Which Light Meter to Trust?

RedSun · May 21, 2014

I did a little further test with the D70 and D200. Filters won't make any difference. One lens is Nikor 28-70 (film) macro zoom. The other one is Nikkor 18-70 DX AF-S. The 28-70 uses 52mm filter and the 18-70 DX uses 65mm filter.

On both cameras, the 28-70 film lens gives speeding reading of 1/20.
On both cameras, the 18-70 DX AF-S gives speeding reading of 1/15.

I know the difference is small (at least at this speed range). But lens has something to do with it.

Alex Muir · May 21, 2014

Readings can be affected by lens extension, particularly in zooms, and also internal flare. I've given up trying to find two meters that read the same.
Alex.

Chan Tran · May 21, 2014

RalphLambrecht said:
you can trust sunny 16.I calibrate or verify my meters with it.

Ok Ralph! So sunny 16 means the light level is 14 and 2/3 at ISO 100 right? And that's for an 18% reflectance surface?

RalphLambrecht · May 21, 2014

Chan Tran said:
Ok Ralph! So sunny 16 means the light level is 14 and 2/3 at ISO 100 right? And that's for an 18% reflectance surface?

whatever gives youf/16at1/125sat ISO100in your examleor f/16and 1/250s atISO200etc.just google 'sunny 16'for more detailsbutyes,I have sunny 16 weather here in Florida right now and I'm measuring an EV of 14 and 2/3 at ISO100too.in bright sunny weather, sunny16 works all the time

RalphLambrecht · May 21, 2014

Alex Muir said:
Readings can be affected by lens extension, particularly in zooms, and also internal flare. I've given up trying to find two meters that read the same.
Alex.

Idid send two GossenLuna StarF2s to Gossen to have them calibrated. for $50 they came back and read identical values ever sincebut I don't see why you need that.make adjustments until you can trust one meter and stick to it.if you look at two watches or two thermometers ,you can get confused too.Sticking to one is the ticket.

Chan Tran · May 21, 2014

RalphLambrecht said:
whatever gives youf/16at1/125sat ISO100in your examleor f/16and 1/250s atISO200etc.just google 'sunny 16'for more detailsbutyes,I have sunny 16 weather here in Florida right now and I'm measuring an EV of 14 and 2/3 at ISO100too.in bright sunny weather, sunny16 works all the time

When I am in IL and now I am in TX I measure the Sunny 16 at EV 14 and 2/3 but that's f/16 @1/100 (and not 1/125) @ ISO100 which is according to the Sunny 16 rule.

yulia_s_rey · May 21, 2014

In defense for Ralph, the sunny 16 rule (reciprocal rule) does in fact work as a reliable method to calibrate your meter. Unobscured sunlight gives off ~2000-3000 FCs. I say approx because as odd as it sounds your geographical location/time of year does play into effect. In short, here near New York City the reading won't be the same as Florida, nor as in Illinois. Just accounting for haze alone. To answer the OP's question, in my earnest opinion and having made my living holding a meter in my hand for nearly a decade, is that you have to have some leeway. And that's where your judgement (from experience) comes to play. It's not about "trusting" a meter, it's more about using it as a tool.

In The Negative Adams point out that (followed by a funny anecdote about Weston's method): "Although modern equipment is of remarkable accuracy, the process of determining the ideal camera exposure will always involve a considerable degree of judgement." (Pg. 30)

ic-racer · May 21, 2014

You can calibrate your equipment to the type of B&W film you will be using in the camera. Take a Zone 1 shot and see if it is 0.01 log d on the processed negative. It is that simple . If you want 2000 words on the subject, here is one website to read (but there are many others) : http://www.zone2tone.co.uk/zone-system-film-testing.htm

RedSun · May 21, 2014

I think we have probably made this too complicated. I once had some Tmax 400 film in the back, but set it to be ISO 100. The photo came out very nice, not a big difference from the regularly exposed frame.

At this point, I do not see the need to spend more $$ to get a top of the line spot meter. A decent film camera, like the Nikon N80 can certainly provide some guideline to the exposure. I can still get incident light exposure measure.

benjiboy · May 21, 2014

markbarendt said:
Horse feathers.

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

Properly set digital cameras can be reasonable meters. The wild cards are the settings and modifiers the users dial into their cameras.

Don't tell me it's "horse feathers" Mark tell Professional Photographer Magazine who published an article that proved it after doing extensive and repeatable tests that came to this conclusion.

