When Not To Use An Incident Meter?

[Richard G]

You were right before: you are definitely over thinking this. With over 2000 posts in RFF I bet if you make 4 shots in that place, if you can find it, you will answer your question. Except, as indicated above in many posts, there is no answer to your question as you re-pose it just now. You have to decide, whether with an incident reading or a reflected reading, what you want in the finished shot: blocked shadow (left alley) or blown highlights (right alley). The meter reading can't make that decision. You must have been watching too much tennis this week.

 

[wgerrard]

You were right before: you are definitely over thinking this.

Of course. It's my curse.

You have to decide, whether with an incident reading or a reflected reading, what you want in the finished shot: blocked shadow (left alley) or blown highlights (right alley).

I'd go for the blocked shadows. 🙂

You must have been watching too much tennis this week.

Tennis? There was tennis? I've actually been shooting more than usually, then processing, the joy that is scanning, and all that.

 

[tlitody]

Yes, but in my scenario I am shooting from a position perpendicular to the two alleys. I.e., I'm in the street the alleys run into, looking down their lengths, centered in front of the building. I want the photo to reflect what I see: the well-lit alley on the right and the shaded alley on the left.

So, what I'm trying to understand is whether or not an incident reading from, say, in front of the building looking back to my camera position, is appropriate for that kind of shot.

An incident meter measures the light falling on the scene and not the light being reflected from the scene. If your position across the street is in bright sunlight, then if you point your meter at the sun it will get the same reading as if you were in the brightly lit alley and pointed it at the sun. Therefore to get the correct reading for the brighly lit (in direct sunlight) alley, you can stay where you are and point the meter at the sun. The alley in shadow will fall where it falls relative to your reading which will be darker, i.e. expsoed as for a shadow. Maybe blocked maybe not. It depends on deep the shadow is.

You must make decisions about which lighting source you want to read. If you were standing in full shadow you couldn't take a reading from the sun. It would have to be from the main light source which would be the sky and would therefore make the dark alley look brighter than it does from across the street where the meter would be in bright sunlight.

 

[wgerrard]

If your position across the street is in bright sunlight...

In this scenario, the sun is to my right and the building and the ends of the alleys are in front of me.

With an incident meter, am I not concerned primarily with the light as it illuminates the subject? If my subject was the side of the building facing the bright alley on the right, i.e., if I was shooting the side of the building with the sun behind me, then it would make sense to take a reading toward the sun.

However, my subject is at right angles to the sun. So, I'm thinking that if I take an incident reading midway between those two alleys, in front of the building between them, then I can derive an exposure that stands a reasonable chance of producing an image that reflects what I see, i.e., a building between two alleys with the sun shining strongly on the alley on the right.

That's the purpose of the hemispheric dome, isn't it? To read light from every direction as "seen" by the subject.

 

[alexnotalex]

I'm confusing myself thinking about this. I think the last post makes most sense, for me.

Put the meter in the place you want best exposed, this may be the sunny part, or the shady part.

Take the reading and set your exposure, it should be "correct" for the place you just measured.

But you still might not like the result!

my best regards,
Alex

 

[tlitody]

with an incident meter you measure the light source. The subject will fall where ever it falls relative to that. A white surface will be white a black surface will be black. This assumes they are in the same light. Anything which is not in the same light will be lighter or darker depending on its own light source.
Incident meters are good only when you can put them next to the main subject or when you are confident that the meter is in the same light as the main subject. Otherwise you must guesstimate.
Just pick the part of the subject you want exposed most accurately and put the meter in that light.
When you are distant from your main subject and lighting between you and subject may be different, then a spot meter is the way to go unless you want to walk over to where the subject is (which may not be practical). But a spot meter requires more careful calibratiion of film development so you know where things will fall when metered.
With an incident meter things just fall where they fall which will be correct(ish) if meter is in the same light as main subject.
So once again put meter in same light as main subject. Best policy is to experiment which will teach you much more. A street scene as you describe should be pretty easy to find on a sunny day. Try it out metering in the sun and then metering in the shadows and see what happens.

