Bare-bulb flash exposure advice, please ...

Discussion in 'Lighting' started by dmr, Mar 21, 2011.

  1. dmr

    dmr Member

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    Hopefully we have some hardcore strobe lighting jocks here who can help out on this. I've asked on a couple other boards and gotten some responses, but nothing authoritative. I'm hoping for something more than "bracket" or "take a test roll", from somebody who really knows lighting.

    Next month I'm going to be shooting some interior shots in a rather unusual venue. Groups of people in meeting and dining rooms in a smaller restored "boutique" hotel, with dark wood paneling and darker earth tones. Ceiling, IIRC is maybe an ecru or a dark eggshell at the lightest, quite warmish, IIRC, so bounce flash will probably not be an option. Available light is poor, mixed, and quite warm.

    Here's the problem. To get these shots I'm probably going to have to use the Sigma 18mm ultrawide. (non fisheye)

    I have two flash units, a Vivitar 2600, which is probably out of the question. Then I have the hand-me-down resurrected Sunpak 120 flame-thrower. I know it won't light the scene with the reflector, even at the so-called wide-angle position.

    I can do it bare-bulb, no reflector, either aiming the bulb upward or pointed forward.

    The problem is, I have no clue as to how to expose for such a situation.

    Can auto mode be depended upon in a situation like this? Or should I use manual and do guide numbers? If I do guide numbers, should I try to adjust for the 360 degree coverage of the bulb?

    Yes, I looked at TFM, and it didn't really say much about bare bulb mode except that you can do it.

    Anybody shot a bare bulb unit in a similar situation?

    TIA! :smile:
     
  2. segedi

    segedi Member

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    I'm guessing you are shooting 35mm but what camera and film do you intend to use? Can you trigger more than one flash? Shooting on tripod? How high is the ceiling? Will people be in the photos? Lighting is poor but is it flat/even? Main light sources?
    Do you have an external meter and ability to meter flash/ambient mix?
     
  3. jerry lebens

    jerry lebens Member

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    I'd reconsider using a bare bulb. Shooting groups (it would help if you could say how large the groups are expected to be) with a bare bulb is going to give you harsh, deep, shadows and glaring highlights, more so if the walls and ceilings are relatively dark... Consequently, depending on how you set up the shot, you may find that the shadow cast by one group member will obscure another and that the fall off from the foremost subject to the furthest will be rapid. In short, bare bulb will be unflattering to your subjects.

    If you can't get hold of brollies and more powerful strobes, I'd suggest you fire both flashes (with reflectors) backwards at a larger reflector, behind and above you, to get the required spread. I use an old sheet of Tyvek that I keep in my kit for this, if I haven't got my fold out reflectors with me. However, guide numbers won't help you with this set up, you'll need a flash meter. I wouldn't risk doing this type of thing without one, especially if I was shooting film.

    However you go about it, you need to diffuse/reflect those lights to soften the output...

    Regards
    Jerry
     
  4. brucemuir

    brucemuir Member

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    Barebulb is still going to give you a cast from off colored walls. How bad it will be is impossible to say without seeing the place.
    Like segedi suggests, is it possible to fire off camera with a radio trigger?

    These situations are tough and if you have to go on camera flash for key I'd use a bracket and get the light as far off axis as possibleand use some type of diffuser.

    As to exposure, thats just a question of auto mode or getting REAL comfy using guide numbers on manual mode.
    If you use the same focal length lens throughout it gets east to judge distance.

    Why an 18mm? I know the place is probably tight but it wont exactly flatter guests and good luck if anyone ends up in the corner of the frame.
     
  5. segedi

    segedi Member

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    Couple more questions... Intent of the photos, is it the groups or the meeting space itself? Angle, will you use a ladder?
     
  6. rthomas

    rthomas Member

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    I've shot in similarly tight situations on 35mm, using nothing wider than a 28mm lens (when I worked for my college newspaper, 28mm was the widest lens available to me). 18mm may be far too wide for people shots.

    As far as the lighting goes, if on-camera flash is your only option, diffusion on the Sunpak 120J with the reflector is a good bet, as is a bracket. I've also used a Stofen-style diffuser on Nikon SB-16 or Vivitar 283 flashes. I used to have a Sunpak 120J... now I have a floodlight reflector that I spray-painted powder-coated silver, and cut a rectangular hole in for the SB-16. This is fairly soft.

    Is there any chance of getting into the place in advance and doing some tests, especially if you can at least borrow a flash meter?
     
