Reflective vs. incidence meter reading??

Discussion in 'Medium Format Cameras and Accessories' started by stradibarrius, Feb 6, 2010.

  1. stradibarrius

    stradibarrius Member

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    I am trying once again to copy Keith's "pasta" shot. It is simple but it caught my eye and I felt like trying to duplicate the tone and contrast he captured.

    I set my lights and RB67 and pulled out my meter. The difference between the rel=reflective and incident is about 1-1/3 stops...Is it normal for the two types of reading to be different?
    Which will or should be more accurate?
    Or maybe the question should be when there is a discrepancy which would you choose?
     
  2. SuzanneR

    SuzanneR Moderator Staff Member Moderator

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    Depends on how you want to expose the film. Are you using a spot meter for the reflective reading? If it's an in-camera meter, I'd use the incident reading, but if you have a spot meter, then you can pretty much decide which part of the pic you will place at about 18% grey.
     
  3. stradibarrius

    stradibarrius Member

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    I don't think I have ever seen a camera with an "incidence" meter built in????
    I am using a hand held analogue Gossen Digi-Pro.
     
  4. SuzanneR

    SuzanneR Moderator Staff Member Moderator

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    Sorry, I wasn't clear.

    If the reflective meter you are using is a spot meter, then that can give you a very accurate read. If it's in camera, and measuring the whole scene, then I would use the hand held incident meter, instead.
     
  5. markbarendt

    markbarendt Subscriber

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    Incident meters measure the light falling on the scene and tell you the camera setting.

    If your incident meter is "pressed-against-the-tip-of-subjects-nose" with the dome is pointed at the camera lens; it will normally be right and reliable.

    Reflective meters require more thought because the reading is affected by the subject.

    If for example if your reflective meter was pointed at a white sheet of paper in your scene, the reflective meter reading may differ from the incident meter reading by 2-4 stops, black paper, same offset in the other direction.

    With the reflective meter you need to decide how to adjust the meter's reading based on what you read off of.

    What I'm saying is that the two readings you took may be telling you the same thing, you just haven't adjusted the reflective meter's reading yet.
     
  6. tessar

    tessar Subscriber

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    I always had trouble with incident-meter readings until I realized one simple fact. When pointing the meter at the camera, the camera has to be in the same light as the subject. IOW, if the camera is in different light, point the meter at a location in the same light as the subject as close as possible to the camera position.
     
  7. markbarendt

    markbarendt Subscriber

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    I have to dis-agree.

    The meter has to be in the same light as the subject, the camera position makes no difference as long as it has a clear view.

    Further, in a studio setup with lights like stradibarrius is using, the meter needs to be right at the subject's nose because, depending on the lights, 6 inches or a foot of difference can create a full stop of change in the exposure indicated.
     
  8. eddym

    eddym Member

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    The light on the camera is irrelevant. With an incident meter, you should read the light falling on the subject. After all, that's what you are taking a picture of... not the camera!
     
  9. Ponysoldier

    Ponysoldier Member

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    The short answer is that, unless you were making the reflected light reading from a standard gray card, you should expect the readings to be different. The reflected light reading takes the intensity of light within the field of view and, in effect, arrives at the setting required to produce that light intensity as "standard gray." If the object being read is black - you still get gray; if white- you still get gray.
    The incident light reading measures the amount of light falling on the object and, in effect, calculates an exposure which would correlate to a reading made - in the reflected light mode - of a standard gray card.

    The incident light reading, executed properly, will normally tend to render the scene fairly accurately (assuming normal development) while the reflected light reading will depend on the angle of view of the meter (spot or wider angle), tonality and reflectivity of the object surface measured.
     
  10. Lee L

    Lee L Member

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    The kind of light the camera is in makes no difference at all when reading with an incident meter. What matters is that the meter is in the same light as the subject, and pointed toward the camera. Note that with studio lighting, and especially with lights close to the subject, you should have the meter as near as possible to the subject to avoid the effects of light falloff, which can be significant with small changes of position relative to a close light source.

