Liberation from the light meter can be mentally productive

Discussion in 'Exposure Discussion' started by David Lyga, Oct 14, 2012.

  1. David Lyga

    David Lyga Subscriber

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    Doing crossword puzzles is an impossible task for me. I simply cannot solve puzzles. Getting nearly straight A grades in the accounting curriculum and passing the CPA Exam were easier. Figure out that craziness.

    But figuring 'light' intensity, despite the changing luminary parameters, can also be a formidable task. When is shade, shade? Easier said than done but the key here is making 'shade' mean something very personal to you and not ever deviating from that perception.

    Slowly learning how to harness this complex subject can, at least, be made easier by forgetting 'f stops' for a while. In fact, why are there such things as f stops at all for other than theoretical verification of that all important concept of the focal distance (to film plane, at infinity) divided by lens opening diameter ? Hollywood long ago entered the real world with their sensible 't stops' zeroing in on the ACTUAL light transmission. Much more rational. (Do I sound like the pragmatism of David Vestal yet?)

    There is a certain freedom with taking an extension of your eye, a mechanical camera with adjustments available, and 'knowing' how to expose a certain film. I am still learning after decades of frustration but I am certainly better at it. It is intellectually revealing how right or wrong one can be and this exploration is perfect ammunition to circumvent, even diffuse, an overconfident ego. But there are certainly hurdles here: for example, shade at noon is not necessarily shade at noon merely a block away. Much depends upon the amount of sky allowed to illuminate the scene and whether clouds intervene. Then again, twilight is not an objective measure either: When is the sun low enough? Are buildings or mountains adding to the 'light value' confusion? But there is a kind of beginning benchmark with open, noon sunlight hitting an open space. But even here one has to look just how low that sun is in the dead of winter conflated with how high one's latitude is on planet earth.

    I offer some tips that have helped me in this endeavor. First, translate 'f stops' to the less cumbersome light value system: f2 is '2', f2.8 is '3'....f16 is '8', f22 is '9. Then do the same for the time part: 1 sec is '0', 1/2 sec is '1'....1/30th sec is '5'.....1/250th sec is '8'....1/1000th sec is '10'. (You fill in the grammatical ellipses.)

    Thus, we have a convenient, transferable way to express exposure at least, even if we have still not mastered light itself. To add to this convenience, rate film the same way. Consider a 400 ISO film. For me, I rate negative film about 2/3 stop less than the manufacturer says to. I would, thus, rate HP5+ or Tri-X at EI 250. Translated into light values this becomes (combined light value) LV 16. (NOT downgrading this speed from 400, this LV would be 17 if the manufacturer's recommendation were to be followed.) Similarly, I rate Pan F+ at EI 16. My 'rating' expressed in LVs is 12. What does all this mean?

    Simply, this 'rating' is the amount of exposure given to a brilliant, sun lit, noontime, 'no holds barred' scene that is the epitome of what nature can provide in terms of light intensity. That is my outdoor benchmark. In other words I would expose HP5+ at 'LV 16'. This is the combination of aperture and shutter speed that I would use. For example, that would translate into f22 plus 1/125th sec, or f11 plus 1/500th sec. Both, conveniently and easily, add up to the '16' you want. In the former it would be 9 + 7, in the latter it would be 7 + 9. This is why I convert both apertures and shutter speeds into these easy numbers.

    That's for brilliant sunlight. For other values: My exposure chart column is stated as follows for outdoor lighting: SUN SHD TWL DIM with each category giving four more stops (or, more correctly, steps) exposure than the preceding. This means that HP5+ starts at '16' for sun and proceeds to '12' for shade, then '8' for twilight, then '4' for dim daylight. So for MY interpenetration of 'shade' I would expose HP5+ at, say, 1/60th sec and f8, or '6' + '6' to get the wanted '12' LV. For MY interpretation of dim daylight I would expose HP5+ at, say, 1 sec and f4, or '0' + '4' to get the wanted '4'. You can see that it becomes extremely easy to change the aperture and shutter speeds to accommodate the exposure as all you have to do is add up to the proper combined LV.

