light meter

Discussion in '35mm Cameras and Accessories' started by petefox, May 24, 2006.

  1. petefox

    petefox Member

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    Hi all
    I am new here and think this site is the cats whiskers. I hope you can help me. I am new to photography and still learning. I was out with a buddy a couple of days ago and he gave me his light meter to use. I took some readings but I did'nt know what to do with them . I was too embarressed to ask. I hope you guys can help, I know this is basic stuff but it would clear up a lot.
    If I take a meter reading in bright sunshine am I right to assume that the reading given refers to a medium grey? And if I meter in the shadows any reading will give me the same medium grey reading? Am I making sense?
    Appreciate all replies. Pete
     
  2. htmlguru4242

    htmlguru4242 Member

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    Most light meters do read for a middle grey (18%, Zone V) for whatever they are pointed at. Some meters may be slightly different, though.

    If you're just starting out, try metering and using the reccomended settings. I typically meter towards the shadows of the scene so there will be sufficient details on the negative in those areas.

    Then just dial those settings in on the camera and go.

    You may also want to try to bracket (expose some higher and lower than what the meter says), just to get a feel for what happens with exposure. You'll get the hang of it pretty quickly.
     
  3. mikeg

    mikeg Member

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    Have you still got the light meter?

    If yes, then post the manufacturer and the model number and we'll step you through how to use it.

    By the way, welcome!

    Mike
     
  4. gnashings

    gnashings Inactive

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    Just a quick clarification of the middle gray idea - I don't know if it was clear from the previous post. The simplest (and somewhat oversimplified) way of looking at it is this:

    Lets say you have a house with white walls, black doors and a grey roof.
    Now you take a photo of it with B&W film using your meter. Lets assume that the house is pretty evenly lit (I think you will see how shadows fit into this by extension). Now, if you point your meter at the white wall (so it is ONLY reading the light reflected off the white wall - not the whole scene), it will assume that the wall is in fact middle gray. Now, if you expose as per the meter reading, give the film "normal" development and printing, your white house will be gray. The meter assumes that whatever it is pointed at IS middle gray. (part of the reason why most photos of snowy scenes look so mucky and... grey!). In this case, you would want to meter the gray roof - and the photo would then properly relate the other values.

    This is the very, very basic of how it works. In reality, you would meter the door, so that you would have enough exposure on the darkest thing you still want to see some details of, then develop so that your highlights are controlled - but that is something that I think is getting a little bit ahead of ourselves. I think its something that you will discover the need for when you snap a few rolls. Keep in mind that most consumer cameras are set to take an average of the entire scene you see through your viewfinder - which works surprisingly well most of the time... but when it reaches its limitiations, it really shows. Many hand held meters are what is called "spot" meters - that is to say they take a reading of a very lmited area (imagine a cone 1 to 3 degrees starting at your meter), so that you can be very specific in what you want to meter.

    I don't know if you are familiar with the theory, the basis of apperture and exposure time? I know its basic stuff - but we all had to learn it some time - I simply don't know how far along you are in this arcane knowledge:smile:!

    As far as I know, most if not all light meters work on this principle - whatever they read will give you the middle gray - wether its reflected light (meter in your camera or one you point at the subject) or incident (one you place in front of the subject to meter the light actually falling on the subject and obtain you reading that way).

    I know there are websites with content written by people much more qualified than I am - but I can't seem to find them in my favourites - perhaps someone could direct you. I don't know of any threads here on APUG that go in depth on the subject. I certainly recommend some reading - either on line, or the old fashioned way. Again, I really don't know which books would be best, I hope others will chime in!

    Best of luck and welcome to APUG!

    Peter.
     
  5. Nick Zentena

    Nick Zentena Member

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    What kind of meter? Reflected or incident? Incident will have a white half dome on it.

    If it's incident then you can more or less just use the results it gives you.

    If it's reflected then you need to adjust.

    If it's reflected the question then becomes how big an area it reads.

    You need to tell us more :wink:
     
  6. rbarker

    rbarker Member

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    Welcome, Pete - both to APUG and photography.