    APUG could use some tutorials on the fundamentals:

    From Kodak: http://www.kodak.com/cluster/global/en/consumer/products/techInfo/af9/index.shtml#54503
    .pdf at http://www.kodak.com/global/en/consumer/products/pdf/af9.pdf
     
    Last edited by a moderator: Feb 6, 2010
  11. Eric Rose

    Eric Rose Subscriber

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    Didn't we just have a huge thread on this very subject?
     
  12. CPorter

    CPorter Member

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    A reflective and incident read differently, so a 1 1/3 stop difference does not necessarily mean anything is wrong. But a 1 1/3 stop difference between one meter and another like meter is a red flag that something is wrong.

    Both can be very accurate but under different circumstances. The incident meter is accurate for the reflective surfaces in the subject if those surfaces are receiving pretty much the same intensity of light----such as even sunlight on snow or subjects in full shade. But using the incident meter in sun/shade mix situations will overexpose the high values if read in the shade and under expose the shadow values if read in the sunlight.

    An incident meter is also quite useful in the studio when measuring the light intensity of individual lights, in this way, the power of one light can be set to provide a stop or two more or less powerful than any other light.

    A 30 degree angle reflective meter, like my Gossen Luna Pro F (or in-camera center-weighted meter) can be accurate for the reflective surfaces in the subject if there is about equal amounts of light versus dark areas being reflected. But, if there is more dark than light or light than dark, then these readings can lead to poor exposure too.
     
  13. Lee L

    Lee L Member

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    Yes, but it broke down into nitpicking and factions over exactly what the proper methods are, so it has good and bad info (just like the rest of the internet), making it a mediocre resource for those who don't have enough experience to judge the validity of any given post.

    Lee
     
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  15. CPorter

    CPorter Member

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    LOL! I was just thinking that as I hit "Submit Reply", oh well.
     
  16. Mike1234

    Mike1234 Inactive

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    Yes, but there are too many opinions and much misinformation. :wink:
     
  17. stradibarrius

    stradibarrius Member

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    But when you ask a question on this forum it is easy, for me, to tell who know their stuff and who wishes they did. For me one way to tell is go look at their Gallery. Iare the photos good or do they suck? If they are good then the person know how to make good photographs.
    Plus I just know there are certain people here that I trust what they say more than others.
     
  18. Mike1234

    Mike1234 Inactive

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    STRAD: That's a good general rule of thumb... although darkroom and PS can hide many exposure mistakes. Me... I have nothing in the gallery. I'm just now getting back into serious (fun) photography after twenty-five years of family and financial duties. Even though I haven't shot LF in a quarter century I'll bet I can read and understand a meter (reflective, spot, or incident) better than most. This isn't a defensive posture... just a reply to your generalization. At the risk of alienating some people... many replies (not in this thread necessarily) I see are from folks who couldn't tell a meter from their pete* and probably have difficulties know precisely what to do with either. :smile:
     
  19. Q.G.

    Q.G. Inactive

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    People may use cameras with built-in reflective light meters exclusively, and produce perfectly exposed photos.
    They still may not even have a clue about incident light metering.
    :wink:

    The difference you noticed, Stradibarius, is due to the brightness of the subject.
    It plays no role in incident light metering. But does in reflected light metering.

    You will have to correct the reflected light reading for the reflective properties of the subject.
    And when you do that, you'll find (or should find anyway) that the two agree, that both lead to the same exposure settings.

    You can only correct for the subject brightness by comparing it to that of a standard surface, a surface whose reflective properties are well known: the grey card already mentioned.

    As you see, incident metering leads to the desired result quicker. It involves less separate steps, thus less opportunity to make mistakes.
    So whenever you can, choose incident light metering.
     
  20. Mike1234

    Mike1234 Inactive

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    Learn to use a spot meter and how/where to place tonal values as they relate to the brightness of the object metered and compensational development and final print tonal values. Master this and your exposures will be spot on. You'll never need or want a wide-view reflective or incident meter again. Okay... let the flames begin. :D
     
  21. stradibarrius

    stradibarrius Member

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    Thanks for the good info from all of you. IMO you can also judge the answers by the answers given in this and other threads. So Mike I agree the Gallery is not the only way to judge, it is just a way that is the quickest. For many of us that spend a good deal of time on this site you learn the experienced and less experienced participants. You will notice I ask questions but very seldom offer any answers because I don't really feel I have the expertise.
    I didn't mean to besmirch anyone's abilities only to say that you learn to judge the answers and take them for what they are worth.