    The work comes with mentally anchoring the amount of light that 'sun' 'shade', 'twilight', 'dim' are supposed to represent in order to get proper exposure. For example, if the negative is too dense, you judged the light as too intense. 'Shade' does not necessarily have to be a shaded situation. It can be a level of overcast that equates with the level of proper shade. Likewise, 'TWL' does not have to be actual twilight; it can be a dark alleyway whose light intensity equates with the proper level of actual twilight. This is what really 'teaches' light, folks: refusing, on occasion, to bring your 'crutch' light meter with you. It is an exercise that forces you to come to grips with the reality of actual light intensity and correctly nullifies subjective interpretations that have little to do with this actual measure, such as assuming that shade is always of nearly the same intensity, or that twilight is 'when cars turn on their lights'. It forces you to really 'see' light in objective terms and removes the 'romantic' aspects of light interpretation that can easily get in the way.

    The other side of my exposure chart is for 'tungsten light'. This side is a bit more complex, as the sensitivity of chromogenic (color or B+W) films are markedly more sensitive to the lower Kelvin (say 2800 K) than are traditional black and white films. (I assume NO filtration in all my examples). (For convenience, and usual accuracy, consider fluorescent to be the tungsten equivalent.) My side of the chart for tungsten is as follows: HIGH MED LOW DIM Each category requires two stops more exposure than the previous. For example, again using HP5+, a traditional B+W film, my rating for tungsten starts with '7' for HIGH, then '5' for MED, then '3' for LOW, then '1' for DIM. Here, importantly to understand, is that the SAME intensity exists for daylight's "DIM" and for tungsten's "DIM": the considerable difference in exposure (daylight dim = 4 while tungsten dim = only 1) is because traditional B+W film is very slow when exposed to tungsten light. The ACTUAL intensity of both 'dims' is the same. With chromogenic films this interpretation is more in line with human perceived value. With, say either a ISO 400 chromogenic B+W film or an ISO 400 color film, the tungsten chart is: '10' for HIGH, '8' for MED, '6' for LOW, '4' for DIM. Again, this assumes no 'proper' blue filtration for the chromogenic films. You can easily correct this 'lack' in the darkroom's enlarger. If you were to use the blue filtration (I think the 80A filter?) your numbers would be in line with those for traditional B+W films. Few realize just how much of a bonanza this is for available light black and white photography: an increase of three stops for using the chromogenic films without filtration.

    With outdoor lighting the films' sensitivity is the same. - David Lyga
     
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  2. cliveh

    cliveh Subscriber

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    Aren't you over complicating this a little?
     
  3. David Lyga

    David Lyga Subscriber

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    Really not. I wanted to cover all bases to be clear. It's a bit to read but it is all there. - David Lyga
     
  4. benjiboy

    benjiboy Subscriber

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    It's a lot easier to use a light meter, and avoid confusing myself even further.
     
  5. eddie

    eddie Subscriber

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    I agree with Clive and Benji. I think you're over-complicating things. But, if it works for you, and you're getting the results you want...
     
  6. Steve Smith

    Steve Smith Subscriber

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    There are already light value (LV) and exposure value (EV) numerical systems. Why not use those?

    Relating to Sunny 16 at ISO 100 (where EV = LV) we get 15 for bright sun, decreasing by one for each step in the sequence.


    Steve.
     
  7. Aron

    Aron Subscriber

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    Everyone has his/her favourite exposure system, but for me it is much easier to take a single incident reading and compensate a little if I think I have to. Consistency and utter simplicity. Sunny 16 can work very well, but in my humble opinion there is a reason lightmeters got invented and were improved over time.
     
  8. Steve Smith

    Steve Smith Subscriber

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    It's the same reason automatic exposure and automatic focus were developed but we don't have to use those either!


    Steve.
     
  9. Diapositivo

    Diapositivo Subscriber

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    Personally I find any attempt to measure (or mentally pre-measure or should I say preventively observe) light below LV12 to be so tricky to be useless. When the human iris begins to open we are not aware of it and so we cannot compensate.
    I would never try to guess the light inside of a church for instance.

    Situations between LV15 and LV12 more than being judged by the "eye" are judged by experience, observing the scene and what can influence the lighting (such as white walls, or dark walls near the scene) and "reasoning" about them.

