18% Grey Card. To use it or not.

arturo_rs · Monday at 5:18 AM

A found in a box a 18% grey card and it made me think this:

Nowdays with digital cameras we can do almost everything but with film...things change.

A have a Nikon F100 and I shoot photos using the matrix mode. Until now, it works well for me but, can we improve the technical quality of the photos?

I tried spot metering using the 18% grey card and more than 50% of the takes are 1 stop under or overexposed if I use the matrix mode.

From your knowlegde and experience, does it matter? I mean the fidelity of color, grain, etc... Exposure affects the density of the color layers, so, it must be important, right?

gary mulder · Monday at 5:53 AM

It’s useful it you want to know the entire chain functions as it supposed to. The chain is; Film + Camara (aperture and shutter) + development. The grey card should have a density of ± 18% + base fog in the negative.

loccdor · Monday at 6:23 AM

For wide latitude negative film just set your camera +1/2 or +1 to guard against your in-camera meter's underexposure and realize that camera meters are typically designed with trying not to overexpose slide film in mind.

When working with thin-latitude film its a good idea to keep some sunny 16 rules in the back of your head as a reference point and be careful to notice any very dark or very bright objects important in your frame.

For example, if I have a scene without much highlights but I have a few bright white houses not very prominent in the picture, the camera is likely to overexpose them. Likewise in the opposite direction if I am shooting portraits of my black dog. Exposure compensation +1 or -1 is a good idea here. Digital camera meters will also fail in these situations.

You need to figure out what works best for a particular camera and your process and dial it in, there is a lot of variation out there from many sources. The Nikon F100 helpfully has auto bracketing, if you want to devote a roll to the experiment.

Chan Tran · Monday at 6:53 AM

Using spot meter mode and the gray card you are trying to emulate the incident metering mode which a camera doesn't have. I don't like the matrix metering with negative film. The exposure is fine if the the scene is kind of normal but then there is the bright part it tries not to overexpose the bright part and cause the dark part seriousy underexpsosed. It works well with slide film as well as digital but not with color negative film. However, if you find using the gray card gives you good result then it's better to buy an incident meter which is inexpensvie and easier to use than the gray card.

xkaes · Monday at 8:00 AM

I'm with Chan on this one. Gray cards have their usefulness, but with a spot meter??? or Matrix metering???

If you want accurate metering, get an incident meter -- which is not influenced by the reflectance of the subject.

BrianShaw · Monday at 9:32 AM

Frame it and hang on display in your Darkroom.

Nicholas Lindan · Monday at 11:32 AM

Spot meters aren't any good at incident metering, so if that is what you are carrying then a small grey card makes sense. They are small and light and easier to slip in your camera bag than another meter. Also a lot cheaper.

However, incident metering, with either a grey card or incident meter, turns out to be not that useful in run-of-the-mill photography.

Incident metering's utility comes about in studio lighting when you need to set lighting ratios and in cinematography where it is used to balance fill reflectors and sunlight. The ubiquitous Sekonic 398's sorbiquet is "Studio Master" after all, and it has available a set of aperture cards that allow it to read directly in f-Stops for use on movie sets.

DREW WILEY · Monday at 11:42 AM

Some of the better collapsible gray discs these days have much better quality control than ordinary gray cards, which can be off quite a bit. Or go for the gold standard when calibrating your tests - the middle gray patch on a MacBeth Color Checker Chart (also sold under different brand labels). A handheld spot meter is best for taking the reflective readings. Place it in a scene, and then measure other things in the scene which can later serve as substitutes for a gray card, or else you understand where they fall in relation to that - either lower reflectivity or higher.

In-camera TTL metering introduces more variables; but you can do that in comparison to your handheld meter tests if you wish, and learn and apply the idiosyncrasies of your camera more objectively, versus just letting it think for itself.

Gambling with "latitude" is just plain dicey. But however you go about it, there is no substitute for sheer experience and tested familiarity with your own metering style.

Vaughn · Monday at 12:59 PM

arturo_rs said:
...

I tried spot metering using the 18% grey card and more than 50% of the takes are 1 stop under or overexposed if I use the matrix mode.
...

