View Full Version : Light meters for DV camcorders


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Chris Harring
October 20th, 2003, 12:30 PM
Does anyone have any recommendations for what I should look for in a light meter for use in conjunction with my XL1s? I have far more experience lighting and metering light for film, and I want to indulge in the same kind of micro-management with digital.

Thanks!

Charles Papert
October 20th, 2003, 04:20 PM
Digital video has a very different exposure curve than film, and has the benefit of instant feedback via a monitor. The "zone" system really doesn't apply with DV, and each camera has a different response curve. I would only use a meter for pre-lighting a set to a given stop, but it's much easier to use the monitor for on-set lighting. It allows for even more micro-management as you can see the effect of every change instantly, and don't worry that it's "cheating" in any way--I've yet to see a light meter in regular use on "bigtime" HD shows, even by seasoned film shooters.

Rick Bravo
October 20th, 2003, 05:43 PM
Chris,

As a third generation film cameraman, the hardest thing that I had to do when shooting video is putting away my light meter, and let's not forget the color temp meter.

I had never even picked up a video camera seriously until I came to my present job, just the thought was enough to make me run to church and take up residence in a confessional!

If you use your film techniques, (ratios), when lighting video you are just begging for a bunch of broadcast engineers with pocket protectors (no offense, ours actually wears one), to hunt you down and beat you up!

I can light just using the B/W eyepiece on our BetaCams as a guide...I still have absolutely no trust in the MiniDV cams we currently operate. Do yourself a favor and take Charles's advice...use your monitor.

Geez, what ever happened to dailies?

RB

Charles Papert
October 20th, 2003, 06:46 PM
Dailies??! I'll be happy to see those go...knowing what you are getting when you're getting it is not only convenient at the time, it means not having to take additional time out of your life the next day finding out what you got. I wish I had back all of the hours spent in screening rooms after work or jammed on the camera truck during lunch. And all off the clock!

Rick, I hear you about lighting to Betacam eyepieces. That's why I sucked it up and got the Ikegami viewfinder for the XL1--brings back that familiarity, and I trust the exposures and framing I'm seeing.

Rick Bravo
October 20th, 2003, 07:21 PM
Charles,

I've have two of the IKI eyepieces as well, they are terrific. It's the XL-1S itself that I am having my doubts about.

We've only had them for about 6 months and just took delivery of two more today. I guess it is just a matter of time before I acclimate myself to the "new guys".

I hear you loud and clear about dailies. Maybe I'm just a little too old school when it comes to moviemaking. I remember when a decision to print was made by the director based on performance and whether or not the opetator was happy with the shot.

I hated video assist when it first came out, especially when you were on a commercial and the clients all decide that they want to light the shot based on the crappy ground-glass tv image they were watching...it's a freakin' chicken nugget for Pete's sake!

Old habits die hard!

Regards, RB.

Alex Dunn
October 21st, 2003, 10:17 AM
If you're new to DV, try using your zebra stripes if you don't trust the monitor. They are invaluable when it comes to ensuring good exposure. Most LCD's are adjustable and can therefore be WAY differant than what you're actually recording to tape. So if I'm shooting something that I care about I use them every time.

If you learned how to use a light meter, you can learn to use the stripes.

Rick Bravo
October 21st, 2003, 03:09 PM
Alex,

It's not a Zebra issue, as Zebras work the same regardless of the format in which it is being used, analog, digital, etc. I am not worried about correct exposure, it is a "whether the camera is giving me the correct color balance" issue.

Bottom line is that as nice a camera as the XL-1S is it is still lacking in certain "professional" areas.

RB

Alex Dunn
October 21st, 2003, 03:34 PM
Rick,

Sure, but I wasn't responding to you, I was responding to the original post. I thought he was asking about exposure.

Rick Bravo
October 21st, 2003, 04:29 PM
OOPS, I hate it when I do that!

John Jackman
October 22nd, 2003, 08:51 PM
You CAN use a light meter with video as long as you learn to compress your technique, esp. the top end. Most of the movies shot on HD by "first time" digital DPs have blown-out highlights.

Turn the zebra display ON, leave it ON. I never turn the zebra off. Much more than film, overexposure on video is a no-no. When in doubt, underexpose.

I'm editing a show now where several of the camera ops consistently overexposed, and even though I have an arsenal of color correction tools, I can't get the shots to look the way they would have if they had been properly exposed with the same cam.

A light meter is not really the proper way to monitor video exposure and lighting. A waveform monitor is the proper instrument, essentially giving you a precise metering of every pixel.

