Light metering

oblivion

oblivion

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Richard
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I have just purchased a sekonic light meter and watched a video explaining to me that I should be metering the light source and not pointing it towards the camera. Yet every other video says to point it at the camera? Talk about confusing. Can I have your thoughts please. If you want to see the video it's http://youtu.be/f3CTJJ2uVyg if that doesn't work search for frank doorhof light meter youtube
 
There have been various threads on this, if you search.
Basically you point it at the camera, assuming that the flash isn't behind the subject. If it is, you point it at the light.

Assuming that your meter has a semi-circular sensor cover (rather than one of the flat ones designed for photographing flat subjects) it can be a bit theoretical sometimes, as the 90 degree acceptance angle of the receptor tends to even out errors.
 
See already I'm getting different answers lol !!


I kind of understood it when the video explained that using the lights covers all stops especially when you move the light around to the side of the subject, the. I got lost and thought I would just practice both and see what results I get
 
Check out the sekonic website , there's some good tutorials on there .
 
Yep have a play and see what works best for you, is the best way, always more than 1 way to skin a cat :)
 
Depends what you want to measure;

- Sum total of the light falling on the subject as seen by the camera, then point toward the camera.
- Ratio between lights then point at the lights to check individual levels, then point at the camera to get the sum total.
- Single light source in-front pointing toward the subject, then I'd suggest it probably won't make much difference either way with a 180 degree receptor (as long as your body isn't in the way, number of times I've seen people meter stood between the subject and light source:p).
- at the background, pointing toward the camera, though I have been know to use reflected as opposed to incident readings as I sometimes can't get to the background.
- Measure the effects light pointing at (but behind) the subject, then at the light, but you'd want to balance that with the light falling on the front of the subject, so then at the camera...

...and on & on & on it goes and with anything but the simplest lighting set-up it depends on the set-up, the effect you're trying to achieve. But to be honest over 95% of the time I will end up pointing the meter at the camera, but then I've been using a meter for over thirty years and in the good old film days you tended to learn lessons quickly, even with a Polaroid back to help out film and processing was never cheap. ;)

Paul
 
paul williams said:
Depends what you want to measure;

- Sum total of the light falling on the subject as seen by the camera, then point toward the camera.
- Ratio between lights then point at the lights to check individual levels, then point at the camera to get the sum total.
- Single light source in-front pointing toward the subject, then I'd suggest it probably won't make much difference either way with a 180 degree receptor (as long as your body isn't in the way, number of times I've seen people meter stood between the subject and light source:p).
- at the background, pointing toward the camera, though I have been know to use reflected as opposed to incident readings as I sometimes can't get to the background.
- Measure the effects light pointing at (but behind) the subject, then at the light, but you'd want to balance that with the light falling on the front of the subject, so then at the camera...

...and on & on & on it goes and with anything but the simplest lighting set-up it depends on the set-up, the effect you're trying to achieve. But to be honest over 95% of the time I will end up pointing the meter at the camera, but then I've been using a meter for over thirty years and in the good old film days you tended to learn lessons quickly, even with a Polaroid back to help out film and processing was never cheap. ;)

Paul
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^^^As above in bold.

Light meters are brilliant for setting up ratios, but for the most accurate final exposure setting, check the LCD and histogram, with blinkies enabled.

That is the most accurate method, because it shows you exactly what is actually recorded on the sensor. The meter reading can often be quite a long way different, because there can be a number of variables happening after the light enters the lens that it cannot know about*.

That's one thing, and the other is you may want to adjust settings for 'optimum' exposure (decided by you) rather than technically 'correct' exposure.

* Sensor and ISO calibration, t/stop vs f/number, actual f/number setting not accurate.
 
There IS no definitive way. It depends on where your lights are and what you want. Let's say for instance, you have one light, and it's off to one side and you want to literally split someone's face down the middle from light to dark, then you would meter towards the light. If you metered towards the camera, the lit side will probably be very over exposed because the meter will be mainly seeing the ambient light and the dark side of the face will be relatively well exposed... which was not what you wanted.

If you have a more conventional set up with maybe one light and a reflector, and the light is falling mainly on the subject from the front, then I'd meter towards the camera.

