Problem with Sunny 16 Rule

Discussion in 'Photography Beginners' Forum' started by 70to210mmf4, Jun 27, 2019.

  1. webestang64

    webestang64 Been spending a lot of time on here!

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    Yep, I meant stop. And this method is for film (the OP said film), not digital.


     
  2. 70to210mmf4

    70to210mmf4 TPF Noob!

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    I thought the whole point of the sunny 16 rule is that you're guaranteed a good estimate if you follow the rule on a bright, sunny day. All the parameters were correct: it was taken in bright sun with the correct aperture and shutter settings. I was using the digital camera to understand why my film camera (which was set to aperture priority mode and uses centre weighted average) was giving me such bad results. It seems that I'm about 2-3 stops underexposed and I'm just confused why the so called "rule" is so far away from the expected result. I understand that it's a starting point, but I would have expected it to at least have been close to the correct exposure since all the settings and light conditions were correct.
     
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  3. Derrel

    Derrel Mr. Rain Cloud

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    You are assuming that f/16 is REALLY f/16...around the size of a BB...if the aperture mechanism is sloppy/old/out of calibration, 1 mm too small in width x 3.14 = a significant under-exposure. Shutter speeds with electronically-timed shutters are usually accurate, but lens diaphragms are not always accurate. Also..f /stop is a purely mathematical relationship...The T-stop, for acual transmission, is the movie industry standard for accurate metering. Imagine a 17 to 21-element zoom that loses 8/10 of a stop of light transmission, combined.with a slightly out-of-calibration diaphragm..the difference between actual T-stop and "nominal" might be f/27 or f/32...

    Imagine an oven temp. dial that says 375, but the oven is really 320...not close, over a 60-min roast cook time...

    There is also the possibility of user error..wrong ISO set, wrong speed set. etc..
     
    Last edited: Jun 29, 2019
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  4. dxqcanada

    dxqcanada Been spending a lot of time on here!

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    Ok, how about the Sunny 48 rule (I just made it up ...)?

    ISO x 4 = 1/shutter speed @ f/8

    100 ISo
    1/400s
    f/8
     
  5. dxqcanada

    dxqcanada Been spending a lot of time on here!

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    I've used the Sunny 16 rule when I have lost the ability to use an electronic light meter ... and it has always given me an exposure that is usable (meaning the image/negative can be adjusted within acceptable limits).
     
  6. 70to210mmf4

    70to210mmf4 TPF Noob!

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    The settings are definitely right: I can see it in the raw metadata. But what you're saying about the mechanism is quite possible: both cameras are second hand (Olympus OM-D Mk I and and old Ricoh film camera). Maybe I just need to accept that these cameras will always be a couple of stops under what I would normally expect.
     
  7. Derrel

    Derrel Mr. Rain Cloud

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    AT the smallest apertures like f/22 and f/16. if f/16 is 1mm off in width, the combo is off by a HUGE under-exposure. If the lens has a transmission deficiency of 8/10 of a stop and the aperture is off, at f/16, the error is BIG. I looked at the metadata...all as you stated..but the HISTOGRAM is the definitive code.

    And the Raw data must be interpreted...the raw file could have been brightened quite a bit... like saying, "My steak was bloody !" well....how long was it cooked?
     
  8. AlanKlein

    AlanKlein No longer a newbie, moving up!

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    The f/16 "rule" works as an estimate between 10am-2pm when the sun is high. The sun's power drops off beyond those hours. The (added=long) shadows on your picture seem to indicate that you shot way before or way after the midday hours. So f/16 would be too dark. Note that f/16 is also effected by what time of year and latitude of where you are in the world. The sun is lower or higher in the sky depending on these things as well. So the light received by the earth will be less or more depending on those conditions.

    You also didn't say what type of film you used or how you digitize the image that we see on the web. Did it come from a scan of the photo print or was it a scan of the film? Was it a negative or positive film? How did you scan to get the image? Did you have settings on the scanner set to what? Was it post processed?

    Whatever you did, I would recommend you use a meter to eliminate so many variables you face with the f/16 estimate.
     
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  9. Derrel

    Derrel Mr. Rain Cloud

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    does step = stops

    STEP is sometimes used.

    TO the pedantic, f/stops are s_t_o_p_s

    and shutter speeds represent steps.

    Sometimes we can use the term EV, to refer to either one stop more light from one f/stop wider, OR from one speed slower.
     
  10. 480sparky

    480sparky Chief Free Electron Relocator Supporting Member

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    That's my point.
     
  11. limr

    limr Moderator Staff Member Supporting Member

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    OP said he tried again with his digital camera and it also came out underexposed. He posted the digital image, not the film image.

    OP - as others have said, Sunny 16 is a starting point. Just because it's sunny out doesn't mean it there's enough light to shoot at f16 with shutter speed matching ISO. Yes, the time of day matters, as does location and season. Light is very often weaker than the eye perceives. You're also shooting dark objects, which can eat light, just the same as snow will reflect light and require much less exposure.

    If I were shooting that scene, I would probably have opened it up 2 stops.

    It takes practice to figure out. Once you're used to it, it can be a reliable way to eyeball and meter a scene, but nothing is guaranteed, just like an electronic meter doesn't always give you the exposure you want.
     
  12. 70to210mmf4

    70to210mmf4 TPF Noob!

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    I think there is some confusion. The image I posted was from a digital camera, using the settings recommended by the sunny 16 rule. The light meter indicated it was about 3 stops underexposed although it was a bright sunny day and I was using ISO 200 @ f/16 and 1/200 shutter. I was cross-checking because I'd previously used a film camera in the same location under the same conditions but also got underexposed images.
     

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