Which Light Meter to Trust?

[lxdude]

Horse feathers.

There is an ISO standard for digital just like there is for film.

Who decides what is proper or best digital exposure, therefore exact calibration? Manufacturers. They can choose from several methods employing different parameters, or just set it as they see fit with the Recommended Exposure Index method.
Given the complex design of matrix-type metering, REI is the only thing that really makes sense for those meters. There's no way to make a meaningful standard to cover the different ones, even more so with RGB thrown into the mix.

Here ya go:
http://en.wikipedia.org/wiki/film_speed#The_ISO_12232:2006_standard

 

[markbarendt]

Who decides what is proper or best digital exposure, therefore exact calibration? Manufacturers. They can choose from several methods employing different parameters, or just set it as they see fit with the Recommended Exposure Index method.
Given the complex design of matrix-type metering, REI is the only thing that really makes sense for those meters. There's no way to make a meaningful standard to cover the different ones, even more so with RGB thrown into the mix.

Here ya go:
http://en.wikipedia.org/wiki/film_speed#The_ISO_12232:2006_standard

I stand corrected. That "standard" is obviously not so "standard" and not what I understood it to be.

I will say though that during the years I did studio work using my Sekonic L-358 I could without question set up a shoot at the exact settings I planned to shoot my D200, D70, D90, or F100. The images from the digital cameras, typically portraits, all normally fell exactly where they were planned and almost never required any exposure adjustment in post (which is one of the true joys of studio work). My peers at the time that were using both Nikons & Canons did the same thing.

My point is that regardless of the standards vagueness, at least Nikon and Canon appear to have tried to match some kind of standard and maintain the continuity that allows incident and flash meters to remain relevant and accurate.

 

[RalphLambrecht]

I admit to have had the same experience.

 

[wiltw]

On this topic of "which meter is 'right'? "...
Have any folks stopped to consider that the ISO standard equation for calibration of a meter includes a VARIABLE which is chosen for value by the manufacturer?!

"Exposure equations

"For reflected-light meters, camera settings are related to ISO speed and subject luminance by the reflected-light exposure equation"

​

From the article, one can see the equations http://en.wikipedia.org/wiki/Light_meter

"Calibration constants

"Determination of calibration constants has been largely subjective; ISO 2720:1974 states that

"The constants and shall be chosen by statistical analysis of the results of a large number of tests carried out to determine the acceptability to a large number of observers, of a number of photographs, for which the exposure was known, obtained under various conditions of subject manner and over a range of luminances.

"In practice, the variation of the calibration constants among manufacturers is considerably less than this statement might imply, and values have changed little since the early 1970s.

"ISO 2720:1974 recommends a range for of 10.6 to 13.4 with luminance in cd/m². Two values for are in common use: 12.5 (Canon, Nikon, and Sekonic[1]) and 14 (Minolta,[2] Kenko,[2] and Pentax); the difference between the two values is approximately 1/6 EV."​

Metering has long been stated to be 'a suggestion'. After all, f/stops on lenses are not perfectly accurate, shutter speeds on cameras are not perfectly accurate, the light transmittance of two lenses both of the 'same aperture' is not idential. Film processing techniques and chemistry can introduce variability. With four variable AFTER the exposure button is pressed, the suggestion from the meter is rather questionable in the execution of that suggestion!

 

[removed account4]

This is what can happen if you trust your light meter in extreme or "difficult" lighting conditions...

That is a model on a branch...

your spot meter gave you a 3 stop under exposed negative?
bummer

this is where the human light meter might have come in handy ...
http://www.fredparker.com/ultexp1.htm
if not to figure out the exposure, but to realize the meter wasn't giving you
the right exposure to begin with ...

looks like it would have been a nice image ..

 

[markbarendt]

Metering has long been stated to be 'a suggestion'.

It isn't the equation that makes metering a suggestion. The manufacturers use variables to calibrate their system to the real world, to accurately measure the luminance of a known target.

The reason a reading in the real world is a suggestion is that personally we aren't necessarily trying to match the "common standard". As you suggest we are also adapting to differences in our equipment.

 

[yulia_s_rey]

your spot meter gave you a 3 stop under exposed negative?
bummer

this is where the human light meter might have come in handy ...
http://www.fredparker.com/ultexp1.htm
if not to figure out the exposure, but to realize the meter wasn't giving you
the right exposure to begin with ...

looks like it would have been a nice image ..

+1. I've made it point many moons ago to memorize Parker's UEC method. Works like a charm!

 

[removed account4]

+1. I've made it point many moons ago to memorize Parker's UEC method. Works like a charm!

works well indeed !
if not for the exposure without an electronic meter/camera measuring device
but it is handy to have running in the back of your mind to say
" huh, my handheld meter's suggesting 60th @f8, that seems WRONG"

 

[eclarke]

If you aren't getting enough exposure, give some more. You will learn your meter. As lomg as it repeats, numners mean nothing.

