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Wendy Sanders McDonlad

Light Meter: Do you use spot or incident?

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Question 1) If incident meter only measures the amount of light falling on to the subject, and spot meter measures the light reflected( to the camera),

then, what's the point of using incident meters, wouldn't be using a spot meter more accurate? As in, it's exactly how much the camera will register, without having to consider actor's skin tones ect..

Question 2) I bought a Sekonic L358, which only has the incident mode, and I wonder if I hold it near the position of the camera(lens) with the lumen sphere down, to simulate the total amount of light reflecting into the lens----- How accurate/inaccurate will it function as a spot meter? I don't have a spot meter to compare.

Question 3) how do you guys use light meters incident/spot on set? I'm going to shoot mostly in digital and I don't quite know how light meters will come into play, when I can see everything on the monitor..

Thanks everyone.

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If you want to know where the exposure sits across a larger space, you'd have to have someone walk through it slowly with a grey card, so you could measure the reflected value at each section - you'd also have no way to measure how hot any backlight is in that situation (without moving to the opposite side of the room/space.

With an incident meter, you can just walk through yourself and take readings as you go.

I rely on both spot and incident readings. That's why I put up with the stupid bloody user-interface of my Sekonic L758-C - because it give me both meters in one unit.

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2 hours ago, Wendy Sanders McDonlad said:

 

then, what's the point of using incident meters, wouldn't be using a spot meter more accurate? As in, it's exactly how much the camera will register, without having to consider actor's skin tones ect..

 

An incident meter is neither less nor more accurate than a spotmeter. You have to interpret the reading either way.

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3 hours ago, Wendy Sanders McDonlad said:

Question 2) I bought a Sekonic L358, which only has the incident mode, and I wonder if I hold it near the position of the camera(lens) with the lumen sphere down, to simulate the total amount of light reflecting into the lens----- How accurate/inaccurate will it function as a spot meter? I don't have a spot meter to compare.

Question 3) how do you guys use light meters incident/spot on set? I'm going to shoot mostly in digital and I don't quite know how light meters will come into play, when I can see everything on the monitor..

2. If you do this, then you will basically be replicating a wide angle reflected meter, which is a generalized exposure reading. The value of a spot meter is that it can read very narrow angles, so you can pinpoint a window in the background, a dark wall, or a practical lamp shade and know how much over or underexposed that area will be compared to your shooting stop.

3. If you’re shooting on film, meters are invaluable. With digital video cameras, they often have tools built in that essentially will give you the same info. However, if you’re working on a bigger shoot where you have location scout days and pre-light days on set without the camera (though nowadays you usually will have the camera on a pre-light), then it’s good to know how much light you’re getting from each lamp and in what ratios. In that case, an incident meter with a Footcandles or Lux mode will be more useful. 

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Yes it's easier and more accurate to point the spot-meter at an object to find it's exposure value, say the shaded tree trunk in the background, or the sunlight hitting the wall, or the sky. But spot-meter is only useful if there is a physical object that light is hitting. It also keeps you from running around the set with an incident meter.

But, if you need the light value of the empty air that your actor will be in, then incident-meter is easier. Or I suppose, spot-meter your hand. Combination meters like sekonic 758 make both possible, so you can incident-meter the open yard, then spot-meter the background shady fence line and visualize the exposure difference and make your decisions from there.

Ultimately, they're tools. Use what you find useful. Some people use false color, which is like a visual representation of what the spot meter can do. And of course, the incident-meter tells you the exact measure of light at a position in 3D space, via lux or foot candles. So you could calculate the wattage necessary from a certain distance to get you the value you want. Again, it's a tool.

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3 hours ago, Stuart Brereton said:

An incident meter is neither less nor more accurate than a spotmeter. You have to interpret the reading either way.

I say the spot meter is more "accurate" in the sense it gives you the reflected light value instead of the amount of light falling onto it. For example, a black couch with velvet upholstery. If you light it from the incident reading it will be completely off, since the fabrics is not nearly as reflective.

 

 

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2 hours ago, Stephen Sanchez said:

Yes it's easier and more accurate to point the spot-meter at an object to find it's exposure value, say the shaded tree trunk in the background, or the sunlight hitting the wall, or the sky. But spot-meter is only useful if there is a physical object that light is hitting. It also keeps you from running around the set with an incident meter.

But, if you need the light value of the empty air that your actor will be in, then incident-meter is easier.

