Problems bouncing flash off wall

Discussion in 'Lighting' started by Edimilson, Jan 10, 2009.

  1. Edimilson

    Edimilson Member

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    Hello!

    I have another newbie question for you guys.

    I've just bought a Vivitar 2800 form my old film cameras. I'm trying to learn how to best use it. I soon had sucess bouncing the light off my living room ceiling. Then I tried bouncing the flash off a wall. A voice in my head told me it was not going to work. It in fact didn't but I just can't understand why.

    I mounted the flash on my Olympus OM 2000 hot shoe. This flash model has a moving head. The head does not swivel, though I can set it at 90º, 75º, 60º and 0 degrees. Since the head doesn't swivel, I tried directing the flash at different angles towards the wall by holding the camera sideways (hope you can understand me now; English is not my native language). The problem is: I tried every aperture from 5.6 to 1.4 on the 50mm lens I was using. The negatives were all severely underexposed. The one shot at 5.6 was simply blank. The negatives shot with the flash pointing to the ceiling, on the other hand, looked quite all right. This is a mistery to me. I have tried both automatic and manual operation of the flash, to no avail.

    Perhaps it has to do with the so-called thrystor. It's for some reason quenching the flash sooner than it should because the flash is not upright. I don't see why that should happen, though. Any ideas?

    Thanks a lot!
    Edimilson
     
  2. Konical

    Konical Subscriber

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    Good Afternoon, Edimilson,

    What is the distance from the flash to the wall? What color is the wall? What color is the ceiling? How high is the ceiling? Are the surfaces highly reflective or relatively dull? All these factors will have an effect on how much light bounces. In general, a small, portable flash such as the 2800 will probably be marginal for bounce use. Even in Manual mode, it just doesn't have enough output to be very effective, unless the reflective surface is white and fairly close. Count on losing at least two or three stops in bounce mode compared to direct flash.

    Konical
     
  3. archphoto

    archphoto Member

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    Bom dia, Edimilson,

    Sorry, Portugese is not my language, but I am learning.
    The main reason why you get under-exposed negatives is the distance between your flash and the bouncing surface.
    The ceiling is closer to it than the wall.
    The more a bouncing surface is removed the more the flash is spread, giving you less light-concentration on one spot.

    Try to bounce off a white card board next to you and you will, with some experimenting, get a good result.

    Greetings,
    Peter, Goiânia, GO
     
  4. Edimilson

    Edimilson Member

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    I am always amazed at how nice you guys are.

    Well, I calculated 5 meters from the camera to the ceiling and from there to the sofa (which was then my subject). The pictures were well exposed.

    When I tried boucing the flash off the wall, the distance from the camera to the wall was about 0.5 meter and from the wall to my nephew another meter. The pictures were all underexposed.

    I am pretty sure I followed the same reasoning as before when I turned the flash towards the wall. I just thought that something goes wrong when you don't use the flash upright on the hot shoe. If it's not that, then maybe I just missed my nephew because he and the flash were not at the right angles. I mean, perhaps the light just didn't hit him. I just don't know. I'll look into that.

    Thanks anyway! You're great.

    Edimilson
     
  5. Edimilson

    Edimilson Member

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    One more thing: as to the color of the wall and of the ceiling, they are the same, almost white.
     
  6. archphoto

    archphoto Member

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    We are nice here, we respect each other and try to help each other !

    Quote: [when you don't use the flash upright on the hot shoe] it is still connected with the hot-shoe is it ?!
    Try it with an empty camera and see if the flash fires.

    Peter
     
  7. Edimilson

    Edimilson Member

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    Hi Peter,

    Yes, I am sure the flash fires. I took pictures of my nephew then and he too saw it fire each time. I will try increasing the distance between me and the wall so that the light will spread more. If you don't see any reason why the flash shouldn't work when not upright, perhaps the bounced light was just not hitting the boy right.

    According to that dial on the back of the unit, I should have used f 16 on the camera for that distance, which was around 2 meters (a little more than 6 feet). I tried all apertures from f 16 to f 5.6. This last aperture resulted in less in a better negative. The negative corresponding to the shot done at f 16 was simply blank.
     
  8. jnanian

    jnanian Advertiser Advertiser

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    hi edimilson

    sounds like your flash isn't giving off enough light to
    bounce off the wall and illuminate your subject.
    i am guessing that the sync speed ( x ) for camera is 60thS.
    just to have a little fun, and play a little bit,
    what i would do is put the flash on manual, and full power.
    but instead of shooting at 60th, bracket your shutter speeds and "drag" your shutter.
    the first burst do at 6oth, then 30th then 15th then 8th ...
    and you should hopefully be able to see your subject getting in the light ...
    another thing you could do, is instead of being so far from the wall or ceiling, and then
    from the wal / ceiling to your subject,
    get a white card - like foam core or matboard and make believe IT is the wall or ceiling
    and bounce the flash off of IT, and have the board closer to the camera and your subject.
    it will soften the light and bounce the light (hopefully :wink: )
    at the end of your experiment you will be able to see better what you need to do
    in the way of shutter speed, light and bounce distances. don't forget you need
    a TON of light to bounce ( as konical said ).

    good luck and have fun!

    john
     
  9. Edimilson

    Edimilson Member

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    Nice! Thanks. I'll try that tomorrow too.
     
