What's the point of using an Incident meter?

I don't understand:

 

If a spot meter can you give the reading of the amount of light reflected from the subject, which is essentially is what the camera sensor/film will be exposed to, then why bother using a *Incident meter* and then having to adjust the skin tone/reflective surface factor?

 

Could anyone explain?

 

(Moderator Note - the content has been edited to reflect post #8)

Edited September 3, 2020 by William Michael

No.

Link The Difference Between Reflective and Incident Metering and How They Work

 

This isn't bad and should provide some info.

Yes...incident meters measure light falling on subject, not light reflected from subject.

 

People come in all sorts of colors, their skin reflectance varies a lot with perspiration and makeup..that can make spot metering more tricky.

Link The Difference Between Reflective and Incident Metering and How They Work

 

This isn't bad and should provide some info.

I know how each meter works, but I don't understand why ----what my first post asks...

There are uses and advantages / disadvantages to both types of metering. I use both, but because I have used spot for a very long time, I often place the spot selectively on areas of the subject that will get the result I want rather than the most important area. Just habit & practice - my cameras are nearly always set on spot.

Yes...incident meters measure light falling on subject, not light reflected from subject.

 

People come in all sorts of colors, their skin reflectance varies a lot with perspiration and makeup..that can make spot metering more tricky.

I don't understand what this "more tricky" mean? At the end of the day we are metering what we want to see on the image, don't we.

 

Then, "People come in all sorts of colors, their skin reflectance varies a lot with perspiration and makeup"

is preceisely my point, if we can spot meter it accruately to what the camera sees, why get an average reading and not factor in the skin colors????

There is a correction for a typo in my original post"

I don't understand:

 

If a spot meter can you give the reading of the amount of light reflected from the subject, which is essentially is what the camera sensor/film will be exposed to, then why bother using a *Incident meter* and then having to adjust the skin tone/reflective surface factor?

"

Why indeed?

A meter is stupid. It doesn't know what object you pointed it too. Since a black skinned person reflects less light to the meter than a white skinned person, you have to make an adjustment that reflects which skin you pointed it at.

Strongly encourage you to do some reading on the effectiveness of each type of metering. For 60 years I've preferred incident metering, but that doesn't mean that it is best in all circumstances. An understanding of the shortfalls of each methodology can immeasurably improve your exposure, becasue you have knowledge and choices.

A handheld spot meter will be more precise at giving you a reflective reading than a camera meter. The incident meter is good for general light readings. Either will require interpretation of where different subjects/objects will fall and what adjustments are need to have them fall where you wish.

If you are only shooting with one area that is prioritized then you can point your spot/reflective meter at that area, adjust exposure and be done. But as soon as you want to consider other areas and find the exisiting relationship you will need to take more readings. The incident reading is concerned with the light source(s) and can most often be done in a single reading. Either way you will need to run some quick calculations to place your subject where you want.

Some prefer reflective metering for a sense of accuracy, some prefer incident metering for the control based on a known constant. Most prefer in camera reflective averaging meters for ease and speed.

If you want to measure Flash then you definitely need an incident light meter called a flash meter to determine the right amount which will fall on a subject.

 

The Difference Between Reflective and Incident Metering and How They Work

Good point about flash metering. Even tho I have always relied on doing the calculations in my head.

Strongly encourage you to do some reading on the effectiveness of each type of metering. For 60 years I've preferred incident metering, but that doesn't mean that it is best in all circumstances. An understanding of the shortfalls of each methodology can immeasurably improve your exposure, becasue you have knowledge and choices.

This is not really helpful. Can you elaborate more and how it can answer my original questions? I already know how each meter work..

Ok, if you taking an image which includes a black labrador retriever, a snow white bunny, and a large section of green foliage, where are you going to point your spot meter? Pointing it at the black lab or white bunny will result in dramatically different camera settings, so where will you point it? Does it make a difference to you if you are using color slide film, color print film, high contrast black and white negative film, a vintage CDC sensor from the early 2000's, or a modern CMOS sensor? Do you understand what your meter is telling you when you take a meter reading?

If you want to measure Flash then you definitely need an incident light meter called a flash meter to determine the right amount which will fall on a subject.

 

The Difference Between Reflective and Incident Metering and How They Work

I never use flash, and even if I do, I don't understand why can't I keep the flash turned on continuously and use a spot meter...

If you are only shooting with one area that is prioritized then you can point your spot/reflective meter at that area, adjust exposure and be done. But as soon as you want to consider other areas and find the exisiting relationship you will need to take more readings.

 

The incident reading is concerned with the light source(s) and can most often be done in a single reading. Either way you will need to run some quick calculations to place your subject where you want.

 

I don't believe this is true, you need to meter many times with incident meter as much as spot meter. Just because it measures the amount of light falling on to the subject doesn't mean it's constant, say over a surface..

Ok, if you taking an image which includes a black labrador retriever, a snow white bunny, and a large section of green foliage, where are you going to point your spot meter? Pointing it at the black lab or white bunny will result in dramatically different camera settings, so where will you point it? Does it make a difference to you if you are using color slide film, color print film, high contrast black and white negative film, a vintage CDC sensor from the early 2000's, or a modern CMOS sensor? Do you understand what your meter is telling you when you take a meter reading?

