your cameras exposure/iris/aperature to auto.

I'll adjust the light until the the camera, in auto, is reading f/4

Now adjust your meter's frame rate to match the frame rate of the camera and finally adjust the ISO of the meter until it reads F/4.

Taaaaadaaaaa. Now you're in the ballpark but you should go shoot some tests before using your meter on set. There is a lot of literature out there about 12%, 13% and 18% grey and their use for calibration. Shoot some tests and you'll see how you like to expose for your camera.

Meters like the Sekonic 508C and 608C are great for bouncing between shooting stills and moving pix as they have both T and f/s modes.

[Sean McHenry]

I didn't get to reading the entire thread yet but one thing to keep in mind that has always been handy for me in the field is that if you set your Zebra for 70, in my broadcast days that was generally considered to be the average caucasion skin level. It's also one of the chips in the B&W chip chart so if you just start hitting the zebras on the face of your principal subject and he/she is caucasion, this is a good indicator of what is considered proper level for that skin tone in the broadcast world. Broadcast, as in News that is.

Theatrical lighting is completely different and as wild as your imagination HOWEVER, you must still stay within the contrast ratio boundaries of the medium. If your in film and you have 7 Stops to work with, feel free to use them. In DV, if you have 4, don't make those dark areas as dark as you would in film or there won't be any detail seen in your video, etc.

It's a sad fact that the contrast range in video is so much lower than film. For those that want a film look, there is generally a gama trick or two or a "black stretch" that can be applied in post to simulate a better S-curve and so on. Trouble is, you can't make it have more dynamic range or contrast than the final medium or it's just lost.

If you really want the film look, you're going to have to shoot film. That's just the truth of it. I know you can simulate it convincingly but it's not going to be the same no matter what you shoot with, what frame rate etc. Video just doesn't have the range.

Sean McHenry
http://www.DeepBlueEdit.com