Another meter question???

Discussion in 'Lighting' started by stradibarrius, Feb 5, 2011.

  1. stradibarrius

    stradibarrius Member

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    I have an old analogue Gossen Luna-Pro F and just got a new Gossen DigiPro F yesterday. I am trying to learn how to use the meter effectively so please try to understand the question.

    I set out taking reading in different places comparing the reading in the "Incident" mode.
    The two meters surprisingly give the same readings. I also used My Nikon F4, F100 Bronica ETRS and my NIkon D300 to compare the reading with the meters. I would then take the shot with the digital for instant feedback and see if ti was correctly exposed.

    When I set the DigiPro F to f/5.6 and take a reading the meter shows the f/stop in 1/10 of a stop so the reading would be f/5.6 and the a small number showing the tenths over f/5.6.
    Is there a way to Make the meter read exactly f/5.6 without showing the tents of a stop?
    The problem is when the DigiPro-F reads 5.6 plus 6/10s of a stop, for example, it produces a shot that is overexposed. If I change the meters aperture setting it give a reading of f/4 and 6/10s and also changes the shutter speed...

    I hope this question makes sense????
     
  2. Q.G.

    Q.G. Inactive

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    The meter displays what you should use for the 'perfect' exposure.
    Why would you want to ignore the information it provides, that a full f-stop setting is not quite it, and you need to open up or close the aperture more to get that 'perfect' exposure?

    Did you set those fractional f-stops (or nearest possible setting) on your digicamera when testing?
     
  3. stradibarrius

    stradibarrius Member

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    Yes I did use the fractional setting with my digital but I am not really interested in my digital. My RB67 does not have fractional settings. Neither does my M645 or ETRS. The only film camera, I have, that has fractional settings is my F100.
    How do I correctly use the information given by the meter when my cameras will not adjust to such precise settings? If the meter has a f/stop reading that is 5/10 or higher should I adjust my reading to the next higher stop? Conversely if the reading is 5/10 or lower should I adjust to the next lower stop?

    Do all the digital meters read in fractions of f/stops?
     
  4. Q.G.

    Q.G. Inactive

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    Your cameras will allow setting apertures in at least half, possibly 1/3 stops settings.
    Even with 'only' 1/2 stop settings, you will never be off more than 2/10 of a stop. Close enough.

    So you just round the reading the meter gives to the nearest settable setting, keeping in mind the old thingy that negative film likes overexposure better, slide film underexposure better than the other thing.

    And yes, all the digital meters give readings in at least 1/3, most in 1/10 stop steps.
    You want metering devices to give accurate readings, after all.
    :wink:

    Analog meters do the same, by the way. Their meter needles don't treat the scale as only having full stop positions they can move to, but will happily move to any position in between.
     
  5. stradibarrius

    stradibarrius Member

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    Thanks!
     
  6. stradibarrius

    stradibarrius Member

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    I started a different thread asking a specific question about the Gossen DigiPro-F. Help if you can.
     
  7. cowanw

    cowanw Member

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    I am a bit puzzled why the example would lead to overexposure as 5.6 + 6/10's is closer to f8 and less exposure.
     
  8. markbarendt

    markbarendt Subscriber

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    What mode is the meter in?

    If it is in Shutter Priority mode it will display fractional/decimal F-stops. That's the only way it can get it right.

    Aperture Priority mode will/should keep a constant F-stop (i.e. exactly f/5.6) and time will instead float to get it right.
     
  9. Q.G.

    Q.G. Inactive

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    If you would ignore the decimal bit, set f/5.6 instead of f/5.6 + 0.6, you'd be overexposing by 0.6 of a stop.
     
  10. wiltw

    wiltw Subscriber

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    If you use the AE Prism of the ETRS, it sets shutter speed with 1/3EV increments; the AE-II Prism sets shutter speed with 1/6EV increments.

    And the PE lenses allow the meter to detect 1/2EV settings of the aperture.
     
  11. John Koehrer

    John Koehrer Subscriber

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    I agree, in A priority it should stay where you put it. Is there a bit of (+.10) compensation dialed in?

    Following along this line of thought, you should be able to choose whether you want 1/10 or 1/3 stop displayed.
     
