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On camera bouncing from far away walls using high ISO

agc1976agc1976 Member
edited January 2011 in flash & lighting
I started a thread on DPR posting a picture where I used a wall that was about 30 feet away to create directional light on my subject on a very overcast afternoon. I'm pretty sure the flash did what I asked it to do but other posters questioned it and it's been suggested that the flash did not contribute to the exposure.

The subject is my wife and I think I know how my wife look under flat lighting :)

I purposely chose F2.8 @ ISO3200 to max the range of my flash. I wanted to get some reassurance as to wether I did the right thing and the flash did in fact contribute to the light pattern on my subject. I think there's no better place to ask than here :)

FWIW here's a link to the thread:
http://forums.dpreview.com/forums/readflat.asp?forum=1025&message=37372358

Comments

  • I dunno, it seems a bit far for the flash to have an impact on the lighting, as it was said a shot without flash would have settled that one. But as long as you got a nice image that you are pleased with, how you got to it matters less.
  • At a range of 30 feet, the bounced light probably did not contribute very much, if at all. Light intensity follows the inverse square law, so the light rays travelling 30 feet to the wall and then any reflected rays travelling 30 feet back probably weakened the light intensity to virtually nothing.

    Your final image seems to have turned out fine in any case.
  • At ISO 3200 ... and ... depending upon the flash settings ... the flash could have and probably did contribute to the scene even though it would be a small difference ...

    I shoot action sports with fill flash at ISO 3200 at ranges in excess of 60 feet quite often, mostly to keep better, more consistent skin tones and WB under field lights and battle the rainbow color effects of lights cycling in many HS gyms ... both bounced and direct.

    Here is an example of two frames from the same series where on the left, the first frame of the series, has noticeable fill, and on the right, the last frame of the series, received no flash as the flash had not fully recycled ... the difference is subtle ... but noticeable ...

    http://www.butchmiller.com/forum/FP_Fill.jpg
  • Neil vNNeil vN Administrator
    I'd say it is entirely possible. 3200 ISO at f2.8 ? Definitely.

    Here's an earlier thread, where I bounced flash off a wall outside. The wall was about 5 car lengths away, and the bounce flash does make a difference.
    http://neilvn.com/tangents/2009/05/15/high-iso-is-no-substitute-for-good-light/

    It isn't the greatest photo, but it does show the difference.

    Here is another thread with a relevant image.
    I bounced the flash off a far wall inside a museum.

    http://neilvn.com/tangents/2008/07/11/a-light-touch/

  • I guess I have a lot more to learn about light properties.
  • @Stephen Ah, not really. Not that you dont understand light.
    I couldnt tell you the first thing about light physics and know very little inverse square whatever. Truth is....dont care. I cant think of this in middle of session. Just have to call on experience and understanding camera settings and how they work together.
    Just happen to know from experience that at 2.8 and ISO 3200...flash goes a looooong way.
    I also know, that wont work at ISO800. I also know it wont even work at ISO3200 and say f5.6. It the combo that made it possible. You can pick up flash from one endzone to the other on football field at ISO3200 and say f1.8 or f1.4.

    Dont cut yourself too short, just that you may have never tried those settings and bouncing from walls that far. I have cause you get in a pinch and you'd bounce off anything.
    I bounced off a group of 4 people wearing very light cloths once in an open field.
    Just asked, stand here and close your eyes, this is gonna be bright. But it worked.

    So no, you dont need to learn more light physics....just grab your camera and see what works.
  • agreed ... The mitigating factors here were the combination of the aperture and ISO ... f/2.8 and ISO 3200 can extend the effective distance between the flash and subject considerably ... The inverse square law still applies ... Larger numbers incorporated into the calculation factor into the result.

    The average top of the line hot shoe flash units have a Guide Number of 100-120 ... This should give you settings in the neighborhood of f/11 at a distance of 10 feet at ISO 100 when using direct flash firing at full power ... So bouncing a total distance of 60 feet at ISO 3200 is well within the output capabilities of the flash including factoring in the reflective efficiency of the surface you are using to bounce the light.
  • dgvdgv Member
    make sure you zoom out your flash head to its max for a better punch.
  • q5rickmanq5rickman Member

    I just noticed this post from 2011, AGC1976 the fill flash did exactly what you wanted it to do, look at the catch light in her eyes.

    Quin

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