Is my incident meter correct?

Discussion in 'Miscellaneous Equipment' started by marcmarc, Feb 25, 2013.

  1. marcmarc

    marcmarc Member

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    Hi Everyone,
    I've been using a Sekonic L508 for years. I've noticed that it reads 1/2 stop slow when comparing it to "sunny 16" i.e. it will read f16 and 1/2 at 1/125 rather then an even 16 when I use FP4. However, when I take the iso down to 100, it then reads an even f16 at 1/125. The difference between iso 125 and 100 is about 1/3 of a stop correct? So is my meter under exposing? I normally down rate my film at half the box speed anyways but still my negs look a little thin in the shadows. Thanks for replies.
    Regard,
    Marc
     
  2. nicholai

    nicholai Member

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    To my best knowledge, sunny 16 applies to ISO 100, so your meter should be good?
     
  3. markbarendt

    markbarendt Subscriber

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    Couple thoughts.

    Your negatives are only thin in the shadows if they don't let you print the shadow detail you want, how does it look on paper?

    Sunny 16 assumes a front lit subject, if the subject is instead cross lit, backlit, or the sun is really high in the sky, like a Lahaina Noon where the sun is directly overhead the meter should indicate differently.
     
  4. Jim Noel

    Jim Noel Member

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    Sunny 16 applies to films of any speed.
    It is not unusual for a meter whether incident or reflective to disagree with it. Like all other rules in photography, rules are meant to be broken. Clouds, atmospheric haze, smog and other abnormalities in the air will alter the amount of light falling on the subject. If your negatives please you, don't worry about the meter. If the readings are close to the Sunny 16 rule you are OK. If it begins to vary a lot then you need to worry about it.
     
  5. benjiboy

    benjiboy Subscriber

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    The Sekonic L508 light meter is more likely to be accurate than your sunny sixteen.
     
  6. Chan Tran

    Chan Tran Member

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    My meter would read f/11 and 2/3 @ 1/125 with ISO 100.
     
  7. marcmarc

    marcmarc Member

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    Thanks for the quick replies. I always side with the meter and my thin negs could just be shutter variances of course. Here in LA where it's mostly bright and sunny throughout the year, sunny 16 I figured would be a starting point to see of my meter might be off.
     
  8. marcmarc

    marcmarc Member

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    I forgot to add that this meter has been around the block quite a bit and has been dropped once or twice so I have no idea if something has been knocked loose which may affect its reading.
     
  9. Marc B.

    Marc B. Member

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    Speaking of light meters, living in the LA/Hollywood area, you're lucky.
    Contact the folks at 'Quality Light Metric' for light meter repairs/calibration.
    Word has it, they do a lot of work on photog's meters at the studios.


    Quality Light Metric Co
    7095 Hollywood Blvd # 550
    Los Angeles, California 90028


    Ph# (323) 467-2265
     
  10. Peltigera

    Peltigera Member

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    If Sunny 16 were both accurate and reliable, no one would use a meter, would they? If the meter was several stops away from Sunny 16 I might worry but not for part of a stop.

    Also, in LA, I would expect Sunny 16 to overexpose somewhat as "sunny" is going to be a lot brighter than in a northern state or in Europe.
     
  11. marcmarc

    marcmarc Member

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    Thanks for the additional replies Marc B and Peltigera. I'll contact Quality Light Metric just to be safe. If my meter checks out OK, then I know it's a shutter variance.
     
  12. BrianShaw

    BrianShaw Member

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    There are many factors, a lot of which have been already mentioned, that makes Sunny-16 only approximate. It isn't just shutter variation that will cause what you are experiencing. But getting shutters checked is as easy (maybe even easier) than getting your light meter checked.

    Check this out for more details on exposure approximation factors:
    http://www.apug.org/forums/viewpost.php?p=1283800
     
  13. benjiboy

    benjiboy Subscriber

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    Or failure of your sunny sixteen guestimate.
     
  14. George Collier

    George Collier Member

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    To benjiboy's point - I think the sunny 16's biggest variation is in our own judgement of the conditions - the only sure condition is "bright sun", as soon as there are clouds, the conditions get gray (pun intended).
    As an inappropriate aside, the other day (I was using a d*****l camera) I was shooting in an empty church, lights low to balance intensity with late afternoon window lighting. ASA was 200, I was exposing manually with a 28PC Nikkor. Took a reading with my trusty old Sekonic L-398 Studio. The exposure was f/16 at 5 seconds, and although I had expected to make an adjustment, the image was perfect.
    As a variation on Deming's well known saying, "In incident we trust, all others be careful."
     
  15. Jim Noel

    Jim Noel Member

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    I live in San Diego.
    Through testing I have discovered that except during Santa Ana winds, it is closer to Sunny f11, than Sunny f 16.
    As several have said, it is only a ball park estimate at best.
     
  16. Poisson Du Jour

    Poisson Du Jour Member

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    The Sunny 16 rule is an approximation only, at best, an estimation which must be used with experience.

    BTW, is the meter set to 0.3 or 0.5 stop reading in its custom functions? Customised readout is one of the biggest causes of confusion with Sekonics because there is no visible warning on the display that a core metric has been altered, other than to realise the exposure steps at wider or narrower. Having said that, it is most unlikely that the Sekonic is at error with its metering: it is very fine and precise instrument. People really should move on from these cute, clubby, "rules of thumb" that only provide for increasing risk and failure and not refinement of metering technique that is so much a calling when armed with a Sekonic.
     
  17. John Koehrer

    John Koehrer Subscriber

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    Another factor to consider is your EI. if you haven't determined it. the film/developer/exposure combination can be off too.
    Rather than equipment problems I'd consider exposure/development first. If the exposure is consistently a bit under It may be you're using too high a film speed.

    As far as Sunny 16 being an approximation. so is any system is until tested and proven.
     
  18. cliveh

    cliveh Subscriber

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    Without experience of using your meter with camera/ lighting ratio of what you photograph and the processed shots you produce, I would suggest this is an impossible question to answer.
     
  19. benjiboy

    benjiboy Subscriber

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    I've always thought George that the human eye is a very poor instrument for judging changes in light intensity because it reacts to changes so imperceptibly without the person noticing them.