Bounce Flash

Discussion in 'Lighting' started by Mark in SD, Jan 17, 2003.

  1. Mark in SD

    Mark in SD Member

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    OK. I must admit that I debated on where to put this for some time before settling here. This discussion seems to be mostly centered on studio lighting and I apologize if I guessed incorrectly.

    My question is on how to effectively use a bounce flash with a rotating flash head on a hot shoe. I can use it effectively when taking technical pictures by rotating the flash head and then using a white peice of paper or something similar to diffuse and reflect the light back onto my subject. My problem is when I try to take a picture, usually of people, without using this method (in other words, bouncing off the ceiling). The rooms are all low ceiling rooms so it isn't like I'm trying to bounce the roof of a gym. I'm using TTL metering so that shouldn't be an issue and I have tried with multiple flashes (SB-50 and SB-80). In all cases, the pictures end up underexposed. On rare occasions, I get good results but I don't remember doing anything different than normal.

    If somebody could provide me with a quick primer and then a couple of excercises (I don't mind burning film to learn), I would appreciate it.
     
  2. glbeas

    glbeas Member

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    One thing to remember is a high proportion of these small flashes are rated for more power than they really have. Do some test bracketing to find out its real power for both straight on and bounced and see what you get. And be sure you aren't shooting beyond the flashes range.
     
  3. Mark in SD

    Mark in SD Member

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    I thought of that. The SB50 as a GN of 72 at ISO 100 and the SB80 of 125 at ISO 100. I have been shooting a variety of 400 speed print films so the effective GN should be a bit higher. I know that I can light a subject at 50+ feet with the SB50 when shooting straight but have never tested the limits of the SB80 (although I have shot well over 50 feet).

    The typical light path from flash to subject for my bounces is about 10-20 feet. I have a hard time believing that I couldn't bounce either one of the flashes at that distance. I figure I must be doing something else wrong.
     
  4. b.e.wilson

    b.e.wilson Member

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    You can try overexposing a bit (to make the flash put out everything it's got), but the reality is these little flashes just don't have much power to illuminate anything but with a directed beam. They absolutely need the reflectors and the lenses (fresnel) to focus the beam tight enough to defeat the inverse square law.

    Picture a flashlight bulb in its reflector and out. The bounced flash is illuminating half a sphere, after ceiling absorbtion. Just isn't enough power to illuminate anything beyond 6-8 feet from the center of the 'bounce'. Even studio flashes get tamed by a 3' x 3' soft box, and they still have reflectors helping.

    If you just can't get the distance you need, find a way of limiting the area illuminated by the flash. The wall+ceiling bounce can give almost a stop more than a ceiling bounce due to the quarter-sphere illuminated, and a corner bounce (tricky to do as the flash is typically shooting over your head, leaving your shadow on the scene) can give a stop more.

    But the best trick is to get more than one flash going. Porters, and I suppose everyone else, sells those cheap little photo flash triggers that fire a flash when they see one. You can buy some cheap, dumb flashes each with a light trigger, and position them strategically (or is that tactically?) around the room to light up the ceiling and walls. The trick is to get the slave flashes nearer the subject than you are, without making the scene look harsh. (Having a digital camera or polaroid to see the overall effect is a very handy thing while setting up.) One method: put a slave in each table lamp in the room pointing at the light bulb. That way of you include a lamp in your shot, it looks normal (and the lamp acts something like a modeling light, previewing the effect for you). Please note that you'll need to take your camera off full-automatic mode to keep the exposure right (unless you have a EOS 3 with multiple 540 flashes, all controlled by the camera). Multiple-flash setups is why they have flash meters.

    Get some old Kodak How To Take Pictures books. They are full of stuff like this.
     
  5. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member

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    You might be underexposing those print films, and the lab could be compensating. Try a test with slide film, which is much less forgiving, to determine the real guide number.

    That said, I suspect those units should be able to handle bounce flash in a small room. I do all this stuff manually, so I'm not sure what to tell you about your TTL system, but I suspect that if it's just underexposing, there is a way to fool the system (say by adjusting exposure compensation or the ISO dial either on the camera or on the flash) to get it to put out more power.
     
  6. Mark in SD

    Mark in SD Member

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    OK. Here is what I'll try.

    First, both flash units will work with a Nikon Wireless flash controller, so that should be relatively easy to set up. I've always kind of wanted to try that anyway so I guess this would be a good excuse to blow another $70 on a new toy.

    Second, and I should have stated this before, the negatives are definitely underexposed (I worked in a photo lab for 4 years during college as well as doing my own developing and printing in High School). When I started getting the dark prints, the first thing I did was drag out the negs and look at what I had done. The negatives that I have tried to use a bounce flash on are consistantly underexposed. That is the problem. For some reason, weak flash, operator error, etc, I am not properly exposing the prints when trying to use the flash off the ceiling.