    At this point I only have a Gossen Luna Pro, ( not a Digi-Pro) so I will have to learn to use it for the time being.
     
  22. Ric Trexell

    Ric Trexell Member

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    Make sure you don't get in the way of the meter.

    While this is a no brainer for those of you that have a lot of experiance with incident meters, I know novices like me read these posts and learn from them. So that said, I would like to point out that it is easy to get in the way with an incident meter with your arm or body and cause an affect on the reading. Also, if you are wearing a white shirt, that might bounce a little light into your meter. (Nothing you probably didn't know but thought I'd say it anyway.) Thanks. Ric.
     
  23. 2F/2F

    2F/2F Member

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    It is very normal for the readings to be that different.

    However, try comparing two incident meters and see what you get. The only variation you get should come from the fact that different manufacturers use different values for a mid tone.

    Incident meters tell you the "correct normal exposure", based on the light. In-camera reflected meters tell you the exposure that will average everything to a mid tone, based on the composition. Do you ever really want the latter when you have the option of the former?

    Simply put, if you are exposing directly off of your meter, in-camera reflected meters are only "right" in one situation: A situation in which every tone in the composition averages to a mid tone (metering patterns considered). Incident meters, on the other hand, are always "right".

    In-camera reflected metering is a compromise, plain and simple. It is only worth doing when no other method is available, IMHO. Of course there are situations when no other method is available, and the in-camera meter might be better than no meter at all, and certainly better than missing a shot...however, in-camera reflected meters must constantly be adjusted from the recommended exposure based on your experience and judgment, just to get a good exposure at all. IMO, directly-read in-camera meters are the number one hindrance to most people obtaining properly exposed film. To me, it is an utter shame that beginners are taught with in-camera meters, and then taught all sorts of rules of thumb, various erroneous information about film and light meters and exposure, and other dances just to get decently exposed film.

    For a still life, I can't think of a single reason to ever use an in-camera meter.
     
  24. markbarendt

    markbarendt Subscriber

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    Good observations.
     
  25. MattKing

    MattKing Subscriber

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    I use my handheld meters in "incident" mode whenever I can. I like measuring the light that falls on the subject, rather than the light bouncing back from the subject, because I know how often the reflectance of a subject can end up being different than what one would expect.

    That being said, I use in camera meters, and reflectance based meters too.

    The most important "accessory" for any meter is an eye attached to a brain.

    You need to be able to evaluate a scene, including the subject and the light falling on it, and then use that evaluation to help determine whether to follow the meter's recommendation without change, or to make an adjustment.

    Obviously, experience is incredibly useful, but a willingness to look carefully at your subject helps just as much.

    In stradibarrius' case, I would hazard a guess that he is intimately familiar with how light and the surface of wooden stringed musical instruments interact. I would suggest he think about photographs he has taken in the past of those instruments - the meter readings he has taken previously, and how previous photographs have come out.

    I'd bet he has an excellent eye for reflectance when it comes to those instruments, even if he doesn't realize it yet. It isn't difficult to make use of that skill for other subjects.

    Matt
     
  26. stradibarrius

    stradibarrius Member

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    Because I am doing the photography thing in reverse to many of the folks with lots of experience, starting with digital and moving forward (IMHO) to film I have much more experience with the in camera meter. I am trying to learn to use my hand held more effectively. My old Luna Pro, analogue model, seems to have so much information that I have not taken advantage of yet. Learning to use the incident capability is some of that information. Of all my cameras my RB67 is my favorite and I need to learn to use my hand held effectively with this camera. I shot a roll of film yesterday and exposed each still life scene based on the reflective reading and then the next frame on the incident reading. I am thinking this will teach me something?????