I couldn't think of such case where i'm metering an area(air) where I can not get the actors/ stand in positioned there to get a more accurate reading, unless it's a stunt/action situation, in which case are you implying you only use incident meter in those rare occasions?

No body seems to answer my first question, that if spot meter will tell you more accurately how much light reflected off the subject, then why bother will an incident meter and calibrate the light absorbing/reflecting factors???

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4 hours ago, Mark Kenfield said:

If you want to know where the exposure sits across a larger space, you'd have to have someone walk through it slowly with a grey card, so you could measure the reflected value at each section - you'd also have no way to measure how hot any backlight is in that situation (without moving to the opposite side of the room/space.

With an incident meter, you can just walk through yourself and take readings as you go.

I rely on both spot and incident readings. That's why I put up with the stupid bloody user-interface of my Sekonic L758-C - because it give me both meters in one unit.

Ok, just to confirm. Is the difference between using the two meters a matter of if "I walk across the room" and "I walk across the room with a standin"?

"you'd also have no way to measure how hot any backlight is in that situation (without moving to the opposite side of the room/space."

I don't quite understand this part, if I'm shooting in from the other side, (where the camera is) why can't I just use the spot meter to look from there the camera is? Again, is this a matter of whether I can meter with a standin or not?

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Posted (edited)
2 hours ago, Satsuki Murashige said:

2. If you do this, then you will basically be replicating a wide angle reflected meter, which is a generalized exposure reading. The value of a spot meter is that it can read very narrow angles, so you can pinpoint a window in the background, a dark wall, or a practical lamp shade and know how much over or underexposed that area will be compared to your shooting stop.

1) Do you know what's the general focal lengths of the a spot meter?

2 hours ago, Satsuki Murashige said:

3. If you’re shooting on film, meters are invaluable. With digital video cameras, they often have tools built in that essentially will give you the same info. However, if you’re working on a bigger shoot where you have location scout days and pre-light days on set without the camera (though nowadays you usually will have the camera on a pre-light), then it’s good to know how much light you’re getting from each lamp and in what ratios. In that case, an incident meter with a Footcandles or Lux mode will be more useful. 

I agree, it seems like to me nowadays this is what a light meter is designed for, given all the zebra/ histograms and other build in functions of the digital cameras. Am I correct?

Edited by Wendy Sanders McDonlad

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2 hours ago, Satsuki Murashige said:

2. If you do this, then you will basically be replicating a wide angle reflected meter, which is a generalized exposure reading. The value of a spot meter is that it can read very narrow angles, so you can pinpoint a window in the background, a dark wall, or a practical lamp shade and know how much over or underexposed that area will be compared to your shooting stop.

So let's say I want to save money. Can I salvage an old still camera like Nikon FM2N and put a telephoto lens on it to use as a spot meter?

I'm just curious, do you use either of these meters while shooting a relatively low profile, with digital camera, nowadays?

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2 hours ago, Satsuki Murashige said:

2. If you do this, then you will basically be replicating a wide angle reflected meter, which is a generalized exposure reading. The value of a spot meter is that it can read very narrow angles, so you can pinpoint a window in the background, a dark wall, or a practical lamp shade and know how much over or underexposed that area will be compared to your shooting stop.

Follow up: what if I walk close to my subject and point my incident meter TOWARDS the subject with the lumen sphere down? Will that simulate the function of a spot meter, sort of only taking the reading of the light reflected from the subject? (that is to say, there's no smoke or dust between the subject and the actor)

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25 minutes ago, Wendy Sanders McDonlad said:

I say the spot meter is more "accurate" in the sense it gives you the reflected light value instead of the amount of light falling onto it. For example, a black couch with velvet upholstery. If you light it from the incident reading it will be completely off, since the fabrics is not nearly as reflective.

If you take an incident reading of an area, the meter doesn’t take into account the subject at all. If you put that stop from the meter directly on the lens, your black couch will appear black. So in that sense, it will be a ‘more accurate’ (direct) reading. But if you want to know precisely how many stops under middle grey the black fabric will appear on film, then that is a function of the film stock and not the light, so the incident meter can’t tell you that.

On the other hand, a spot meter reading of the same black couch requires interpretation - should it be two stops darker than middle grey? Three stops? More? If you simply put the given stop on the lens, the back couch will appear 18 percent grey, which is definitely not accurate.