    I'll try some of the suggestions and let you know.
     
  7. Mark in SD

    Mark in SD Member

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    </span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Mark in SD @ Jan 17 2003, 10:18 PM)</td></tr><tr><td id='QUOTE'>First, both flash units will work with a Nikon Wireless flash controller, so that should be relatively easy to set up.&nbsp; I've always kind of wanted to try that anyway so I guess this would be a good excuse to blow another $70 on a new toy.
    </td></tr></table><span class='postcolor'>
    OK. I hate replying to myself but somebody with the answer may have already read the above so...

    I went to the Nikon Web Site and read about the SU-4 Flash Controller, got confused, and broke out my SB-50 and SB-80 manuals.

    Now I thought I needed something mounted on the camera to control the remote flash units. From what I am reading, the SU-4 is a device that fits on the remote flashes (not the camera like I originally thought) and triggers the remote flashes at a signal from the camera. That signal appears to be a flash from the main camera.

    Now, both the SB-50 and SB-80 can do this already without the need for the SU-4. In fact, if I use the built in speedlight on the N80, I could trigger both flashes remotely. It also appears as if either the SB-50 or SB-80 will trigger the other using the IR Focusing beams without firing itself.

    Do I have this roughly correct? Is it really true that I can play with this without buying another toy (not that I don't like toys, but I could spend the money on a different toy)?

    Finally, the exposure here seems to be more complicated than I had thought. The TTL flash control MAY work, but it appears that it will be much safer to use manual calculations. This will definitely take some practice.

    All of which begs the other question I have regarding this operation. How do you mount the remote flashes? Do they make stands or special tripod heads I could use?
     
  8. Nige

    Nige Subscriber

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    I bounce a flash with a guide number of 35 (metres... whatever that is in feet! about 115ft if my calculations are right!) and it works fine. For 100 asa film it has 3 "computer" ranges of 1-8m @ f4, 0.8-6m @ f5.6 and 0.5-4m @ f8. So, what f-stop are you shooting at?
     
  9. Mark in SD

    Mark in SD Member

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    Nige,

    That may be part of the problem. I have been trusting the camera to "choose" the appropriate exposure settings for me. I probably haven't been paying enough attention to what it is doing. Like I said, it works fine for using diffused and reflected light when I'm doing Macro work. I'm not sure if the problem is weak flash, poor geometry (I'm simply not getting the light to the subject), or poor exposure settings and am unsure how I should go about figuring it out.
     
  10. Robert Kennedy

    Robert Kennedy Member

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    Maybe it is your geometry. I tend to shoot closer to 90 degrees when I bounce. The "normal" 45 degrees just doesn't seem right to me. And I have gotten good results with 11 foot high ceilings in my house. I use a Sigma Ef-430 Super and an N80. Nothing fancy there. I just figure that since the subjects are usually pretty close, 45 would be too steep an angle. You might play with that a bit.

    Or, if you want a compromise, try an on-flash diffuser. I use a Photoflex which you blow up. Works with TTL and my AF assist light, and you get a soft light from it. Shadows are still an issue though.....
     
  11. Nige

    Nige Subscriber

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    I hadn't thought of mentioning about the angle, but I always bounce almost straight up due to the distance involved. At 45degrees, the light would be going straight over the top of them!

    Attached pic is an example (although this one might have been with a 2nd slaved flash as well... can't remember)
     
  12. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member

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    Great shot, Nige! I love the expression.
     
  13. Donald Miller

    Donald Miller Member

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    Great lighting ratio. Very nicely done.
     
  14. Mark in SD

    Mark in SD Member

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    Ooh. I like that picture.

    As for Angle, I've been using 70 degrees. I thought that would be good but maybe I was wrong. I'll try straight up and see if that helps.

    Also, I'm strongly considering slaving in my other flashes. Nobody has responded to my questions above but it certainly looks like it should work. Any suggestions on how to mount them (not placement, physical mounting).
     
  15. John Hicks

    John Hicks Member

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    OK, a couple of things.

    First of all, I'm not familiar with those flashes, but if they're Vivitar 283-class output flashes they should work. Or iow, about the same or more power as the old Nikon SB-24. You can of course use less-powerful flashes for bounce flash but you must take care; more about that later.

    The flash-to-subject distance using bounce is of course from flash to the ceiling and from the ceiling to the subject, but bear in mind that there's _lots_ of light loss, I think generally two+ stops with an ordinary white ceiling, so it takes much more flash output to do ceiling bounce than direct flash or even if you use one of those relatively useless bounce gizmos.

    If you're letting the camera fend for itself, most likely it's selecting an aperture that would demand far more flash power than is available, so take it off auto and manually set an aperture of f4 or so, assuming you're using EI 400 film. If your flash is one of the less-powerful models you may need to set the aperture to f2.8 or even f2 to assure sufficient exposure.

