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Thread: Need explanation on metering/ sunny 16

  1. #1
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    Default Need explanation on metering/ sunny 16

    Hi,
    I have difficulty grasping the concept of metering, which i think is a very important thing for me to learn.

    Over at John Shaw's book on nature photography field guide, the explanation is really too tough for me to grasp.

    Can someone explain it in laymen's term to me? Like when do i know where to meter using spot metering?

    And can someone enlighten me on the sunny 16 rule?

    Thanks!

    Regards

  2. #2

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    Sunny 16? Tot that applies only if you don't have a working meter with you? Basically, when its sunny and you are using ISO100 film, just set aperture to f16 and you will have a good chance of getting reasonably correct exposures when using negatives. Basically, these approximations can be found on the inside of every film package.

    Tried it once when I was caught without batteries on an old manual cam, snapped a few shots(Slides) without metering and was surprised to find that they turned out ok.

    As for the rest of your query..think u need to paste the extract here, some of us may not have acces to john shaw's book.

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    Oh i see...

    As for the metering, lets do away with the john shaw book? Hehe..

    What i hope is that some guru can give me some simple explaination on its usage and technique?

    And they say...2stops of light or 1/3 stops of light, what do they really mean?

    For eg, 'I lost 2 stops of light'

    Regards

  4. #4

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    Losing 2 stops of light means that the light loss was equivalent to what shutter speed you would get had you lower the aperture by 2 stops. i.e f1.4 to f2.8.

    f1.4 to f2 is one stop, f2 to f2.8 is another stop.

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    Moderator ziploc's Avatar
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    Sunny 16 rule just states that under bright, direct mid day sun light, for correct exposure of mid tone subjects, the shutter speed is approximately the film's iso if you set your aperture to f/16. For example, if you are using iso 100 and f/16, under sunny 16 the shutter speed speed would be 1/125s for the correct exposure. In other words under sunny16 rule, for iso100, you can use the following exposure settings:

    f/16 1/125s, f/8 1/250s, f/5.6 1/500s, and so on...

    A "stop" on the aperture or shutter speed allows double or half of the amount of light reaching the film. First let's look at the aperture values:

    f/1, f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32... etc

    Each of the above is one stop from the next, and allows in double or half of the light. So for example, if you increase the aperture from f/4 to f/2.8, you are allowing double amount of light in. Similary, from f/4 to f/5.6 and you are cutting it by half.

    Same for the shutter speed, each of the following are 1 stop from the next:

    1s, 1/2s, 1/4s, 1/8s, 1/15s, 1/30s, 1/60s, 1/125s, 1/250s, 1/500s... etc

    Now assume an exposure metered by the camera is f/8 1/125s. If you want to keep the exposure constant but want to open up the aperture to f/5.6 for shallower DOF for example, since you are letting 1 stop more light in, you will need to cut 1 stop on the shutter speed, so:

    f/8 1/125s ==> f/5.6 1/250s will give you the same exposure. (Aperture open up 1 stop, shutter speed close down by 1 stop)

    Similarly, you can also do this:

    f/8 1/125s ==> f/4 1/500s (aperture open up 2 stops, shutter speed close down by 2 stops).

    Hope that helps.

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    Default

    so means say if i use a CPL,
    i lose 2 stops of light, means i have use a slower shutter speed to compensate?

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    Oh i see! Thanks ziploc and Zerstorer!

    anyone can help me out regarding the metering?

    Regards!

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    Originally posted by Wryer
    so means say if i use a CPL,
    i lose 2 stops of light, means i have use a slower shutter speed to compensate?
    Either you open up your aperture by 2 stops, slow down shutter speed by 2 stops, or use 2 stops higher iso. So for example:

    f/8 => f/4, 1/250s => 1/60s, or iso 100 => iso 400.

    Anyway, if you are using program, aperture priority or shutter priority mode, you shouldn't worry too much about it. The camera's meter will take care of it for you.

