Sekonic L-398 is 1 stop off..

Discussion in 'Lighting' started by Cor, Apr 19, 2011.

  1. Cor

    Cor Member

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    I just got a second hand Sekonic L-398 (as a back up meter, since it does not batteries).

    Checking it against my other meters (a Gossen Luna Six Pro 6 and another smaller Gossen) and it seems to be 1 stop off (less sensitive) consistently (have to check taht further. This is in incident mode, reflective mode is less clear, but I am most interested in incident metering for this particular meter anyway.

    Not a big deal, one can adjust by dialing in say 50 ASA instead of the needed 100 ASA

    So do these big selenium cells get less light sensitive over time?

    thanks,

    Best,

    Cor
     
  2. Kevin Kehler

    Kevin Kehler Member

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    If the meter is heated (i.e. left in the car on a hot day), there are plenty of stories about the meter becoming less accurate. Have you calibrated it? Hold some black cloth over the dome and push the button - if it does not read 0, there is a small screw on the back you can turn to calibrate to 0.
     
  3. Cor

    Cor Member

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    Thanks for the feedback, Kevin. I did calibrate it, it needed a small adjustment (1/3 stop or so). What has happened with the meter I do not know, just got it second hand, but its in fine shape for it's age. Ít seems to be accurate , once I adjust it's asa speed, but further testing is needed to know for sure though.

    I now recall that you should keep it away from heat, thanks for reminding!

    I guess there is no way it could regain it's sensitivity?

    Best,

    Cor
     
  4. ic-racer

    ic-racer Member

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    In my experience selenium cell meters that are not accurate demonstrate a response that is difficult to correct. For example in bright light it may be 1.5 stops off, but in dim light it may be only 1/3 stop off. Did you check the Sekonic across the whole range with your Gossen?
     
  5. Cor

    Cor Member

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    Hi Ic,

    That's the plan indeed, last evening the light was getting to dim, I hope I have more of a change tonight!

    Thanks,

    Cor

     
  6. jerry lebens

    jerry lebens Member

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    It could be that your other gear isn't 100% accurate either, but you've compensated for the error (either knowingly or not) within your exposure/development regime. Say you were half a stop wrong with your other meters and half a stop wrong with your new meter... that adds up to a full stop very quickly.

    People who calibrate their exposure/dev regimes often forget that they may only be internally cohesive, and comparing it to another photographer's regime may throw up quite large differences.
    Regards
    Jerry
     
  7. Cor

    Cor Member

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    I am aware of possible faults adding, but if I can get the Sekonic in incident mode in line with my 2 Gossens (which seem quite consistent together) over a decent lighting level range, I would be happy..

    Best,

    Cor

     
  8. Kevin Kehler

    Kevin Kehler Member

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    I like to have a meter assigned to a camera - as in, when I am using camera X, I use meter A; when using camera Y, I use meter B, etc. This does limit the number of cameras one uses or the number of meters needed. The big issue is consistency: if your meter is wrong but consistently wrong, it doesn't matter since you quickly learn to adjust the settings on the meter; if your meter is wrong and not consistent in its' wrongness (as ic-racer mentioned), the meter is useless. At that point, either send the meter for servicing or get a new one.
     
  9. Diapositivo

    Diapositivo Member

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    Your meter might have a calibration screw and you should use that to align its readings with those of other lightmeters you use. If you use it both outdoor and indoor I would perform this alignment at no more than EV12 (1/125 f/5.6, 100 ISO) or probably less.
    If you use it mainly outdoors better to make the alignment at EV14.

    I would not rely on ISO fiddling for alignment as this is your backup light meter, you are going to use it rarely, and when you use it you might forget that you have to perform the ISO trick.

    If the calibration procedure does not allow you to align its response to that of the other two, then I think the instrument is unreliable and better no instrument than an unreliable one.

    Fabrizio
     
  10. Cor

    Cor Member

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    Hi Fabrizio,

    thanks for your feedback, I thought about that option too.

    You have to zero the meter by covering the dome and use the screw at the back to put the needle at zero. I could compensate the 1 stop difference by putting the needle one stop further, but I reasoned that I than will miss 1 EV (stop) from the total dynamic range.

    The different ISO setting is indeed a risk, which I hope to avoid by putting a small sticker right next to the ISO dial :whistling:

    The meter seems to be consistent over a normal range of lighting conditions when compared to my Gossen Lunasix Pro (within 1/3 -1/2 stop)