More OCF portrait Questions

Discussion in 'People Photography' started by Bend The Light, Aug 6, 2010.

  1. Bend The Light

    Bend The Light No longer a newbie, moving up!

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    Hi,

    I am having another go at OCF. I have 2 off camera flash guns, both old, and will not work in sync with the camera. I have optical trigger devices on each, and the on-camera flash triggers them. I have fashioned a "deflector" for the built-in flash, so the light does not go forward, but rather, out to where the two off-camera flashes are. I have the camera set to "second shutter" and 1/200 speed (it's either that, or auto) and I shot at 1/100th sec.

    But i have problems...

    1. In this one, the set-up is as I said above...but one flash doesn't seem to be powerful enough, so I get the shadow behind - do you think it's the position, or somthing else?

    [​IMG]

    2. In this one, I turned off the main flash (camera left) and had on-camera flash and smaller OCF just below and right of the subject. This looks better to me, but I expected it to be worse using the built-in flash head on!

    [​IMG]

    Anyone explain where I went wrong (as I surely did!)
     
  2. Derrel

    Derrel Mr. Rain Cloud

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    In photo 1, the main light flash, to the left of the camera, is casting a hard-edged shadow on the wall behind the subject...that makes me wonder if the fill-light is actually firing. I mean, if the flash to the camera right were actually firing in the first shot, then wouldn't the background be illuminated well, like it is in the second photo???

    In photo 1--are you absolutely positive, beyond all doubt, that BOTH flashguns fired????
    I ask this question mostly because some of the newer flash triggers can go into "sleep" mode after a period of inactivity, as can some newer flashguns. (I know your flashes are older, but even the most-basic question's on tricky problems can sometimes be the actual answer...Occam's Razor and all that you know.)

    How are the off-camera flash guns set, power-wise? Are they set to manual power settings, like Full, or 1/2, and so on? It might be possible that if one of the flashes were set to an AUTO Thyristor mode (usually defined by a color-coded f/stop setting with switch or dial), that your second flash, the one to the camera right in photo #1, squelched its output almost immediately upon sensing the flash from the MAIN flash,located to the camera's left.... that is another possible explanation for why Photo #1 appears to have absolutely no fill-lighting coming in to lighten that hard shadow on the wall behind.

    I suppose also that the second-curtain synch might be affecting the secondary flash...some optical triggers will fire on the pre-flash, while other more sophisticated optical triggering slaves can sense a pre-flash, and will "wait" until the "real" flash comes along....

    So, if you are using the camera's pop-up flash in any kind of an automatic exposure mode, like TTL Flash mode, there's a strong possibility that the very brief pre-flash from the in-built flash is triggering ONE flashgun, the left one, but that the secondary or fill-flash camera right is NOT being triggered at the same,exact time.

    As you can see, there is more to troubleshooting this setup this than might meet the eye. DETAILS (camera make and model,camera's exposure mode, the in-built flash's exposure control mode, the power level mode of both off-camera flashguns, brand and model of optical triggers, your mother's maiden name,etc) would be helpful. You could re-try with the inbuilt flash set to MANUAL flash output control, at say, 1/8 power level, which will cancel the pre-flash feature, and might perhaps get both flash units to fire....because looking at shot #1, it does not appear that two off-camera flash units fired at the same time.
     
  3. Bend The Light

    Bend The Light No longer a newbie, moving up!

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    First of all, THANKS for putting the time in to answer my questions..apreciated!

    Yes, I am nearly almost certain it is...but you can go cross-eyed trying to watch 2 flashes at the same time ;)


    My next practice will concentrate on this...it is possible the flash at camera right was asleep...


    The one camera right is at full power (if it fired!). The one camera left doesn't have "power" settings as such - it has a switch to red or green which is a power switch, but as I read the info on the dial at the back, either can be used at these apertures at these distances to subject (now, am I reading the info on the flash correctly? Hmmm...maybe, maybe not).
    The camera right flash DOES have an auto setting, but I had it on M. It has 4 thyristor settings, too (4 colours) with red being the most powerful...I had it on red.

    I switch the focus assist flash to "does not emit" - would this be the pre-flash you mention? I haven't had issues with premature flashing!

    Canon 400d, Manual mode, in built flash as stated above can't be adjusted (unless we change the "Flash Exposure compensation" which goes from -2 to 2.

    Anyway, once again, thanks for your time, Derrel...very much appreciated. I learn all the time from people like you, it just takes me time, that's all!

    I will keep practicing!

