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Light meters (plural) don't agree with camera's (plural)
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PostPosted: Sat Jun 29, 2024 1:05 pm    Post subject: Light meters (plural) don't agree with camera's (plural) Reply with quote
I am stumped and could use some help Smile

I have been doing some testing today with various camera's and light meters I own. All the camera's agree. But the light meters do not agree with the camera's. Please allow me to explain.

Camera's used:
Olympus E-M1 Mk.II (mirrorless)
Olympus OM40 (film)
Olympus OM2SP (film)

All three camera's are set at ASA/ISO200. The mirrorless E-M1 Mk.II does some funny stuff with ISO electronically so take that with a pinch of salt, but the shutter speeds I am getting from it closely match the OM40 and OM2SP.

Lightmeters used
Weston Master V - Died since I last used it
Gossen Lunasix F
Gossen Lunasix 3 - (with original mercury batteries!). measures wildly too bright. Needs work at the least
Sekonic L398 - Measures MUCH too dark - dead
Sekonic L208

So of these five I consider the Lunasix F and the L208 to be usable. They measure fairly close, with the L208 usually about ½ stop brighter than the Lunasix F.

Results:
All the camera's were set to ISO 200. For the test I made sure I set the ISO/ASA on the light meters to 200 as well. I double checked this. The Lunasix F reads 1 full stop brighter than the three camera's. The L208, about 1½ stops. In other words, all three camera's show 1/500 at f/8. The Lunasix F will read 1/1000 at f/8 and L208 varies between 2/3 and 1½ stops.

I will believe the E-M1 MkII doing funny things. But I recently shot a test role of film through the OM40 so I know it reads correctly at ISO200.

Aside: I tested Sunny 16 on the E-M1 MkII. It is a bright sunny day, so I set the lens to f/16 and adjusted shutter speed until the camera thought the exposure was correct. The ISO I ended up at? 100. Plausible with the weird stuff Olympus does with ISO in these camera's. But since the shutter speeds I get on it do match with the OM40 and OM2SP on the same ISO (namely 200), that would imply that both of these film camera's are also off? While giving correctly exposed pictures in the case of the OM40? One of them, sure. But both?

EDIT: I also made sure I had the incident/reflective sliding thing set correctly on the light meters. Reflective measurement, so the white cone not covering the sensor.

Any idea what gives?

Regards, Christine

Last edited by connloyalist on Sat Jun 29, 2024 1:31 pm; edited 1 time in total


PostPosted: Sat Jun 29, 2024 1:18 pm    Post subject: Reply with quote
https://en.m.wikipedia.org/wiki/Light_meter
Research the difference between selenium, CdS, and silicon photodetectors.

Selenium wears out iirc.

BTW the Weston is easy to repair.


PostPosted: Sat Jun 29, 2024 1:19 pm    Post subject: Reply with quote
visualopsins wrote:
https://en.m.wikipedia.org/wiki/Light_meter
Research the difference between selenium, CdS, and silicon photodetectors.

Selenium wears out iirc.

BTW the Weston is easy to repair.


Edit: suggest using a white card as the meters have different angles of reception.


PostPosted: Sat Jun 29, 2024 1:37 pm    Post subject: Reply with quote
visualopsins wrote:

Selenium wears out iirc.


Yes, I remember reading that as well about selenium wearing out.

visualopsins wrote:

BTW the Weston is easy to repair.


That would be nice! It doesn't have sentimental value to me, but I do like it and would like to get it fixed if possible. How or who could do that?

Regards, C.


PostPosted: Sat Jun 29, 2024 1:48 pm    Post subject: Reply with quote
https://duckduckgo.com/?q=repair+weston+light+meter&t=fpas&ia=web


PostPosted: Sat Jun 29, 2024 2:16 pm    Post subject: Reply with quote
visualopsins wrote:
https://duckduckgo.com/?q=repair+weston+light+meter&t=fpas&ia=web


I guess I could have found that myself Wink

This Ian Partridge looks interesting, bookmarked his website. Should have done that a few years ago before the UK left the EU, would have made it more convenient with customs.

Regards, C.


PostPosted: Sat Jun 29, 2024 2:48 pm    Post subject: Reply with quote
visualopsins wrote:
visualopsins wrote:
https://en.m.wikipedia.org/wiki/Light_meter
Research the difference between selenium, CdS, and silicon photodetectors.

Selenium wears out iirc.

BTW the Weston is easy to repair.


Edit: suggest using a white card as the meters have different angles of reception.


This. Comparing reflected light readings with different meters is very hit and miss unless the subject is of uniform illumination and colour. Hence so many professionals preferred to use incident light readings in the film days. I used to use incident readings in combination with bracketing (static subjects Wink ), and almost always the central image of the three bracketed ones was the correct exposure. To the point that I wondered if I wasn't wasting my time with the bracketing (I wasn't; subjects were rare items brought in from afar for a collectors' magazine cover shots; no second chance to get the right shots).