If I had two or more lights I'd meter them separately to establish what the ratio is between them, then meter towards the camera to get an aggregate reading, then decide from experience where I expose between the two.

If you want it backlit then meter towards the light.

As for checking the screen and histogram, sure, but if you get practised enough with a meter you really don't need to. If you know your lighting ratios then you know how much contrast you have. Those of us who shoot on film will tell you that your histogram will not be telling you anything your meter hasn't already told you if you are using it properly.
 
norrisphysio said:
I use a 308s and point it at the camera. Set iso and shutter speed (I use f8 and 125). Flash stobes and adjust accordingly. That's what I have been taught, so assumed I was doing it correctly.
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I also do this that the way i told when i first started taking pictures in a studio,but others may not but it works for me ;)

All the best, Ian
 
Ian White said:
I also do this that the way i told when i first started taking pictures in a studio,but others may not but it works for me ;)

All the best, Ian
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So what if you have dramatically side lit the subject with one light.. still meter to the camera? Backlit? Still meter to the camera?
 
Wow, that was a long read and very heated in parts. I do have one question that was raised but I either skim read the answer or couldn't find it. If I have a simple two light soft box set up both angled towards the subject, meter toward the lights, first one gives f16 and other say f18 then what am I to choose? Someone mentioned a ratio but I got lost? Should I Meter toward the camera then it only gives me one reading and I use that without any issues. I'm beginning to wish I never asked now but I would like to understand which numbers to use (if I chose the first option). Someone did mention a black girl, Asian girl and white girl and all metered different numbers, but can someone explain in laymans terms how I then come to a correct exposure from the three readings given ? I promise I will never raise this debate again
 
oblivion said:
Wow, that was a long read and very heated in parts. I do have one question that was raised but I either skim read the answer or couldn't find it. If I have a simple two light soft box set up both angled towards the subject, meter toward the lights, first one gives f16 and other say f18 then what am I to choose? Someone mentioned a ratio but I got lost? Should I Meter toward the camera then it only gives me one reading and I use that without any issues. I'm beginning to wish I never asked now but I would like to understand which numbers to use (if I chose the first option).
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Please check the link to another thread I gave above, it could save a lot of trouble.

I've also given the ultimate answer, which is to check the LCD, histogram, and be sure to enable blinkies. It's far more reliable than any meter reading.

Someone did mention a black girl, Asian girl and white girl and all metered different numbers, but can someone explain in laymans terms how I then come to a correct exposure from the three readings given ? I promise I will never raise this debate again
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They would all meter the same if you take an incident reading - that's the whole point of it. And that would give you 'correct' exposure that should always put mid-grey in the subject in the middle of the sensor's dynamic range, ie in the middle of the histogram.

That may not be optimum exposure though, and you may want to moderate it accordingly. Basically Expose To The Right (of the histogram) technique.

Bottom line: use a meter to set up lights and adjust balance/ratios, then refer to the histogram etc for final exposure setting. You will then have all the information you need, and will be using each tool in the most efficient manner.
 
f/18 when read by a flash meter indicates half a stop more light than f/16. Therefore, if you have two lights, one either side of the camera and pointing towards the subject, fitted with an identical modifier to each and at an identical distance (not a lighting arrangement I'd be likely to favour but there you go...) the one that is reading f/18 has been set to half a stop more power than the one that's reading f/16.

Depending on the angle of the lights, each light could be lighting both sides of the face or just one. If you meter from the side nearest the flash towards the flash using a flat receptor then the resultant reading will be an accurate measurement of the light reaching that side of the face, it will only read the quantity of light from that flash because it cannot 'see' the light from the other flash. If you measure using a dome reflector then the reading may be different, because it may also see the flash from the other head (depending on angle).

So, if you measure each flash in turn, the theoretical reading of f/16 and f/18 indicates that you have a ratio of 3:2 (assuming that each flash is lighting only the side nearest to it) if knowing what the ratio is matters to you...

But that doesn't tell you the theoretically 'correct' exposure. To get that, simply point the meter at the camera. Given that you are using 2 flash heads, both of which are in front of the subject, and both of which are outputting very similar quantities of light, the reading to camera will be very similar to a compromise of the reading from each flash head. It probably won't matter in this case.