Hugh DiMauro
October 29th, 2003, 12:16 PM
I calibrate my XL1s to a monitor and I can lay my head on my pillow at night. I'm shooting an hour long indepedent geared towards the film festivals and my actors are all work colleagues with families whose relationships are strained due to my calling out their hubbies to shoot on one of the only days they can spend with the rugrats: SUNDAY. Therefore, I'd better make damned sure I am not wasting one iota of their precious Sundays by having to re-shoot everything because I guffed up the lighting. If it's on screen and it looks good, it will more than likely look good during playback.

Were it not for the digital video revolution, I'd still be only screenwriting. I jumped into one of the open doors of this passing digital video boxcar. I'm in it for the long haul.

Alex Dunn
October 29th, 2003, 01:07 PM
Hugh,

Would you mind describing the process you use to calibrate your XL1 to a monitor?

Hugh DiMauro
October 30th, 2003, 01:41 PM
I'd be glad to:

1) Connect the XL1s to the monitor via RCA cables or s-video cable, depending upon what your monitor accepts.

2) Activate color bars through the XL1s so they appear on your monitor screen.

3) I usually don't bother tweaking the color through the monitor. I leave those settings on default. However, brightness is important because you are using that to visually calibrate the look of your movie. If brightness is incorrectly calibrated, then your entire movie will either be under or over exposed. So, warm up your monitor for at least ten minutes, set the brightness to the pluge pattern in the lower right hand part of the screen. (Please double check "Setting up your monitor" which appears in the DV INFO website :

http://www.dvinfo.net/articles/production/graff1.php

The pluge pattern is the three black bars in the lower right hand corner of the color bars on your TV screen. Adjust your brightness until the first two left bars just merge and the third bar is lighter. Again, please check out the above link and/or type in "calibrating a video monitor" on Google. It's a piece of case and what I have just written is bare bones basic.

Hoe that helps.

Hugh DiMauro
October 30th, 2003, 01:42 PM
Damn! but ain't I a non-spelling freak today?

Alex Dunn
October 30th, 2003, 01:46 PM
I may be dense, but how does that calibrate the LCD on the XL1? That is the goal, right? I thought I was asking how to calibrate the LCD to match the monitor. Were you talking about something different?

Alex Taylor
November 1st, 2003, 03:38 AM
I think Hugh's talking about calibrating an external monitor to use instead of an on-camera LCD.

Bryan Beasleigh
November 1st, 2003, 12:38 PM
Alex
There is no on camera LCD just the 180k viewfinder. There's only so much that you can expect from a .7 inch LCD viewfinder , that's why people use a production monitor.

John Jackman
November 2nd, 2003, 09:25 PM
Alex, you cannot calibrate the LCD flipout monitor on prosumer cameras, and LCD monitors have different gamma than a real CRT monitor. You should not make critical lighting judgments based on a flip-out LCD.

Actually, though the procedure described in Graff's article is the correct procedure, it doesn't QUITE work for prosumer cameras, which do not add setup. The SMPTE bars are intended to work with setup (pedestal) added. The XL1s, GL2, etc. do not add setup to the output signal and display black as 0 IRE rather than 7.5 IRE. A wrist slap all round. To make matters worse, Sony added a setup control on the VX2000, but did it the wrong way -- recording the setup to tape rather than adding it to analog otuput. Haven't ahd a chance to see if they fixed this on the new version.

A "fudge" for calibrating monitors with non-setup camcorders is at:

http://www.greatdv.com/video/smptebars2.htm

Hugh, I don't understand why you don't calibrate the color. It ain't that hard and you can run into silly problems if it's off to far.

Bryan Beasleigh
November 2nd, 2003, 10:07 PM
Nice site John. Loads of good reading.
I've bookmarked it and included it in my sites for newbies file.

Alex Dunn
November 3rd, 2003, 09:24 AM
I didn't think you could (with accuracy), that's why I asked for clarification. The attachable 4 inch LCDs seem to be growing in popularity, I thought maybe this is what he was using. I made a big assumption, oops!

Marc Young
November 7th, 2003, 07:34 PM
Well, you guys convinced me to buy a pro monitor and not rely on my lcd. There goes another $1500 ... for a Sony PVM-8045Q.

Brad Simmons
November 9th, 2003, 12:30 AM
<<<-- Originally posted by Marc Young : Well, you guys convinced me to buy a pro monitor and not rely on my lcd. There goes another $1500 ... for a Sony PVM-8045Q. -->>>

Great little monitor. You'll be happy with it.

David Ziegelheim
November 9th, 2003, 02:52 AM
Is it safe to by an 8045 now? Don't you need an 8045QD with SDI? And will these work with the rumored HDV mini-cams (XL2 elsewhere on this site).