  9. #9

    Default Re: Need explanation on metering/ sunny 16

    If you are referring to the Meter Calibration in J.Shaw's book, then this article would elaborate:

    Test your meter
    Exposure seems to be the most difficult part of photography for many. There are those who totally rely on their camera meters and those who want to use their meters as a starting point. Relying on your camera all the time can give good exposure some of the times but not all the time. I look at all built-in features in my camera as tools that are designed for me to control rather than them controlling me. All meters are designed to produce middletone results. Middletone is neither black nor white, its neither light nor dark. It is half way in between. Green grass, blue sky, tree trunks for example are all middletone. Your camera meter should give proper exposure when photographing a middletone subject, otherwise you must compensate. This is true regardless of the type of camera or built-in meter you have. First thing you should do with any meter, whether camera or hand meters is to make sure it is calibrated correctly. Meters can be off by several stops resulting in wrong exposures. You don't have to send your camera for repairs if your meter is off. You can easily calibrate it yourself by using the Sunny f-16 rule. Sunny f-16 rule states that correct exposure for a frontlit middletone subject in bright sun, two hours after sunrise and two hours before sunset, is f-16 at the shutter speed closest to the film's ISO. With an ISO 50 film for example, your exposure would be 1/60 at f-16, or 1/125 sec at f-16 with ISO 100. You can use any equivalent exposure when using the Sunny f-16 rule. With ISO 50 film you can use 1/125 sec at f-11, 1/250 sec at f-8 and so on. All these combinations provide same overall exposure. Use Sunny f-16 in bright sun to photograph middletone subject regardless of what your meter says. You will get the best exposure by using the Sunny f-16 rule. Knowing this, you can test your meter and calibrate it if necessary. Go out on a clear sunny day. Set your camera on manual exposure mode. Set your ISO dial to the type of film you use most. It can be any ISO and you don't have to load any film. Set your f-stop to f-16. Now focus on a middletone subject that is frontlit and make sure it fills most of the viewfinder. An 18% gray card which can be purchased at any photo supplier is great for this test. You can also use the sky, green grass, or even your faded blue jeans. Change shutter speed and set it to the number closest to the ISO you set. For instance, if you set ISO dial to 100, your meter should read zero when shutter speed is set to 1/125 at f-16. If you get this reading, your meter is fine, otherwise you must calibrate it. If the meter does not zero, change ISO until it does. It doesn't matter which number you end up with. You may end up with ISO 200 or ISO 50 or any other number. Note this number and use it whenever you use the ISO you tested it for. If setting ISO to 200 gave zero reading with ISO 100, then you would set your ISO to 200 whenever using ISO 100 film. You should run this test with all film speeds you use. This has nothing to do with pushing or pulling films or film processing times. You simply corrected your meter. You can do this test if you have a separate hand meter. With incident light meters, hold the meter so the dome is pointed at the light. Set it to the shutter speed closest to the ISO you want to calibrate your meter to and take a reading. Meters have dials for calibration. If the meter does not give f-16, turn the dial to re-calibrate.

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    yep lennon! there was this quote.

    After more hard reading,
    am i right to conclude that,

    as long as i spot meter on a tone, it will be mid-tone?

    For eg, if i spot meter on a brown colour, if i move 1 stop down, it will become a darker brown?

    Thanks!

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    Originally posted by Wryer
    yep lennon! there was this quote.

    After more hard reading,
    am i right to conclude that,

    as long as i spot meter on a tone, it will be mid-tone?

    For eg, if i spot meter on a brown colour, if i move 1 stop down, it will become a darker brown?

    Thanks!

  12. #12
    Moderator ziploc's Avatar
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    Erm... "spot meter on a tone" does not make sense, because tone can be any tone, like highlight, mid tone, shadow, or anything in between. Turn to page 25 of your "Nature Photography Field Guide". There is a tonality chart there.

    The best way of metering on mid tone is to get a grey card. Otherwise, you can also learn to recognise what in our surroundings are mid tone (note it can be any color). And you got the spot meter part right: the technique will only work on spot and center weighted metering and won't work on matrix/evaluative.

    Hope that helps.

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    Ahh...yes!

    thanks ziploc!
    Think i missed the word mid-tone.

    But if i meter on the mid-tone, and move the stops in accordance to my preferance, what happens to the other tones in my frame?

    For eg, i spot meter on a beige colour, and i want it to be darker, so i move 1 stop down, what happens to the other colours (or tone, for that matter) in the frame? Will they become 1 stop down as well?

    Regards!

  14. #14
    Moderator ziploc's Avatar
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    Yes, everything will be 1 stop darker.

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    Oh i see...

    Thank you!

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