    Because the eyes are very adaptable and are totally unreliable as a measure instrument the mental appreciation of light should be thought as more the result of a reasoning based on experience rather than on a visual impression. The height of the sun over the horizon, the amount of clouds, the presence of a bright reflected surface can be observed "objectively" and there is no margin of error in this observations. The error comes when trying to infer, or mentally calculate, which is the lighting created by these factors.

    The only other situations where I think things become easy is floodlit monuments at night, where LV4 normally works decently well.

    I would in any case confirm my mental hypothesis with a light meter any time I have it with me and if it's the right kind (for monuments at night, for instance, an in-camera light meter is in many situation pretty useless and LV 4 probably works better unless one has a proper instrument such as an incident light meter or a spot light meter). Mentally pre-calculating the exposure is as said in another thread important to avoid silly mistakes such as ISO setting mistakes.

    A floodlit monument at night outside of the EV 3-5 range would make me pause and doubt, just as an exposure far from EV14 in sun light. It's just a way to be mentally aware and vigilant about exposure instead of relying solely on the instrument. Instruments are precise but their use can prone to error. That's true especially for light meters.

    In any case for B&W the entire reasoning should be skewed toward overexposure in case of least doubt.
     
  10. Aron

    Aron Subscriber

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    I agree to a point, but transferring a meter reading to the camera and manual focusing are simple mechanical actions, while judging the (not always "simple") light more or less precisely is quite another thing.
     
  11. Diapositivo

    Diapositivo Subscriber

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    The system used by David Lyga is in fact strictly using the EV indication that we find on light meters. For ISO 400, 1/125@f/16 the light meter indicates EV17. The same exposure values at ISO 100 would be rendered as EV15.
     
  12. Ken Nadvornick

    Ken Nadvornick Subscriber

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    Too much analytical horsepower applied to too simple of a problem. Mounting a huge powerplant on a rowboat doesn't make it a speedboat. It just makes it an unwieldy rowboat—and one that was performing its intended function just fine using oars alone in the first place.

    Ken
     
  13. Andy K

    Andy K Member

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    Light meter and EV scale works for me. Nice and simple. Like me.
     
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  15. markbarendt

    markbarendt Subscriber

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    (Psst, Clive, he's a CPA. :whistling: )

    In seriousness though David, it is nice to be able to look at the scene and say "X" should be good.
     
  16. Jeff Kubach

    Jeff Kubach Member

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    I just use a light meter and if the battery fails then use sunny 16 rule.

    Jeff
     
  17. cliveh

    cliveh Subscriber

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    I look at a scene as I approach it and think that looks like 1/125 at f8, so when I'm there I don't have to waste time with this sort of thing.
     
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  18. Chan Tran

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    David! In your original post you presented 2 different things.
    1. The first is similar to what was called APEX system which I didn't know about until I started to use the same thing like you did. By assigning a number value to aperture and shutter speed it does make it's easier to calculate the shutter speed and aperture from a light value. This has nothing to do with a meter. You can use a calculating wheel similar to that of many older exposure meter. And yes I do like to assign numerical values to aperture and shutter speeds like the way you do. While at first it takes time to remember them but I found that I could learn them by heart quickly.
    2. The second part you assign a light value to a condition for example full sun EV15 etc.. This part replaces the meter but one can elect to use this or not. One can use a meter to get the EV reading off the meter. However, I am like Cliveh that when I look at the scene I tend to intutively thought of an exposure in term or shutter speed and aperture combination rather than an ev number. And thus may need to those back to EV number mentally if I need to.
     
  19. summicron1

    summicron1 Subscriber

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    dave -- your system is not all that much different from some of the old methods of calculating exposure used before guys invented light meters -- I've got some in my collection, small books that go at great detail into sun, subject, time of day, time of season, etc etc etc.

    It all boils down to being aware of your film, your equipment and your surroundings ... if your system does this for you, then good on you, ignore those who say you over-complicate things. I personally like light meters but consider them advisory only -- final subject assessment is done in that greatest of all micro-processors, the human brain.
     