StoneNYC · May 21, 2014

RedSun said:
I think we have probably made this too complicated. I once had some Tmax 400 film in the back, but set it to be ISO 100. The photo came out very nice, not a big difference from the regularly exposed frame.

At this point, I do not see the need to spend more $$ to get a top of the line spot meter. A decent film camera, like the Nikon N80 can certainly provide some guideline to the exposure. I can still get incident light exposure measure.

It's a question of need of critical exposure... If the OP is shooting B&W it's not really going to matter even if it's a whole stop off.. But if he/she is shooting E-6, then even 1/2 stop off could ruin the shot.

So it does matter in certain circumstances.

But I still think the OP doing their own testing against a real spot meter in various lighting scenarios will provide more valuable info than all of us talking...

removed account4 · May 21, 2014

why don't you take a roll of film,
put in in each camera
bracket the exposures
and see what works for you ?

Tom1956 · May 21, 2014

All my printing is done and delivered, so tomorrow is a day with my 2 Luna-Pro SBC's my Luna Pro regular, my Sekonic, 2 Nikon F2's and a Nikkormat. I'm going to get out there and pin down an average on both ends of all dials. That ought to be a hair-puller.

Mark Fisher · May 22, 2014

Does it really matter. When I shoot a camera without a lightmeter, I tend to shoot the box speed with my deveopment. For my Fuji with a built in meter, I need to rate it about 1/3 stop lower speed. My darkroom thermometer is about 4 deg low, I could get a different one, but all my film development times are around that thermometer. If your Bronica negs turn out how you want them, I wouldn't worry too much

John Koehrer · May 22, 2014

When you play with your Sinar, It's not going to make a whole hill of beans difference what you use.
Until you have a consistent technique established everything is up for grabs.

To simplify your life though, if you start with the 200 stay with it, don't be swapping things around You'll never get consistent results.

BTW if your testing was done indoors even the color temperature of lighting, the color of the walls or drapes can affect meter readings.

Tom1956 · May 22, 2014

Somebody help with card usage please

I put the subtitle up there to solicit input as to proper gray card usage to establish "sunny f/16". I've been in photography for decades and never was clear on this. Kodak always recommended turning the card some non-specific angle to the light source. Seems to me if you are going to establish "sunny f/16", then the card should be pointed dead at the Sun, and then turned just a hair to keep the meter and your hand from casting a shadow on it, but not 1/2 a degree more than that.
But Kodak states turning it 45 degrees to the sky, or something. With that kind of advice, f/16 can be all over the place between f/8 and 22. So what's the poop on this? I've got meters to calibrate tomorrow and want to turn my card correctly. Thx.

RalphLambrecht · May 22, 2014

not sure;with my incident meters, I just point the dome directly at the sun angrt EV142/3at ISO100.gray cards are a mystery to me.I don't even know if 18% is the right value anymore.Steve is the best to answer this.

Poisson Du Jour · May 22, 2014

What!?
A grey card is aimed back at the camera in the same or approximate light as the principle subject.
Where, how and why does the sun come into it!? The foregoing post about poking an incident meter dome at the sun is ridiculous.
The "Sunny f16" is not a universal panacea for perfect exposures by any stretch of the imagination.

Tom1956 · May 22, 2014

Poisson Du Jour said:
What!?
A grey card is aimed back at the camera in the same or approximate light as the principle subject.
Where, how and why does the sun come into it!? The foregoing post about poking an incident meter dome at the sun is ridiculous.
The "Sunny f16" is not a universal panacea for perfect exposures by any stretch of the imagination.

???

Edit: So, Ralph Lambrecht doesn't know what he's talking about. Hmm.....
The guy who has more test procedures and other bits of information on the internet and in print that works perfectly, all of a sudden doesn't know what he's talking about on this question. Somehow I' having a hard time swallowing that.
The light comes from the Sun, maybe? Duh.

Tom1956 · May 22, 2014

I was standing up for Ralph's knowledge, in case my sarcasm was misunderstood.

yulia_s_rey · May 22, 2014

Poisson Du Jour said:
What!?
The foregoing post about poking an incident meter dome at the sun is ridiculous.
The "Sunny f16" is not a universal panacea for perfect exposures by any stretch of the imagination.