I recently shot with an SDX900 and the video viewed as SDI was different than the video viewed through the monitor port.

John Hartney
November 9th, 2003, 06:00 PM
Hi Chris,

I agree with the consensus that a monitor is the best referance for video lighting. But, I use a Sekonic L-398M Studio Deluxe II - Analog Incident and Reflected Light Meter to check for drops in level on large sets.

I'll use it as a final confirmation to check where levels change on a set.

Camera zebra pattens are useful for judging exposure on a given frame, but when a large area must be set checked, and you have talent working a stage where the director wants a uniform light over a large area, a meter is the best choice for the final check imho.

Best,

John Hartney
werks.tv
Elgin, Illinois
847.608.1357

John Jackman
November 9th, 2003, 09:01 PM
<<<-- Originally posted by David Ziegelheim : I recently shot with an SDX900 and the video viewed as SDI was different than the video viewed through the monitor port. -->>>

No setup.

Alain Aguilar
November 15th, 2003, 10:57 PM
When I look through my LCD color viewfinders I always get at least some zebra lines, specially if the actor is waring a white shirt. Should I try to underexpose these areas or zebra on some bright areas should be acceptable?

John Jackman
November 17th, 2003, 08:39 PM
You are better off underexposing slightly.

Alain Aguilar
November 18th, 2003, 01:37 PM
I'll go for the FT 5.6 and try to level the light accordingly.

Brad Horner
November 18th, 2003, 09:24 PM
I'm new at this so bear with me.

Wouldn't it make sense for a DV to be able to use color correction from your NLE, for example Adobe rbg? Plug your monitor into your NLE and get it corrected to something standardized.

This is a big stretch. How about connecting the monitor to a pc/mac and have some software look at your monitor while you are viewing footage. It would show color bars, right?

This might be the case of a newbie stretching too far for a solution that can be handled easier somehow.

Jeff Donald
November 18th, 2003, 10:03 PM
I'm not sure what you're trying to solve. There are hardware calibrators for monitors. They are fairly expensive, so most editors use SMPTE color bars to calibrate NTSC monitors.

Ken Tanaka
November 18th, 2003, 11:52 PM
Extending Jeff's remarks back to your idea, Brad, there is such a round-about calibration solution. Some of the newer Sony production monitors, such as the PVM-14L5 (http://www.bhphotovideo.com/bnh/controller/home?BI=155&O=productlist&A=details&Q=&sku=262238&is=REG), can calibrate themselves if fed SMPTE bars. I have one and it does a very good job, certainly as good as I can by hand, when I feed it bars from FCP.

Calibration, however, in not something you should need to do frequently.

Jeff Donald
November 19th, 2003, 07:54 AM
Calibration is checked daily with color bars and blue gun. If it has drifted then calibration is preformed. Newer models don't drift nearly as much and PPL circuitry to prevent drift. Older, more analog models will drift more frequently and require manual adjustments. Phosphors change over time on all models and will necessitate infrequent corrections.

Brad Horner
November 19th, 2003, 11:32 AM
I guess the problem with me right now is that I am trying to understand the big picture of color correction from camera to NLE, so my questions are all over the place on the subject. This goes for another thread where I am grappling with the subject. I found a tutorial that will help me with the color bars, but they claim that Adobe Premiere 6.0+ has correct SMPTE bars are correct.
http://www.greatdv.com/video/smptebars.htm

Okay, now seperating the monitor calibration from my mind I (a little) I have some other quirky thing that I found. A waveform monitor and vectorscope in Premiere! Anyone use this in realtime correction to replace a waveform monitor?

Roger Berry
November 22nd, 2003, 08:21 AM
Brad: I've looked everywhere for the waveform monitor/vectorscope in Premiere 6 and can't find it. I'm not even sure what these do but I've read about them and would like to know more. Can you help?

Thanks in advance,
Roger

Brad Horner
November 22nd, 2003, 11:56 PM
Here is a link to a tutorial at the Adobe site. You need to sign up so I'm not sure that this link will just ask for a password or registration. The tutorial is "Correct color in video".

http://studio.adobe.com/tips/tip.jsp?p=1&id=400&xml=prepcolorcor

I haven't had good luck with my posts lately; they are off topic or just confusing. That seems to happen to newbie types in most any forum. Hopefuly the link works.