    As noted by others, there are two basic types of meters - incident meters (with the white dome) that are intended to measure the light falling on the subject, and reflective meters that measure the light being reflected from the scene.

    Point an incident meter at the light source and it will give you an exposure reading that will render the subject in that light at its "true tonality". Other factors, like nearby reflective surfaces, or multiple light sources, can complicate things, but that's the basic idea.

    With reflective meters, the trick is to know what the meter is actually measuring and, thus, what the meter is really telling you. By their nature, reflective meters have a "field of view", and will give you an average of whatever the meter is "seeing" within that field of view. If what the meter is seeing is an even balance of bright and dark areas, the suggested exposure will similarly be a reasonable balance. Otherwise, you have to do a bit of interpreting to get the "right" exposure.

    For example, if what the reflective meter is seeing is mostly a white area, you'll want to open up a couple of stops to properly render the scene on film. Conversely, if the meter is seeing mostly shadow areas, you may need to close down a couple of stops.

    Spot meters get around this problem to a degree by metering a very small area, and giving you a visual indication of what area they are reading. The result is then easier to interpret, but the same sort of adjustment to the actual exposure will be required.

    At the heart of these interpretations or adjustments is the idea that the exposure suggested by the reflective meter is that which will render the metered area as a middle gray - a Zone V, in Zone System terms. Thus, how much you adjust the reading for the actual exposure will shift the metered area up (toward white) or down (toward black) the corresponding amount in relation to the real middle gray in the scene.

    The multi-segment matrix meters in modern SLR cameras attempt to make intelligent interpretations of the scene by examining the patterns of brightness and darkness within the camera's firmware. Most of the time, they do a fairly good job, but can be fooled (just like photographers) by unusual lighting situations, such as strong backlighting, etc. Using a good hand-held meter simply puts the photographer in charge of that decision-making process.
     
  7. naturephoto1

    naturephoto1 Subscriber

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    Actually, a light meter be it averaging reflected or spot reads 18% be it gray, green, blue, red, orange...... The dome on an incident meter "creates" the conditions when facing the correct direction to simulate and record 18%.

    Rich
     
  8. bob01721

    bob01721 Member

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    Pete,

    Are you thoroughly confused yet? Ha!
     
  9. roteague

    roteague Member

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    Pete,

    Are you shooting color or B&W? What type of meter were you given (see previous messages)? Once we know these details, then we will be able to help you learn to user your meter properly.
     
  10. petefox

    petefox Member

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    Hi!

    This is great and helps a lot. Thank you. For the record it was a sekonic 308/608? meter - incident ( with white dome) - and b/w film.
    I don't develop film myself. It is sent away.
    Can I use the one reading from an incident meter and assume I am getting an 'accurate' reading - ( if the imaginary shot is not too complicated with light and dark)?
    Thanks again Pete
     
  11. naturephoto1

    naturephoto1 Subscriber

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    Hi Pete,

    An incident meter when used properly should at least give a good starting point for exposure. Remember, with an incident meter, the dome must be incident to the light source and in the same lighting conditions as the subject. If not, your exposure will be incorrect. If the dome and meter position follow the aforementioned conditions, generally B&W film will have enough latitude to cover your error.

    The more your experience with the meter and working with incident light the better and more consistent your results. I have an old Minolta Flash Meter III which I use for incident readings on occasion. I shoot primarily transparencies and for me, I prefer the use of a 1 degree spot meter. I then try to find the range of the exposure for the objects and the portions of the scene to be included in the image and determine the proper exposure accordingly.

    With enough experience, in most instances however, the incident meter or either an averaging reflected or a reflected spot meter can all be used successfully to at least give a good starting point for exposure.

    Good luck with the meter and welcome to APUG.

    Rich
     
  12. roteague

    roteague Member

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  13. naturephoto1

    naturephoto1 Subscriber

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    Gee Robert,

    It does seem that way doesn't it. I too have the booster to meter off the ground glass. Of course, you can also do that but perhaps with a bit more difficulty with a spot meter as well.