I don't see how this has anything to do what I am asking... in your stated scenario, I will meter whatever subject I intend to "bring out", let it be the dog, bunny or leaves. What I am saying is that why would I meter for the bunny using an incident and then adjust the compensation due to its skin tone, instead of using a spot and exposure as what the meter tells me....

And if I want to do an averaging of the three, I can step back and let the viewfinder include all three, or spot meter each and find a common ground. Still, if I use an incident, not only I'm doing all that, I also have to mentally add/subtract the reflective factor

Edited August 31, 2020 by jamietea20

With incident,

typically you stand near your subject and point the meter's white dome directly back toward the camera and you have your reading (It does not see light coming from behind the subject.). Often you can even take a single reading from your own position if you are in the same lighting as the subject of your photo. But with the dome it allows it to measure how much light is illuminating ALL surfaces in the scene. That's about as constant as you can expect.

If you are needing to take several readings then you can switch over to spot/reflective readings. But some photographers can easily make the necessary calculations for the different reflective surfaces based on experience with using incident.

Really one of the reasons some prefer incident is the single read... it is fast and accurate with experience.

Edited August 31, 2020 by inoneeye

With incident,

typically you stand near your subject and point the meter's white dome directly back toward the camera and you have your reading (It does not see light coming from behind the subject.). Often you can even take a single reading from your own position if you are in the same lighting as the subject of your photo. But with the dome it allows it to measure how much light is illuminating ALL surfaces in the scene. That's about as constant as you can expect.

If you are needing to take several readings then you can switch over to spot/reflective readings. But some photographers can easily make the necessary calculations for the different reflective surfaces based on experience with using incident.

Really one of the reasons some prefer incident is the single read... it is fast and accurate with experience.

I can see this is true for mostly outdoor settings with only wide shot of an assortment of subjects in the frame, where there's a single light source(sun), and the reflective factors are negligible. Otherwise, even for an outdoor portrait, you still need to calculate, either mentally or with a spot meter for the skin tone differences.

What I am saying is that why would I meter for the bunny using an incident and then adjust the compensation due to its skin tone, instead of using a spot and exposure as what the meter tells me....

Actually, this is the opposite of what you should do! Let me explain.

 

Let's take the white bunny. How much light is falling on it? To answer that, use the incident meter (you can point it at the camera if you want, but you probably should point it at the key light, although sometimes the 'key light' is in the shade). The incident meter tells you the correct exposure. It does not care about what shade of grey the bunny is. It simply says, this amount of light is falling on this location. That's it.

 

And so the bunny will be correctly exposed, whatever its shade of grey. The caveat is if the camera cannot capture a highlight that strong. If you know this, underexpose a bit, then bring it up later. Phone cameras are not great at pure white subjects, for example.

 

But with a spot meter, you definitely need to know how bright the bunny is, relative to 18% grey. So you take your reading, and compensate afterward.

 

Your original question also made the above mistake: you got it the wrong way around. Incident meters don't require compensation, but spot meters do. Having said that, spot meters let you measure light without having to approach the subject. Some people only use spot meters, and they know how to compensate for different subjects.

 

These days, a lot of cinematographers use their monitors instead of light meters. They are properly set up to do so. I often use the LCD of my camera to meter, depending on the situation. Sometimes it pays to take a more precise reading. If I can I take a bunch of test shots. Sometimes I'll bracket, just like with slide film.

Incident metering is not restricted to sunlit subjects. And yes with either method calculations & adjustments have to be made to find the exposure best suited to your vision.

Actually, this is the opposite of what you should do! Let me explain.

 

And so the bunny will be correctly exposed, whatever its shade of grey. The caveat is if the camera cannot capture a highlight that strong. If you know this, underexpose a bit, then bring it up later. Phone cameras are not great at pure white subjects, for example.

 

But with a spot meter, you definitely need to know how bright the bunny is, relative to 18% grey. So you take your reading, and compensate afterward.

Umm.... no, with the incident meter, the bunny under the metered reading will be over exposed, as you said the camera will not handle the brightness, hence you need to "compensate" to under expose from what the meter reading is... with a spot meter you see exactly how bright it is, so I don't understand what you need to "compensate" afterwards...?

Umm.... no, with the incident meter, the bunny under the metered reading will be over exposed, as you said the camera will not handle the brightness, hence you need to "compensate" to under expose from what the meter reading is... with a spot meter you see exactly how bright it is, so I don't understand what you need to "compensate" afterwards...?

You only have to compensate if you know your sensor can't handle the brightness of the white bunny. Usually it won't matter as any decent camera can easily handle two stops above middle grey. I was just giving an example of where you might want to underexpose if you camera has limited DR. Not that you would really use an incident meter with a phone camera. It was just a technical point. Sorry if I confused the issue.

 

If you used a spot meter on the white bunny, your reading will give you an 18% grey bunny. If you used a spot meter on a black bunny, your reading will give you an 18% grey bunny. The incident meter will not make those mistakes.

 

Spot meters are sometimes used on set to determine lighting ratios. Because all you want is the difference in brightness. An incident meter would be not as useful for this task, because you might want to measure a lighting ratio of two subjects of different reflectance under the same light.