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Light meter HDV shooting

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Carlos E. Martinez
Light meter HDV shooting
on Jun 27, 2007 at 11:45:55 am

This may not be a new subject, but I would like to get some comments.

High quality HD monitors are still quite expensive. And people shooting in HDV are, by definition, trying to get HD quality on a low budget.

So I am getting back to this dilemma: how far can you rely on the zebra pattern, except on situation where contrast is very high? Can you really trust a viewfinder or an external monitor to handle your contrasts? Wouldn't an incident light-meter and a spot-light meter be better to know what you are really getting?


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Leo Ticheli
Re: Light meter HDV shooting
on Jun 27, 2007 at 12:07:32 pm

No.

A light meter only tells you what the light meter itself is getting! It has no idea what kind of exposure you're actually getting.

The lens on an HDV camera is marked in f-stops, not t-stops so the actual transmission is probably far different than the light meter assumes. The lens stops on an HDV camera are most certainly wildly optimistic.

Don't forget that the light transmission and t-stop can change with the focal length!

Furthermore, the response of the CCDs may not be linear, so the "ASA," the exposure index changes depending on the amount of light.

The best light meter is the one built in, both in the camera and in you, your eyes and your monitor.

You can use your meter to light your set, but not to set your camera aperture.

Good shooting and best regards,

Leo



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Carlos E. Martinez
Re: Light meter HDV shooting
on Jun 27, 2007 at 12:43:50 pm

Of course I am aware how a light meter works, and you should use two types: incident and reflective (spot). Then you can see what contrast ratio you have or what you should adjust to.

And the T versus F stops was a problem we also had when I started shooting film many years ago. The working horse mostly used in 16mm back then, the 12-120, was only calibrated in F stops.

The ASA exposure is an issue, certainly. But I am not sure you can trust your eye or your monitor in HDV, except if you have a quality monitor, which was the problem I started from in the first time.

In my case I am shooting with a Sony Z1.


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Leo Ticheli
Re: Light meter HDV shooting
on Jun 27, 2007 at 1:15:44 pm

The difference between incident and spot meter has nothing whatsoever to do with the basic unsuitability of using a light meter to set the iris on your camera.

They are both analogs of what's really happening at and beyond the CCD.

If you persist in setting your iris with a light meter, ignoring what you see on even a modest quality LCD, you do so at your own peril.

LCD monitors are very inexpensive these days, probably about the same or even less than a high quality light meter, and are far more accurate for judging exposure than any light meter.

Good shooting and best regards,

Leo






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Peter Ralph
Re: Light meter HDV shooting
on Jun 27, 2007 at 1:22:23 pm

hook the camera up to a laptop, fire up your NLE and use the waveform monitor. Not a substitute for a calibrated monitor but a lot more useful than a light meter.

peter

http://www.shootingbynumbers.com


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Todd at Fantastic Plastic
Re: Light meter HDV shooting
on Jun 27, 2007 at 2:19:02 pm

Totally agreed.

Trust Leo, he knows what he is talking about... and has probably been using light meters since the day they invented sprocket holes (not trying to date you, Leo... I'm not far behind).

Yes, light meters are useful for setting a scene, but for setting exposure for HDV? No way.

I've found that on a video set a meter's most useful feature is so the DP can look cool walking around taking readings and impressing the client.

I have a meter that's worth more than I paid for my first car, but it almost never comes out of its case unless we are shooting 35mm... it's virtually worthless on a video set (and I'm using spot-on accurate cine lenses).

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com






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MarkNY
Re: Light meter HDV shooting
on Jun 27, 2007 at 11:43:50 pm

I think, it's a good idea to double check exposure using viewfinder in black and white. Because color could fool you around. I have Sony Z1.



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bruce alan greene
Re: Light meter HDV shooting
on Jun 28, 2007 at 5:00:09 am

Carlos,

The challenge of using the light meter with most video cameras is that the iris on the camera is so sensitive that getting a good exposure by setting the iris will be hit and miss.

Judging exposure in the viewfinder can be tough if the finder changes brightness as you move your head (poor quality LCD).

So you're left with zebras + your imagination, or a decent monitor which you find too expensive.

I guess you could light using the light meter and expose using the zebras after careful testing of the camera using a good quality monitor (just for the test)...


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Carlos E. Martinez
Re: Light meter HDV shooting
on Jun 28, 2007 at 11:54:16 am

Thanks for the honest and realistic answers.

Except for the laptop suggestion, which I do not think might be practical for most location work and because I do not trust firewire interconnection for mobile situations, the others might be the way for me to go.

The firewire interface is also the reason why I do not like portable HDD recording, which is a must for cameras using Panasonic's P2. Plugging and unplugging that connection is a path for trouble, as I see it, but I might be wrong about it. I only trust locking connectors for serious work.

So unfortunately the waveform option is out.

For the others, except for the light meter, which I haven't yet tried except for short tests on video work, the viewfinder + zebra + external monitor combo is what I already use. The question is always that of dynamic range, as when I correct down what zebra spots high for me, I may lose detail in the shadows. Which is more critical in HDV than in DV.

And it's darker areas where less than $1,000 monitors do not behave that well.

When you view it through the B & W viewfinder things seem to be fine, but when you get to the NLE you it seemed a bit "optimistic" too.


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P. J. in Hollywood
Re: Light meter HDV shooting
on Aug 22, 2007 at 5:08:57 am

Hi Carlos,

The tools you use depend on what you're shooting. Since this is a cinematography forum, perhaps you're doing set-up shots with the camera on sticks? If so, have you tried DV Rack?

DV Rack has been purchased by Adobe, but it doesn't appear to be on their product list. They do appear to have some support for it, however.

DV Rack can be purchased from Videoguys.com http://www.videoguys.com/dvrack.html

Here's a link to a great review of DV Rack by Tim Kolb of the Creative Cow:
http://library.creativecow.net/articles/kolb_tim/hdv_dv_rack.php

Here's another from Event DV:
http://www.eventdv.net/articles/readarticle.aspx?articleid=12543

Light Meters: Light meters are quite useful for videographers who know what to do with them.

Here's a link to an informative tutorial by Kendal Miller on calibrating a light meter in digital cinematography:
http://www.freshdv.com/2007/07/calibrating-a-light-meter-for-digital-video....

Here is another article on using a light meter in videography:
http://www.simvideo.com/downloads/UsingaLightMeter.pdf

Another interesting article is from digitalContentproducer.com:
http://digitalcontentproducer.com/fieldprod/revfeat/video_check_meter/


Yes, an external monitor is also needed, but is a different tool; mainly used for composition and overall exposure. It is not a spot meter and cannot tell you what your f stop is for specific areas of your image. For that you need a light meter. Refer back to DV Rack. Those little flip out thingies also can be very misleading. I've never seen one that is accurate for composition.

An external monitor usually takes the signal from a composite output and is pre-format and pre-compression. It doesn't tell what you'll wind up with at the end of the day after editing
and making a DVD. For this, you need to do tests and see what the dynamic range and ASA rating are of your camera.

Hope this is of some assistance.

Good shooting,

P. J. in Hollywood



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