Incident light meters question
So, I know that incident meters measure the light falling on a subject, but I would like to know how they arrive at an exposure recommendation. I have always used center weighted reflected light meters in my cameras and know that I can measure an area of the subject and adjust upward or downward depending on whether I'm exposing for the highlights or the shadows. I am in a position where I need a meter to use with an unmetered camera and it seems that most affordable hand held meters are incident meters. So, what does the reading tell you? Does it simply tell you what exposure is needed for a middle gray based on the falling light? Also, any recommendations for something under $200, new or used, and not too large? Thanks.
I just got a Gossen Lunasix F incident/flash meter for $50. Nice size dome, works very well.
Just put the white dome across the sensor, hold in in the same light, optionally pointing towards the camera from the subject, and take a reading. Put that in your camera and shoot!
My understanding is that an incident light meter gives you a reading approximately equal to a gray card reflectance of the light falling on the subject (and thus the range between the highlights and shadows is ignored). Works great in most situations, but it still helps to know the contrast range.
My favorite meter is the Sekonic L-308s (or any of the previous versions). It's a digital meter; a new one is within your price range. It takes 1 AA battery, will do incident or reflected for ambient or flash and is about the size of a cell phone. The ISO and aperture range of this meter is outside anything most of us are likely to use.
“For me, the camera is a sketch book, an instrument of intuition and spontaneity.”
― Henri Cartier-Bresson
An incident meter has nothing to do with the subject. It has no idea what the subject is, because it doesn't look at it. It tells you how much light is FALLING ON the subject, not how much is reflected by it. But WE know that dark subjects will reflect less light than white subjects. And we know that the subject contrast range is rarely less than 7 stops. So for the vast majority of scenes, all you have to do is meter the ambient light, which is what an incident meter does. Dark subjects will be dark and light subjects will be light. You only need to worry if you know that the brightness range is going to exceed the range that your film is capable of capturing. In that case, you will have to choose whether to lose highlight or shadow detail, and that depends upon the film you are shooting. These situations are more accurately metered with a spot meter rather than incident. But with experience, you will usually know whether and how much to adjust your exposure. All others should bracket.
An incident meter measures existing light that is falling from the light source itself, regardless of what light levels are being reflected off of the things within your composition. If you know this, and know your film speed, then you can suggest an exposure that will make a grey card grey. That is all that an incident meter does. Where other tones fall on your negative in relation to the grey card will depend on how many times more or less light than middle grey they reflect, combined with the contrast of your film. If you know through experience that your film with normal exposure and development will not render the range of luminances within the composition in the way you would like, you can tweak exposure and development to manipulate the way your film behaves.
If I had to use only one meter, it would be an incident meter. They are almost 100% idiot proof, and give far more practically useful information than a reflected meter in most circumstances, IMO. If I have time, however, I use an incident meter and a spot meter (which measures reflected light) together. When I do this, I only really use the spot meter to measure luminance range, or luminances of certain objects in relation to middle grey, not to actually decide an exposure.
Last edited by 2F/2F; 12-21-2009 at 07:46 AM. Click to view previous post history.
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I suggest reading the incident meter technique outlined by Phil Davis in his Beyond the Zone System book. It describes an advanced method to set exposure and determine subject brightness range (SBR) for subsequent development time.
When you are using an incident meter, don't forget that most subjects receive light from more than one direction. In many cases, subjects receive light from more than one source.
It can be very useful to take more than one incident reading. As an example, for a subject that receives most of it's illumination from a window, as well as additional light reflecting off an adjacent wall, a reading that measures the general highlight illumination (window plus wall reflected light, plus a reading of the light that is hitting the parts of the subject in shadow (wall reflected light only), will give you lots of useful information about contrast and character of your resulting photograph.
You must live on a planet of a binary star system...
Originally Posted by MattKing
(joking! joking! Your explanation was relevant.)
Gosh, I don't see where anyone mentioned that the incident meter works from the subject pointed toward the camera. You are actually measuring the light that illuminates the subject from the direction from which the camera sees it. Of course, if you are in the same light as the subject lit by a distant light source, like the sun or sky, you can be at the camera position and point the meter away from the subject, preferably along the axis passing through the subject and the camera.
If you are at the camera pointing the incident light toward the subject, you may be doing a good job of measuring the illumination on the backside of the subject, away from and invisible to the camera. Most of us wouldn't generally want to do that.
Using a reflected light meter, such as the one in the camera, you can replicate the incident meter's function by holding your hand in front of the camera, palm facing the lens and parallel to the film plane. Be careful not to cast a shadow on it and entirely fill the frame with the palm. Doesn't have to be in focus; better to leave the focus where the subject requires to avoid extension errors. Take the reading the camera gives you and add one stop. That is, if it's f/11, give f/8, etc.
It doesn't matter whether you are racially puce, blue, pink, or green. Palms are remarkably consistent regardless.
For all the zone system stuff he promoted, Minor White could often be seen taking readings like this.
Edit: Looking again, I see that Chris, above, mentioned taking the reading from the position of the subject.
I used to meter the palm of my hand with a Weston before I found a dome for it. Worked fine as long as I remembered to take my glove off... It is also useful to have a white card around for low light conditions. The correction is more than one stop, and a quick test will tell you how much. It does help with meter sensitivity, especially if, like most selenium cells, the low end tends to be optimistic.
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