Palm of hand, summer noon, should be Zone VI. Meaning EI 125, 1/250 f/16. Not scientific, but more than good enough for all negative films. Also a critical test for Selenium meters, that usually fail most at high EV, due to increased internal resistance of the photocell.Question: is there a way to accurately meter light to calibrate your light meters? There must be some kind of physics hack, like adjusting rangefinders without infinity. I am thinking about a reliable light source with a known output within predetermined distance from a 18% grey card in complete darkness, but finding a light source like that is probably difficult.
First you must determine if you can calibrate the meter. Can the meter be adjusted for offset and gain? If you determine that you can then you can buy calibrated light source. They are expensive or you can borrow a known good meter to compare. The fact that the OP knew the meter is incorrect he must have some mean to compare.Question: is there a way to accurately meter light to calibrate your light meters? There must be some kind of physics hack, like adjusting rangefinders without infinity. I am thinking about a reliable light source with a known output within predetermined distance from a 18% grey card in complete darkness, but finding a light source like that is probably difficult.
Finding the proper replacement is virtually impossible. While CdS cells have a linear current-voltage relation (at a fixed illumination), the other relation, current versus illumination at constant voltage, is non-linear; generally, doubling the illumination causes less than doubling the current. That is beneficial for lightmeter design, because the dynamic range of light values is compressed and made more manageable. But that extra parameter --the degree of non-linearity-- makes it virtually impossible to find a cell matched to the lightmeter design and scales. As an example, see the datasheet from one of the cells shown in the ink provided by N.Lindan:The problem with finding a replacement is knowing the cell's resistance and sensitivity.
Which way is it off? Telling you to expose more than the correct value? or less?it's readings are about 3-4 stops off
Did you clean the battery contacts? Use very fine abrasive paper, or a "fiberglass pen", or an eraser for ink (becoming a rare item). Absent these, try the abrasive powder for kitchen pans, followed with careful wiping.got a fresh battery in it
Send it to Quality Light Metric for recalibration.
Make a lot of sense.George gave me the name Spectra Cine in LA as an alternative. they are not interested in dealing with old meters. They suggested I contact Gossen. They responded that it
is not a service they offer, ie old meters are not of interest to them.
CDS is fine for my needs. ... the hard part is looking at the descriptions and trying to figure out if it will be accurate.
Well, I wasn't particularly over joyed at their "rationalism". And as far as Gossen is concerned, I figured out how to fix my Luna Pro S and then bought a new SEkonic. I guess they don't really understand how to support their brand long term. One customer at a time.Make a lot of sense.
not at all;we all have a very constant and reliable light source.Most of us call it the 'sun'. full sunlight between 10am and4pm, regardless of season or location on earth reads almost exactly at EV15.Question: is there a way to accurately meter light to calibrate your light meters? There must be some kind of physics hack, like adjusting rangefinders without infinity. I am thinking about a reliable light source with a known output within predetermined distance from a 18% grey card in complete darkness, but finding a light source like that is probably difficult.
But it makes sense because they are in business to make money and it's tough to make money fixing old meter.Well, I wasn't particularly over joyed at their "rationalism". And as far as Gossen is concerned, I figured out how to fix my Luna Pro S and then bought a new SEkonic. I guess they don't really understand how to support their brand long term. One customer at a time.
Small and accurate with a dial (of sorts) - a Digisix or Digiflash.You're surely right Nicholas, but I like a dial. Tried some digital meters some years ago and they just didn't work. On a conventional dial meter, I can tell at a glance where all the speeds and f stops are. That's a nice feature to have. Silicon is better, but those meters tend to be big and/or pricey.
... I like a dial. Tried some digital meters some years ago and they just didn't work. On a conventional dial meter, I can tell at a glance where all the speeds and f stops are.
This is good advice. Most of the CDS cell meters are getting on to 20 or 30 years old. Also, many or possibly most of them required the Mercury battery to serve as a calibration constant because of the 1.35 volt output.That's why CdS doesn't make sense any more. Even if it is accurate today it may be a different story next year.
A meter with a silicon cell will not go out of whack. The current crop of small ~$50 digital clip-on meters will stay accurate for a very, very long time.
Small and accurate with a dial (of sorts) - a Digisix or Digiflash.
Reasonable, but not cheap.
The meter displays a number (EV), you turn the dial to that number, and all the combinations available are right there.
strange; Gossen fixed two of mine for just €50 each.Make a lot of sense.
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