watt seconds and meter readings low

Discussion in 'Lighting' started by djkloss, Jun 8, 2006.

  1. djkloss

    djkloss Subscriber

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    I'm new at this and have no clue on flash / studio lighting. My question is ... with 1400 watt seconds how much light should I be getting from my flash meter reading? Is that (1400 ws) relativlely low? That would be 700 each. I'm using two units w/bounce umbrellas at about 5 ft from my subject. My readings are very consistent at about 1/8th second at about f/2.8. Walls are dark paneling, carpet is dark blue, subject is dark brown, film speed is 100. This is just a test - nothing major. It just seems as though I'm not getting much of a reading. I expected more from studio lights. Camera to subject was 6 ft. Is this normal for this power supply? Its a brownline.

    Thanks!

    Dorothy
     
  2. blansky

    blansky Subscriber

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    Are you using a flashmeter?

    At that distance 5 feet, you should be getting F8 or F11 at about 200-300 ws.

    If you're using a leaf shutter, set it at maybe 125 or 250 of a second, unless you want to pick up some ambient room light.

    I use a soft box as a main light at about 3-4 feet and am at less that 300ws and F81/2 at 125. (125asa)

    With my lights and an unbrella at 600ws at 12 feet it's still 5.6, so something is not right.

    Michael
     
  3. JBrunner

    JBrunner Moderator Staff Member Moderator

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    Yes, something is not right, that 2.8-1/8 sounds more like a reading of the rooms ambient level, or nearly so. I would suspect the meter is not syncing to the flash correctly.
     
  4. djkloss

    djkloss Subscriber

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    I'm using a Gossen flash meter and tried it both with reflective reading and incident. With just the modeling lights i got a reading of 1/8 sec @ f/5.6.
     
  5. blansky

    blansky Subscriber

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    Do you have the flashmeter set to "flash". Is the sync cord attached to the meter?

    You take the sync cord running from the lights to the camera and use it on the flashmeter until you get the settings then attach it back on the camera.

    It does sound like you're just getting a reading of ambient light.

    I think with that meter you only use incident (for flash) and point the dome at the light but close to the face.




    Michael
     
  6. djkloss

    djkloss Subscriber

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    If I used a bigger reflector would that help?
     
  7. blansky

    blansky Subscriber

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    No something is fundamentally wrong.

    You need to plug the sync into the flashmeter and push the button to flash the lights, that is the reading you need.

    700 ws is way too much light for what you described. With that much light you would be at f22 and 125 of a second

    Michael
     
  8. djkloss

    djkloss Subscriber

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    My meter is set to flash, but there's no where to plug in a cord on the meter. I plug the sync cord into the power supply and the lights into the power supply. I pointed the incident reading at the camera, close to the subject, and with reflective, held the meter next to the camera...
     
  9. djkloss

    djkloss Subscriber

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    I trigger the flash with one hand using a spare camera body (sync from camera to power supply) and with the other hand take a reading
     
  10. Paul Sorensen

    Paul Sorensen Member

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    My flash meter (a really cheesy Quantum) has a setting where you press a button and have a few seconds to manually trigger the flash. Perhaps you are pressing the wrong button and only getting an ambient reading. I imagine that your Gossen should have that capability. Which model is it? Maybe we can hunt down a manual on the net that will help.
     
  11. blansky

    blansky Subscriber

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    What is the model of the meter. You say you are using a speedotron brownline?

    I've never used them but if nobody here knows, contact a pro camera place and describe what you are doing. There needs to be a way to trigger the lights to get your reading.

    Even if you can't plug into that particular meter, there must be a speedotron trigger you can plug into the sync and have a ten foot cord so you stand at the subject, and can trigger and get your reading at the same time.

    Michael
     
  12. djkloss

    djkloss Subscriber

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    Thanks Paul, I already have the manual and there is a button on the side - one for flash and one for ambient. I'm using the right setting. Its a Luna Pro F - a pretty good meter - I like it. Lightning bolt for flash & sun for ambient.
     
  13. djkloss

    djkloss Subscriber

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    Gossen Luna Pro F
    Speedotron D1402
    I triggered the flash with a 6 ft cord connected from camera to powersupply (camera in one hand) and meter in the other hand (incident)

    Ok, what about the wattage of the flash bulbs themselves? I don't know what they are. I know they're supposed to be lower than the pwr supply
     
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  15. JBrunner

    JBrunner Moderator Staff Member Moderator

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    Ok I read up (sideways) on the closest thing to this meter I could find-here-

    http://www.gossen-photo.de/pdf/ba_lunasixf_e.pdf

    If your meter operates the same (it probably does) you have to set the meter to flash, then depress, and release the meter button, then trigger the flash, then calculate the reading using your chosen ASA and 1/60 of a second as your shutter speed. So you push and release the button first, then trigger the flash. Theoretically, at least thats how I read it. No sync needed. Never seen this before. But I live in Utah :smile: If that doesn't do it, IDK.
     
  16. blansky

    blansky Subscriber

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    If the power supply is 1400ws like you mentioned that is the power available to you. If you use one head, I think you can get 1400ws out of it.(not sure) It depends on what the head can handle. It should say on the back.

    If you use 2 heads there should be a way on the power pack to configure what you want to go to each head.

    The ws numbers apply to the flash not the modeling lights. Those are probably adjustable on the power pack but they are only for your convenience to see where the light is going and to show you approximately what the picture would look like.