  12. stradibarrius

    stradibarrius Member

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    In aperture priority it does not allow you to set exactly 5.6...it also gives the 0.0f as well. I can set it to f/5.6 but it reads f/5.6 + x/10. I would have thought that it would show the the over or under by increasing/decreasing the shuuter speed???
    I guess that is just one of the peculiarities of this meter...
     
  13. jerry lebens

    jerry lebens Member

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    Firstly, stop comparing meters. It's good to know that they're in the same ball park - but unless you intend to use two meters (why?) they will tend to give slightly different results. Not because either is wrong, just because they're unlikely to be perfectly matched and absolutely accurate. Stick with one meter and your metering regime will become more consistent.

    Second, stop comparing digital exposures to analogue exposures, they aren't the same animal.

    Think of it this way : With (negative type) films you should err towards overexposure because a little too much film density is easier to print than no density : With digital (and transparency film) you should err towards underexposure, because overexposure in digital means unmanageable highlights.

    The dynamic of 'a good exposure', then, depends on what film material/sensor you're using. Thus, if you use a digital camera to assess the exposures for B&W film, you run the risk of losing valuable information in the shadow details of the film.

    Regards
    Jerry
     
  14. stradibarrius

    stradibarrius Member

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    I don't know what you are talking about???? I think you need to re-read this entire thread.
     
  15. MattKing

    MattKing Subscriber

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    Barry:

    This is a guess ...

    It may be that this approach to aperture priority is a reflection of the fact that many cameras don't permit you to set intermediate shutter speeds, but do permit you to set intermediate apertures.

    So if you ask the meter to give you a useful reading near as possible to f/5.6, it may be recommending:
    1) a shutter speed easily set on most cameras, plus
    2) the necessary less-than-one stop adjustment to your preferred aperture.

    Hope this helps.
     
  16. jerry lebens

    jerry lebens Member

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    I may not be expressing myself well but, if I understood your OP correctly, what I'm saying is relevant to your original question.

    If you use a digital camera to asses a light meter, which you later use for metering negative type film, the opposing dynamics of the two systems will tend to work against each other and thus may be the cause of poor exposures.

    Using a digital camera to asses meter readings for neg stock is like running and trying to touch the hand of someone who's running at you from the other direction. It's easier if the person is standing still and easier again if they're running alongside you.

    To put it in a purely film context. When I used to shoot Polaroid (essentially a transparency material) to proof advertising images that were later to be shot on negative film, I'd use compensation factors to compensate for the opposing dynamics of the different materials. If I'd shot at the same exposure, it would have been wrong.

    Regards
    Jerry
     
  17. stradibarrius

    stradibarrius Member

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    Matt, I think you may be right. I can certainly use the new meter and I really like it so far. I was just curious if I was missing something. I read and re-read the manual and it made no mention of how to change the "A" priority choices.
    thanks for the information.
     
  18. MattKing

    MattKing Subscriber

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    Barry:

    I've now read the manual too :smile:

    It appears that the applicable section is:

    3.2.5 Aperture priority mode
    · Select f with the function buttons
    · Set the desired aperture with the value buttons. The intermediate
    1/10 stop values stored from the last measurement appear when
    the aperture is preset. These are not valid, because the valid and
    actual 1/10th stops will only appear after the next meter reading is
    taken.
    · Measure by pressing the meas. button M
    · The measured shutter speed appears in the right-hand digital display
    Automatic adaptation of the aperture in 1/10 stops to the measured shutter speed
    · Select other paired aperture/shutter values with the value buttons.


    I think that the portion I've highlighted above is the one that deals with this.

    I wonder if this is clearer in the German version of the manual (here is the link: http://www.gossen-photo.de/pdf/ba_digipro_d.pdf)

    Have fun with your meter!
     
  19. markbarendt

    markbarendt Subscriber

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    I found and read the manual too Barry.

    Same conclusion.

    Some meters like my Sekonic have dip switches that can reprogram the meter but doesn't look like the digipro has that.
     
  20. Q.G.

    Q.G. Inactive

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    I wouldn't worry about whether the thing gives readings in 1/3 or 1/10 stops.
    It's easy enough to round either to the nearest 'setable' aperture setting, whether that be in 1/3 or 1/2 stops.
     
  21. stradibarrius

    stradibarrius Member

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    I agree. I was just asking if there was a setting that I didn't see in the manual.