1. avisonjohn

    avisonjohn

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    Hi all.

    Having some trouble working out how to correctly use a light meter in a particular situation.

    I wont go into the particulars, but I sometimes have to shoot a subject through glass which has a dark tint to it.

    In normal situations in a studio, I can use a light meter to determine the correct SS/A/ISO to use.

    In this situation, the camera is behind the glass, but the strobe is not.

    I cant use a light meter as the meter will not account for the fact that the camera is behind the glass - let's just assume the glass is an ND filter with a unknown stop value and varies from glass to glass

    Can anybody think of a way I can use a light meter in this scenario?

    Maybe I could work out the stop value of the glass (nd filter) and adjust accordingly? If so, how would I determine the value of the glass?
     
  2. MatBin

    MatBin

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    When you say light meter do you mean the one in the camera or hand held external meter How about an external flash meter behind the glass (next to the camera) which would then meter for the actual amount of light falling into your sensor/film.
     
  3. Phil V

    Phil V

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    2 off the top of my head

    1 use the meter as a reflective meter.

    2. Do a measurement with the light behind the glass to determine its strength as an ND filter.
     
  4. mike weeks

    mike weeks

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    some meters such as the 858 give you the ability to dial in ND filters but simply meter, take a shot and adjust until you know how much light you are losing and repeat

    Mike
     
  5. avisonjohn

    avisonjohn

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    Well I have the Sekonic L308 light meter but dont mind using either that or the camera's built in meter.
    If I were to use the sekonic meter next to the camera, how would I go about that?
    I've never metered that way before so not sure if it would be the same process as when metering next to the subject ot not, or if I would need to make adjustments to either the measurement or the meter.


    1. Never used it as a reflective meter before - will dig out the instruction manual and have a look at that.
    2. This would work for me - but never done this before. How would I work out the strength as an ND filter? Are there any tutorials that you know of which I could look at?


    Thank you - I'll see if the L308 has this feature
     
  6. Phil V

    Phil V

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    Place the light and the meter at a fixed distance, test.

    Place the Nd filter between the 2, test again.

    The number of stops difference is your ND strength.
     
    Scooter likes this.
  7. avisonjohn

    avisonjohn

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    Seems
    Seems so obvious now :) Thank you
     
  8. HoppyUK

    HoppyUK

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    Take a shot, check LCD and histogram, adjust as necessary. Then you know it's right :)
     
    Bobsyeruncle likes this.
  9. DG Phototraining

    DG Phototraining Woof

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    Beat me to the "obvious" solution, which seemingly isn't that obvious :)

    Dave
     

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