I wouldn't call it ridiculous at all, like I said in a previous post (with a minor correction now) if you measure unobscured sunlight you will get 2000-3500 FCs w/ an incident meter. Ev 14 2/3 is approx ~3300 fcs. Even if you double this 6600 FCs (say if you're on the ISS or hang out in nuclear reactors), or half-it (say you're in a smoggy city) that's only one stop difference either way. I'd say that's a pretty reliable way to get the close to the determining the right exposure. And, as for perfect exposure, I think none of my negs ever where 'perfectly' exposed, as I exposed for my subject(s). In my opinion the sunny 16 principle combined with bracketing you just can't go wrong. And if your meter doesn't agree with this, wait for a nice sunny day to calibrate it.

Mr Bill · May 22, 2014

Tom1956 said:
I put the subtitle up there to solicit input as to proper gray card usage to establish "sunny f/16". I've been in photography for decades and never was clear on this. Kodak always recommended turning the card some non-specific angle to the light source. Seems to me if you are going to establish "sunny f/16", then the card should be pointed dead at the Sun, and then turned just a hair to keep the meter and your hand from casting a shadow on it, but not 1/2 a degree more than that.
But Kodak states turning it 45 degrees to the sky, or something. With that kind of advice, f/16 can be all over the place between f/8 and 22. So what's the poop on this? I've got meters to calibrate tomorrow and want to turn my card correctly. Thx.

Circa 1997, Kodak's instructions essentially say to make the meter readings from the same position (or direction) as the camera, and to be sure that both the gray card and subject are illuminated by the same light. Regarding angles, etc., it's too wordy for me to quote directly, but essentially they say to turn the gray card 1/3 of the way from camera toward the light. It's been said by some people that Kodak once specified some sort of angle for the card along with an exposure correction, but I've never actually seen that, nor do my instructions say anything about a correction.

Personally I'm in the same camp as you - if you want to know how bright the sunny day is, then point the card directly at the sun. But if one wants to get finicky, the situation seems to be exactly the same as using a flat diffusor on an incident meter. Tilting either the card or the flat diffusor away from the main light presents a narrower crossection, meaning that it sees a lesser amount of light energy. This is exactly the right way to meter for flat artwork, but I don't believe it is so good with a human subject.

At any rate, you can simply take the position that you intend to shoot with the sun very nearly behind you. This lets you have the card nearly perpendicular to the sunlight.

Mainecoonmaniac · May 22, 2014

If a shot is important, I bracket. However, I wonder if the cells inside the different cameras are sensitive to different colored light? Maybe some are sensitive to bluish light and some are more sensitive towards the red end of the spectrum? Camera light meters are just like any tool. You have to get familiar with the quirks of each.

Mr Bill · May 22, 2014

Mainecoonmaniac said:
However, I wonder if the cells inside the different cameras are sensitive to different colored light? Maybe some are sensitive to bluish light and some are more sensitive towards the red end of the spectrum?

Certainly they vary. in fact, Tom1956 started a thread not too long ago on this same subject - (there was a url link here which no longer exists). I don't know about today, but the ANSI exposure meter standards of ~40 years ago were not real stringent in this respect (I quoted from one of these in said thread). I don't think he got much pertinent information, though; mostly older data (roughly as old as my ANSI standard).

A few years back, I saw a dissassembled Minolta incident meter, it had an elaborate set of filters over the sensor. My point is that the spectral response can be made to be just about anything a designer wants by filtering a silicon-based sensor.

If someone wanted to compare different types/brands of meters, it would be interesting to see comparative results under tungsten (~2,800 K), sunny daylight (~ 5,500 K), and shade (perhaps 8,000 to 10,000 K and up). It would be interesting to test through various colored filters with known spectral characteristics, but probably not much practical value. Still, one could probably map out (roughly) a given meter's spectral response.

Metering is one of those things that seems very simple, at first glance. But as one wants more and more accuracy, things can get pretty complicated. Maybe someday exposure meters will be built as spectrophotometers with preset spectral setups to mimic different films. But I sort of doubt it, I don't think the demand exists.

MattKing · May 22, 2014

From the 1973 edition of the Kodak Master Photoguide:

"Hold the gray card straight up and down, close to and in front of your subject, with the card facing halfway between your camera and the (light source). Then make the meter reading of the card, with your meter not more than 6 inches away so that the meter reads only the card. Do not let your shadow fall on the card."

The above is a slight paraphrase, in that it combines the instructions for both indoor and outdoor exposure.

As I understand it, the reason you are supposed to hold the card at an angle is that it eliminates problems with specular reflection off of the surface of the card.

Which Light Meter to Trust?

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