Metering using an incident meter from the camera position

ymc226 · Jul 6, 2009

Rather than going to the subject and pointing the sensor toward the camera position, can I just stay where I would take the picture, place the meter in front of me using an outstretched arm, turn the meter so it faces away from the subject (toward the camera position) and take a reading?

With street photography, I don't have the luxury of approaching my subjects and then running back to the place where I want to shoot from.

How do most people who use incident meters remote from the main subject take readings? Can you be specific in where to aim the sensor.

In a backlit subject, if you were also in the same lighting situation, could you just turn with your back faced to the subject, take a reading pointing away from the subject?

archphoto · Jul 6, 2009

If the light conditions are the same: yes, as long as you point the little white sphere towards the lens.

However, if you measure in the shade and your subject is in the sun, you will have to adjust for that.
As an architectural photographer I have the luxury of being able to walk around and take my readings first.

For back lit situations: yes, see my first line.

Peter

Thomas Wilson · Jul 6, 2009

I use the Luna Pro F. Most of the time I just hold it over my shoulder and point it more or less on a tangent from the subject. It's fast, easy, and accurate.

Q.G. · Jul 6, 2009

I once saw a photographer busy doing what photographers do.
Some, though, in different ways than others.

In a very public place, he was setting up to take a picture, making a big show of it.
Big production too, apparently, with no expenses spared. Even an arm lift with platform at his disposal, which he used as a camera platform.

Sun beating down, drowning everything in light.

Then the man did something that demonstrated that he was more show than anything else.
He moved the platform towards his subject. Couldn't get close enough, so he climbed the railing of the basket he was in on the end of the arm, and then started leaning out precariously, stretching out his arm as far as he dared, trying to hold his incident light meter as close to his subject as possible.

He apparently thought that, with the sun being as close to his scene as it is (what? 150,000,000 km?), the extra 6 meters or so would make or break his exposure.

Gave me a good laugh.

So just remember what Peter said, and that alone will make you a better photographer than that strange fellow.

eddym · Jul 6, 2009

Q.G., hilarious story!

Ed Sukach · Jul 6, 2009

ymc226 said:
Rather than going to the subject and pointing the sensor toward the camera position, can I just stay where I would take the picture, place the meter in front of me using an outstretched arm, turn the meter so it faces away from the subject (toward the camera position) and take a reading?

Of course you CAN... however, if the amount of light falling on the subject is not the same, you will not obtain a useful reading.
A truly accurate way to go would be spot metering, although this is also dependent of the amount of light reflected back from the subject - 'light' subjects require less exposure, and the time involved taking multiple readings might well be phohibitve.
"Reflective" metering would probably be best, simplest, fastest, and with a little practice, acceptably accurate.

Q.G. · Jul 7, 2009

Incident light metering when your subject is in different light requires judgement.
You can create your own shade, so when you are in the shade and your subject is not is not a huge, difficult problem. But how deep 'your' created shade is, and how deep the one your subject is in, needs to be judged by eye.

Reflected light metering always takes the same sort of call. Except when metering off something known to be 'middle grey', the reading needs to be adjusted by an amount you will have to estimate.

So not much difference there.

Incident light metering generally is the easiest and most acurate method.
It bears reminding, perhaps, that what it does is meter light. Not a subject. So you do not need the subject (or be near the subject - why, the subject does not even have to be there when you meter) to get a correct reading.

Reflective light metering also meters light, of course. But only after it has bounced off a subject that (unless it is flat) not just has bright and shaded bits, but also has its very own reflective properties.
Works great too. But always depends on your judgement, and takes more practice to get acurate results.

benjiboy · Jul 25, 2009

I find with incidental metering and backlighting the white dome of the lightmeter can't see round the subject to take the backlighting into consideration, I use a method called the Duplex System in which you take one reading from the subject position to the camera position in the normal way and note the reading, then take a second reading pointing the dome at the Sun, then average the readings by setting the camera between the two readings .

Rich Ullsmith · Jul 28, 2009

The reflectance of the ground beneath your feet compared to the reflectance of the ground beneath your subject is what will throw off incident metering, if you don't meter at the subject. If it's grass under your feet and you're taking a photo of a tree in the same field, then what the heck.

And don't hold the meter in front of you, with the bulb sensor towards you and the light behind you, for obvious reasons.

jeffreyg · Jul 28, 2009

Overcast days can't miss. If your camera has a built-in meter an 18% gray card can work. Personally I prefer a hand held spotmeter.
Jeffreyg

2F/2F · Jul 28, 2009

Think carefully about what an incident meter measures, as opposed to what a reflected meter does.

It measures the light that falls on its dome, not the light coming from the subject.

Therefore, if the same sunlight that is hitting your subject is hitting you, you are OK to meter from where you are.

Closer light sources than the Sun are a different story. Remember the inverse square law, which applies to all light: The amount of light falling on an object is inversely proportional with the square of the distance of the object from the light source. Therefore, you lose or gain light exponentially with distance. Thus, the closer your subject and light source, the greater an effect a given change in distance will have.

On a clear day, what is the distance of the Sun to your subject? About 90 million miles. On an overcast day, what is the distance of the blanket of haze to your subject? Likely several thousand feet. Considering the inverse square law, at these distances, what difference does 5, 10, 20, 30, etc. feet have?

Now, in the studio, with a 1K hot light, what is the distance of the light from your subject? What about with a 1000Ws studio flash piped through a main and a fill light? Very close. Under 10 feet 99% of the time, in my experience. Apply the inverse square law to those distances, and you get huge differences in illumination with small differences in distance. Take a main light that is four feet from your subject, move it back one foot, and you already need to change your exposure setting by 1/2 stop.