That sounds like you might have had some variabilty in how you used the gray card (angle held to the light, angle the meter was aimed at the card, etc).

Paul Howell · Monday at 1:28 PM

I agree with those who feel that in day to day photography matrix is more than adequate, the F100 has a very good matrix metering mode. A gray card is useful with slide film in tricky lighting and acts as a second opinion to the in camera TTL metering. It does take practice to know how to hold the hard to get a flat reading, just a small pitch to one or the other can throw off the reading.

jdart3000 · Monday at 2:42 PM

Just my 2-cents added into the conversation . . . It's always a good idea to open the Histogram window to check exposure, no matter what you use to determine exposure. Expose enough to keep the histogram graph as close to the right as possible, thereby preventing a blowout of highlights while moving the shadow exposure to the right giving you more usable pixels for shadow detail.

John

Chan Tran · Monday at 2:53 PM

jdart3000 said:
Just my 2-cents added into the conversation . . . It's always a good idea to open the Histogram window to check exposure, no matter what you use to determine exposure. Expose enough to keep the histogram graph as close to the right as possible, thereby preventing a blowout of highlights while moving the shadow exposure to the right giving you more usable pixels for shadow detail.

John

Histogram isn't an option for the Nikon F100.

arturo_rs · Monday at 2:55 PM

jdart3000 said:
Just my 2-cents added into the conversation . . . It's always a good idea to open the Histogram window to check exposure, no matter what you use to determine exposure. Expose enough to keep the histogram graph as close to the right as possible, thereby preventing a blowout of highlights while moving the shadow exposure to the right giving you more usable pixels for shadow detail.

John

Really?

jdart3000 · Monday at 3:01 PM

That's unfortunate because the Histogram feature is really useful.

Vaughn · Monday at 3:18 PM

jdart3000 said:
That's unfortunate because the Histogram feature is really useful.

But not a feature on any film cameras....

runswithsizzers · Monday at 4:05 PM

Nicholas Lindan said:
However, incident metering, with either a grey card or incident meter, turns out to be not that useful in run-of-the-mill photography.

Incident metering's utility comes about in studio lighting when you need to set lighting ratios and in cinematography where it is used to balance fill reflectors and sunlight.

Actually, I find incident metering to be very useful when doing run-of-the-mill photography with a camera that lacks an internal light meter, such as my Rolleicord. For me, run-of-the-mill photography is mostly b&w, mostly outdoors, using whatever natural light is available. The vast majority of the time, an incident reading from my Sekonic L308s (or Gossen Luna-Lux) gives me satisfactory exposure settings. Why wouldn't it?

On the other hand, when using my Pentax 35mm SLR film cameras, I can usually get by just fine using the camera's built-in light meter.

I think the key to success when using any light meter is knowing where to point it when taking a reading. This requires understanding the circumstances that can "trick" the meter into giving a misleading result. In my opinion, there are very few circumstances that can trick an incident reading, and far too many that can trick a reflected reading.

DREW WILEY · Monday at 4:23 PM

I can think of insurmountable circumstances that can render an incident meter useless, like trying to estimate the light falling on the opposite side of a canyon thousands of feet deep. You can't just hop over there, take an incident reading, and hop right back. Maybe you studio types scratch your head when someone like me states that; but for some of us, it's been the real world a multitude of times. A one degree real spot meter, however, makes that kind of circumstance easy.

Histograms are late to the game, and don't relate to film photography; neither do pixels.

MattKing · Monday at 5:53 PM

A grey card can serve as an excellent and repeatable reference if you place it within the field of view in a test exposure. You need to take care with orientation in reference to the plane that the card is held at, and the direction of light and the line between the subject and the camera.
And if you compare it visually with subject details when those details are side by side in the light incident on the subject, it can be useful when you make judgments about placement when using Zone system approaches.

Alan Edward Klein · Monday at 6:00 PM

DREW WILEY said:
I can think of insurmountable circumstances that can render an incident meter useless, like trying to estimate the light falling on the opposite side of a canyon thousands of feet deep. You can't just hop over there, take an incident reading, and hop right back. Maybe you studio types scratch your head when someone like me states that; but for some of us, it's been the real world a multitude of times. A one degree real spot meter, however, makes that kind of circumstance easy.