 

[RedSun]

Just of curiosity, I tested the in-camera meters of several cameras. For a certain scene, with ISO 200 and F8,

Bronica ETR AE III spot reading 1/10 sec.
Bronica SQ AE III spot reading 1/10 sec.
Nikon F100 spot reading 1/15 sec.
Nikon D200 spot reading 1/15 sec.
Nikon D70 spot reading 1/20 sec.

I do not have a hand-held spot meter and would like to bring a 35mm or MF camera and to use the built-in spot meter. With the above, should I trust the old Bronica meter, or the newer D200 meter? I know the difference is small, but 1/2 a stop is still very important with my LF.

Thank you for the info and help. I've done some more work and now am happy with what I've got.

I acquired a Pentax Spot meter II at bargain price. But I did not realize the battery issue. So I'm going to sell it (no $ loss here). Also, this thing is huge to carry.

I tried a couple of outdoor scenes with my N80 in matrix metering, then used the Gossen Luna Pro in incident mode. Both gave the exact metering. I exposed a couple of 4x5 sheets and I'm still waiting for the films to dry. They look fine to me now.

I know the Nikon D70 metering has been off for a long time. I normally set +1 exposure compensation.

So I figure the film camera metering should be trusted better than DSLR. If I come upon a small spot meter, I may get one. But it is cheaper and lighter to carry my N80 with a prime lens. It costs almost nothing now. The Gossen Luna Pro is still good. I also have a Sekonic 308 and I may sell it. Too much....

 

[markbarendt]

I also have a Sekonic 308 and I may sell it. Too much....

Really, you ask us which light meter to trust and now you are thinking of selling off arguably the most trustworthy meter that you appear to own.

What's up with that?

 

[wiltw]

It isn't the equation that makes metering a suggestion. The manufacturers use variables to calibrate their system to the real world, to accurately measure the luminance of a known target.

The reason a reading in the real world is a suggestion is that personally we aren't necessarily trying to match the "common standard". As you suggest we are also adapting to differences in our equipment.

My point was that metering was a suggestion even without the additional consideration of the equation for calibration have VARIABLES.

 

[markbarendt]

My point was that metering was a suggestion

Yes, the settings the meter spits out are a suggestion.

 

[RedSun]

Really, you ask us which light meter to trust and now you are thinking of selling off arguably the most trustworthy meter that you appear to own.

What's up with that?

I'm not sure about the "most trustworthy" meter. All the high quality meters are trustworthy, Pentax, Minolta, Gossen, Sekonic. Some even trust the old Weston better than the modern meter.

As we all said, metering only gives a guide. It is only a tool. There are many tools and I do not need all of them to do one job.

 

[markbarendt]

I'm not sure about the "most trustworthy" meter. All the high quality meters are trustworthy, Pentax, Minolta, Gossen, Sekonic. Some even trust the old Weston better than the modern meter.

As we all said, metering only gives a guide. It is only a tool. There are many tools and I do not need all of them to do one job.

I agree that you don't need them all and even that good work can be done with any of them.

My point is that the Sekonic is an incident meter, and a good one at that. Incident metering is the most objective (scientific) way to find a reference point to use as a basis for an exposure setting because it isn't affected by the reflectivity of the subject and does not rely on subjective choices made by the user and IMO judging reflectivity (tone/zone) and user error are the biggest problems in metering.

 

[RedSun]

I agree that you don't need them all and even that good work can be done with any of them.

My point is that the Sekonic is an incident meter, and a good one at that. Incident metering is the most objective (scientific) way to find a reference point to use as a basis for an exposure setting because it isn't affected by the reflectivity of the subject and does not rely on subjective choices made by the user and IMO judging reflectivity (tone/zone) and user error are the biggest problems in metering.

The Gossen Luna Pro is also an incident meter. It has both aperture and speed priority and the Sekonic 308 does not. Other than that, they do the same thing.

 

[markbarendt]

Fair answer

 

[John Koehrer]

Picking a nit.
The Luna Pro is a reflected light meter with an incident dome.
Has one of the BEST calculator dials around.
It's failing is the CDS cell that responds very slowly
in low light and takes a bit of time to recover from bright light.

The Luna Pro SBC solved this by using Silicon Blue Cells. When the did that, they also added flash metering.

 

[benjiboy]

Too many people blame their light meter when what's at fault is their understanding of the basic principals of exposure.

 

[markbarendt]

Picking a nit.
The Luna Pro is a reflected light meter with an incident dome.

So it is used pointing at the subject?

 

[RalphLambrecht]

So it is used pointing at the subject?

No, from the subject towards the camera.

 

[markbarendt]

No, from the subject towards the camera.

That's what I thought, so it is reading the incident light.

 

[yulia_s_rey]

Oh no, I'm going to have to say it But here it goes: "K Factor"

 

[Poisson Du Jour]

Too many people blame their light meter when what's at fault is their understanding of the basic principals of exposure.

Bonza! A very good way of putting it.

 

[BrianShaw]

Oh no, I'm going to have to say it But here it goes: "K Factor"

... or C factor.