PostPosted: Sat Jun 29, 2024 2:50 pm    Post subject: Reply with quote
First, none of your meters are going to ever read that close to each other. There are just too many variables, among them angle of acceptance.

Selenium cells, even when at their freshest, are not as accurate as CDS, Silicon Blue, etc. The L398 is designed for studio use, so I wouldn't use one for general photography. The Luna Six 3, can be used with a silver oxide battery adapter to replace the mercury cells.

If your handheld meters ever get within one stop of each other, stop testing. That's as good as it gets. Remember, the ISO settings are a guideline, not the ball-end all.

PS - I still have a couple of handheld meters, a Minolta Spot Meter F and a Sekonic L508, but they're largely relegated to extreme back-up. The meters in my Nikon D810, D850, and Z7ii are superb.[/i]


PostPosted: Sat Jun 29, 2024 3:55 pm    Post subject: Reply with quote
pendennis wrote:
PS - I still have a couple of handheld meters, a Minolta Spot Meter F and a Sekonic L508, but they're largely relegated to extreme back-up. The meters in my Nikon D810, D850, and Z7ii are superb.[/i]


I am thinking more along the lines of when/if I try a (film) camera that doesn't have a light meter. I will want something more or less reliable.

Regards, C.


PostPosted: Sat Jun 29, 2024 8:56 pm    Post subject: Reply with quote
connloyalist wrote:
I am thinking more along the lines of when/if I try a (film) camera that doesn't have a light meter. I will want something more or less reliable.

Regards, C.


One stop is nothing really. Sunny 16 works, some cameras have no exposure settings and people still get good pictures.

The Lunasix F is probably the most accurate I use mine regularly and it gives consistent results. And yes, compared to my digital camera is gives about a stop over - just like yours. I put that down to the lens absorbing light. But the end result on film is perfect exposure


PostPosted: Sat Jun 29, 2024 9:33 pm    Post subject: Reply with quote
philslizzy wrote:
One stop is nothing really. Sunny 16 works, some cameras have no exposure settings and people still get good pictures.

The Lunasix F is probably the most accurate I use mine regularly and it gives consistent results. And yes, compared to my digital camera is gives about a stop over - just like yours. I put that down to the lens absorbing light. But the end result on film is perfect exposure


It depends.

Negative film is far more forgiving than slide film. On high contrast slide film one stop out is likely a failed image that hopefully can be rescued during printing or in PP after scanning. Especially one stop overexposed slides can easily mean blown highlights from which detail cannot be recovered.


PostPosted: Mon Jul 01, 2024 2:24 pm    Post subject: Reply with quote
Odd there's no mention of the Kodak 18% reflectance gray/grey card here, which was at one time, the way things were usually done.
That is one accessory I'd love to see resurrected. My copy is getting pretty banged up.

The D-810's metering system can be very accurate, especially in spot mode.
The matrix pattern is another kettle of fish though, with a horrid tendency to lean towards heavy over-exposure, even with chipped lenses. Blown highlights become a real problem for me with this mode.

The commentary on bracketing for exposure still stands today, even with all the digitized equipment we now use.

-D.S.


PostPosted: Mon Jul 01, 2024 2:40 pm    Post subject: Reply with quote
Doc Sharptail wrote:
Odd there's no mention of the Kodak 18% reflectance gray/grey card here, which was at one time, the way things were usually done.
That is one accessory I'd love to see resurrected. My copy is getting pretty banged up.

The D-810's metering system can be very accurate, especially in spot mode.
The matrix pattern is another kettle of fish though, with a horrid tendency to lean towards heavy over-exposure, even with chipped lenses. Blown highlights become a real problem for me with this mode.

The commentary on bracketing for exposure still stands today, even with all the digitized equipment we now use.

-D.S.


Hi Doc,

I am curious, what made the Kodak card different from other gray cards?

Regards, C.


PostPosted: Mon Jul 01, 2024 3:44 pm    Post subject: Reply with quote
Doc Sharptail wrote:
Odd there's no mention of the Kodak 18% reflectance gray/grey card here, which was at one time, the way things were usually done.
That is one accessory I'd love to see resurrected. My copy is getting pretty banged up.
-D.S.


Indeed. The white card mentioned is fine if you just want to compare meter readings, especially agains a known good meter. If you also want the meter reading to indicate a reliable exposure, 18% grey card is better.


PostPosted: Mon Jul 01, 2024 4:09 pm    Post subject: Reply with quote
RokkorDoctor wrote:
Doc Sharptail wrote:
Odd there's no mention of the Kodak 18% reflectance gray/grey card here, which was at one time, the way things were usually done.
That is one accessory I'd love to see resurrected. My copy is getting pretty banged up.
-D.S.


Indeed. The white card mentioned is fine if you just want to compare meter readings, especially agains a known good meter. If you also want the meter reading to indicate a reliable exposure, 18% grey card is better.