It's when lighting is more creative, or when the subject is very reflective, that the difference in results between metering to the light and metering to the camera becomes more important.
 
Oh yes, I forgot the skin colour thing - it makes no difference when metering incident light (light incident upon [reaching] the subject). And if you want to portray those skin tones accurately, you wouldn't 'adjust' the aperture setting to compensate for different skin colours or tones.
 
There is a lot of noise here, but essentially whatever route you choose, you need to interpret things to suit what you are shooting and how you want it to look. there is no substitute for experience here

If you are shooting a whole range of things, on the same background, same camera position, and you want to make a faithful reproduction of the tone and colour from shot to shot, then a towards the camera reading is often the best starting point

The issue with histogram readings, and the "shoot to the right" philosophy is that they are subject agnostic. if you are shooting a low key portrait of a black man on a dark background, the histogram isn't going to he,p you get the nuances of the skin tones nailed.. for that you need experience. Equally, if you are shooting a pale bride on a white background, the histogram is only of partial use

Light meters are incredibly useful for checking the consistency of lighting (between point A and Point B) and the ratio of lighting. A light-meter doesn't know the dynamic range of your film or sensor, or what you had in mind for the shot. this is where, sitting down with the meter, a range of subjects, and a notepad pays you back in spades
 
Richard King said:
There is a lot of noise here, but essentially whatever route you choose, you need to interpret things to suit what you are shooting and how you want it to look. there is no substitute for experience here

If you are shooting a whole range of things, on the same background, same camera position, and you want to make a faithful reproduction of the tone and colour from shot to shot, then a towards the camera reading is often the best starting point

The issue with histogram readings, and the "shoot to the right" philosophy is that they are subject agnostic. if you are shooting a low key portrait of a black man on a dark background, the histogram isn't going to he,p you get the nuances of the skin tones nailed.. for that you need experience. Equally, if you are shooting a pale bride on a white background, the histogram is only of partial use

Light meters are incredibly useful for checking the consistency of lighting (between point A and Point B) and the ratio of lighting. A light-meter doesn't know the dynamic range of your film or sensor, or what you had in mind for the shot. this is where, sitting down with the meter, a range of subjects, and a notepad pays you back in spades
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That's it isn't it. There is no such thing as perfect exposure, measured in a certain way, every time.

Though it's very easy to get pretty damn close, with a very safe and usable exposure 99% of the time. In this case, incident reading from subject position, facing camera - job done.
 
Meter towards the light source..... I don't understand why you would do anything else?:wacky:
 
Safe doesn't equal the correct exposure. And there is a correct exposure for every image based on what the photographer is looking for. If you're using ratios you can't upset that by getting a mid exposure pointing towards the camera.

I know it's going over old ground.
 
EOS_JD said:
Safe doesn't equal the correct exposure. And there is a correct exposure for every image based on what the photographer is looking for. If you're using ratios you can't upset that by getting a mid exposure pointing towards the camera.

I know it's going over old ground.
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'Correct' exposure is when mid-grey in the subject is represented as mid-grey on the sensor - in the middle of the histogram, at standard JPEG output. That's not the same as optimum exposure, and I never said it was.

Have you read the other thread, and this one?
 
:bang: This thread is dead :bang:

It will now be (should be) obvious to all (from this and the other thread) that there isn't a single definitive answer and the meter is merely a tool and it is just down to the user to learn how best to use it, or how they prefer to use it, to get the results they want...

Paul

thread 'unsubscribed' :)
 
Look at sekoniks videos. Meter to the lights.
 
