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Panasonic LUMIX G / GF / GH / GX Series
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Old August 10th, 2011, 06:13 PM   #1
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external Light meter or system light meter

I was wondering if using and external lightmeter (sekonic 3800) would give me better results than using the internal gh2's lightmeter

ric
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Old August 14th, 2011, 04:39 AM   #2
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Re: external Light meter or system light meter

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Originally Posted by Ric Marrty View Post
I was wondering if using and external lightmeter (sekonic 3800) would give me better results than using the internal gh2's lightmeter

ric
Possibly, but a lot spends on how you use the meter. There are other issues too.

1. A good external meter gives the option of incident light reading, where you read the light as it falls on the subject. This can be more reliable and accurate than the standard, reflected light, method (as used by in-camera meters), which is affected by the colour, and reflectivity of the subject.

2. If the camera's on a tripod, or has to be in affixed position, there's a benefit in being able to take readings with a meter from various parts of the frame to work out your settings.

3. Using a mater needs an understanding of how exposure works, and the ability to interpret readings into settings relevant for the subject. You need to understand ISO, aperture and shutter speed and their relationships and effects on the image. If you don't, you'll just give yourself a headache.

4. You have to calibrate the meter's implementation of ISO to that of your camera. Although ISO ratings are a standard, they were developed for film, not digital, to indicate how match exposure a film stock needed to generate a given image density. In digital cameras, ISO is a measure of how much electronic amplification is applied to the raw sensor data. Different manufacturers implement this in different easy so ISO 100 on camera A might equate to ISO 160 or even 200 on camera B. You need to calibrate your meter to your camera by (a) setting the same ISO and seeing what shutter/aperture combination you get on each and, if they differ, shooting RAW images at each setting and examining the results. That will tell you what, if any, adjustment you need to make between camera and meter. If you have more than one camera, you need to do this for each one you have.

5. In the old days, you'd have used a grey (or gray) card (18% reflectance) as your subject, but there's an argument about whether digital sensors interpret grey cards in the same way as film. In the end, so long as you use the same subject in the same light, you'll get the calibration you need.

6. At the end of all that, I like using handheld meter as backup and for tricky situations. I have a Sekonic 308 for incident readings and a lovely Sekonic 1 degree spot meter for the really tricky situations. I personally think that being able to use a meter effectively is an essential skill for aspiring photographers.

Hope that all makes sense
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Old August 14th, 2011, 10:59 AM   #3
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Re: external Light meter or system light meter

Thanks for your input. I was not clear in how I asked.

My inquiry is mainly for the use of the meter for the video capabilities of the gh2

Would the same hold true or would it be an overkill?

Ric
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Old August 14th, 2011, 11:43 AM   #4
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Re: external Light meter or system light meter

The same principles apply; the main differences are:

1. For video, your choice of shutter speeds is restricted to the ones that fit your frame rate - normally 1/60 or maybe 1/120 or 1/30 (for PAL 1/50, 1/100, 1/25 respectively), so if you use a meter, you need to remember that.

2. Pro videographers and cinematographers routinely use incident metering. In nearly all those "Making of ..." packages on DVDs, there's a shot of one of the film crew holding a meter next to an actor's face. So that's a clue that it's not overkill. Unless you're doing run and gun, in which case, let the camera decide for you and just get the shot.

Hope that helps
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Old August 14th, 2011, 05:53 PM   #5
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Re: external Light meter or system light meter

Back in school we use to avareage the exposure (if I remember correctly) back,key and fill light. also average the set lights and all others.

That was in a studio back in 1979 using rca tk45 cameras

Is better cinema/videograpfhy done this way by measuring all and averaging?

I ask because I want my video to look different and better


what do think of this app meter:

Introducing Exposure Pro for iPhone/iPad & Android


Thanks

Ric
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Old August 15th, 2011, 02:52 AM   #6
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Re: external Light meter or system light meter

The fundamentals haven't changed since 1979 - digital has only changed some of the technicalities. What you're describing still works if you want to take complete control of your exposure and is what serious pros still do. It's fine if you have control of all aspects of the set - position, lighting etc - and in those cases, would be a more reliable method than using the camera's in-built meter. You'd still have to calibrate the meter against the camera's ISO implementation, but that's something you only have to do once.

I don't know the app you linked to, but it seems like an unnecessary substitute for a grey card.
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Old August 15th, 2011, 05:06 AM   #7
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Re: external Light meter or system light meter

The GH2 has:
1) histogram
2) 100 IRE flasher
3) a spot meter that can be scrolled to any spot on the frame for readings
4) mutlple meter mode
5) averaging metering mode

You also can eyeball on the LCD, the EVF, or an external monitor.

That's 8 ways to measure exposure, if you still can't get it right, I don't think an incident light meter will save you. External meter is probably only useful for ratios.
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