How to position a Grey Card (Landscape)

[Jeff Conrad]

Directions included with Kodak gray cards indicate, for a frontlighted outdoor scene, to hold the card vertically, oriented halfway between the light source and the camera, and increase the metered exposure by 1/2 step. This is at best an approximation, because exposure meter calibration derives from integrated (average) scene luminance, and has nothing to do with a gray card.

I agree with Steve that it's far more important to know where the highs and lows fall; if they're under control, the midtones fall where they will, and can be adjusted in post-exposure processing if necessary. If the highs (for reversal film) or lows (for negative film) are out of bounds, the information isn't there and the image is lost.

[Helen Bach]

I don't have much to add to the previous answers, except that one advantage of using an incident meter instead of a grey card is that incident meters with domes or Invercones may make more sense for three-dimensional objects because they are three-dimensional in themselves, and they take account of light coming from the side and even from the back - they are generally considered to have a cardioid response instead of the cosine response of a grey card.

The other thing is that Minor White, in his Zone System Manual, covers the use of grey card readings for estimating subject brightness range.

Finally, here is a photo of Professor Karapetoff using the 14% Neutrowe Gray Card in '39 or '40. I didn't take the photo.



Best,
Helen

[Brian Ellis]

Thanks, Tim.

So, to put this into a real life situation, if I was shooting a creek with some round-ish grey rocks in it, and I want to get the area under the crown of the rock as Zone V, I would lay the card on this area of the rock? This assumes that the card will assume a plane equal to the zenith of the rock...

Hope this makes some sense!!Lachlan.

Sorry but it doesn't make sense to me. If you want to get the area under the crown of the rock as Zone V, why not just meter the area? The resulting reading will be Zone V (approximately but as close as any meter reading gets given the fact that the zone system involves zones, not pin points). In other words, I don't see what purpose the gray card serves. I've used gray cards for color balance purposes but never to determine exposure. For that I find the darkest area in the scene in which I want texture or detail (i.e. that I don't want to appear as solid black), meter it, and stop down one or two stops. It's really pretty simple, at least with a spot meter.

[Lachlan 717]

It's really pretty simple, at least with a spot meter.

Thanks, Brian.

Whilst I understand how to use a spot meter and the Zone System, I was actually after advice on how to place a grey card. Seems my scenario has taken this post somewhat off topic.

Lachlan.

[vonstauren]

Can anyone assist with advice on how to position an 18% Grey Card?

Many threads refer to "...place your grey card and..." without explaining [I]exactly[I] how this should be done.

Should I lace the card so that it is parallel to the film plane? Do I tilt it towards the sun?

Thanks in advance for any help!!

Lachlan.

Take it with a common sense, it's enough. The gray card should logically be in the same angle toward the Sun as the subject surface you want to measure. If that surface were a huge gray card, you should have the same result.That is, if the church wall is 40° off the sun direction and you want to measure the exposure for it, you incline the gray card in the same way as the wall is directed. Were the wall of a gray color it would be a huge gray card to measure from. Of course, as the subject has many faces you will always get some parts that do not correspond to the measured angle but that's life. Then you have to average in whatever logical way...

[Brian Ellis]

Thanks, Brian.

Whilst I understand how to use a spot meter and the Zone System, I was actually after advice on how to place a grey card. Seems my scenario has taken this post somewhat off topic.

Lachlan.

You said you hoped your scenario made sense. I was responding to that. It doesn't make sense, at least to me. But if you insist on using a gray card then just aim the card at the camera lens and place it at an angle such that there's no glare coming from the card. I think that's about as good as you can do when you're using a gray card outdoors to determine exposure.

[Jorge Gasteazoro]

Jesus, why does everything has to be a pissing match lately?

So, to put this into a real life situation, if I was shooting a creek with some round-ish grey rocks in it, and I want to get the area under the crown of the rock as Zone V, I would lay the card on this area of the rock? This assumes that the card will assume a plane equal to the zenith of the rock...

You got it right, someone mentioned put the gray card in the same light as your subject, so for your scenario, yes you would place the gray card on the area of the rock that you want to be zone V, meter the card and the meter the rock and you can determine how much to vary the exposure.

If you have an incident meter, this is the same as a gray card, just place the dome towards the light source next to your subject and meter.

[GPS]

...
If you have an incident meter, this is the same as a gray card, just place the dome towards the light source next to your subject and meter.

Dear lovely Jorge, why would you place the dome toward the light source? Or do you mean just not to put the exposure dome the other way round, backward? The dome is there just to take care of the direction of the light source, it should face the camera as the subject does. I must be missing something in your expression...