  10. Lee L

    Lee L Member

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    Here's the manual for the 2800 in case you didn't get one with the flash. http://www.mattdentonphoto.com/cameras/vivitar_2800.pdf

    However, their instructions for measuring from the flash to the bounce surface to the subject, and making sure that distance is within the range you have set on automatic mode, are overly optimistic. I'd say to be sure not to be greater than 1/4 to 1/2 the maximum distance for whatever automatic range you're using when measuring the distance from flash to reflector to subject, even with white walls. Walls tend to bounce the flash everywhere, nice for diffusion, but very costly in terms of the amount of light reaching your subject.

    Also, if you're square to the wall when bouncing the flash, make sure that the flash hits the wall no more than half way to your subject. If you aim the flash too far along the wall (or ceiling), the reflected light will fall mostly behind your subject.

    Read about the auto-check indicator on the 2800 in the instructions. It allows you to check on whether the subject is getting enough light, either after an actual exposure, or with a test flash button. It will work both straight ahead or with bounce.

    Use the videos here http://www.abetterbouncecard.com/ to show you how to make your own bounce card for use on the flash to achieve softer light.

    Lee
     
  11. Ralph Javins

    Ralph Javins Member

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    Good morning, Edimilson;

    The Vivitar 2800 has a thyristor flash control circuit operated by a light sensor on the front of the flash. I think the light sensor is a small round eye. If you are using the 2800 flash in the normal Automatic Mode, the light sensor must be looking at the subject you are trying to photograph. If the light sensor can see the subject, then it can "meter" or measure the light falling on the subject to decide when to stop the flash.

    If the light sensor is also facing the wall when you take the picture, the light sensor will very accurately measure the light falling on the wall, and not the light falling on the subject. That will give you a very dark picture of the subject.

    If the light sensor cannot see the subject, try putting the 2800 into Manual Mode and do the old fashioned calculations for the flash to bounce surface to subject distance, and see if you get better results in Manual Mode.
     
    Last edited by a moderator: Jan 10, 2009
  12. MattKing

    MattKing Subscriber

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    What Ralph said.

    If you are using the auto function on the flash, the sensor on the flash needs to point toward the subject, in order to ensure that the subject is properly exposed.

    It might be possible to use a mirror or reflector to allow you to leave the sensor facing forward, while re-directing the light toward the wall.

    Matt
     
  13. Lee L

    Lee L Member

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    Matt & Ralph,

    The 2800 has a tilting bounce head, and a sensor that always points in the same direction as the lens, i.e. always at the subject, and not at the wall or ceiling used for bounce. See the manual I linked to. You're warning about a problem that can't occur unless the flash is taken off the hot shoe, a configuration the OP isn't using.

    Lee
     
  14. MattKing

    MattKing Subscriber

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    Lee:

    I think I (and Ralph) probably misunderstood Edimilson when he referred to "holding the camera sideways". After thinking further I assume now he meant holding the camera in a way that results in a vertically oriented photo.

    Reviewing again his description, I wonder if Edimilson is right and he had the bounce angle set wrong, so that the light is missing the subject. The distances (1/2 meter, and then 1 meter) are quite short, so the tolerances are probably narrow.

    Edimilson:

    Hope we can help.

    Matt
     
  15. tac

    tac Member

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    It's possible that the flash sensor is seeing the reflection off the wall and quenching the flash output when the wall is properly exposed, leaving the sofa/subject underexposed by 2-3 stops;
    try shielding the sensor from the wall with a bit of masking tape and a small cut piece of exposed and developed in roomlight photopaper(completely black side toward sensor eye, matte surface best, but glossy works), so the sensor can only "see" the subject.
     
  16. Lee L

    Lee L Member

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    I think you are probably right about the flash bouncing beyond the subject, especially at such a close distance. He should probably be tilting the flash head to 75 degrees minimum, and likely 90 degrees at that distance.

    On the other note mentioned, I haven't seen any of these flashes have a problem reading the subject rather than the bounce wall. The sensor is inset a little. A small piece of cardboard for a "gobo" can't hurt, but it's likely unnecessary.

    So a sketch being worth at least 10 words, I'll attach one showing how to aim the flash so that the light hits about halfway along the wall to the subject, the green line, rather than putting it so far along the wall that the light falls behind the subject, as with the red line.

    For the distance that Edimilson was using, I'd start at 90 degrees, the flash head tilted to go straight at the wall, so that the bounce is in front of the subject.

    Lee
     

    Attached Files:

  17. Chan Tran

    Chan Tran Member

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    Like other have pointed out, your problem relates to the fact that in trying to orient the flash you have the sensor pointing not at the subject but to the wall. You can use the flash in manual mode, estimate exposure and bracket. You can use a flash meter but that costs money. If you have a digital camera that can fire the flash you can use it to take test shots to determine exposure.
     
  18. Edimilson

    Edimilson Member

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    Hello Chan,

    I am not sure about this. You see, I have just tested the same thing with another flash, a Vivitar 285HV I bought for my newest film cameras. I bounced it off the same wall as mentioned and also off a white board. The results were very satisfactory (have a look: http://www.apug.org/gallery/showphoto.php?photo=40916&limit=1). I guess the older Vivitar 2800 didn't work either because:

    1) I the flash didn't properly hit the subject, or
    2) I should have opened up a stop or two on the camera, or
    3) The thrystor thing on the Vivitar 2800 does not work so well as the one on the 285 HV (which worked very well)

    I will try to sort this out next time I use the 2800.

    Thank you everyone!
    Edimilson