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02-03-2012, 07:28 PM   #1
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My Old Light Meter

I have an old light meter I haven't had much occasion to use... but now I'll need to make sure it's reliable - I'm going on a month-long trip to Puerto Rico and lots of my photography will be done using a Yashica-Mat and my Pentax 645N. I use 6x7 lenses on the latter and the camera's built-in meter is often totally off when I stop those down. The former doesn't have a built-in meter.

The meter is called Sekonic Auto-Lumi, like the one here:


How can I double check it's metering fine? Forgive if it's a dumb question - If I were to use this meter's readings on my Pentax K-x DSLR and the exposure seemed correct, would it still be correct for my film cameras?

PS The only time I did use it, for one roll on my Edixa Reflex, it seemed to underexpose somewhat. Here are some drugstore scans from that roll: Flickr: Search dubesor's photostream

02-03-2012, 08:06 PM   #2
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I would not have any way to check it except against another light meter. I there a way to adjust the Sekonic? Take readings with the meter and compare to your K-X. One thing that may hamper you is the battery for the Sekonic. Does it have full voltage? Some old light meters (and cameras too) used a mercury battery that is no longer made. People will put in a new battery that fits but does not have the same voltage as the old mercury battery. This voltage difference can make the meter give incorrect readings. It must be calibrated to the new battery voltage.
02-03-2012, 08:12 PM   #3
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If it's sunny out in the next couple days, I'd say bring it out and see if it meters to the "sunny 16" rule. That may provide a clue if it's close or not...
02-03-2012, 08:20 PM   #4
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@cscurrier i just had the same thought. i'll give that a shot - as it's been unseasonally sunny here in rainy vancouver.

02-03-2012, 08:39 PM   #5
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This is a Selenium cell meter, and doesn't use a battery - the cell generates voltage by light intensity.
Selenium cells often deteriorate with time, if left exposed to light. If it has been stored in a dark place, it may still work very well.
02-03-2012, 09:05 PM   #6
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QuoteOriginally posted by TomB_tx Quote
This is a Selenium cell meter, and doesn't use a battery - the cell generates voltage by light intensity.
Selenium cells often deteriorate with time, if left exposed to light. If it has been stored in a dark place, it may still work very well.
Pretty sure it's been stored in darkness for the last 10 years or so; i found it inside a pristine camera case bought at a thrift store (it contained a lot of other goodies - like the Takumar 85/1.8)
02-03-2012, 11:25 PM   #7
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Hah, Dubesor. The only reason I thought of that is because it's been nice and sunny here just south of the border, as well. Good luck and let us know how it works out!
02-04-2012, 09:18 AM   #8
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QuoteOriginally posted by cscurrier Quote
If it's sunny out in the next couple days, I'd say bring it out and see if it meters to the "sunny 16" rule. That may provide a clue if it's close or not...
'cept it is winter and the rule seldom applies unless the sun is high with little cloud cover. This time of year in the northern latitudes, it is more like the sunny 11 or 8 rule. (At least that was the case yesterday at "high" noon in Portland.)

If the OP lives near a camera repair place, they usually have a calibrated light source and will likely check the meter for free.


Steve

02-04-2012, 06:05 PM   #9
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Great little meter

I own the identical model light meter, a Sekonic L-86. At 30+ years old I am amazed that it is still accurate.

The selenium cell has a very wide FOV, so I always try to get a close-up reading.
When that's not possible I point it downwards a bit to prevent a bright sky from inflating the reading
(which would result in underexposure) .

Chris

Last edited by ChrisPlatt; 02-04-2012 at 06:16 PM.
02-04-2012, 06:32 PM   #10
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yes those are good. Only worry is in low light, is it sensitive enough?
02-04-2012, 07:11 PM   #11
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i did a little bit of testing outdoors today and it seems to meter well for my DSLR (K-x) anyway.
i'll do more testing tomorrow with the medium format camera.
02-04-2012, 07:48 PM   #12
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Like most selenium meters it is not very sensitive in low light. However used
judiciously I have found it works well for most normal picture taking situations,
i.e. daylight, using medium speed and faster films at handholdable shutter speeds.

Chris

Last edited by ChrisPlatt; 02-05-2012 at 11:44 AM.
02-05-2012, 07:37 PM   #13
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QuoteOriginally posted by ChrisPlatt Quote
Like most selenium meters it is not very sensitive in low light. However used
judiciously I have found it works well for most normal picture taking situations,
i.e. daylight, using medium speed and faster films at handholdable shutter speeds.

Chris
I wonder how accurate it is for metering in the 4-8 second shutter speed range (and slower)? Ever try metering for these long-ish exposures?

(I often use ISO 50-100 films and stop down to f8-f11, which means multiple seconds even in broad daylight)
02-05-2012, 08:15 PM   #14
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QuoteOriginally posted by Dubesor Quote
I wonder how accurate it is for metering in the 4-8 second shutter speed range (and slower)? Ever try metering for these long-ish exposures?

(I often use ISO 50-100 films and stop down to f8-f11, which means multiple seconds even in broad daylight)
The issue is the amount of light that hits the sensor. How you set your camera does not effect the meter. Meter sensitivity is generally expressed as EV(100) with 1 being 1 second at f/1 at ISO 100. Selenium meters are only good to about EV(100) 4 or 5 (f/2 at 1/4 or 1/8 second with ISO 100) or maybe even a stop or more worse, IIRC.
02-05-2012, 09:21 PM   #15
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If you often expose in the range of EV 4-5 and below you should probably get something else.
Many CdS cell meters would be adequate but I'd look for something more sensitive, e.g. silicon.

Chris

Last edited by ChrisPlatt; 02-05-2012 at 09:29 PM.
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