Could anyone shed a little light?

Started 11 months ago | Questions thread
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Joaquin_peme
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Could anyone shed a little light?
11 months ago

Hi,

I'm on the road to trying to understand flash lightning. Now, I'm a bit stuck with how strobe-to-subject distance influence on background rending.

SAMPLE A

This prop was set up in my flat corridor. The background wall is 9.8feet away from the subject. As for my strobe, which is snooted in order to avoid light bouncing off the corridor walls, is 15 inches away from my prop. The flash is in M mode at 1/64. My camera is set in M mode as well at ISO 200,f/4, 1/200

When I move my flash 13feet off my prop, I need to compensate up tp 4 stops to get a properly exposed frame.

SAMPLE B

Now my flash is at 1/16 ( +2 stops), my ISO at 400 (+1 stops) and my aperture is set at f/2.8 ( +1 stop)

Here I've lost control over my background. My strobe is, somehow, contaminating my background. Conversely, settings in sample A would allow me to control the background at will by adding a second light.

So far...., so good..., BUT.....

In theory, the further you move your strobe away, the softer the light fall-off is. The tradeoff here is the loss of power. To some extent, I understand this might account for now the background showing in my frame..., but...

Isn't it even more meaningful that 4-stop difference?

Besides, light quality in sample B seems to be softer than in sample A. Again, in theory, the further a light source is, the smaller it becomes in relation to the subject, hence producing a harder light. Sample B light looks much softer, though.

How can this be?

Thanks from Spain

(Edited to correct some particulars)

 Joaquin_peme's gear list:Joaquin_peme's gear list
Canon EOS-1D X Canon EF 135mm f/2.0L USM Canon EF 24-70mm f/2.8L USM Canon EF 70-200mm f/2.8L IS II USM Carl Zeiss Distagon T* 2,8/21 +2 more
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