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3 minutes ago, Satsuki Murashige said:

If you take an incident reading of an area, the meter doesn’t take into account the subject at all. If you put that stop from the meter directly on the lens, your black couch will appear black. So in that sense, it will be a ‘more accurate’ (direct) reading. But if you want to know precisely how many stops under middle grey the black fabric will appear on film, then that is a function of the film stock and not the light, so the incident meter can’t tell you that.

On the other hand, a spot meter reading of the same black couch requires interpretation - should it be two stops darker than middle grey? Three stops? More? If you simply put the given stop on the lens, the back couch will appear 18 percent grey, which is definitely not accurate.

I'm even more confused with this black couch thing... let's say a black person's face then..

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30 minutes ago, Wendy Sanders McDonlad said:

I couldn't think of such case where i'm metering an area(air) where I can not get the actors/ stand in positioned there to get a more accurate reading, unless it's a stunt/action situation, in which case are you implying you only use incident meter in those rare occasions?

No body seems to answer my first question, that if spot meter will tell you more accurately how much light reflected off the subject, then why bother will an incident meter and calibrate the light absorbing/reflecting factors???

Think of it like this: the spot meter takes into account the perspective of the lens. You take a reading from the camera position, so essentially all of your readings are of a two dimensional space. This works great if you have a camera angle that doesn’t radically change perspective during a shot.

For example, a wide landscape shot with distant mountains and clouds - it’s much more convenient to take a spot meter reading from the camera position and meter the clouds so they don’t clip or burn out. Or an interior wide shot with bright windows and practical lamps. 

But actors and cameras move in three dimensional space. The closer the camera is to the subject, the more the light can change from moment to moment. Imagine a Steadicam tracking shot thru an underground tunnel with shafts of light filtering in thru overhead grating. The actor runs toward the camera thru smoke and light, with reflections bouncing up into their face from water below. You could have the actor or a stand-in stop every few feet to take a spot reading of their face. Or you could use an incident meter and walk the path of the actor, taking readings at every light source. In this case, the incident meter works better.

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7 minutes ago, Wendy Sanders McDonlad said:

I'm even more confused with this black couch thing... let's say a black person's face then..

Same thing. The incident meter doesn’t care what the subject is. It only reads the amount of light falling on the meter’s dome and gives a reading for proper exposure of an 18 percent grey card. A subject with darker skin will naturally appear darker if their tonality is under middle grey, which is what you want for accuracy. 

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3 minutes ago, Satsuki Murashige said:

You could have the actor or a stand-in stop every few feet to take a spot reading of their face. Or you could use an incident meter and walk the path of the actor, taking readings at every light source. In this case, the incident meter works better.

Why couldn't I walk with the actor and take continuous spot readings?

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36 minutes ago, Wendy Sanders McDonlad said:

1) Do you know what's the general focal lengths of the a spot meter?

I agree, it seems like to me nowadays this is what a light meter is designed for, given all the zebra/ histograms and other build in functions of the digital cameras. Am I correct?

It’s usually given in degrees of field of view. The most common spot meters are 1 degree, so very narrow.

Sure, you could say that most digital cameras have reflective meters built-in. Some also have spot functionality, where you can select a very small area of pixels and have it tell you how bright something is. What’s important to note is that these are all camera dependent measurements. So you couldn’t accurately use one camera type to spot meter, and then transfer that reading to another type of camera. 

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6 minutes ago, Wendy Sanders McDonlad said:

Why couldn't I walk with the actor and take continuous spot readings?

You could, although you need to take the camera perspective into account. A reflective reading is only valid from the camera perspective, because the light is reflecting off the subject and into the the lens. 

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Just now, Satsuki Murashige said:

You could, although you need to take the camera perspective into account. A reflective reading is only valid from the camera perspective, because the light is reflecting off the subject and into the the lens. 

Well, for a sophisticated sequence as we are referring to, I'll need a walk through with the cameras anyway....so i don't see the problem here....

It seems to me people arguing there's advantage in using an incident meter only when:

You can get a stand in, you can't take the camera there... LMAO

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Some DPs will carry a little grey card with their spot meter, and meter the card. At that point, you’ve effectively turned your spot meter into an incident meter. That’s what Barry Stone, csc did on my very first film job. Then of course, one day he forgot his grey card...

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4 minutes ago, Satsuki Murashige said:

Some DPs will carry a little grey card with their spot meter, and meter the card. At that point, you’ve effectively turned your spot meter into an incident meter. That’s what Barry Stone, csc did on my very first film job. Then of course, one day he forgot his grey card...