    Rich
     
  14. gnashings

    gnashings Inactive

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    Ah, all this metering chit chat... throw that junk away. Look outside, throw a few blades of grass in the air, watch them fall, squint a bit (try squatting while you do this - looks more impressive that way), listen to the wind, make framing shapes with your hands for a few minutes, then take the apperture ring and apply the same amount of movements as it did to open your high school locker, pick a shutter speed that you think looks creative and shoot. You are now an artist, and if anyone asks you what and why you're doing these things, look down your nose at them make a "pfft!" sound and turn away waving your hand dsimissively:D:D:D

    Jokes aside - I found that a reflective meter (one you point at things) was easier for me to learn. Has anyone else found that the principle of its operation just sort of translates more directly to what you camera is doing (as in: capturing reflected light).?? I also find that you can always use a reflective meter (excpet I suppose if you want to measure actual flash), but 3/4 of what I shoot can't be approached closely enough to use an incident meter. Is it just me, or has anyone else found this to be true?

    Peter.
     
  15. roteague

    roteague Member

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    You don't necessarily have to get close to your subject in order to meter, you just need to have the same amount/quality of light falling where you are metering from.
     
  16. gnashings

    gnashings Inactive

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    You see, while I am NOT at all questioning the truth and accuracy of that statement... I sincerely question MY ability to determine the sameness of said light. For a guy of my limited know how, that is kind of why I need a meter in the first place!:smile:

    Peter.
     
  17. Roger Hicks

    Roger Hicks Member

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    For something that looks dead simple, metering is amazingly complicated. Fortunately a lot of approximations are possible because photography is very flexible and not anything like as critical as some people like to pretend.

    First, there's the question of 'keying' exposure to the highlights (or brightest areas) or the shadows (or darkest areas).

    With color slide or digital, exposure must be keyed to the highlights, because if it isn't, these will 'blow' to a featureless white. An incident light meter is ideal for slides and digital because the incident dome provides an artificial highlight. Indeed the old name for these meters was 'artificial highlight'.

    But because the exposure is keyed to the highlighs, anything that is too dark will record as a featureless black. This doesn't matter with slides -- anything is better than large areas of blown highlight -- but with negatives it means you lose shadow detail if the brightness range of the subject is more than about 7 stops. This is unusual but it can happen, especially on a bright sunny day or when shooting interiors.

    Now, it is difficult or impossible to 'blow' highlights in a negative (they can always be recovered via appropriate burning-in at the printing stage) so with negative (mono or colour), exposure should be keyed to the darkest tone in which you want texture. Ideally you therefore need a limited area reading of this area BUT, as already noted, because the meter is calibrated to deliver a mid-grey you need to modify your reading and give 2-1/3 stops LESS exposure (this seems counter-intuitive but it works if you think it through).

    Limited-area metering is too complicated to go into here -- I once wrote an entire book on exposiure, called Perfect Exposure (reissued in paperback in 2004, details on www.rogerandfrances.com) -- so for negatives the best advice for a beginner is to favour the darker areas of the subject, i.e. point the meter cell towards the subject from the camera position, towards the darker areas rather than the lighter ones, usually angling it down slightly to avoid reading too much sky. This will usually give you enough shadow detail.

    You may later revise your technique on the basis of experience (and, I hope, reading my book or some of the modules in the Photo School on the same website) but this is a good start.

    Be wary of the '18% grey' myth (there's a free module about this in the Photo School on the website too). Overall reflectivity of 'typical' scenes as determined by the original Kodak research is 12-13 per cent, not 18 per cent.

    Eighteen per cent is a Munsell mid-grey, that is to say, if faced with a series of cards from the brightest while available to the darkest black available, most people will pick 18 per cent as a mid-tone. No ISO speed criterion is based on 18 per cent grey and it is of much more limited use in metering than many people would have you believe.

    The first commercially successful spot meter, the SEI Photometer which still enjoys a cult following today, didn't even have a 'mid point' index because such an index was substantially useless before people started carrying grey cards around with them: it had only indices for brightest highlight with texture (reversal metering) and shadow detail (negative metering).