Kind of yes but no one has given me a simple answer to the below,
Example:
If the key light was metered at f16, fill light at f18 and towards the camera it was f8. Am I suppose to make both key and fill the same value. I keep hearing the word ratio being mentioned but not being good at math it means nothing to me. Surely whatever the key and fill come out at its irrelevant as I end up using whatever value the meter says whilst pointing to the camera. This is my confusion, ratios etc....it's all new to me and the manuals expect me to understand but I don't
 
oblivion said:
Kind of yes but no one has given me a simple answer to the below,
Example:
If the key light was metered at f16, fill light at f18 and towards the camera it was f8. Am I suppose to make both key and fill the same value. I keep hearing the word ratio being mentioned but not being good at math it means nothing to me. Surely whatever the key and fill come out at its irrelevant as I end up using whatever value the meter says whilst pointing to the camera. This is my confusion, ratios etc....it's all new to me and the manuals expect me to understand but I don't
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Let's see if we can get onto the same page, before we go into detail...

What you're talking about isn't in fact a key and a fill. What you're talking about is a separate light each side of the subject, as per crap magazines, crap youtube videos and crap photographers in general - that's 2 separate suns, which never looks right because on my planet, there is just the one sun.

That lighting arrangement is very popular with event photographers because it's close to being the only one that actually works for them, given their time constraints.But for other people, it's a very poor choice unless the subject has an extremely long, thin face that needs to be fattened by lighting both sides of it. Everyone else just ends up looking fat.

Generally, true fill lights go in only one of two possible places. Either where the lens is (on axis fill) or, if the subject isn't looking directly towards the camera, directly in front of where the subject is facing.

This is relevant to your question because when there is a true fill light the subject is lit by at least two lights, the key light and the fill. When it's a light each side, each part of (say) the face is lit separately and it's unlikely that light from one side will light the other side of the face. This affects the lighting ratio, if ratio is important to you.

Some people like to know what the lighting ratio is, for a very good reason; they may want the hardest possible lighting (highest possible ratio) that will provide detail in both the highlights and the deepest shadows - if they know, for example, that their digital sensor or film can cope with x stops difference, then they may want to set a ratio that uses all of that capacity. Or they may just feel that a ratio of y is a good choice - personally I feel that the latter is about as creative as painting by numbers, my own preferred method is to place the key light where it creates the effect needed and then, but only if necessary, to add a fill light, set at the lowest possible power setting. I then take a shot, and then adjust the strength of the fill light gradually, testing all the time, until I'm happy with the end result. To me, if it looks right, it is right, and the ratio is irrelevant.

Work out the ratio roughly like this.
If different parts of the subject are each being lit by just one light, if the light on say the right reads f/11 and the light on the left reads f/8 then that's a lighting difference of 1 stop or 100% and the ratio is therefore 2:1.
If the light on the right reads say f/11 and the light on the left reads f/4 then that's a difference of 3 stops and the ratio is 8:1.
With a true fill light, if the light on the right reads f/11 and the light from the fill position reads f/8 then that isn't a stop of difference, because the light from the fill light will illuminate the highlight areas as well as the shadow areas, so the ratio will be 3:2, not 2:1
 
oblivion said:
Kind of yes but no one has given me a simple answer to the below,
Example:
If the key light was metered at f16, fill light at f18 and towards the camera it was f8. Am I suppose to make both key and fill the same value. I keep hearing the word ratio being mentioned but not being good at math it means nothing to me. Surely whatever the key and fill come out at its irrelevant as I end up using whatever value the meter says whilst pointing to the camera. This is my confusion, ratios etc....it's all new to me and the manuals expect me to understand but I don't
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I will explain this in 3 parts

1. from a purely technical "Camera operator" POV, you are interested in how much light is "possibly" heading towards the camera. i..e. the illumination from the camera's point of view). How much light actually ends up headding towards the camera, depends on the subject. You are metering illumination, not reflection. Since (if you point the meter towards a light, or the camera), you are ignoring how reflective the subject is, in theory, if you take this meter reading, a dark object will look dark, a light object will look light, and a medium tone object will look medium toned. This method takes no account of the subject shape or colour or reflectivity, it only gives you the "averaged" amount of lighting. This is a very useful measurement, as from shot to shot, things will look approximately OK, and you can also reproduce the overall level of lighting from shoot to shoot and shot to shot

2. The ratio of lighting is literally as simple as this example: light a is twice as bright a light B, so the ratio is 2:1 (bright is a crap word to use here but it works