Histograms are late to the game, and don't relate to film photography; neither do pixels.

As long as you don't slip off the ledge.

Alan Edward Klein · Monday at 6:04 PM

arturo_rs said:
A found in a box a 18% grey card and it made me think this:

Nowdays with digital cameras we can do almost everything but with film...things change.

A have a Nikon F100 and I shoot photos using the matrix mode. Until now, it works well for me but, can we improve the technical quality of the photos?

I tried spot metering using the 18% grey card and more than 50% of the takes are 1 stop under or overexposed if I use the matrix mode.

From your knowlegde and experience, does it matter? I mean the fidelity of color, grain, etc... Exposure affects the density of the color layers, so, it must be important, right?

Matrix mode looks at the entire image to estimate exposure. The view could take in more than the 18% gray card. That may account for your under- and over-readings. You want to use center or spot so the camera's meter only sees the gray card.

bags27 · Monday at 6:05 PM

Honestly, most current film has so much latitude that I rarely worry.
Notable exceptions:
I'll use my spot meter with MF (less so with FF) if it's an exceptionally difficult situation
Snowy scene: then it's the 18% grey card for sure.

Nicholas Lindan · Monday at 6:12 PM

Incident metering falls apart if the subject is very dark or very light, such as a snow scene. The subject needs to be an average of ~18% reflectance with normal contrast for incident metering to work- but then most subjects fit this criteria.

The meter does not need to be up against the subject, the meter just needs to be illuminated by the same light. In a studio, where the light sources are close to the subject, that does mean the meter is close to the subject.

Mike Lopez · Monday at 6:27 PM

DREW WILEY said:
I can think of insurmountable circumstances that can render an incident meter useless, like trying to estimate the light falling on the opposite side of a canyon thousands of feet deep. You can't just hop over there, take an incident reading, and hop right back. Maybe you studio types scratch your head when someone like me states that; but for some of us, it's been the real world a multitude of times. A one degree real spot meter, however, makes that kind of circumstance easy.

Histograms are late to the game, and don't relate to film photography; neither do pixels.

The last time I saw the lens cap for my spot meter, in 2005, it was rolling off a cliff edge onto the floor of the Canyon de Chelly.

runswithsizzers · Monday at 6:36 PM

DREW WILEY said:
I can think of insurmountable circumstances that can render an incident meter useless, like trying to estimate the light falling on the opposite side of a canyon thousands of feet deep. You can't just hop over there, take an incident reading, and hop right back. Maybe you studio types scratch your head when someone like me states that; but for some of us, it's been the real world a multitude of times. A one degree real spot meter, however, makes that kind of circumstance easy.

Yes, one of the rules for taking a valid incident reading is, "The incident reading must be taken in the same light as falling on the subject."

If I had a spot meter (I don't), then spot readings might be useful in the "other-side-of-the-canyon" scenario. However, under normal circumstances, I might be tempted to assume the light falling on my side of the canyon is very similar to the light falling on the other side of the canyon?

But the nice thing about my incident meters is this, I can slide the little dome over to the side and have a very useful meter for taking reflected readings when common sense tells me circumstances require it. If the light is at all tricky, I will probably take both an incident reading and several reflected readings and consider the limitations of each type before setting the camera.

DREW WILEY · Monday at 6:41 PM

"Tempted to assume" can get you electrocuted by lightning when your side or the canyon is under inky black clouds, and the other side is still in brilliant sunlight.

That being said, I cut my teeth with an early Pentax H1 camera with an external coupled CDs averaging meter, and after a brief learning curved, never botched even a Kodachrome exposure in the mountains.

Another time, toting 4X5 gear on the tripod over my shoulder, hopping rocks, I accidentally dropped my spotmeter in an icy stream. So I had to expose my Ektachromes and black and white sheet film by memory, based upon many previous scenarios in analogous lighting; and every one of them came out correct. The meter itself was dried out and serviced later, and I'm still using it.

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