  7. dmr

    dmr Member

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    A Real Camera<tm> of course! :smile: Seriously, Pentax K1000, Sigma 18mm rectilinear ultrawide, probably plain vanilla Fuji 200 C41 color film. Not TTL auto exposure, but auto via the Sunpak's "eye" in the unit.

    I won't be able to do anything fancy at all, just hand held. I do have the stroboframe, so the flash will be somewhat above the normal hot shoe position.

    I'm also guessing that I'll have 5 minutes or so to get everybody together, posed, and hold their attention long enough to get enough shots before they start grumbling and wander off. This group is the type who will groan when we pose them, but will go "ooooohhh, can I get a copy!" when I show the prints.

    IIRC, 10 or 12 feet. Higher than the usual home of office ceiling.

    Of course, that's the whole point! :smile:

    Last time I was there, it was a mix of incandescent (might be those curly-que fluorescent) and those small reflector type highlight lights hitting artwork on the walls and such. My guess is that if I were shooting candids in available light with the RF, 800 film, 1/30, and close to wide open on the lens would be in the ballpark. In other words, I don't think the ambient light is enough to really consider here.

    No flash meter. I could meter the ambient but I'm sure it will be at least a number of stops down from what the flash will do.

    I'm not after perfection here. I certainly don't want to let what is ideal stand in the way of what is good.

    As for the expectation of quality here, if I can do "good snapshot quality" or better, it's a winner! Something better than cam phone or typical P&S digicam quality will be fine. They were tickled pink when I said I was confident that I could get some good shots of them in there, particularly after our resident know-it-all DSLR jock said it was impossible. :smile: (Jees! I hope he doesn't read this board!) {blush}

    Anyway, a few who have replied have confidently said "Trust The Force" and trust the auto-exposure and not futz around with computing guide numbers and such. This does make sense now that I think about it.

    Thanks to all for the quick replies on this. I got more responses here than anywhere else. :smile:
     
  8. jnanian

    jnanian Advertiser Advertiser

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    b+h and other photo retailers sell screw-in slave flash bulbs
    so you can replace a normal 1/4" socket c/f or incandescent bulb
    with a bright flash/strobe that will slave to the flash you have on your camera.

    it might be worth considering asking the folks that work at the place you want to photograph
    if you can replace a few of their bulbs with yours. it will help you a lot!
    i am not familiar with your flash but i have a feeling it won't really be bright enough to light a who room
    so you will see more than "hot" and shadows. i used to shoot barebulb with
    a lumedyne pretty often, but it threw off 200-400 WS of light, probably a bit more
    than yours can do ...
    something to consider is to use an elastic and a white card and tape it to the flash you have and shoot straight up.
    the card will bounce the light forward and you will be able to bounce the light off the ceiling down ...
    but 8-10' ceilings needs a lot of light ...

    if you can go after hours and do a test roll you probably will be better for it ... shooting
    something like this on the fly can be "fun" :wink:

    good luck !
    john
     
  9. benjiboy

    benjiboy Subscriber

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    I suggest you invest in a Sto-Fen Omni bounce Diffuser http://www.stofen.com/index.asp it even covers my 17mm wide angle lens and produces soft shadows when shooting groups, it is always used bounced at 45 degrees not used directly, and allows the flash to bounce off the ceiling and throws it forward at the same time and can be used with auto computer flash and gives correct exposure, I use one with a Metz 45 CL5 and a Vivitar 285 and it works for me.
     
    Last edited by a moderator: Mar 21, 2011
  10. John Koehrer

    John Koehrer Subscriber

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    The auto flash will grossly overexpose your subject with dark paneled walls, it ain't pretty. even with umbrellas you're going to need a flash meter OR do some test shots to give you exposure at set distances.
     
  11. markbarendt

    markbarendt Subscriber

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    Being unfamiliar with the Sunpak 120, I am assuming that you are talking about the strobe's auto mode and it's built in sensor.

    My experience with Nikon speed lights is that auto does very well.

    Make sure the settings on the strobe match the camera settings, if this is done the subject the strobe sees will expose properly. Bare bulb or not.

    There are several wild cards that can bite you.

    First the strobe's sensor is a "reflective" meter; if the main subject is a bunch of people in black it will over expose, all white dresses means under exposure. With a bit of practice you can manipulate the camera or strobe to compensate.

    The other wild card is your ability to bounce.

    I regularly bounce off of things behind me, if you can put a large reflector or two above and behind yourself it will help. Bigger the better.

