Flash!

Discussion in 'Beyond the Basics' started by magicmonkey, Jul 7, 2006.

  1. magicmonkey

    magicmonkey TPF Noob!

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    That's not an order but is optional ;)

    Anyway, I've just go my first 'real' flash and it's confusing the hell out of me! It's a 'Sigma 500 DG super' so I'd love to have a few hints on this model but I'm really after a much broader overview of how to use a flash on manual as it'll be used as a slave flash quite a lot with no TTL. Any help would be much appreciated!
     
  2. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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  3. mysteryscribe

    mysteryscribe TPF Noob!

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    how to use a flash on full manuel.....
    1. set the shutter speed of the camera to sync speed for flash

    2. read the manual on the flash for the guide number around 120 or so usually.

    3. devide the number of feet to the thing you want to illuminate into the guide number

    4. the result is the true aperture. You will chose one close.

    example guide 120
    distance to naked lady 10ft.
    aperture would be f11

    all there is to it.

    unless its raining.... unless its foggy.... if it is rain ask yourself do i really want this shot that bad. Fog the light will bounce back at you so dont bother use exisiting light if possible.
     
  4. Orrin

    Orrin No longer a newbie, moving up!

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    This is good advice except that the GUIDE NUMBER may be in meters since the
    original question was from someone in the UK. Not sure if the UK has gone completely
    metric. In any event, be aware of the unit of measurement given in the flash instructions.
     
  5. mysteryscribe

    mysteryscribe TPF Noob!

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    glad you mentioned that I didn't even think of it. Im too old to figure meters I would have to do it in meters then convert to feet to make it work..
     
  6. magicmonkey

    magicmonkey TPF Noob!

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    Thanks guys, I'm going to have a long night playing with this tonight so don't be too surprised if I come back tomorrow with more questions!

    Thnks for the link Big Mike, that loks like a really good site :)
     
  7. Hertz van Rental

    Hertz van Rental TPF Noob!

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    European flash units frequently have dual scales that are quite clearly marked as feet or metres.
    But it's easy to tell from the Guide Number.
    A metre being approximately 3 feet means that the GN for metres is smaller than the GN for feet (by a factor of 3).
    A GN of 32 for ISO100 in metres gives a GN for feet of about 104.
    Common sense should tell you which is which. A small flash on the top of the camera with a GN of 100 is hardly going to be working with metres - it just won't be capable of kicking out that much power (work it out).

    On another issue. You say you are going to be using it as a slave, MM. That usually means you will be using it in conjunction with a master flash.
    Two or more flashes working together on manual require somewhat different calculations to get the exposure.
    Please clarify and I'll provide the necessary formulae (or search the forums because I've posted the formulae before).
     
  8. mysteryscribe

    mysteryscribe TPF Noob!

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    Hertz comments reminded me of my last studio lighting setup. I sold my studio equipment when I left one town and had to rebuid it in the next town, but I was doing mostly bank, mortage, and insurance company photography so I was in no hurry to replace it. Every now and then I needed to shoot a head shot for some executive so I finally decided to install a real lighting system (haha my version of real)

    Freestyle of all places have a truck load of small strobes and was almost giving them away. 6bucks each I think. I bought ten. Now I do NOT recommend this as a good idea especially if you are not using film cameras. Even then it is dicey.

    My studio is 25ft by 10 feet or it was anyway now its a shop space more or less. I did the calculations for multiple strobes which is really pretty easy, IF they all have the same guide number. Mine did #56. I used a front light bounce system. Instead of an umbrella I mounted then near the ceiling pointed away from the subject and angled up. In the space where the ceiling and the wall meet, I mounted a piece of cardboard covered in a white cotton material. The angle bounced the light back at the subject and in a wide enough pattern to light about three people sitting side by side quite evenly.

    NO drama but always an shot. Didn't have the luxury of preview screens or the ability to explain how artsy it was for his business card. Yeah you look a little sinister but after all you are a lawyer I figured wouldn't get it.

    Then one as a back light on a stand behind the subject to knock the shadows down. That one needed a cloth over the flash to cut the output.

    So the question was how many strobes to gang for the main light. Here's how I figured it.. The actual distance was about eight feet but to make this simple I'll use ten feet. One strobe fired direct would be 5.6 but bounced it would be about f4.. Just not enough light to give any room for bad eyesight. Two matched strobes double the output and you are back to f5.6 still not enough for my eyes. To get from 5.6 to f8 did not require one more strobe but two more. To kick the f stop up one notch you have to double the light. 2 x 2 = 4 so it was four strobes. I tossed in one more for kentucky windage. Now if the 5th strobe fired it would add very little to the light but more light is always good. If even two of the strobes failed to fire I would still have enough density in the negative to print it.

    Now of course all these lights were dc and the studio current was ac, what's a camera butcher to do. Im not much for climbing ladders to change batteries everytime I want to use the place. (My balance sucks not to mention the inconvience." I went looking for "DC" power source. I could find all kinds of them for 500 bucks but that would defeat the purpose of a thirty dollar light system. I found the power source in a auto battery charger. The three volt flashes didn't burn up under the six volt power supply. At least not when I parallel wired them. No idea why but I was grateful. I planned to just use the lights until I went back to shooting more than the occasional realtor, preacher or lawyer's headshot. But they worked so well I never replaced them till I retired completely. Then I just scraped them.

    I made second variation when I went back to doing weddings. Those went the length of the studio against a black drop. It was an interesting and cheap stuido light solution but I wouldn't use it with modern digital I think the latitude of light is to tight. But then again I don't really know that for a fact.
     

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