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Light meter readings
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PostPosted: Thu Feb 14, 2008 11:03 pm    Post subject: Light meter readings Reply with quote
With incidental light readings I am not sure where you should be pointing the meter. take the following examples X is the subject with the sun in positions A B and C (and there's me, minus a few pounds with my Kowa!)




I have read that you point the domed incident light meter at the camera
With the sun behind the camera A I can see how that would hold true

But hwen the sun is in position B and C surely pointing the dome at the camera is going to result in shadow falling on the dome and a false reading? Or do you point the meter at the light source? (2 and 3)
Confused Confused


PostPosted: Thu Feb 14, 2008 11:35 pm    Post subject: Reply with quote
With the dome on, you stand where the subject is and face the camera, so you're reading the actual light that's falling on the subject and being reflected towards the camera.
Without the dome on, you simply act as the camera.

http://www.luminous-landscape.com/tutorials/meters.shtml#A%20Tutorial%20on%20Incident%20Metering


PostPosted: Thu Feb 14, 2008 11:54 pm    Post subject: Reply with quote
Yes I can see that but if the light source is behind the subject (ie C) and you point at the camera then the dome will be in the shadow of the meter. Is that still how you would meter it?


PostPosted: Fri Feb 15, 2008 12:08 am    Post subject: Reply with quote
Bob,

it is totally irrelevant if the light cell is under the shadow of the meter body: whatever happens behind it, shadow or whatever else, does not matter to it. Because, the whole point of using this type of metering is to get rid of the object-related problems in the metering - and this includes shadows, together with colours, reflections, refractions, etc.

If you prefer you can simplify it that way: when doing incident light metering, the object (and the light meter that takes its place) does not exist.

-


PostPosted: Fri Feb 15, 2008 12:59 am    Post subject: Reply with quote
Or, you can think of it as a big old mixing bowl of light...it's all mixed together when you take an incident reading. So, Orio is showing a good analogy, that you don't have to worry if the meter is in light or shade...the dome is simply reading the whole "mix" of colors in the bowl.


PostPosted: Fri Feb 15, 2008 3:32 am    Post subject: Reply with quote
Laurence wrote:
Or, you can think of it as a big old mixing bowl of light...it's all mixed together when you take an incident reading. So, Orio is showing a good analogy, that you don't have to worry if the meter is in light or shade...the dome is simply reading the whole "mix" of colors in the bowl.


Actually the point is that, when you are going to photograph a bowl, the light meter becomes the bowl.
It's like the bowl had eyes and could read the light around it self (in the viewing angle of the light meter of course)

Direct metering: the meter measures the light reflected from the bowl

Indirect (incident) metering: the meter becomes the bowl and measures the light around it self within the limit of its viewing angle.


PostPosted: Fri Feb 15, 2008 3:44 am    Post subject: Reply with quote
Orio wrote:
Laurence wrote:
Or, you can think of it as a big old mixing bowl of light...it's all mixed together when you take an incident reading. So, Orio is showing a good analogy, that you don't have to worry if the meter is in light or shade...the dome is simply reading the whole "mix" of colors in the bowl.


Actually the point is that, when you are going to photograph a bowl, the light meter becomes the bowl.
It's like the bowl had eyes and could read the light around it self (in the viewing angle of the light meter of course)

Direct metering: the meter measures the light reflected from the bowl

Indirect (incident) metering: the meter becomes the bowl and measures the light around it self within the limit of its viewing angle.


You NAILED it! Perfect explanation. Smile


PostPosted: Fri Feb 15, 2008 4:04 am    Post subject: Reply with quote
hacksawbob wrote:
Yes I can see that but if the light source is behind the subject (ie C) and you point at the camera then the dome will be in the shadow of the meter. Is that still how you would meter it?


If the subject was big enough, yes, for you would be wanting to expose for the front of the subject anyway, which would be in shadow too.
I've found that no meter is 100% foolproof - well they are; they prove that we are fools a lot of the time- but it's really just getting familiar with it and realising that the LM gives a guide, a starting point, not necessarily a hard and fast rule. The more you use it, the better it gets Wink
That's the magical thing about digital, you can click away while learning the use of the LM and it's not cost a bean. It's bloody expensive doing the same with film.