I guess I should have gotten a spot meter... anyone looking for a sekonic L358? hahah

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2 minutes ago, Wendy Sanders McDonlad said:

Well, for a sophisticated sequence as we are referring to, I'll need a walk through with the cameras anyway....so i don't see the problem here....

It seems to me people arguing there's advantage in using an incident meter only when:

You can get a stand in, you can't take the camera there... LMAO

It’s fine to use whatever you’re comfortable with. That’s what all of us do to start with. I started with a spot meter and took a few years to get comfortable trusting the incident meter. I’ve read some tricks that David Mullen shared on this forum about incident metering techniques and still scratch my head on how he was able to do that. I’d be lost in those situations without a spot meter, but I guess if you mostly rely on an incident meter you can figure it out. 

I think over time, you’ll run into situations where one method works better than the other. But you’ll have to discover that for yourself, as we all do. 

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1 minute ago, Satsuki Murashige said:

It’s fine to use whatever you’re comfortable with. That’s what all of us do to start with. I started with a spot meter and took a few years to get comfortable trusting the incident meter. I’ve read some tricks that David Mullen shared on this forum about incident metering techniques and still scratch my head on how he was able to do that. I’d be lost in those situations without a spot meter, but I guess if you mostly rely on an incident meter you can figure it out. 

I think over time, you’ll run into situations where one method works better than the other. But you’ll have to discover that for yourself, as we all do. 

very helpful... thank you

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I prefer an incident meter, some prefer a spot meter.  The main issue with spot meters is that every result has to be interpreted against how many stops you want to adjust from the reading, unless all your subjects are 18% grey.  It's almost too much information.  Let's say you have a wide shot of a room full of furniture, some dark, some light, lit by one giant window with soft skylight coming through... but obvious it is a wide shot so all those objects are in the frame.

You could take an incident reading where you want the "normal" brightness of light to be, maybe in the middle of the room. Then the bright and dark objects would all render "normal" in that level of light.  But take out your spot meter and then you'll find yourself either hunting for an object in that light close to 18% grey or taking out an 18% grey card, otherwise you'll be making judgement calls like "that tan couch is maybe 1-stop over 18% grey so I'll meter that and then open up one-stop..."

So if you are rushed and don't want to take a lot of spot meter readings and think about the relative values of everything, then an incident meter may be faster. Plus what happens when you get into coverage? With an incident meter reading, you can decide that the main light in the room falling on everything is f/2.8  -- so when you go in and light for coverage, you know you still might want the light to be f/2.8 on the subject. In other words, with an incident meter, you can set levels for the light falling into the room and then whatever walks into the room, etc. will be in that known level of light, and dark objects will look dark and light objects will look light, etc.

Where spot meters are useful, besides for self-illuminated objects like a sunset sky, a TV set screen, etc., is to check the extreme ends when you know from testing when something goes to black or to white, so if you want to hold texture in a hot curtain sheer, for example, you need a spot meter to read that.

But there are plenty of DPs and still photographers who are more comfortable with spot meter readings and have a whole system, some use an 18% grey card or the back of their hand as a known brightness level, etc.

As for digital, a meter is more useful in scouting and pre-lighting before a camera and monitor are set-up. Or when you have a steadicam move through multiple rooms of a house and you want the light hitting the actor to hit a certain level in each room -- with a meter, you don't need to keep dragging the camera around from room to room (though I often do that, if the Steadicam is parked on a rolling stand, I just have them drag it around, pan it around, etc. to check the exposure on the monitors at the DIT cart.) But some DPs have a system using meters to light and set exposure on digital, based on testing.

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When shooting dramatic scenes with coverage, exposure and contrast consistency from set-up to set-up can matter more than getting the exposure exactly right -- so while a spot meter can be more precise, it can be too precise, causing you to vary your exposures shot by shot, set-up by set-up, so individually each shot is correctly exposed perhaps but when cut together, you can see the exposures being "corrected" on each shot -- for example, if an actor is sweating in a scene and if their skin gets more shiny on some takes, the spot meter might tell you to stop down because the face is getting a stronger hot spot from the sweat. And again, in each set-up in a room, there may be different subjects and objects in that frame so it is simpler to decide what the light levels you want in each part of the room and then let the objects fall where they may when they move through that light.  So you might light a room where in the center under a chandelier, the light is one-stop overexposed based on an incident meter reading and then around the edges of the room, someone is two-stops underexposed. Then when you shoot coverage and if you have to do any relighting, you can start knowing what the levels were in the wide shot that you have to match to.

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