    Bounce and/or big reflectors will mitigate what many people call flash over exposure. What you are doing is simply "bringing up the house lights". A good share of the strobe's light is simply filling in the dark areas so that the properly exposed subject will be in a nice room rather than in a black pit.

    One more tip, use the widest aperture that you can, this let's the real house light "help".
     
  12. markbarendt

    markbarendt Subscriber

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    I should have also said use the slowest shutter speed you can get away with.

    If the groups are relatively well behaved adults, tell them that you are using a slow shutter and ask them not to wiggle. 1/30 or even 1/15 may work. This technique allows more ambient light to reach the film and will not cause over exposure of the main subject, the auto mode of the Nikon strobe's control main exposure by limiting flash duration, that is much faster than the shutter, say maybe 1/1423rd for example. The strobe can see the ambient light too.
     
  13. daleeman

    daleeman Subscriber

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    Bare bulb is a unique way of lighting. I used to use Mazda 75 bulbs a lot. These are like harvesting the sun and could do a gym full of students in one bulb. Had to lock the shutter open on the camera and use the lens cap. At 75 feet to the first row, F22 plus a 4x ND filter. Lock the shutter open, pull the lens cap, detonate the bulb in a clamplight fixture with a switch and 9V battery then put the cap back. You have never hear so many people yell D@mn at one time after setting one of them off. I wore sunglasses and kept my eyes closed.
    I now see you can get $ 85.00 each for them, they are monsters. Our historian at the Air Force Museum said they would mount these under the wings of aircraft in Korea to do recon photos from way up.

    I also use them to do crowd photography off the top of a 25 story building along the Ohio river for the WEBN firworks, that attracts 200,000 people. The radio radio station paid well for those night shots with the crowd lit up and fireworks over them. They would wonder if the space ship had landed when we would set them off.

    I would buy 3 or 4 of them and do a test with one or two. Chances are you will not be able to get the crowd to pose for a second image without SPF 75 sun block and free welder's hoods.

    You can find a few here. I sold off my last 17 bulbs. It paid for a couple of days at Yosemite park. I was always worried a static spark would set one off. A company in Hollywood purchased mine for a FX pyro tech. They add a lot of light when you blow something up I guess.

    http://www.colescameras.com/flashbulbs.htm
     
  14. eddym

    eddym Member

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    Is there any way you can get out of doing this shoot? :wink:
    Seriously, it sounded only difficult until you said you might only have 5 minutes setup time. Pressure like that is bound to make you forget something and/or otherwise screw up.
    Others have given you good suggestions, so I will just reiterate the ones I agree with:
    No bare bulb, unless you put a diffuser in front of it and a large reflecting surface behind it. A portable reflector, or even a big sheet of white foamboard will suffice. Alternatively, a large diffuser in front of the flash. But either will cut your light by a couple of stops or more.
    You really, really need a flash meter. An auto flash will read the dark background and overexpose the people. An ambient flash meter will give you the right exposure in seconds, and let you check to be sure it is even across the spread of the group.
    An 18mm is a really bad lens for this. If you use it, put the fat people in the middle and the skinny ones on the ends. Or put the people you like in the middle and the ones you hate on the ends. Really. I never use more than a 35mm for groups when shooting 35mm, and even then, I try not to fill the width of the frame.
    But really, consider a change of venue.
     
  15. John Koehrer

    John Koehrer Subscriber

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    If you have ever seen the shots at the school play where the background is jet black and the kids faces are completely over exposed? That's what you get.
    The only way you know who's who is from the costume. It's from using an auto sensor flash. The exact same thing will happen with a dark paneled room.
    Just as eddym says.

    There's nothing you can do about it as long as you're using auto flash.
     
  16. Trask

    Trask Subscriber

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    Well I, for one, would be interested to see how the shot turned out using the bare bulb flash! It's easy for me to say that, as I'm not on the hook to produce the photograph. My interest stems from my high school days in the 1960s when I had a Braun Hobby wet-battery flash = shoulder battery pack, big coiled cord feeding the flash head with removable reflector. (Can I get an amen?) With the reflector off, the three inch tube was vertical and threw light the full 360 degrees. The advantage was that light bounced everywhere, filling in the shadows, so less harsh lighting than with a directional flash.

    I've always wanted a Sunpak 120J just to be able to play with bare bulb again. I say, go for it! Maybe mixed with a few remote triggered small flashes, if you wish.
     
  17. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    I like Jerry Lebens\' answer. Better to diffuse the light for more coverage that\'s more flattering, than to shoot barebulb (autocorrect changed that to \"barefoot\").
     
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