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Saturday, March 20, 2010

Flash : Dramatic lighting in daylight

Today I did some tests to see what working distance I could get outdoors during the day with one flash and an under-exposed background .
I set the camera up in manual mode and metered the lighting at iso 200 , 1/200th and F16 . Occasionally the meter jumped to show that I needed F18 but that was due to the bright cloud .

And of course with me standing in the shade this is what it looks like without flash .

[ It has been pointed out that there is a difference in the background exposure - this is due to the clouds moving and the sun appearing occasionally , these things are never simple :) ]

Then we add direct flash .

And then I added the diffuser dome ....

There is very little difference with direct flash and the diffuser dome - the face of the dome is the same size as the flash head and provides the same amount of diffusion outdoors besides wasting a lot of energy on nothing by firing the flash at a much wider angle than the lens is taking in .

I haven't yet seen a logical reason to use the diffuser dome outdoors - all it does is waste power without adding anything to the picture .
I also tried a few shots with my large bounce card at an angle and realistically all it does is shift the angle of the flash a bit to the side and waste power . If you are close enough to the subject this change in angle can look quite dramatic but for practical photography it makes very little difference .

Now on to the 'dramatic' aspect of the experiment . Some people will dial in "-1.7" on the ambient [ any light that isn't flash ] exposure to make the background darker and the subject stand out . I was in manual mode and dialed in an aperture of F29 which showed me "-1.7" on the exposure scale of my meter .

Now at the aperture of F16 the flash was already telling me I had about 4 m working distance at best . By dialing in -1.7 I am also making it harder for the flash - smaller apertures mean it needs more power to get the same amount of exposure on the subject . [ A smaller aperture lets in much less light - ambient or flash - and so while darkening the background also requires more flash power for the subject ] .
At F29 the flash head was telling me I had 2.2 metres working distance at 50mm and 0.8 metres with the diffuser dome on . Since we are under-exposing the ambient by so much the flash will need to light the subject on its own so we aren't just using 'fill-flash' here . 
If we only have 0.8m with the diffuser dome on then tilting the flash head and using the bounce card would waste more power and render that approach useless basically .
I went to plan-B and took the flash off the camera using an SC-17 flash cord .

This was held in one hand facing directly at the subject and provides the very different look of off-camera flash along with the dramatic side lighting and dark background which makes the picture look very different to the first picture with flash .
 These images are all straight out of the camera with no processing or adjustments to the flash [ TTL/BL mode ] and obviously could look better with some adjustments and a prettier subject !

We are saving a lot of power with direct flash and hence maintaining our working distance compared to diffusers . We would need more flash power if we wanted to diffuse the light as well - or darker ambient lighting - then we could open the aperture up a bit more to help the flash . Late afternoon or dusk would provide ideal conditions to be able to have a dark sky and a wide enough aperture for the flash to be strong enough to also be diffused for even more professional results . The resulting image demonstrates hard lighting which gives a more dramatic image than soft lighting.



  1. I agree on using the flash diffuser outdoor is a waste of power... And even for me, during events in halls and large room I too feel that using the diffuser is a waste of power because the area of light coming out is still the same.. I get less burst and lower number of shots with the diffuser, and sometimes a lot less.
    Worst, not enough power at all!

    Nice post.. Thanks a lot.

  2. Yeah , it obviously wastes a bit of power [ besides the way it spreads the light ] because in TTL/BL the program increases flash output when the little button on the flash head is pushed down - an attempt to compensate for the power loss caused by the diffuser dome being fitted .
    Many people use it because they see the [misinformed ]pro's using it .