    The main reasons 18% grey cards work for many people are (a) the flexibility of silver halide photography as noted above and (b) the fact that many of them re-rate their films a lot lower than the true ISO speed. ISO speeds are a repeatable and usually accurate standard, but this is not the same as saying they are ideal for all types of photography or metering. On a sunny day, I will set a broad-area reflected-light meter 2/3 stop slower than the ISO speed to get good shadow detail -- but with a spot meter, with a shadow value 2-1/3 stops below the mid point, I'll use the full ISO speed.

    Sorry for a long and possibly confusing post but it's as well at the start of your metering career, as it were, to realize three things:

    1 There's a lot of myth and misunderstanding in metering

    2 This doesn't necessarily matter much because the system is very flexible

    3 With negatives, there is enormous latitude for overexposure, often several stops, but there is far less latitude for underexposure, especially on a sunny day where even 1/2 stop may result in loss of shadow detail depending on the metering technique.

    Cheers,

    Roger
     
    Last edited by a moderator: May 25, 2006
  18. Nick Zentena

    Nick Zentena Member

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    I thought the point of the 18% card was when you tilt it the card become 13%.
     
  19. rbarker

    rbarker Member

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    With a few more posts to this thread, we'll be able to confirm that the number of explanations of "proper metering" is equal to the number of photographers in the room, plus at least one. :wink:
     
  20. Roger Hicks

    Roger Hicks Member

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    Dear Nick,

    More of a work-around than a point, I'd have thought.

    Cheers,

    Roger
     
  21. Helen B

    Helen B Member

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    Kodak grey cards used to have instructions about opening up half a stop to allow for the difference between the 18% grey card reading and the 12-ish%. 18% grey corresponds to an L* of 50 in CIELAB (L*a*b*, max L* is 100). A perfect 100% reflecting diffuse surface is, of course, only 2½ stops brighter than a grey card. That's a bit of a waste of the dynamic range of many films.

    There is no reason to restrict your choice of key metering tone to the highlights or to the shadows. You may wish to place the most important tones on the right part of the curve. In many cases the most important tones are skin tones. Exactly where you place them on the curve is up to you. This is perhaps getting a little less important as the graininess of recent colour neg films is not increasing with decreasing density as much as it used to (ie the graininess of the film is more consistent with regards to density, with the exception of the increase in graininess at the toe).

    Standardised example of this, for good reason:
    The Aim Density method keys your exposure to an 18% grey card. This is a standard method in cinematography. EK give you the Status M aim densities in each layer for an 18% grey card exposure. You do your tests with your lenses and your meter and find which meter setting gives you the closest density in the three layers. It is likely that the three layers will not give the same result, but I've never known any layer to be more than a third of a stop from the chosen speed. If in doubt, err on the side of the blue-sensitive layer, because that is likely to be the most grainy*. From the manufacturer's curves or, better, from your own tests you know the latitude above and below that midtone key. There is an exact video equivalent of this film technique using a waveform monitor.

    Best,
    Helen
    * one reason why a single RMS value for a colour film is not the whole truth.
     
  22. roteague

    roteague Member

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    Roger,

    Thanks for your very through explanation, and one that is easy to follow.

    I shoot almost exclusively transparencies, and I find that I generally make 2 or more meter readings of my subject area. The first is to get a reading of my highlight; from there I determine if I want the hightlight to be lighter or darker than the meter indicates. A lot of times I am shooting towards the sun, and I may need to just let it blow out. From that I meter my shadow areas, to determine the amount of latitude that I have to work with. If I determine that the shadow areas are too important to allow to fade away into blackness, I will use a 1 or 2 stop split neutral density filter (I don't like 3 stop filters) over the top area and compensate. This can be a juggling act, since I normally use a center filter with my widest lens.

    I admit that if the light is changing too fast, I will sometimes cheat and use my Nikon F5 as a meter.

    Thanks again for your excellent explanation,
     
  23. Roger Hicks

    Roger Hicks Member

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    Dear Robert,

    Then there's the fascinating observation from Garry Coward-Williams, who remarked that no two photographers get exactly the same reading, even with the same meter, and when they use different meters, agreements of +/- 2/3 stop are not unusual. And yet, we all get 'correct' exposures, even with slides...

    Cheers,

    Roger