    Another thing you can do when using ceiling bounce is use a kicker card; this is a small piece of white card (a business card is fine) attached to the back of the flash head, when the head's aimed upwards, that kicks just a little light straight ahead. This can prevent dark eye shadows when working close with bounce flash plus of course puts a little more light forward rather than behind you.

    Also be sure you're not aiming the flash behind the subject; it should be aimed at the ceiling roughly 1/3 to half the distance from you to the subject.
     
  16. Mark in SD

    Mark in SD Member

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    Thanks for the advice. I use the "kicker card" concept when I am doing macro photography at work. I hadn't considered it for my other pictures, although i must confess I don't know why.

    I have been trying to let the camera TTL flash control do all the work. In retrospect, that may be part of the problem. Now for what may be a dumb question:

    You say to give about two stops extra exposure and you suggest doing this by going completely manual. While I don't have a problem with that, I'm wonder why either setting the camer to overexpose by two stops OR setting the flash to fire at two stops of overexposure wouldn't accomplish the same thing. I realize that I will have much better control with manual settings but shouldn't the other methods work?
     
  17. John Hicks

    John Hicks Member

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    > I have been trying to let the camera TTL flash control do all the work.

    TTL-controlled autoflash exposure is ok although of course you may have to bias it. What I meant (and one wonders why I didn't just say so) is to not let the camera run in a program mode in which it automatically sets the aperture. The camera may happily set a small aperture while the flash just doesn't have enough juice for that.

    > You say to give about two stops extra exposure and you suggest doing this by going completely manual.

    No, you shouldn't have to give the extra exposure; the camera's ttl flash control should take care of that _assuming the flash has enough power for the aperture in use_.

    Let me give you a few examples; I use a Sunpak 1600A, a couple of Metz 32-Z2s and a Metz 45, all with bounce flash. It's extremely rare that I've ever used direct flash. The Sunpak is a tiny low-power thing about half the size of a cigarette pack, the Metz 32 has about the same power as a Vivitar 283/285 or Nikon SB-24, and the Metz 45 has about a stop more power.

    Using the little Sunpak and EI 400 film I can confidently shoot bounce flash in ordinary home-sized rooms using autoexposure at f2.8 Although the flash has settings for smaller apertures and those can be used in direct flash it simply doesn't have enough output to use the smaller apertures for bounce flash regardless of the fact that they can be set. The Metz 32 runs at f5.6 and the Metz 45 at f8. I simply set the lens aperture setting appropriate to the flash I'm using and let it rip in auto...perhaps with a minor exposure bias.

    The point of all that is that to do bounce flash you must use a film speed and aperture setting that's appropriate to the flash you're using. If you're consistently getting dramatic underexposure then most likely the flash isn't powerful enough to operate with the aperture you've set and/or the speed film you're using.

    You can (and should) let the flash run in TTL, but if you're letting the camera pick its aperture you may simply need to switch modes so you can set the aperture directly to something that'll likely work, such as f2.8 or f4. If your lens is a slow f5.6 zoom and you can't set a wider aperture then you'll need either a more-powerful flash or faster film.

    Most likely an exposure-compensation adjustment will be needed, perhaps up to +1, to turn a maybe-adequate TTL-controlled exposure into a good TTL-controlled exposure. This is normal; in fact the exposure-control circuits for continuous light and flash are often separate and have separate sensors. While the results should be the same they rarely are. But at any rate, while a TTL-controlled autoflash exposure may be slightly less than a continuous-light exposure it definitely shouldn't be dramatically less whether the flash is direct, bounced off a gizmo, bounced off your white shirt, the floor or the ceiling. If it is, that indicates to me too small a lens aperture and/or too low speed film being used for the available flash power.
     
  18. Mark in SD

    Mark in SD Member

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    Thank you for the explaination. One more question, and excuse me if I am being extra dense here.

    If I understand you correctly, I should be shooting in Aperature Priority mode with an appropriate f-stop and about +1 correction dialed in. The exact f-stop chosen will probably be determined by some experimentation.
     
  19. DKT

    DKT Member

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    Hey, we just got an SB80 where I work, and I don't have alot of practical experience with it yet, but I have been using SB26s and 28s for shooting events with both N90S and F100s for years. Before that, we used 283s, 285s and FMs for this sort of workand shot all manual with bounce or slaved units as well. I don't see why you shouldn't be able to bounce a small strobe in the situation you describe, but the thing to remember is the TTL or the programmed TTL that the Nikons use (I don't know how you got the camera set up?). But the camera's "brains" aren't necessarily smarter than yours in certain conditions and they can be fooled just like auto flash by dark or light tones and big, expansive areas.....with the Nikons, usually you control the background exposure on the camera (like dragging a shutter on a manual camera) and control the foreground (the strobe exposure) with the controls on the flash. The speedlights meter off a pattern that's close to centerweighted too. Alot of times I shoot on centerweighted and skip matrix altogether....I really only use that outside for fill flash....