I can't answer any questions on the topic because I know little to none about it. I am hoping that with some card like the Canopus 2 that it would be possible to make "live" color correction using the aforementioned software vectorscope and waveform monitor. Maybe it's possible but not worth the trouble? Someone (you or I) could start a new thread to try and find out more.

signed,
Overwhelmed

Josh Bass
November 23rd, 2003, 12:33 AM
Have I been doing this wrong for all this time?

I've been following these instructions:

1. Allow the monitor to warm up for a few minutes

2. Dim the room lights and block any reflections on the monitor

3. Feed color bars to the monitor either from a camera or "house bars" from your editing system

4. Set the contrast also called "picture" to its midpoint

5. Turn the chroma also called "color" all the way down until the color bars are shades of black and white
6. Notice the three narrow bars labeled 3.5, 7.5 and 11.5 on the bottom right. These are the Pluge Bars which stands for Picture Lineup Generating Equipment. Adjust the brightness control until the middle (7.5 units) pluge bar is not quite visible. The lightest bar on the right (11.5 units) should be barely visible. If it's not visible, turn the brightness up until it becomes visible.

Since 7.5 units is as dark as video gets, you should not see any difference between the left bar (3.5 units) and the middle bar (7.5 units). There should be no dividing line between these two bars. The only division you should see is between 11.5 and 7.5 (Note this same technique is used in setting the b&w viewfinder on your video camera.)

7. The next step is to set the contrast control for a proper white level. To do so, turn the contrast all the way up. The white (100 unit) bar will bloom and flare. Now turn the contrast down until this white bar just begins to respond. The image below shows what it should look like at this point.
8. With the blue switch on (or your blue gel in front of your eye) turn the chroma or color until the grey bar at the far left and the blue bar at the far right are of equal brightness. One trick is to match either the gray or blue bar with its sub-bar.

9. Adjust the hue control until the cyan and magenta bars are also of equal brightness. You can also match either of them with their sub-bars. Now the four bars - gray, blue, cyan, and magenta should be of equal intensity. The yellow, green and red (which are black in the diagram below) should be completely black.




They're from some site. . .don't remember where; I know it's referenced here.

What happens if I do it this way and the setup is 0, instead of 7.5 as these instructions are made for? That additional step sounds difficult to do by eye, which is the only available method I have right now.

Also, does anyone know if I should recalibrate when color correcting in post (I use the same monitor in the field as I do for the color correction)--meaning should I use the camera's bars for shooting and the bars in Vegas 4 for editing, or is it all the same?

Roger Berry
November 23rd, 2003, 07:13 AM
Thanks for the feedback Brad. That tutorial was well worth reading even though I only have basic Premiere 6, not the Pro version. The controls mentioned are not included in my version -- the nearest I've got is a color correction workspace and no wave form monitor.

I'm not sure it's worth upgrading just for this feature, at least until I understand it's importance properly. Are there any other important reasons why I should shell out more dosh for the Pro version?

JOSH: I don't own a proper monitor... just use TV sets... but your calibration method is the same as mine and it seems to work. I too would like to know if we're doing it wrong.

BTW, I disagree, most of what you write seems to be right but then, who am I to say?

Josh Bass
November 23rd, 2003, 09:20 AM
Yeah, and also, I remember reading elsewhere on this forum that you had to LOWER the setup on the XL1s to get it to 7.5, like down two notches. I swear.

Wayne Orr
November 24th, 2003, 06:45 PM
Sounds like you guys are doing it right, but are you certain you have accurate color bars? There are some bogus bars floating around the web, and even some supplied with software are NG. One of the best places on the web to get accurate color bars for FREE is from Synthetic aperture at http://www.synthetic-ap.com/products/tpm/index.html

Video University has some infor for setting up monitors for PAL, as I recall. Also try Tektronix website. They have an excellent technical tutorial.

Wayne Orr, SOC

Josh Bass
November 24th, 2003, 07:03 PM
Like I said, I use the ones out of Vegas, or the ones straight from the XL1s.

Wayne Orr
November 24th, 2003, 07:13 PM
Sorry, Josh, but that does not necessarily mean they are accurate. Best way is to check 'em out in Photoshop. Especially the ones from the camera.

W.

Josh Bass
November 24th, 2003, 07:20 PM
Alas, I have no photoshop. I thought one of the big pluses of the XL1s is that it had honest to God SEMPTE bars.

Wayne Orr
November 24th, 2003, 07:33 PM
That is very likely true, Josh. I didn't mean to imply otherwise. I am sure someone will come along and set the record straight. Can you run your cursor over the bars in your edit software and read the luminance values on the various chips?

W.

David Ziegelheim
December 2nd, 2003, 11:13 PM
A high res monitor is always nice...but not always there, especially with miniDVs. They are bigger than the camera.