    Cheers
     
  4. Derrel

    Derrel Mr. Rain Cloud

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    It can be very difficult to make sure two flashes fired. A few things. First, the AF Assist Emits/DOES NOT emit setting is not, specifically what I am talking about...what I was referring to is the way the flash is actually meted out, and then squelched (shut down) by the Canon's TTL exposure metering system. I am not intimately familiar with the 400D...I just reviewed my 350D's set-up and Custom Function menus and did not see a Manual flash output level setting, only flash exposure compensation settings, which can be found in the Camera Setup menu field on the 2nd Camera Setup page on the 350D. (As an aside AF-assist however, can result in premature slave triggering, so switching it off can be a good idea if your cam uses the flash as AF-assist; some bodies use a white light,not the flash--it depends on make and model of camera.)

    However, when you mentioned that the camera-right flash (the fill-in light in the above case on shot #1) was set to the RED Thyrisor mode, I think that is indeed the root of the problem! When in an AUTO Thyristor mode, the flash's sensor will sense the output of other flash units,and will squelch its output really quickly if there is output coming from another flash,or two.

    One needs to use the remote flashes in Manual modes for control and dependable and consistent output. I think you will definitely want to have both off camera flashguns set to Manual power control levels.

    I would set the 400D into Manual shutter mode, manually select my f/stop, and manually set a 1/100 second shutter speed, then set up my MAIN flash at say 5.6 feet from the subject and my secondary or fill-flash right over my head,aimed straight ahead, at exactly 8 feet from the subject. If both OCF's are of the same power output, the positioning of them at 5.6 and 8 feet, or 8 feet and 11 feet, will give a nice three to one lighting ratio, with nice shadows, and controlled fill lighting.

    With the on-camera flash set to AF Assist does NOT EMIT, and the flash compensation setting dialed way down to Minus 3 stops or so, your flash deflector ought to (hopefully) direct enough of that weak flash burst to trip the off-camera pair of flashes, and have virtually no real impact on the total exposure.

    In the past, I have had difficulty using flash deflectors at very low on-camera flash output levels, and sometimes you might need to boost the on-camera flash's power to make sure, 100% sure, that there's enough light directed toward the slaves to trigger them. If the slaves have a Hi- and Lo-sensitivity switch, you can try adjusting that.

    I think this is about all that's needed to get your set-up tidied up and shooting right!
     
    Last edited: Aug 6, 2010
  5. Bend The Light

    Bend The Light No longer a newbie, moving up!

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    Brilliant. I'll have another go tonight...Might find a different dolly, though, this one looks like something from a horror movie!

    Thanks for all your help.

    Craig
     
  6. lisa_13

    lisa_13 TPF Noob!

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    i jsut wanted to see i saw the photo before i read anything and that doll is terrifying. i'm sorry that this is no help at all but i'm going to have nightmares now, hahahah
     
  7. Bend The Light

    Bend The Light No longer a newbie, moving up!

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    Ohhh, sorry! :confused:
     
  8. Bend The Light

    Bend The Light No longer a newbie, moving up!

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    I hope you guys don't mind taking a look at this little lot...I set up again using the scary doll. I set up the shot and TOOK NOTES when I changed anything! So I can say what I did. Could you comment on these, and confirm my judgement on some of the problems?

    Here is the set up. You'll see from the photo taken with the wife's camera what I have to contend with - the clutter in our house is immense! Anyway...

    [​IMG]
    [​IMG]

    Camera at 1/100, f5. Doll set much further forward from curtains, camera further back (lose shadows on background?)
    1. No reflectors, OCF camera right reflecting off cupboards to right. On-camera flash full power. OCF behind left of doll angled to hair.
    2. Lights as in 1, but Flash Exposure Compensation set to -2.
    [​IMG][​IMG]

    3. OCF camera right angled up (bounce off white cupboard AND ceiling). Reflectors in place, one above head at rear andgled down, one at camera left (4 foot away)
    4. Left reflector moved to 2 foot from doll, camera left.
    [​IMG][​IMG]

    5. OCF camera right didn't fire?
    [​IMG]

    6, 7, 8. f16, both flashes fire, but gets darker? Recycling not complete?
    [​IMG][​IMG][​IMG]

    9. f10, both flashes fire.
    [​IMG]

    10. f5, both fire.
    [​IMG]

    So, I set out with harsh light, then harsh light on the right of the doll's face. Managed to soften that, but did have problems on the way. I know which one I think is the better of these. I will wait to see what you all think first.

    Thanks

    Craig
     

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