    I use an SU-4 with the SB26s as well as the older wireless automatic slave function they had. The SU4 is a buggy PIA to use and needs constant monitoring if you're actually using it on the run--what we do is to have the fill light be on the camera in the form of a SB unit with a Stofen kicked up at a slight angle. We shoot in close with fast, wide angles, and put the second strobe on a pole with the SU4 attached with a SC17 cable. This way you get the sensor down close to you so you can aim it at the main strobe on the camera or wherever. The SU4 works by line of sight for the light from the main unit--when it kicks on, it fires the slaved strobe. When the main shuts off, it shuts off. It really works, but is a PIA when things aren't "right" for it. It also draws it's power from the strobes AAs. So, it acts weird when they drop in power. We run them all off Turbos, but they still need fresh AAs in the Speedlight to power the SU4 correctly. This way, the assistant runs around with the slaved uni (btw--we zoom that unit out to the widest setting--flood it out) and is, in effect either fill or main depending on where they are positioned and how the speedlight is powered up. We like to shoot cocktail parties & night time events like this, with the stofen unit acting as fill and the second light on a pole above the grouping--think people in black-tie grinning at the camera. Or we do shots with this second light as rim light or lighting the background....the SC17 cord is good for this because you can hide that second strobe and the remote SU4 triggers it.....when I play "human lightstand", I usually hold the SC17/SU4 in my hand and aim it at the camera....the most *important* thing to remember with multiple lights is that you need to shield the lens for flare or avoid aiming that second strobe at the lens....it really helps to have the second person understand lighting if you do it this as well.

    FWIW, when I shoot events alone, I often put the second SB on a stand with a SU4 and turbo, and either use it as the main (direct) or the fill (bounce or stofen)....I shoot kids every year with history projects at an awards convention like this with N90s...I put the SB26 on camera with a Stofen and the second one on a stand off about 45 degrees right or left., a little higher than my head and titled down, zooomed out to 20-24mm. This is my main....I shoot on manual TTL, usually 60th at 5.6 or so with a 28 or 35mm lens.....the room that they held it in last year was about 13000 sq ft and painted black. Big, black pit with overhead work lights that were mercury vapor..it worked great, with both chrome and b&w film.

    KT
     
  20. Mark in SD

    Mark in SD Member

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    No questions here, just a thank you to everybody who has responded. I have a lot to try out here and a lot of ideas on things that I could be doing but didn't think I had the capability to try. One week in this forum already has me trying things that I wouldn't have in several years of experimentation.
     
  21. John Hicks

    John Hicks Member

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    > If I understand you correctly, I should be shooting in Aperature Priority mode with an appropriate f-stop and about +1 correction dialed in.

    More or less right. Aperture priority should be fine assuming the camera doesn't let the shutter speed drop below the synch speed when you're using flash. Most don't.

    As for correction, experiment. Shoot one without correction, one with +1/2 or so and one at +1; perhaps when you have the film printed you could ask the lab techs to tell you which of the three exposures was best. The main thing to remember is that negative film loves more exposure, the more the better (to a point of course), while underexposure kills it.

    > The exact f-stop chosen will probably be determined by some experimentation.

    Right. Your camera should provide you some feedback regarding that in the form of some sort of in-viewfinder "flash OK" indicator. If you don't get the OK indication then you'll need to use a wider aperture.

    BTW, I assume you've eliminated printing variables as the cause of the problem. Modern machine prints can be superb or horrible; it all depends on the operator.
     
  22. Mark in SD

    Mark in SD Member

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    Actually, both the camera and the flashes have indications. They will indicate that the flash fired OK and there is a different indication for the flash firing at full power but the camera still didn't think it was enough.

    Now that you mention it, I'm not positive how the camera handles the flash in aperature priority mode. I'll check on that, but I don't think it will force the the shutter any faster than the fastest flash sync speed (1/125 for the N80). A good thing to check though before I start.
     
  23. Mark in SD

    Mark in SD Member

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    A quick update here.

    I got an Ecosphere for my birthday (a sealed glass sphere with a self contained environment inside) and decided I would like to take some pictures of it to send to my family. Because the thing is all glass filled with water, my normal "mount flash on the camera and blaze away" technique wasn't going to work.

    So, I took a deep breath, put a diffuser on the SB-50 and set it up about 45 degrees off to one side, used some white paper to diffuse the on camer flash and...

    It all seemed to work. The SB-50 did trigger automatically and, after I got over my surprise at how well it worked, I experimented with different angles on the remote lighting. I haven't gotten the pictures back yet but I will probably post one or two on this thread so you can tell me what I could have done better.