Fractional reading on Sekonic meter

Discussion in 'Lighting' started by tkamiya, Jan 14, 2011.

  1. tkamiya

    tkamiya Member

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    I'm confusing myself and the manual isn't all that helpful, so here's a question....

    On Sekonic meter (mine is 758DR), the display reads out 1/10th value. When set to F mode (aperture priority mode) and the meter reads T=4 and 9/10th and F = 5.6, does this mean it's proximately t=1/8th of a second and f/=5.6??

    My question isn't how T=4 means 1/4 second. It's about when fractions are displayed, how it translate to the shutter speed value.

    Assuming t=1/4 second and 9/10th is almost 1/8 second
    Does t=2s (note SECOND) and 9/10 is almost 4s or 1s?

    Is the fraction about MORE or LESS light in fraction or actual value displayed (with would be reciprocal in most instances as it's really 1/x for shutter speed and f/ itself is already a reciprocal.

    Argh....!
     
  2. RalphLambrecht

    RalphLambrecht Member

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    Strange. My Gossen always displays fixed timing increments, even in aperture mode. How else would you set the shutter?
     
  3. tkamiya

    tkamiya Member

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    Hi, Ralph....

    Mine does that too. In aperture priority mode, it displays 4, 2, 1, 1/2, 1/4, 1/8....1/60, 1/125, 1/250, etc.
    Along with it there is a 1/10th scale. 1/10th scale is right next to the aperture display but according to the manual, it refers to the shutter speed, not aperture. (in this mode)

    On Sekonic, 1/10th becomes 1/10th shutter speed (in stops) when in Aperture priority mode and the area dedicated to shutter speed only displays in fixed increments. My confusion is how to apply this fractions. Also, as we know, when we cross 1 second in + or - directions, the numerical value means opposite. How do we translate that? (I don't know how else to describe this)
     
  4. tkamiya

    tkamiya Member

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    I called Sekonic. Apparently, this means 9/10 OVER. (ie. meter is seeing more light)
    So 1/60 and 9/10 would mean almost 1/125
    and 4 second and 9/10 would mean almost 2 second

    and Sekonic support says I can also read this as fractional component to the f stop as well. Now thinking more clearly, that makes sense.
     
  5. CGW

    CGW Member

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    All display modes can be customized to display different increments of reading on my 558 and I suspect on the 758 as well. Check your manual's custom setting list for a setting that works best for you.
     
  6. Robert Hall

    Robert Hall Subscriber

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    tkamiya,

    you are correct. These meters were made for the studio and having 1/10th stop adjustments just help position lights.

    As I use mine with black and white film, 1/2 stop is close enough so that if I am over 5/10ths I just move the aperture to the appropriate setting.

    I have not found any way to make the display go to say 1/3rd stops, but I've not looked that hard either.
     
  7. Diapositivo

    Diapositivo Subscriber

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    Just to state the obvious, the meter gives you a reading, and a positive offset to that reading.

    If it says 1/125 at f/16, +5/10, that means 1/125 at f/16, "plus half a stop". How you compute this half stop, as aperture or shutter time, it is totally irrelevant.

    Normally though if you have an old-school lens you would certainly see this, in your mind, as an aperture modifier, because normally you can place aperture anywhere (they don't have to coincide with "clicks", you can close the diaphragm "1/3") whereas with shutter times you are not guaranteed how the shutter time works in intermediate positions between "clicks". Some shutters might even be damaged, maybe. Diaphragms, on the other hand, are 99% of the times designed to be closed "continuously"(*)

    So if the light meter tells you 1/125, f/11 plus 2/10, and you want to use exactly that value, you can set the aperture ring just a little bit past f/11.

    I agree the main use of 1/10th of stop is to check luminance rations, and even illumination of background, etc. in studio work. Otherwise makers would rather make lightmeters work in 1/3, or 1/2 of a stop.

    Fabrizio

    (*) This might not apply to your lens. Your mileage may vary. Do any experiment to your own risk. By reading this text, you acknowledge that no damage, present of future, will be claimed from its author. Etc. etc. etc.:getlost:
     
  8. tkamiya

    tkamiya Member

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    The tech support guy put it this way.

    "The meter is receiving light THAT much (tenth of stop reading) more than what shutter speed and aperture reading."

    That made it very clear to me. Why don't they say that in the manual.... for us beginners....
     
  9. benjiboy

    benjiboy Subscriber

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    It really Isn't rocket science I'm almost seventy two and I have no problem understanding the L-358, I have three digital light meters and find them all quicker to use and less liable to misinterpretation than the Gossen Profisix (Lunapro S.B.C), and Western Euromaster that I have since retired, I find they take some of the mental arithmatic out of calculating my exposures by being able to to remember up to nine readings and average them at the push of a button.
     
  10. Greg Davis

    Greg Davis Subscriber

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    Even though the manual states that the fraction is for shutter speed when in SS Priority, there is no reason you can't use it the same as 1/10 f/stop in Aperture Priority mode. Switch between modes and you get the same reading. In fact, until you posted this problem, I had never read that part stating the fraction referred to the shutter speed in that mode. If it says, f/5.6 .3, just set it 1/3 between 5.6 and 8.
     
  11. tkamiya

    tkamiya Member

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    Greg,

    I thought about this and came to conclusion that yes, indeed, they are the same thing. Since the measurement unit is stops in 10th, it doesn't matter if it refers to shutter speed or aperture. That is, we can adjust aperture by 0.3 stops by closing it or do the same with shutter speed by 0.3 stops by going faster.

    "that much more than indicated combination" expression really made sense to me.
     
  12. Greg Davis

    Greg Davis Subscriber

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    It's a great meter, I hope you enjoy yours.
     
  13. tkamiya

    tkamiya Member

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    Oh, yes. I am very pleased with my meter.