PostPosted: Fri Feb 15, 2008 9:05 am    Post subject: Reply with quote
Farside wrote:

I've found that no meter is 100% foolproof


I know that many expert support the indirect (incident) metering.
However, for most practical uses, I found it unnecessarily awkward.
Not always we have the time or the physical possibility to reach the point of our target to do the metering. Try to do that when photographing a mountain top, for instance. Or a horse race.
Yes, we can make approximation, if we are standing on a place that more or less receives the same amount of light than the target area. But in that case, a compromise is a compromise, so it's easier just to make another kind of compromise, that is faster.
If a photographer is an average experienced one, he can just go with direct metering. In front of a landscape, for instance, he will know where to meter in order to obtain a good average, even if he does not want to make a full average sample number of 4-5 meterings like they teach you.
I personally do not even do that, and prefer to make a simple "grey card substitute" metering my measuring the light reflected from the palm of my hand, placing in in a sunny or shade position depending if in my target image the sunny or shade parts are more important - or sometimes measuring both and averaging. This might not be the most scientifical way, but I rarely (if ever) missed a shot this way. This is an especially useful way when you are shooting live events, where people might move fast from sunlight to shade. You set the camera to manual mode, choose a needed time (in my case it's 1/250), make an average metering on the palm of the hands, then go with it, in mid day you are usually able to go on with it quite some time before you readjust. Near sunrise or sunset you need of course to readjust much often.
There are, lastly, cases, like closeup photographing, especially of bright subjects over dark backgrounds (like bright flowers), where you really need to do a spot metering and no other metering is really enough accurate.


PostPosted: Fri Feb 15, 2008 10:59 am    Post subject: Reply with quote
Orio wrote:
I know that many expert support the indirect (incident) metering. However, for most practical uses, I found it unnecessarily awkward....


Absolutely - me too!

Bob, with the sun in position C on your sketch, taking a direct meter reading from the camera position will compensate for the sunlight, resulting in the subject being under-exposed. The same happens with, say, a shot of someone skiing with snow in the background. The reverse can happen when you shoot a bride in a white dress against a dark background. The meter will over-expose the dress because it's trying to pick up detail in the shadows. Incident metering measures the light falling onto the subject, not reflected from it, so in the backlit situation pointing the dome at the sun would also result in underexposure of the subject. The camera will see only the shadow side of the subject, so you need to measure the shadows.

However, incident metering is not precise - it takes a more general reading. Unless you're using a spot meter, the best way to ensure you get the exposure you want in either case is to go right up close to the subject and measure only the reflected light, excluding as much of the background as possible.


PostPosted: Fri Feb 15, 2008 11:02 am    Post subject: Reply with quote
Thanks for that explanation, I'll give it a try. I have been spot-metering at the moment and guessing on a balance.

Next question?

Can I use my digital to provide a Polaroid type metering of the scene, will I need to use the same focal length lens presumably?


PostPosted: Fri Feb 15, 2008 11:21 am    Post subject: Reply with quote
hacksawbob wrote:
Can I use my digital to provide a Polaroid type metering of the scene, will I need to use the same focal length lens presumably?


Yes, many people use their digicams for metering. I don't trust mine a lot though Shocked I agree with what Dave said, the best way to get the feel of using the hand-held meter is to take a reading of a shot from the camera position, set your lens aperture and ther ISO and shutter speed on your DSLR (in manual mode) according to the light meter, and see how the picture turns out. Take hundreds of shots if necessary, it's cheap!! Smile


PostPosted: Fri Feb 15, 2008 12:13 pm    Post subject: Reply with quote
Here's a very helpful page about using lightmeters from Kodak:
http://www.kodak.com/cluster/global/en/consumer/products/techInfo/af9/index.shtml


PostPosted: Fri Feb 15, 2008 2:12 pm    Post subject: Reply with quote
Orio wrote:
I personally do not even do that, and prefer to make a simple "grey card substitute" metering my measuring the light reflected from the palm of my hand, placing in in a sunny or shade position depending if in my target image the sunny or shade parts are more important - or sometimes measuring both and averaging. This might not be the most scientifical way, but I rarely (if ever) missed a shot this way. This is an especially useful way when you are shooting live events, where people might move fast from sunlight to shade. You set the camera to manual mode, choose a needed time (in my case it's 1/250), make an average metering on the palm of the hands, then go with it, in mid day you are usually able to go on with it quite some time before you readjust. Near sunrise or sunset you need of course to readjust much often.


I used to do that a lot and it worked very well indeed.


PostPosted: Fri Feb 15, 2008 6:48 pm    Post subject: Reply with quote
Today I tried both metering methods reflective and incidental, my incedental readings always seemed much lower (less light) than my reflective.
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