 

[alexnotalex]

I'm confusing myself thinking about this. I think the last post makes most sense, for me.

Put the meter in the place you want best exposed, this may be the sunny part, or the shady part.

Take the reading and set your exposure, it should be "correct" for the place you just measured.

But you still might not like the result!

my best regards,
Alex

somewhere I read that "mostly nothing will be brighter than the light that falls on it" and that's what the incident light meter measures.

(i.e. not how much light it reflects, so the black cat in a coal mine exposure comp rule doesn't apply.)

I guess you shouldn't use it if you can't put the meter anywhere like in the light that's falling on your *desired* subject.

 

[tlitody]

One thing I have never understood is the often given advice to stand at the main subject and point the incident meter at the camera. You may be standing in bright sunlight but behind the camera there could be black wall. Why you would want the black wall to influence the result when the subject is in bright sunlight never made any sense to me. Personally I would always point meter at main light source.

 

[wgerrard]

One thing I have never understood is the often given advice to stand at the main subject and point the incident meter at the camera. You may be standing in bright sunlight but behind the camera there could be black wall. Why you would want the black wall to influence the result when the subject is in bright sunlight never made any sense to me. Personally I would always point meter at main light source.

Because you are interested in the illumination of the scene from the camera's perspective? The reason for the plastic hemisphere on an incident meter is to read light coming from all directions other than behind the subject. In that sense, you don't actually "point" it at any single source of light. You align it along a line drawn from the camera to the subject. In you case, the black wall isn't an issue. The meter will simply read the amount of light falling on your subject.

 

[tlitody]

Because you are interested in the illumination of the scene from the camera's perspective? The reason for the plastic hemisphere on an incident meter is to read light coming from all directions other than behind the subject. In that sense, you don't actually "point" it at any single source of light. You align it along a line drawn from the camera to the subject. In you case, the black wall isn't an issue. The meter will simply read the amount of light falling on your subject.

But you are not metering the light from the cameras' perspective. That is the role of a reflected light meter such as those in camera meters or a spot meter.
No it won't meter the light falling on the subject because 50% of the hemisphere will be pointing at the ground and black wall.🙂

 

[charjohncarter]

Here are two examples, the first reflective reading of the subject, second incident reading holding the incident meter at the subjects face (and pointing it at the camera).

Maybe the question should be 'when not to use a reflective meter'?

 

[tlitody]

but that proves bothing. The white picket fence is in the central portion of the image so will affect reflected metering unless you are using spot or area metering of the face only. Spot meter which is a reflected meter could meter just the face.
But incident meter works just as well providing it is pointing at light source suitable for the subject lighting. In this case because the subject is in shade you wouldn't want the incident meter pointing at the sun. Pointing it at the camera may be just about right as you are getting shade from above and shade from below and some of what is behind the camera which we don't know but it won't be direct sun.

 

[Sparrow]

but that proves bothing. The white picket fence is in the central portion of the image so will affect reflected metering unless you are using spot or area metering of the face only. Spot meter which is a reflected meter could meter just the face.
But incident meter works just as well providing it is pointing at light source suitable for the subject lighting. In this case because the subject is in shade you wouldn't want the incident meter pointing at the sun. Pointing it at the camera may be just about right as you are getting shade from above and shade from below and some of what is behind the camera which we don't know but it won't be direct sun.

If you ever get a photo-shoot with Naomi Campbell and Cindy Crawford you'er going to get very confused with the metering 😉

The whole point of an incident reading is that it is independent of the subject, it's ambient not specific to the subjects relative brightness

 

[wgerrard]

No it won't meter the light falling on the subject because 50% of the hemisphere will be pointing at the ground and black wall.🙂

I was imprecise. The plastic cover is not a sphere, at least on my meter, which would read light coming from behind the subject. It's a hemisphere, half a sphere, so it can't read light coming from behind. It's OK if it reads light coming from the ground and from the sides and from above because the light illuminating the subject comes from all those places, too.