Besides this theoretical explanation, there is simply the practical fact that in the studio, I cannot think of a situation I have shot in which the same light that is falling on my subject was the same light that was falling on me and the camera.

Therefore, I would make the general statement that outside, in natural light, if the light you are in is no different than the light your subject is in, take the reading from where you are, and if you are using artificial light, take the reading from where the subject is. I hate making general statements, but this is a pretty decent one.

With incident metering, you are measuring the light source itself, from the subject (or from the same effective distance from the subject). So, always point your meter AT the light source, not at the camera lens.

Ektagraphic · Jul 28, 2009

You are one sharp guy 2F/2F! Many of your posts in this area of the forums have really been helping me understand. Thank you!

Q.G. · Jul 28, 2009

2F/2F said:
With incident metering, you are measuring the light source itself, from the subject (or from the same effective distance from the subject). So, always point your meter AT the light source, not at the camera lens.

That's what i'd say, with one small, but important difference:
point the light meter AT the light source that is illuminating the part of the subject you want to expose 'properly'.

In backlit situations, if you do not want a black silhouette against a well exposed background, meter the light that is falling on the side of the subject facing the camera. Not the light that is falling on the (mostly invisible from the camera bright side of the subject.
If you want a silhouette, measure the light falling on the bright bits.

So sometimes, you might indeed want to point the meter at the camera lens.

Mahler_one · Jul 28, 2009

Yes, a good story. Almost as good as the ones concerning those who used a flash to illuminate the moon when there was a partial eclipse. Possible? Those who witnessed the flashes going off swear it's true.

Ed

2F/2F · Jul 28, 2009

Q.G. said:
That's what i'd say, with one small, but important difference:
point the light meter AT the light source that is illuminating the part of the subject you want to expose 'properly'.

In backlit situations, if you do not want a black silhouette against a well exposed background, meter the light that is falling on the side of the subject facing the camera. Not the light that is falling on the (mostly invisible from the camera bright side of the subject.
If you want a silhouette, measure the light falling on the bright bits.

So sometimes, you might indeed want to point the meter at the camera lens.

True indeed. To make it more clear, I should have said what Q.G. said: point the dome at whatever is illuminating the part of your subject that want to expose for in the pic.

I did not, because for a backlit or shaded situation, I was not considering the Sun to be the light source for the composition (though as he sez, in a backlit situation, it is the direct source for the BACK of the subject). I consider sky light and reflected light from the ground, walls, etc. to be the light source in these cases, so would measure them, not the Sun. I should have explained that, however.

Denis K · Jul 28, 2009

You also want to make sure that you get your own body out of the hemisphere covered by the integrating bulb of the light meter. This is especially true if you're wearing light colored clothing which can add extra light that will not be in the picture at the time the shutter is triggered. This is often why you will see photographers stick their arm way out when taking an incident light meter reeding as this cuts down on their body light.

PeteZ8 · Aug 2, 2009

Mahler_one said:
Yes, a good story. Almost as good as the ones concerning those who used a flash to illuminate the moon when there was a partial eclipse. Possible? Those who witnessed the flashes going off swear it's true.

Ed

HAHA!!! It would have to be a rather long exposure as it takes 1.3 seconds for the light just to reach the moon, then another 1.3 for it to get back.

Then there is the whole inverse square law thing to deal with; twice actually.

Lee L · Aug 2, 2009

PeteZ8 said:
HAHA!!! It would have to be a rather long exposure as it takes 1.3 seconds for the light just to reach the moon, then another 1.3 for it to get back.

Isn't that what the "M" flash sync setting is for? :confused:

Lee

PeteZ8 · Aug 2, 2009

Lee L said:
Isn't that what the "M" flash sync setting is for? :confused:

Lee

And here I was, the whole time, thinking the "M" was for "Modest" and the "X" was for nudes...

Sirius Glass · Aug 2, 2009

PeteZ8 said:
HAHA!!! It would have to be a rather long exposure as it takes 1.3 seconds for the light just to reach the moon, then another 1.3 for it to get back.

Then there is the whole inverse square law thing to deal with; twice actually.

Actually use the 1/r^^4 [1/r**4] rather than 2 * 1/r^^2 [2 * 1/r**2].

Steve

PeteZ8 · Aug 2, 2009

Sirius Glass said:
Actually use the 1/r^^4 [1/r**4] rather than 2 * 1/r^^2 [2 * 1/r**2].

Steve

Wow, I don't think I have that language pack installed on my computer (and to keep in the non digital spirit, I'm talking about my analog computer )

Ed Sukach · Aug 2, 2009

Now that the dust has settled, somewhat, I've downloaded an image to the "Technical Gallery", taken where the appropriate metering was "Reflected Averaging", with a Gossen UltraPro.

Situation:
Tired after driving from Stuttgart over ice covered roads in late January. Arrived for check-in at ~ 2000 - 2100 hours. I was impressed by the appearance of the entrance, and decided to take a quick image.
Incident metering would NOT be appropriate ... that would measure the light FALLING ON the scene, actually liitle to none. Spot metering would indicate great range of light ... and, most probably extensive calculations, if that range was not in the capability of the meter processing. In any event, It would take more time and energy than I wanted to expend at that time. I pointed the meter at the scene, pressed the button once or twice, and "flew" with the result.

Now, there is more to the story... which I wll post on the Coolor Analyzer thread.

Metering using an incident meter from the camera position

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