Exposure meter variation

Discussion in 'Exposure Discussion' started by maisiemouse, Mar 28, 2006.

  1. maisiemouse

    maisiemouse Member

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    I recently bought a Bronica SQA kit to wean myself off digital cameras. So far I've only shot in B&W, and I develop all my own film. I use a Sekonic 308 for metering, but I've found it consistently underexposes when compared to other metering methods (various Nikon SLR's). I know I can make a mental adjustment after taking a meter reading to compensate for the underexposure, but when I'm trying to sort out filter factors/metering shadow areas/contrast etc I get hopelessly confused and often miss the shot I want.

    The question is - can I get a more reliable meter, or one that can be calibrated? Can non-digital meters be adjusted in any way? Can the Sekonic 308 be internally tweaked?

    Ok, that's 4 questions. Sorry.

    Sean
     
  2. Nick Zentena

    Nick Zentena Member

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    The first question is the 308 really having problems? It might be metering methods. If it is having problems you could send it in to be fixed. I've no idea who does that in the UK. The 358 has various adjustments. I assume the 308 has similar range of adjustments. But user adjustments are only good if the meter is always screwing up by the same amount.

    I'm not sure what you mean by non-digital meters. The 308 is a digital meter.

    I think it might help if you described how you're using the 308.
     
  3. Lee Shively

    Lee Shively Member

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    Meters can vary in their readings. If yours can be manually adjusted by some means, you can set it to agree with another meter that gives a consistent reading that you consider correct. If not, you'll have to adjust the ISO dial and make note of how "off" it is. Since it's consistently underexposing by the same amount, you can work around the inaccuracy.
     
  4. maisiemouse

    maisiemouse Member

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    Thanks for the replies. I'm using the 308 to take reflected light readings. I don't think there's any way to make adjustments on the meter (at least not without taking it apart).

    When I said non-digital meters, I meant the needle pointer type (ie Weston Master). Sorry if that was confusing.

    Sean
     
  5. John Koehrer

    John Koehrer Subscriber

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    The differences may just be the field of view that the meters are seeing.
    This will change with different focal length lenses on the slr.
    Most older Nikons use a 60/40 combination where 60% of the reading is from the larger circle in the finder & 40% from the area outside it.
    The sekonic sees only a fixed angle, so to get a more precise value, you may have to walk up to a subject to get an accurate reading.
    Also if you are directing the Sekonic towards the sky it will influence the reading towards underexposure.
    You don't have the incdent ball over the sensor do you? that would certainly affect readings too.
     
  6. maisiemouse

    maisiemouse Member

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    John

    I used an F4, F80, D70 and Fuji S2 to check the meter, all of which were in their 'matrix' metering modes (ie. not centre weighted or Spot). I chose not to use my partner's FE, as I was aware that the metering was centre weighted (although I didn't know the exact ratio - thanks for the info). I used the same lens for all tests (Nikon 50mm 1.8) to try and give the results some consistency. I assume that a 'standard' lens is the right one to use, as I would guess that the meter is tuned for a normal field of view.

    However, this has got me thinking - there's no reason I can't use the D70 or S2 as a fancy light meter. It would be good to blow the dust off them once in a while, as they've not had much use since I got the Bronica :smile:

    Thanks again for the help

    Sean
     
  7. TheFlyingCamera

    TheFlyingCamera Membership Council Council

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    IIRC, when you open up the battery compartment of the 308 (I had one some years ago so I forget exactly), there should be a little dial that you can set with an eyeglasses screwdriver to calibrate the meter. You would turn it one direction to adjust for underexposure, the other for overexposure.

    When you say it consistently underexposes, by how much does it vary from the meter in your D70?

    Make certain that you are orienting the meter in a purely vertical orientation, perpendicular to the ground, or at least parallel to your film plane. It is a great little meter and very easy to work with.
     
  8. Buster6X6

    Buster6X6 Member

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    maisiemouse
    Sekonic has a web site and forum to discus problems you have, I am not sure if is Mamiya.com or Sekonic.com
    Hope this helps

    Greg
     
  9. manjo

    manjo Member

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    I believe you should compare the reading from your light meter with that of a known light meter. That will get the light meter out of the equation. The you should evaluate your metering techniques. Also make sure your camera (back) is set to the correct ISO, or is the back bad ? have you tried a differnt back and checked if the iso readings the camera back is transmitting is correct ? I got a soligor 1degree spotmeter and got it calibrated. you might want to borrow a light meter from a friend and try that. But I suspect that the ISO dial on your back is set to the wrong ISO speed or it is mis-behaving.
     
  10. maisiemouse

    maisiemouse Member

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    Wow - loads of answers, loads of things to try. I haven't taken the Sekonic apart yet, but I will if I can't sort it any other way.

    The underexposure is pretty constant at 1 stop. I generally meter with the back of the Sekonic held lightly against the lens hood of the camera to ensure it's in the correct plane as the film, and pointing in the same direction.

    Manjo - does the ISO setting on the film back make any difference? I generally leave it set correctly (so far I've only put FP4 through it so I don't need to change the settings). But should it affect the exposure at all if I'm not using a metering prism on the camera?

    I may take the meter into a local dealer and compare it to theirs, although my local branches of Jessops don't cater for film users any more. Indeed they managed to scrape together exactly 1 roll of Pan F between them recently - "not much call for it round here Guv'nor"

    Thanks again for the help - it's appreciated.

    Sean
     
  11. Bob F.

    Bob F. Member

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    You may be getting too much sky in the meter reading. To avoid this while testing, take it indoors where the lighting is even and see what it reads against an evenly lit wall compared to your cameras. Alternately, use it outside in incident mode and see what you get then. I use a Soligor spot meter for general work, but have a 308 for flash use and they seem to agree fairly closely (about 1/3 of a stop IIRC).

    Good luck! Bob.
     
  12. Hlop

    Hlop Member

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    Hi Everyone!

    maisiemouse, I'd try to compare 308 with center weighted metering of FE because it isn't that smart as matrix metering. I'm sure it's closer to center weighted meter with 80/20 combination

    Also, as been suggested I'd try more fair comparison and take reading from grey card or white list of paper. You should be careful about an angle - different light reflection angles can cause different readings even from the same meter

    Hope this helps
     
  13. Soeren

    Soeren Member

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    Untill now it's been talk about comparison in readings as far as I read it.
    I would like to know if your negs actually are underexposed by 1 stop ?
    As mentioned it could be your way of making the readings and you may have to adjust your ISO settings for that. I have the Sekonic 308 and it is spot on compared to my Nikons metered of a greycard. I havn't noticed whether it is possible to adjust my meter. I have heard (rumour allert) about photographers making dots on the dome using a speedmarker to adjust the incident light metering.
    You also mention filterfactors, well if you don't want to calculate or make tables the only option is the metered prism. The ISO settings on your filmback don't matter when you are not using the metered prism.
    Cheers Søren
     
  14. John Koehrer

    John Koehrer Subscriber

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    Sean
    I would suspect metering technique if you're holding the meter against the lens hood. I think you're overthinking the angle of acceptance of the meter.
    There have been a number of threads about having too many meters to compare. If you consider the 308 as your standard & expose/process film to a proper density using the 308 you'll be fine. Comparing it too several different cameras will drive you bonkers. It's all about determining your EI with a given film.