Zebra's also nice, but not very exact.

The meters allow you to cover a large area, get objective readings on contrast and on shadow detail (usually impossible to see on the LCD, and difficult on a small field monitor being viewed in the native field lighting).

Last weekend I needed to light a table, and the meter quickly found some 1-stop holes that I don't think I could pick up with the camera, especially before the subjects arrived.

David

Carlos E. Martinez
December 3rd, 2003, 12:31 PM
<<<-- Originally posted by David Ziegelheim :
The meters allow you to cover a large area, get objective readings on contrast and on shadow detail (usually impossible to see on the LCD, and difficult on a small field monitor being viewed in the native field lighting).
-->>>

As I had a discussion over this question on another DV Info Forum recently, and got many attacks from it, I can say I absolutely agree with you.

People look at film tools, when used for video, as an "old" thing. And I think it's quite the opposite.

In my opinion some practical basic things are getting forgotten.

No doubt a CRT monitor and a waveform are excellent tools to work in video, probably some of the best.

But metering a frame using a combination of incident and spot meter may go a bit farther.

What can I say: maybe I have become an old bloke.

As long as you can use the right ASA reference (where do you get that for different camera models?) and know how to handle a spot meter (not many really do) what is the real problem?

They are all tools, folks. Like a screwdriver or a hammer. And they never got old fashioned.



Carlos

Roger Berry
December 3rd, 2003, 03:41 PM
This has been a really brilliant thread and I've tried out a lot of the suggestions and learned loads of things so thanks everyone. Like Carlos, I'm probably becoming an old bloke and finding it hard to accept new ideas but I'm starting to get there (BTW Carlos, my wife's sister's husband's mother is a Martinez; from Guadalajara near Madrid. Are you related? Probably not).

Anyhow, after reading all your comments, this is how I've got this thing figured. Hard as it is to accept, we don't need light meters any more. Set gain to zero and the stripes to about 90 and if you can't get zebras in your highlights at something like 1/50th at F8, there's probably not enough light to produce a nicely saturated image.

You've still go to get white balance and exposure right but that's another issue. I still wish I could use a light meter and know I was going to get the exposure right but I'm now convinced that's not the way it works.

Oh yes, one more thing; I reckon from the tests I've done the ASA/ISO rating for the XL1s is between 320 and 400... not that this matters any more.

Thanks again everyone.

Helen Bach
December 4th, 2003, 11:22 AM
Carlos asked: 'As long as you can use the right ASA reference (where do you get that for different camera models?)...'

The same way that you get the rating for film? Do a test with your meter, your lenses etc. Instead of having to read densities with a densitometer, you read values in your NLE. "More details upon request".

Best,
Helen

Carlos E. Martinez
December 4th, 2003, 12:59 PM
<<<-- Originally posted by Helen Bach :
The same way that you get the rating for film? Do a test with your meter, your lenses etc. Instead of having to read densities with a densitometer, you read values in your NLE. "More details upon request".-->>>

Well, I used to get my rating from the film manufacturer. As that's usually the "conservative" rating, we went up and down that value to work on the black resolution (deeper or thinner blacks). Using a densitometer for colour negative wasn't really something I cared for.

In any case my question was to see if someone had already seen or done some sort of table for some camera models. E.g.: the DVX100 is considered as having a "320 ASA" sensitivity.

The problems with "video-ASA" sensitivity is that you have to be "conservative", as the latitude is critical. Particularly in DV cameras.


Carlos

Helen Bach
December 4th, 2003, 04:56 PM
Carlos,
'Using a densitometer for colour negative wasn't really something I cared for. '
Just out of interest, why?

Best,
Helen

Carlos E. Martinez
December 4th, 2003, 07:00 PM
<<<-- Originally posted by Helen Bach : Carlos,
'Using a densitometer for colour negative wasn't really something I cared for. '
Just out of interest, why?

Well: one thing because that was the way I was taught cinematography. Projection tests, using a projector you did know, on a lab screen you were used to, were the real test.

A second one because where I started filmmaking, in Argentina, the DP took the film until first copy. So you had more control on what you were doing.

Densitometry made more sense in black & white days, where you could have a direct relationship because grays card and grays reflections from costumes and props were more readily measurable. It still makes sense in optical negative control.

But in color photography there are so many variables in the game that, in my opinion, it's very difficult to get the same accuracy even if you intend to.

Even color metering I think it's a waste of time. Going strictly by the book is a kind of precision that it's difficult to keep up with and gives too little to have fun with.

Of course nobody has to agree with me.


Carlos E. Martinez