using multiple flashes manually

Discussion in 'Lighting' started by beautgrainger147, Jan 6, 2010.

  1. beautgrainger147

    beautgrainger147 Member

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    I wondered how people go on using multiple flashes on the manual settings?
    - specifically the formula. I tend to use a medium format folding camera and have now installed a pc socket on my crown graphic and have been thinking about dual flash guns for increasing the range but also for lighting a subject from two directions.

    Thankyou
    J Grainger
     
  2. Brandon D.

    Brandon D. Member

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    Typically, I use a pc sync cord to trigger the main flash. As you know, the pc sync cord connects the pc socket on the camera to the pc socket on the flash.

    The rest of the flashes are triggered by the main flash (wirelessly) through optical slaves. That way, when the optical slaves (on the other flashes) begin to see the main flash fire, the other flashes fire as well. That essentially happens simultaneously in what is called a short flash duration.

    To work out the exposure value, I use a Sekonic L-358 hand held meter. I use the incident meter dome, and I set the meter to "flash metering" mode. To do the metering, I connect the pc sync cord from my main flash to the hand held meter (via pc sockets), and then I place the meter's dome exactly where the subject will be positioned. From the subject's position, I point the meter's dome towards the camera lens. When I trigger the meter, it fires the main flash, and the main flash simultaneously triggers the other flashes (via wireless optical slaves).

    As a result the meter gives me an incident exposure value based upon all of the lighting falling upon the dome. I can use that exposure value as a starting point for determining how I want to expose the image (e.g., shutter speed, aperture, and ISO/EI settings). Most photographers take test shots (e.g., polaroids, instant film, etc.) to determine whether or not deviate from the recommended exposure, or they might decide to adjust the lighting scenario to better fit their vision.

    Here are great videos on flash lighting and flash metering, and they might be able to give you a better understand of all of this than I can:
    http://www.studiolighting.net/digital-photography-one-on-one-e002-using-a-light-meter/
    http://www.studiolighting.net/digital-photography-one-on-one-e010-light-ratios
    http://www.studiolighting.net/digit...g-lighting-equipment-basic-three-light-setup/
     
  3. beautgrainger147

    beautgrainger147 Member

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    thankyou, I'll start looking for a flash meter. Thankyou for the links.

    I'm also looking to increase my effective flash range for hand held candid pictures, as might be used in a pub/ small music venue (perhaps when having a fancy dress competition).
     
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  4. wclark5179

    wclark5179 Member

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    I use Pocket Wizards to remotely fire all my flashes. The challenge of using optical slaves is that if someone takes a picture with a point & shoot camera and the flash goes off then mine would as well. If you are making pictures of people then take a peek at this:

    http://forum.montezucker.com/index.php?act=ST&f=11&t=8344&

    Matter of fact take a look at several of the threads at Monte's site under the heading:

    "Photo Tips, Tricks, Articles & Education"

    Rick Delorme has a good thread.

    Another good source to learn about off camera lighting is this:

    http://strobist.blogspot.com/

    Photography means painting with light.

    Hope this helps you.
     
  5. Mike Wilde

    Mike Wilde Member

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    Once you get the flash meter, here is my next trick.

    I have two 'potato masher' head and pack flash units. One, a Metz 60CT2, and the other, and older Braun Hobby EF300. Both can discharge a whack of light. The Hobby lets you switch to half power.

    The Metz, without a Mecamat remote sesnor won't do anything but full power on manual, or a really wimpy output on winder mode. You can fool the auto sensor on the metz with ND gel though. For portraits (pre mecamat) I gel the metz sensor and set it's auto range selector (it has several) to give me f/4 for a fill flash, bounced into an umbrella. I then position the main flash Hobby, (usaully in a soft box) either at full or half power at a distance to give me the main/key light, at the lighting ratio that I desire. One of the two fires off an optical slave; I haven't allocated funds to buy a radio trigger system to date.
     
  6. jp498

    jp498 Member

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    The math part of it is basically the inverse square law, and understanding what a "1 stop change" is; half as much light or twice as much light. If you can understand the ratios of light based on both the flash power and the subject distance and the angle of lighting, you can visual the result with some practice.

    A flash meter is good for the combined exposure; I have a minolta flash meter. The modern equivalent of polaroid test shots is chimping on a DSLR.

    I would use flashes with adjustable power output. Vivitar 285hv, Nikon sb24 or other outdated used Nikon high end flashes, or monolights.
     
  7. panchro-press

    panchro-press Member

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    Oh, the world we lost!
    This would be such a simple problem easily solved. Just put a sheet of Polaroid in the camera and see exactly how your lighting set-up works.
    Sorry, for being completely un-helpful.

    -30-
     
  8. rmolson

    rmolson Member

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    multi flash

    Multi flash


    Before the days of flash meters. and slaves Using Multi flash was essentially common sense. Your main light established the exposure All other lights are fill And unless they are at the same angle and distance as the main they did not effect the main exposure They were fill light, Using the f stop on the lens as a scale ,if the main light was say 8 feet from the subject then 11 feet or f/11 would be a1:2 ratio and16 feet or f16 would be 1:4 ratio Back lights were not compensated for but were moved for effect. Strong effect would be about the same distance as the main Working with flash bulbs and under short time lines it was surprising how fast you could set up ,shoot and get out. On my Speed graphic the guide number of the flashbulb was calculated and pasted next to the verinier footage scale.So a No.5 flash bulb at say 10 feet would be f/8 and I could place my other two lights extension cords and all at 11 or 16 feet depending on what I wanted. Simplicity was the name of the game
     
  9. beautgrainger147

    beautgrainger147 Member

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    I dont have any polaroids, a modern back is on my to do list but I cant afford to be buying one at the moment, I only have a digital P&S to which I can link the flashes, might give it a try as a guide. Funnily enough I have an SB-24 and an old 285. Think I might be making this more complicated than it needs to be.
    Assuming I use two flashes next to one another with the same guide number, does that mean I'll get 1 stop more distance? (as in twice the power)
     
  10. jp498

    jp498 Member

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    Exactly! You're doubling the light, so that's one more stop.
     
  11. MattKing

    MattKing Subscriber

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    Mostly yes (but maybe slightly no) :smile:.

    Guide numbers are strange beasts.

    When manufacturers determine guide numbers, there is usually at least some reflected light (off surfaces like ceilings or walls) involved. The conditions used may affect the results, and most likely were at least slightly different for the two different flashes.

    In addition, two different flashes may have different angles of coverage.

    So if you put two different flashes side by side, you may get light that is at least a little bit different than if you had two copies of the same flash side by side.

    It cannot hurt to experiment.

    Matt
     
  12. beautgrainger147

    beautgrainger147 Member

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    it all makes sense :smile:
     
  13. Benjamin Kanarek

    Benjamin Kanarek Member

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    I always use a flash meter to read the rendition of each of the flash sources on the area that it is lighting.

    I also read the principal area to be lit and imagine the difference prior to testing and take a test image.

    Ben :smile: