Why use incident metering instead of reflective metering?
Asked 10/22/2022
3 views
2 answers
0
I understand that reflective metering measures the light reflected from the subject, while incident metering measures the light falling on the subject. But if the goal is simply to expose the subject correctly on the sensor, why should the incoming light matter more than the reflected light? With spot metering, I can meter directly from the subject I care about. So why is incident metering often considered more accurate or reliable than reflective metering, and in what situations does it actually help?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
3y ago
2 Answers
20
You said:
What is important is the subject being well-exposed to the sensor.
Exactly – you've hit the nail on the head.
Imagine photographing a bride and groom. The groom has worn a black suit and the bride a white dress. If you spot-meter off the bride's dress, you'll get one reading. If you spot-meter off the groom's suit, you'll get a different reading. Which one is correct? Neither. That's because the camera will try to expose anything as a midtone, but these are not midtones. The suit should appear darker than a midtone, and the dress should appear lighter than a midtone. In order to get a correct exposure, you'll have to have this knowledge in your head, and start messing around with exposure compensation (or, meter compensation, as I personally like to call it).
If you instead just take an incident reading of the light falling on your subjects – which is the same intensity on both, and so by definition requires a uniform exposure – and use that reading instead, then the blackness or whiteness of the subjects themselves won't have any negative influence.
It's probably worth also clearly stating that to take an incident meter reading, you don't just point your camera at the light source. You use a dedicated incident light meter, which will have a diffusor fitted.
Originally by user38159. Source · Licensed CC BY-SA 4.0
user38159
3y ago
0
Generated from our catalog & community — verify before relying on it.
Incident metering is useful because reflected metering is strongly affected by subject brightness. A reflective meter assumes whatever it sees should average to a midtone, so a white dress, black suit, dark skin, bright snow, etc. can all fool it unless you add compensation.
An incident meter ignores subject reflectance and measures the illumination itself. That gives a consistent exposure for the light on the subject, regardless of whether the subject is black, white, or anything in between. That’s why it’s often preferred for portraits, studio work, and controlled lighting.
With spot metering, you can still get excellent results—but only if you know what tone you’re metering and how much to adjust from “midtone.” Metering a face is often a practical compromise because skin is usually closer to a useful reference than clothing.
So incident metering is not automatically “better”; it’s simply less dependent on the subject’s reflectivity. Reflected metering is often more convenient and works very well when you understand its assumptions. Both are just tools—the right exposure is the one that matches your intent.
Recommended products
UniqueBot
AI3y ago
Your Answer
Related Questions
Why use an incident light meter in studio photography?
Is an incident light meter useful for outdoor environmental portraits?
What’s the difference between illuminance and luminance, and why are incident light meters useful?
Why did Ansel Adams emphasize reflected light instead of incident light metering?
Are light meters and exposure meters the same, and which one measures light falling on the subject?