Why is grey card better? Smile (Actually, I use my palm, which I always have with me Smile)


PostPosted: Mon Jul 01, 2024 6:49 pm    Post subject: Reply with quote
visualopsins wrote:
RokkorDoctor wrote:
Doc Sharptail wrote:
Odd there's no mention of the Kodak 18% reflectance gray/grey card here, which was at one time, the way things were usually done.
That is one accessory I'd love to see resurrected. My copy is getting pretty banged up.
-D.S.


Indeed. The white card mentioned is fine if you just want to compare meter readings, especially agains a known good meter. If you also want the meter reading to indicate a reliable exposure, 18% grey card is better.


Why is grey card better? Smile (Actually, I use my palm, which I always have with me Smile)


A white card has higher reflectance than an 18% grey card, leading to underexposure of the image (if used for exposure measurement).

I can't remember exactly but I believe that an 18% grey card is supposed to be representative of the averaged-out reflected light of an average outdoor scene, given the same illumination. I.e. if an average light reading is taken of a (average) scene, the theory goes that it is found to reflect 18% of the incident light. But that is for an average outdoor scene, hence snowy white landscapes or black volcanic pumice slopes need special consideration.


PostPosted: Mon Jul 01, 2024 7:19 pm    Post subject: Reply with quote
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PostPosted: Mon Jul 01, 2024 7:32 pm    Post subject: Reply with quote
connloyalist wrote:
Hi Doc,

I am curious, what made the Kodak card different from other gray cards?

Regards, C.


I'm not sure- I think it has something to do with reflectance, but more likely personal user confidence.
In a pinch, the covers of the Kodak pocket photo guide will do, but they are not the same reflectance value as the "real" gray card.
My card is getting close to 45 years old, and as well as metering, it gets used for flash (which it excels at), and of course as a reference point for the enlarger at the odd times.

-D.S.


PostPosted: Mon Jul 01, 2024 8:04 pm    Post subject: Reply with quote
RokkorDoctor wrote:
visualopsins wrote:
...

Why is grey card better? Smile (Actually, I use my palm, which I always have with me Smile)


A white card has higher reflectance than an 18% grey card, leading to underexposure of the image (if used for exposure measurement).

I can't remember exactly but I believe that an 18% grey card is supposed to be representative of the averaged-out reflected light of an average outdoor scene, given the same illumination. I.e. if an average light reading is taken of a (average) scene, the theory goes that it is found to reflect 18% of the incident light. But that is for an average outdoor scene, hence snowy white landscapes or black volcanic pumice slopes need special consideration.


Just to make sure my memory wasn't playing tricks on me (it often does Wink ): if in doubt I always refer to the writings of the late Roger Hicks, an expert on everyting & anything related to photographic exposure and associated measurements, author of "Perfect Exposure - From Theory To Practice", Roger Hicks and Frances Schultz, David & Charles publishing, 1999.
https://en.wikipedia.org/wiki/Roger_Hicks_(author)

Roger Hicks wrote:

You have to begin by considering the brightness range of the scene in front of the camera. In the 1940s, empirical research determined that the important parts of a 'typical' scene cover a brightness range of about 128:1, or 7 stops. Although this research has never been bettered, individual scenes can var enormously from this average, and all kinds of cautions and caveats need to be entered.


Further on in the same book:

Roger Hicks wrote:

Typical Subjects

As mentioned earlier, a 'typical' subject is taken to have a brightness range of 128:1, 7 stops, a log range of 2.1. It is also assumed, again on the basis of extensive empirical evidence, that the tones within the picture are reasonably evenly distributed, so that the overall scene reflects something between 12 and 18 percent of the light falling on it. This may seem quite a wide range, but it represents a variation of only 1/2 stop, which is really not very much.
Many thousands of observations went into the establishment of of these averages, but they suffer from two (or perhaps three) fundamental drawbacks. The first is that most or all of them were taken within 200 miles or so of Rochester, New York. The second is that we all have plenty of experience of subjects with broader or narrower tonal ranges and which may reflect more or less light overall. And the third is that the 128:1 range excludes both light sources and specular highlights.


PostPosted: Tue Jul 02, 2024 1:07 pm    Post subject: Reply with quote
connloyalist wrote:
Doc Sharptail wrote:
Odd there's no mention of the Kodak 18% reflectance gray/grey card here, which was at one time, the way things were usually done.
That is one accessory I'd love to see resurrected. My copy is getting pretty banged up.

The D-810's metering system can be very accurate, especially in spot mode.
The matrix pattern is another kettle of fish though, with a horrid tendency to lean towards heavy over-exposure, even with chipped lenses. Blown highlights become a real problem for me with this mode.

The commentary on bracketing for exposure still stands today, even with all the digitized equipment we now use.

-D.S.


Hi Doc,

I am curious, what made the Kodak card different from other gray cards?

Regards, C.


Kodak was/is the de facto standard for the 18% gray card. They were the leader in camera film development for years.

But, as others have stated, there's a huge amount of latitude when it comes to print film, especially B&W, and the "Sunny f/16" works especially well for B&W.
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