3. On a shoot, you use the ratio's to get the overall feel of the shot right. the ratio's are useful for remembering and setting the shot up each time.. Sometimes (say if you are outdoors in the sun), you cant change the power of one of the lights (the sun), so you alter the flash head you are using to get the right ratio. In all cases, you then need to set the overall exposure right in the camera, and you do that by pointing the meter towards the camera

In optics / photography there are a couple of principles you need to get under your belt
A. reversibility of light in a system
B ISL (Inverse squared law)
C. that the power of reflective light Vs distance

A. reversibility of light in a system... Imagine a mirror, and a laser. fire the laser in at 45 degrees, expect to get a beam of light back out at 45 degrees. move the laser to the other side (where it made the dot on the wall), and point it back at the mirror, expect the laser to fire a beam straight back where the laser was before you moved it

Bigger light sources spread light about all over the house, this means that the only true measurement you can make that is relevant is the amount of light that heads towards the camera. However, if you drew it as a diagram, you will see that the light is reflected from the subject (which inst normally flat like a mirror, and heads off in all directions)

This is why we use the towards the camera reading, because it directly correlates with the 180 degrees opisite reading of "how much light is landing on the subject" regardless of if the light source is the sun, a huge soft-box, or a tightly gridded snoot, or regardless of how many light sources there were. It is the only easy to measure relevant reading

B. ISL law

for a point source of light, the power diminishes over a distance according to the inverse squared law (google it) . In practical terms, this means that in a small studio, moving the distance of a light a little bit has a fairly big impact on how much light energy hits the subject.

C. Reflected light does not change power over distance - so in essence. Iif I meter a bride and get F8 at her face (pointing towards the camera), I can walk 10 feet, or 100 feet away, and the camera setting still needs to be F8

Equally, if I metered in front of the grooms black suit, or the white dress, the reading would still be f8 under the same lighting conditions

This is exactly why the "towards the camera reading" is so relevant as a starting point for deciding what to set your camera for

In a nutshell - set your lights up in a a"ratio" that looks nice / has the look you were looking for, and then meter towards the camera, and use that as your base setting. Experience will then tell you if you need to alter the exposure you then choose to push the look you are after one way or the other
 
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alexam said:
Take a look at the is video by Mark Wallace, talking about setting up and using light meters.

http://www.youtube.com/watch?v=NfKzY4wMixQ

Hope it helps you.

Malcolm
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So he meters at f8 pointing at the camera? Then he meters the main independantly at f10??!! Surely then shooting at f8 he will OVER expose the setting. he should set it to f10.
 
Hi Richard (Oblivion)

Take all the lights away bar one.......do that and then shoot photographs with it in different positions, taking two shots of each set up, one pointing the meter at the subject and then one at the camera, then study the results.

Now introduce a second light. Lets assume you are using the lights in manual mode. Why would you introduce a second light......in the first example the one light was the main light of course but maybe there was one position you had that light that over all gave nice lighting but there were shadows that you did not like so the job of the second light is to soften those shadows. Of course you might prefer to use a reflector instead of a second light but lets go for the light and call it the fill light.

You do not want the second light to over power the first light so you set it to half power maybe. To confirm all is well you then use a meter....experiment again........and so with back lights and hair lights etc etc.

Remember, different things control the amount of light hitting a subject......power of flash, distance flash is to camera, reflector used etc.

Experiment and you will soon work out what gives the best result for you.


stew
 
EOS_JD said:
So he meters at f8 pointing at the camera? Then he meters the main independantly at f10??!! Surely then shooting at f8 he will OVER expose the setting. he should set it to f10.
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No, he is metering to the camera, not what he metered from the light to the model, which was at a slight angle. Look again.

Malcolm
 
So he sets to f8 metering to the camera yet from model position the main light is f10.... So if he uses f8 the face will be over exposed as it's getting 2/3rd more light than the aperture he's using??!
 
Logically, if the light was at the same angle as the camera, the setting would be the same. If the light is slightly off that angle, then the light going to the camera will be reduced. Think of it this way......... if you put the light at right angles to the model and metered the light directly, do you thing the light reaching the camera at 90* would be the same. The answer is no, it will be lower. That's why if you meter to the light and set the camera the same, you could be underexposed. Always set the camer metered to the camera not the light.
 
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