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  1. #1
    soyelmango's Avatar
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    Advice on Gossen lightmeter and sensitivity to invisible light

    It's been a minor saga with investing in a lightmeter for me.

    I bought a Gossen Digisix: small, cute, and best of all, it shows all f-stop/shutter combinations at once. However, it appeared to give inconsistent readings, compared to my friend's Sekonic 308B.

    I took it back to the very helpful staff at Jacobs (www.jacobs-photo.co.uk) and I upgraded to a Gossen Sixtomat Digital, thinking that it should be a better meter for the higher price. Indeed, it is: better build quality, and a good choice of exposure priorities, and a pseudo-analogue aperture scale.
    However, it was even more inconsistent, reading EVs of up to 4 stops higher than the Sekonic.
    Googling for any known issues with it, I came across this: click

    In short, Gossens are oversensitive to invisible light, which should lead to underexposure. I tend to shoot by artificial light - and I mean artificial colour-casting light, rather than temperature controlled lighting: see some of my work... click

    Given that I shoot in such conditions that would throw the Gossen off the trail, I'd appreciate any of your advice.
    As I do love the Sixtomat Digital and want to keep it, is there anything I can do to work around this "feature"?
    Or do I have to bite my lip, return the Sixtomat Digital, and buy my own Sekonic 308B?

    Regards,
    mango

  2. #2

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    Quote Originally Posted by soyelmango
    It's been a minor saga with investing in a lightmeter for me.

    Given that I shoot in such conditions that would throw the Gossen off the trail, I'd appreciate any of your advice.
    As I do love the Sixtomat Digital and want to keep it, is there anything I can do to work around this "feature"?
    Or do I have to bite my lip, return the Sixtomat Digital, and buy my own Sekonic 308B?

    Regards,
    mango
    I'm using Gossen meters since 1976 when I bought my first (used) Lunasix 3 (still working). Currently I own two Lunasix3, a Sixtomat digital, a Mastersix, a Pentax Spotmeter and a Soligor spot.

    I compared all these meters (after having them calibrated!) and found the results within 1/3 stops at all light levels, using light sources from sunlight over flourescent tubes to incandescent bulbs. I can't really believe that all Gossen meters are grossly off (and who says that the Sekonic is correct?).

    The main problem with low light photography and/or photography with monochromatic lights is the response of the film to the color of light and the Schwarzschild effect... there can be _real_ big differences in response to certain colors between different films.

    Martin

  3. #3
    Flotsam's Avatar
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    I have Digisix and have been impressed by it's consistancy. That is under daylight or quartz lights. I will keep your experience in mind when shooting under "natural" artificial light.
    That is called grain. It is supposed to be there.
    =Neal W.=

  4. #4
    soyelmango's Avatar
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    thanks for your feedback. I realise now that I should have been clearer on that point:

    I believed that the meters were inconsistent, but I was mistaken - the difference in reading was down to the amount of invisible infra-red light. This is evident when using a standard household light bulb (ie: little visible light, more infra-red light), especially if it is dimmed. The effect of a dimmed light reflecting off my red curtains gives a 4 stop difference!
    Considering that you want to expose for visible light, this is certainly a significant margin beyond what you'd normally bracket for.

    So, to reiterate:
    The meters are consistent in all cases.
    And they are accurate AND consistent in daylight.
    But, they are sensitive to the infra-red component of household lighting, which would lead to underexposure on normal film. This may not be much of an issue for those of you who shoot daylight or studio lighting, but I shoot under urban lighting and with normal lamps for the crazy colour.

    Who knows, such a 'feature' may be very useful for IR photography!

  5. #5
    Ed Sukach's Avatar
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    I wonder if this "over-sensitivity" is actually in the area of "Infra-red". Black and white film is generally (and not any where near "universally") less sensitive to visible red.

    I can seen one area where a "reduced" red sensitivty would be detrimental - that is in color photography, both C41 and E6. Color films are designed to have uniform sensitivity across the visible spectrum.

    I have become curious, though. I'll take a reading of a cold frying pan, with my Gossen Ultra-Pro, and compare it to a "hot" reading from the same pan.

    Come to think of it ... "hot" lights are realtively less common in studio work these days- the greatest majority is done with daylight-balanced strobe units. Gossen may have given up some "Black and white bias" to offer more accurate color response.
    Carpe erratum!!

    Ed Sukach, FFP.

  6. #6
    Ed Sukach's Avatar
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    Quote Originally Posted by soyelmango
    .. This is evident when using a standard household light bulb (ie: little visible light, more infra-red light), especially if it is dimmed.
    Uh ... I get your drift, but my tungsten bulbs produce quite a bit of visible light. That is what they are designed for.
    Carpe erratum!!

    Ed Sukach, FFP.



 

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