flash power and 8x10

Discussion in 'Lighting' started by mark, Apr 28, 2006.

  1. mark

    mark Member

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    DO you need a lot of fill flash with an 8x10 camera for portraits? Probably a silly question but I want to know.
     
  2. Charles Webb

    Charles Webb Member

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    The early photographers using 8x10 and larger in the studio worked with sky light and reflectors. A well to do studio photographer might have an adjustable sheer curtain to help controll the light, but reflectors were the fill lights of the day.


    Charlie............................................
     
  3. Ole

    Ole Moderator Staff Member Moderator

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    I read "flash powder", and was going to warn you to stay a l-o-n-g way from that stuff...

    However: The films are the same, the apertures the same, so you need no more flash power with 8x10" than you would with 35mm. As long as you remember the bellows compensation, that is.
     
  4. resummerfield

    resummerfield Subscriber

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    I would say you are right in principle, Ole, but when I do a portrait with 8x10, I’m using a 360mm lens, which requires me to stop down to at least f32 to get what I would call acceptable depth of field. In 35mm I would never use f32. Plus you have the bellows factor. Presently, I’m using available light, so I can’t answer the question with authority, but I know others who use in excess of 5000ws for 8x10 portraiture
     
  5. Petzi

    Petzi Member

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    You could always improve the guide number of your flash with ASA 400 film. The guide number doubles at ASA 400 compared to 100.

    Do the math: for full flash illumination of the subject, divide the guide number by the aperture, and you get the distance. For fill-in purposes, it should work at greater distance than that.

    Or divide guide number by distance to get the aperture.
     
  6. rbarker

    rbarker Member

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    I use White Lightning X3200s as my mains. Enough output to maintain a reasonable aperture selection, even with modifiers.

    You could get by with less, of course, if you use "The Galli Style" and shoot wide open with a Pretzval. :wink:
     
  7. wilsonneal

    wilsonneal Member

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    I have 4800ws of Speedotron Black Line power, and hardly ever use all of it for a waist up shot on 8x10, but probably would feel like I didn't have enough with a 2400ws pack. Probably depends on how many lights you're thinking, too. With a one light set-up in a softbox or umbrella, which I prefer, you might get away with 2400. If you're doing Hurrell-style multi lights (a hair light, a background light, a main, a fill, etc), you'll probably need considerably more total power to work at the small f-stops you desire.

    I tried to do some work with a 200B on location as fill for some (backlit with sun) photos, and the 200B didn't have enough power to help much at the 10 feet or so I was working with.
    Neal
     
  8. per volquartz

    per volquartz Member

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    5000wsec is a good start...

    A 5000wsec power pack with 3 heads - each head variable - is a good way to go for doing commercial 8x10 portraiture...
    You can purchase heads that are "set" in hot light headfixtures giving you a similar look as hot lights - without the weight and the heat...


    You can do 8X10 portraiture with a single lightbulb and plenty of daylight too...
    - different look and different feel...
     
  9. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    It really all depends on your style. I like short DOF, so I'm okay with a Norman 2000 W-s pack, and maybe an extra 200 W-s portable head or two as a fill or highlight. If I'm shooting Hollywood style with a fresnel head as the main light, then that's really a lot of power. If you're using softboxes, though, you probably want at least twice that, since they'll eat up two stops.
     
  10. DeanC

    DeanC Member

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    I've just been starting to dabble in 8x10 portraiture and I can tell you that my Alien Bees 1600 just barely got me to wide open on a Nikkor-M 450/9. I'm starting to wish for one of those Speedotron 4800ws packs.
     
  11. Nick Zentena

    Nick Zentena Member

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    I've only done a couple of sheets of 8x10 like this but the 1000ws mono light was good enough in a 3'x4' softbox. Not wide open on the lens but of course I don't remember what F/stop. With 400 speed film it would have been even easier.

    A couple of issues. It's real dark focussing. The modeling and room lights just didn't give alot of light to focus with. I'm thinking of using a 1000 watt work light to raise the room light level for focussing.

    It seems like a lot of power to hit somebody in the face with.
     
  12. df cardwell

    df cardwell Subscriber

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    There is a big difference between what one needs to make a nice image with 8x10, and what one would want if LF portraits were a daily matter !

    I like 4800 ws. The big thing with 8x10 portraiture today is that sitters are not used to sitting still, however willing, and a little more depth of field is a handy thing because so many people have that silly idea they should be in focus when they pay a guy to take their picture.

    I love the 'open sky look' for portraiture and shoot with a couple big softboxes as close to the subject as I can get them. As David said, that eats up lot of light. I'd venture 1200 ws as the dead minimum.

    250 w modeling lights are VERY nice.

    A neat thing you can do with a single head and a big flash pack is turn a small room into a big, soft studio... the look is distinctly 'open sky', everybody looks good in that light, and you can 'shape' the light as needed by simply putting up dark cards to lessen the reflection.

    You can find good used strobes pretty easily these days.