    Like I said, for what you described, 5 feet etc, you should only need about 2-300 ws for a f8-11 at 125 of a second.

    All power packs are different and configure differently and you probably need the instructions or someone who is familiar with them to understand their capabilities fully.


    Michael
     
  17. Nick Zentena

    Nick Zentena Member

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    Don't know about the brownline but I think most of the blackline bulbs are 3200ws. That's more then any of the packs puts out to the head. Makes sense you don't want to blow a bulb.

    Why not go back and try with just one head plugged in?

    http://www.speedotron.com/BrnInst.htm#anchor2

    "MW3 and M90 series (non-"Q") light units have a maximum rating of 400Ws, while "Q" versions are rated at 1200Ws. M11 light units are rated at 1200Ws (the new MW9H flash tubes supplied with M11 light units handle up to 1200Ws; MW9M flash tubes have a maximum capacity of 1000Ws.) and M11Q light units are rated at 2400Ws."

    "D1204 Power Distribution Table
    One light: Symmetrical mode in any outlet, will receive 1200Ws.
    Asymmetrical mode in outlets 1 or 2, will receive 1200Ws; when using outlets 3 or 4 output is 900Ws.

    Two lights: Symmetrical mode, all outlets share an equal amount of power. Two lights each receive 600Ws (1200Ws divided by 2).
    Asymmetrical mode
    Combination 1: one light in outlet 1 or 2 receives 600Ws; the second light in outlet 3 or 4 receives 300Ws.
    Combination 2: in outlets 1 and 2 receive 600Ws each.
    Combination 3: in outlets 3 and 4 will receive 300Ws each."
     
  18. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    I like JBrunner's answer. I think there's something wrong with the way you are using the meter.

    On my Minolta Flashmeter III, there is a setting for use with a sync cord like Blansky describes, and there is a setting for use without a cord in the way that JBrunner describes based on the Lunasix F manual--press and release the meter button, then trigger the flash.
     
  19. djkloss

    djkloss Subscriber

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    Not to be redundant, but that is the way I'm using it.

    I will keep trying some other options...

    and... thank you all for your suggestions. The only thing I haven't tried so far is a different room - white walls - different reflectors, different umbrella. Different meter! :surprised: doh!
     
  20. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    It could be a problem with the meter. One thing you could do, if you don't have immediate access to another meter, is do a quick objective test on film or Polaroid.

    Before I had a flash meter I did tests on film with each reflector and diffuser that I had, and before a shoot, I would diagram the lighting setup and calculate the exposure based on the tested guide number. I still had some flexibility to move the lights as long as I kept the distance between the main light and subject, fill light and subject, and background light at background constant.
     
  21. djkloss

    djkloss Subscriber

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    the quick objective test sounds like a good idea. just shoot a roll, document it and draw a diagram. I was wondering too, if maybe I'm interpreting the meter reading incorrectly. I tried doing the guide number formula and the numbers matched more closely to what everyone else was saying. I also tried using white walls and a white mat board on a table top, and not much change. Maybe its just me! I never was very good at math! :wink:

    thanks again......time to get back to the drawing board....
     
  22. MattKing

    MattKing Subscriber

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    I think you (djkloss) may be taking your reading from the wrong section of the meter's dials. Check the face of your meter for a "lightning bolt" - if it is like mine that is the mark you need to refer to, not a particular shutter speed.

    I have and use a Gossen Profisix (a European/Canadian designation) with flash metering attachment. It works in much the same way as the Lunasix F referred to above.

    My questions are:

    1) is your meter one of the ones that uses a needle, that you need to "null" - i.e. do you need to adjust the meter dials until the needle is over a mark?
    2) if so, when you are reading the f/stop suggested, what are you using as the reference mark?

    On my meter, I place the meter at the subject location and point it back (either to the flash, or the camera position, depending on my purposes and on how many flashes I am using). I then push the button that turns the meter on, then a "start" button (on the accessory unit) that initializes the meter. The needle moves all the way to the left. I then trigger the flash, and the meter needle responds by moving to a location, and stopping.

    I then rotate the meter dial until the needle lines up with the "O" or null mark.

    Then, I read the f/stop by noting where the special flash indicator (a stylized lightning bolt) is located adjacent to the f/stop dial.

    The "lightning bolt" is on the shutter speed dial, but is not there to indicate a shutter speed. The flash meter function ignores shutter speeds.

    On my meter, the "lightning bolt" is located on the between the 1 second and 2 second marks. Yours may very well be at another location.

    Edit: as I look again at the instruction manual referenced above - I see that the "lightning bolt" is in the same location as on my meter. It is item 8 on the numbered list of markings/parts at the beginning of the manual.

    Hope this helps.

    Matt
     
    Last edited by a moderator: Jun 8, 2006
  23. JBrunner

    JBrunner Moderator Staff Member Moderator

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    Cool, someone with this meter, that is familiar with it. I do think the issue lies with the meter, or the operation, or reading of it, as a reading of 2.8 is way way to low.
     
  24. djkloss

    djkloss Subscriber

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    Matt,

    Thank you! Yes it has a lightning bolt on the face and I think you hit the nail on the head!

    Thank you!

    Dorothy :D
     
  25. blansky

    blansky Subscriber

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    I agree.

    The room you're shooting in etc is not the problem. It is simply the meter or the reading of it. Concentrate on those.


    Michael
     
  26. Helen B

    Helen B Member

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    I'm not so sure. If Watt is on second then Who is on first, and the Infield Fly Rule applies.