  20. jslabovitz

    jslabovitz Member

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    Thanks for describing this, David. Although I've read a lot about EVs and LVs, and have played with the APEX system, it's nice to hear someone's actual experiences with guesstimating light values and exposures.

    --John
     
  21. markbarendt

    markbarendt Subscriber

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    I try to preset for each situation too. It is very valuable. In fact I started a thread about it today http://www.apug.org/forums/forum48/111191-experimenting-bit.html

    So i have a question, what ISO?

    It's an honest question, not flippant. It takes all three.

    Time and aperture are used to make creative choices, time controls blur, aperture controls DOF.

    ISO finishes the equation to get proper exposure.

    Im trying to figure out why.
     
  22. mopar_guy

    mopar_guy Subscriber

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    I will continue to be a slave to a light meter.
     
  23. Chan Tran

    Chan Tran Member

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    Although I can't reply for cliveh, when I think that the scene looks like it's 1/125 @ f/8 I think of ISO100. And then if I do not use ISO100 I would have to convert or if I don't want to use f/8 or 1/125 I would have to convert too. When I came up to a scene I tend to think it's 1/125 @ f/8 rather than EV13. I would have to use the method described by the OP to convert it to an EV value for ISO100. Taking the above example it's 1/125=7 + f/8=6 so it's EV13 at ISO100. If I am using ISO400 then it's 13+2=EV15. Then If I decide to say use f/11 and that's 7. 15-7=8 and that's 1/250.
     
  24. octofish

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    I try to think in EV. It's not too hard to guess an EV for a particular ISO based on stops down from sunny/16.

    Low light is hard, but I guess that's just a matter of experience. That I would approach by having a guess at it at EV100 (which is the same thing as LV, an absolute measure of amount of light) based on previous experiences and converting to EV at whatever ISO. That's a factor like EV400 = EV100 + 2).

    The biggest thing for me was working out how to do the calculation from EV to actual exposure quickly. It's easy enough.
    Start with 2, then add the number of aperture stops past f/2 you want(ie. f/16 is +6EV compared to f/2. You just have to memorise these, but there are only 6 maybe 7 values). Then whatever is left is the shutter speed in the closest power of two. (ie. 1sec = 1/2^0, so +0EV, 1/60 =~ 1/2^6, so +6EV). Powers of two are pretty easy.

    So to get EV100 = 15, (sunny 16), you go 2 + 6 (for f/16) + 7 (1/125sec).

    If you are shooting a scene at ISO1600 that is say -3EV from sunny 16 you say, sunny 16 is EV1600=19 (EV100+4). So I want 16. Which is 2+6 (f/16)+8(1/250s)

    Easy. You can do the shutter speed and aperature around the other way if you want to say pick a particular speed for whatever reason. Say you want to open up as wide as you can using the last example and 1/1000 is the fastest shutter speed you have. 16 = 2+10(1/1000s)+4 (f/8).

    The other thing that really helped getting my head around this is simply realising that an EV value is actually around the wrong way from what it sounds. It's called exposure value, and is referring to how much exposure you give the film, but it is actually less exposure the bigger the number. I try to think of it as 'degree of attenuation'. It's sort of seems to be measuring the amount of light, but this becomes nonsense when you start talking about EV100 vs EV400. It's not amount of light. It's amount of attenuation that light gets before it hits the film. An EV number always means exactly the same shutter speed/aperature irrespective of the ISO value it's for. So once you know what those are, or can get there quickly, the thought process gets much faster.

    This is probably quite basic, but it's really helping me to get quicker at doing this without a meter. It doesn't take me long now from guessing the light to actually setting up the camera to take the shot. As for guessing the light correctly or making sure the photo was worth taking in the first place, still working on that :smile:
     
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  25. Steve Smith

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    EV 15 is 1/125 @ f16 regardless of ISO. EV is purely a factor of shutter speed and aperture, light level or ISO does not affect it.


    Steve.
     
  26. Vaughn

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    I am in the camp of "Whatever works".

    Awareness of the light is not tied to the use or non-use of a light meter, but resides in the eye of the beholder. For me, this awareness has come about by seeing, exposing a sheet of film to that light, and then transferring the light to paper. I find a meter handy for the second step, not so directly important for the first or last steps.

    Vaughn