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Calibrating light meters


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#1 Nor Domingo

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Posted 16 May 2005 - 09:43 PM

Greetings all!!

Here's the situation: Three of us are holding Seconic 506s. We take a reading from the same light source but we all get different readings. For example, mine would read F5.6.3, the other would read F5.6.5, the other F5.6.7. Which should we believe and how ahould we calibrate our meters so it would read the same.

Should we spot meter a medium gray card? But then which of our meter is the right one?

Thanks for the help!
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#2 Mark Sasahara

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Posted 17 May 2005 - 02:14 PM

Standard deviation. Plus or minus 5%. Any time you have more than one meter reading a scene, you will have two different readings.

I have been using the same Minolta Flash Meter IV for over a decade. I shot a lot of transparency film, so and I know it's accurate. My friend's meter is off by a 1/3 of a stop and his 4x5 transparencies look marvelous. Slide film is a good way to check meter's accuracy. Either it's right or it's wrong. With neg, you have a lot of room for error, though the printer lights can tell a tale. Try getting it calibrated at a repair facility that specializes in meters, if you are worried.

My cine film, still film and video have all looked great. Chances are you're all right. Though, maybe the guy reading 5.6.5 is right, he's right in the middle.
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#3 oscar jimenez

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Posted 17 May 2005 - 04:02 PM

with even lightning place your meter flat and then take an incident reading, then change to spot meter and place a gray card in the same place meter was, reading must be quite similar ( spot may be 1/3 to 1/2 stop higher ) but anyway, the differences you are talking about do not exceed 1/2 or 2/3 of a stop, I see no trouble at all, If you have a difference of over a stop, then, there is certainly a problem. I have a Sekonic 508 and they are very much reliable and accurate
Good luck
In the same condition described above, go meter through meter independently
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#4 Sam Wells

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Posted 17 May 2005 - 06:27 PM

Here's how it works in a situation like that.

YOU'RE the DP, so your meter is right.

Unless the footage is over or under exposed. In which case, the gaffer's meter is wrong.

Unless the gaffer is kinda larger than you and you'll be working together in the future.

In which case, the AC's meter is wrong.

HTH,

-Sam
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#5 Bob Hayes

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Posted 18 May 2005 - 10:17 AM

As strange as it may seem the Seconic spot meters are all completely off. I own one. I love it. But the spot meter from the factory is completely wrong. I called them up and complained. They gave me some sort of run around about how spot exposure is subjective. Huh? So what I did is I took the incident reading in front of a gray card. Then I read the gray card with my Seconic spot and adjusted it to match the incident. There is a plus minus adjustment built into the meter. Then I checked it against my old trusted Minolta.

In short you must calibrate your Sekonic meter on you own. DON?T USE THE FACTORY SETTING IT IS A STOP OFF!
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#6 Stephen Williams

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Posted 18 May 2005 - 12:23 PM

As strange as it may seem the Seconic spot meters are all completely off. I own one.  I love it.  But the spot meter from the factory is completely wrong.  I called them up and complained.  They gave me some sort of run around about how spot exposure is subjective.  Huh?  So what I did is I took the incident reading in front of a gray card.  Then I read the gray card with my Seconic spot and adjusted it to match the incident. There is a plus minus adjustment built into the meter.  Then I checked it against my old trusted Minolta. 

In short you must calibrate your Sekonic meter on you own.  DON?T USE THE FACTORY SETTING IT IS A STOP OFF!

<{POST_SNAPBACK}>


Hi,

For some reason meters are calibrated for 12% reflectance and as a grey scale is 18% there will be a half stop difference!

Stephen Williams DP

www.stephenw.com
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#7 Sam Wells

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Posted 18 May 2005 - 12:34 PM

Oddly enough my Sekonic spot (778) and incident (318) meters agree and give predictable results.

Maybe I won at meter roulette ?

When I bought the Sekonic 778 at a photo store (it was sold as a "demo") I took my grey card and compared it to about six different meters they had, it agreed within 1/3 or 1/2 stop with the majority opinion of these various light meters. (There were some dissenters).

The store owners looked at me like I was slightly insane but kept their distance :D

-Sam
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#8 oscar jimenez

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Posted 19 May 2005 - 02:38 PM

It's not the first time I hear that Sekonic Difference beetween spot and incident, Have 2 friends who are very much upset, they have differences over 1 and 2 stops on brand new Sekonics, I have one and it is pretty much calibrated, both meters in the combo
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Ritter Battery

rebotnix Technologies

Glidecam

Visual Products

Broadcast Solutions Inc

Paralinx LLC

Media Blackout - Custom Cables and AKS

Technodolly