 

[alexnotalex]

Thanks for an interesting example. The exposure of the second photo is the one which sings to me... it's all about her, not the house and the fence.

Here are two examples, the first reflective reading of the subject, second incident reading holding the incident meter at the subjects face (and pointing it at the camera).

Maybe the question should be 'when not to use a reflective meter'?

 

[charjohncarter]

If you ever get a photo-shoot with Naomi Campbell and Cindy Crawford you'er going to get very confused with the metering 😉

The whole point of an incident reading is that it is independent of the subject, it's ambient not specific to the subjects relative brightness

Exactly, in the late sixties I was in the Army and had a close friend that was black (zone III-IV); so hard to get a good exposure with all the other whites (zone VI) or even yellows (zone V). That is when I got my first incident meter. I'll wait for the PC remarks.

 

[Gumby]

I'll wait for the PC remarks.

No PC remarks from me. I think using a strobe would have made the sitaution even more difficult. That is the "PC" you were talking about, right?

p.s. That is a perfect example of a good time to use incident metering!

 

[charjohncarter]

No PC remarks from me. I think using a strobe would have made the sitaution even more difficult. That is the "PC" you were talking about, right?

p.s. That is a perfect example of a good time to use incident metering!

Probably right, strobes would not be well used in a mixed photo. I found it better to just incident read and then develop for as many zones/tones as I could.

 

[Richard G]

In this scenario, the sun is to my right and the building and the ends of the alleys are in front of me.

With an incident meter, am I not concerned primarily with the light as it illuminates the subject? If my subject was the side of the building facing the bright alley on the right, i.e., if I was shooting the side of the building with the sun behind me, then it would make sense to take a reading toward the sun.

However, my subject is at right angles to the sun. So, I'm thinking that if I take an incident reading midway between those two alleys, in front of the building between them, then I can derive an exposure that stands a reasonable chance of producing an image that reflects what I see, i.e., a building between two alleys with the sun shining strongly on the alley on the right.

That's the purpose of the hemispheric dome, isn't it? To read light from every direction as "seen" by the subject.

I begin to get your precise question. Below is an image that has the sun from the left (I'm in the southern hemisphere...) The exposure should have been f 16 but I had long planned to photograph this building just after midday and thought I wanted an extra stop or more to bring out the brickwork. I overdid it. In your scenario my incident meter's cone would have had direct sun on half of it, but I don't know how much that would reduce the reading from the full sun reading. Probably half a stop I suspect. I'll test that. The other aspect of this is the arse forwards notion of pointing the meter back to the camera. I never liked the idea of that. I remember seeing the picture of how to do it in my first Gossen manual, for the SIxtar (Super Pilot.) My newer Gossen has a swivel head and I can look at the subject and the read out of the meter, taking an incident reading. Much more satisfying.


F1000012 by Richard GM2, on Flickr

 

[wgerrard]

I begin to get your precise question. Below is an image that has the sun from the left...

Thanks, Richard. I don't think you overdid it in that photo.

If alleys, or streets, ran down both the left and right sides of that building, you'd have my scenario. The alley on the left would be well lit by the sun. The alley on the right would be in the shade. So, I come along with my wide angle and want a straight on photo just like yours, except I want both alleys in the frame. I think that if I took a reading from the front center of that building, with the meter pointing back to my camera position, I'd get the shot I want: A well lit alley on the left, an alley in shadows on the right and a reasonably well exposed building in the middle.

If I took a reading pointing at the sun from the left alley, the shot would be underexposed. If I took a reading pointing away from the sun in the right alley, the shot would be overexposed.

It might be interesting to take and combine 3 readings: One from the center of the building and one from each alley, each with the meter facing out toward the street.