quote: Kenneth Wuepper

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I do not believe that the meter compensates for pulsing light as from a projector.

Perhaps you could ask the manufacturer if they have an arbitrary scale that does what screen ilumination measurements require, integrate pulsed light into a reading of brightness.

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Like I said, apparently this is a new version and I did actually call the manufacturer to find out if it can be used in a cinema situation - which is obviously what I want to do.
What followed was maybe the most pointless phone conversation I ever had in my life. They told me I would be connected to an engineer. The person who picked up the phone was apparently a Chinese immigrant. It was very hard to understand what he was saying. He asked me if I was from China too (most people successfully place my accent as German although some think I am from Russia, but Chinese - a first). Worse, he didn't listen to my questions at all. He just kept blabbering for 5-10 minutes. He had somehow understood that I wanted to use it for cinema purposes and thought I meant cinematography. I tried very hard to explain to him that I wanted to use it for screen illumination measurement with variable shutter speeds. But I failed. I tried really hard, but he wouldn't even listen. I somehow understood that it wasn't quite as exact as a $50,000 light meter for industrial R&D purposes. But that's waht I hadn't expected anyway. I would just like to know if it can be used to measure screen illumination with variable shutter speeds. Actually, the projectors we have a re all 48fps, but they are probably not all exactly the same spedd and shutter sizes. So I would like to know if the meter can successfully integrate these variations.
Again, several people told me it could, but all of them had just heard from other people who had used it, no one had actually used it himself.
 

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Posted by John Pytlak (Member # 331) on 03-23-2006, 09:06 AM:
 
If the meter is stable and precise, just have it calibrated against a known standard meter. You can see if there is a shutter frequency effect by varying the speed of a test projector with a three-blade shutter, and making sure the readings remain constant over the range you are likely to encounter in your theatres (e.g., 48 to 72 interruptions per second).
 

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Posted by Gordon McLeod (Member # 33) on 03-23-2006, 10:15 AM:
 
I believe that the issue was it was not as simple as a conversion table based on when in the shutter cycle that it started to sample would give different readings
 

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Posted by Michael Schaffer (Member # 1204) on 03-23-2006, 01:11 PM:
 
Gordon, I understand that, but this one here is a new modified version *allegedly* capable of handling various shutter speeds, not the one those discussions were about. That's why I am asking if anyone has actually played with it himself under test conditions.
In the meantime, I got feedback from someone who has actually tried it under such conditions and it seems to work just fine. So I will see if I can get one for a test and check it out myself before I fork out the money.
 

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Posted by Pete Naples (Member # 761) on 03-23-2006, 02:06 PM:
 
Like I said, mine is badge engineered, I've put it side by side with a couple of other spot meters on more than one occasions and the readings are spot on. Pardon the pun.
 

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Posted by Michael Schaffer (Member # 1204) on 03-23-2006, 02:57 PM:
 
Good to know. You didn't say you had tested it against other meters. But if your observations also confirm it is accurate and can handle the shutter flicker, then I will definitely go ahead and get one for testing.
 

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Posted by Amanda Mundin (Member # 3386) on 03-25-2006, 06:39 AM:
 
On that subject does anyone know if you can use a Sekonic L-508 Cine Zoom master for measuring screen luminance or if there are any problems with using it?
I think it must be an older version of the one mentioned, it has a spot meter that zooms between 1 and 4 degrees.
 

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Posted by Giorgio Volpi (Member # 1182) on 12-05-2006, 07:17 AM:
 
Hi,
my question for Michael, did you get and tested one of them? What result did you have?
Giorgio.
 

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Posted by Paul Mayer (Member # 355) on 12-05-2006, 08:28 AM:
 
I posted some comments about using photographic meters for measuring screen luminance some time ago. At the time I used a borrowed older Minolta spot meter after calibrating it by shooting a screen that had been set using a Spectra Cinespot meter.

The results were repeatable and so I went with that, but John Pytlak did mention that the meter must have enough precision to be useful. That old Minolta read down to increments of 1/3EV - most camera meters are only good to 1/2EV. A meter that reads only to 1/3EV will barely be able to show the difference between 12fL and 16fL.

If this Sekonic has a fL scale perhaps it can resolve smaller increments than the equivalent of 1/3EV. Let's see some test results Michael!
 

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Posted by Marco Giustini (Member # 4544) on 11-19-2007, 07:27 PM:
 
Ciao from Italy

This is my first time here.
I bought a Sekonic L758 Cine, to measure cinema screen brightness. However, I was not able to measure anything since the sekonic does not have the ability to make an average so I have the FL reading going up and down (the device measures both light and dark) and it is useless.

I saw this thread (and others) some weeks ago and I decided to buy a Sekonic instead of the ScreenChecker, a not so accurate device. I was stuck with the Sekonic and I was not able to use it so I ask for a return since Sekonic US does not reply to my questions and the forum registration was late (doesn't matter Brad Miller!!).
Now I was able to sell the device on ebay (was cheaper for me than return to the seller) but I still have it on my desk.

Can someone confirm me that this device is able to measure cinema's screen brightness? The only way I found is using the auto-reset FLASH mode. This way the reading is stable but I can have only F values (if I'm not wrong with the unit measure) and this is useless for me. I need at least the EV reading that I can convert to FL but I was not able to setup the Sekonic to read the flash mode this way.

I read many posts here confirming that this Sekonic is good for cinema use. The FPS of the Sekonic is useless fo me because is referred to cinema shooting and give the correct values that has to be set in a cinema camera if I'm not wrong.

Can someone help me?

Ciao and thanks

Marco
 

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