Helpful Posts Helpful Posts:  0
Results 1 to 4 of 4

Thread: How do you meter for incident light.

  1. #1
    arith's Avatar
    Join Date
    Sep 2009
    Location
    Burton on Trent, UK
    Posts
    4,789
    Real Name
    Steve

    How do you meter for incident light.

    I thought about getting an old hand held light meter until I saw the price and that old ones are unreliable. It is possible to buy a refurbished Weston Euromaster II for £79 but it isn't a spot meter.

    I know how to use a hand held light meter to measure reflected light very close to a model, because I've done all that, but I've never used one to measure incident light or know what to do with the reading.

    In the Weston handbook it states that you should fit the invercone and point the meter at the light source next to the model the sun it is going to be bright isn't it.

    I found the tutorial about metering very interesting:
    Partial and spot metering give the photographer far more control over the exposure than any of the other settings, but this also means that these is more difficult to use
    but think 'is' could be replaced by 'are' and a little bit said about how to meter incident light, I just realised why I've got a white card or at least found a use for it, and how difficult to meter in low light especially when the main light is directly ahead.

    Normally I just point the camera at the brightest thing I can see in frame and try to set that 1 .667 ev overexposed on spot, but it isn't easy finding the brightest spot and I usually find I'm overexposed after a standard S curve is applied.

    This is terribly bad for the first darkest image in a HDR because blown bits turn pink.

  2. #2

    Join Date
    Dec 2008
    Location
    New Zealand
    Posts
    17,662
    Real Name
    Have a guess :)

    Re: How do you meter for incident light.

    Quote Originally Posted by arith View Post
    I know how to use a hand held light meter to measure reflected light very close to a model, because I've done all that, but I've never used one to measure incident light or know what to do with the reading.
    You simply set the camera to whatever the meter tells you. The only difference between incident & reflected measurements is that you don't have to apply any kind of compensation to the incident measurement.

  3. #3
    rpcrowe's Avatar
    Join Date
    Jul 2008
    Location
    Southern California, USA
    Posts
    12,977
    Real Name
    Richard

    Re: How do you meter for incident light.

    The Weston Master (series) of meters could measure both incident light and reflected light. However, they were IMO better for reflected light. My first photoelectric exposure meter was a Weston Master II which calculated film speeds in Weston units which were forerunners to ASA units which preceded ISO. I would not necessarily choose a Weston Master (Series) meter if I wanted to work with incident light.

    I used a purely incident light meter for ascertaining my motion picture exposure. http://store.vintagepaperads.com/ser...e-Meter/Detail

    The Spectra was neat in that it had a set of slides which you could slip into the meter. Each slide was calibrated for a different ASA (now called ISO) level. I could read the f/stop for my motion picture exposure directly off the dial on the meter. I would send the meter back to the company at intervals and they would recalibrate the photo-electric cell (it didn't use batteries) and re-drill the slides to ensure accurate readings. However, that meant that each meter had a set of slides specific to that meter. The slides were not interchangeable. A supply guy in our Combat Camera Group, once stored the unit's meters in one box and the slides in another case. That really caused some problems because the slides needed to be kept with the individual meters or identified to which meter each set belonged. I was not bothered by this because I owned my meter rather than trusting The Navy issued meters. BTW: $97.50 (U.S. Dollars) was pretty expensive for a meter in the late 1950's and early 1960's but, well worth the cost.


    My present "oldie-but-goodie" Sekonic Digimaster L-718 meter has been around for a long time. It doesn't have the bells and whistles of the newer Sekonic meters but can measure incident ambient light, reflected light (including limited spot metering) and flash as well as the newer meters can.

    In a nutshell, incident meters measure the light which is falling on a subject and reflected light meters measure what they say they do, measure the light reflected back from a subject. You basically point an incident meter toward the light source and point the reflected light meter at the subject.

    With all meters, the readings are simply guides, although they are pretty accurate guides; the readings need to be filtered though the "gray matter meter" that lies between the photographer's ears.

    As an example with a reflected meter, you need to increase exposure when shooting white subjects like snow because without additional exposure, the meter will give you a reading which will turn out about 18% gray rather than a clean white. Conversely, you need to decrease the exposure for a black cat in a coal bin because the metered exposure will turn out gray rather than black.

    You do the reverse with an incident meter; increase for darker subjects and decrease for lighter subjects because the meter is telling you what the exposure should be for 18% gray subjects, not the highly reflective bright snow or the black cat with virtually no reflectance.

    If light is the river from which photographer's drink, exposure meters are the measuring cups that photographers dip into that river to get their drinks....
    Last edited by rpcrowe; 24th February 2011 at 04:53 AM.

  4. #4
    arith's Avatar
    Join Date
    Sep 2009
    Location
    Burton on Trent, UK
    Posts
    4,789
    Real Name
    Steve

    Re: How do you meter for incident light.

    If light is the river from which photographer's drink, exposure meters are the measuring cups that photographers dip into that river to get their drinks....
    Cheers Richard and Colin, that is a great quote and very useful.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •