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Forums Lobby MASTER YOUR TOOLS - Hardware & Software Nikon Speedlights & Lighting topic #61165
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Subject: "Multiple SB910s in Manual?" Previous topic | Next topic
M_Jackson Silver Member Nikonian since 28th Oct 2005Wed 03-Apr-13 03:09 AM
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"Multiple SB910s in Manual?"


Jackson, US
          

I watched a Dave Black training video on Kelby Training.

In one clip, he said he dropped the output on four strobes to 1/8, then said that'd be equal to just using one strobe at full power. Is this a correct statement? Or do you just add up all the fractions...in this case 4 times 1/8 = 1/2?

Are two strobes side by side at half power equal to one at full power in manual mode?

If Dave's comments are accurate, I need to get a better understanding of the formula.

Thanks in advance,
M. Jackson

M. Jackson
Jackson Hole, WY

Blog: www.bestofthetetons.com
Web Site: www.tetonimages.com

  

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gvk Silver Member Nikonian since 16th Feb 2006Wed 03-Apr-13 03:33 PM
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#1. "RE: Multiple SB910s in Manual?"
In response to Reply # 0


Mystic, US
          

> Are two strobes side by side at half power equal to one at full power in manual mode?

Of course. Two identical lights will supply twice the power of one, and twice the illumination is a one stop difference in exposure. Similarly, 4 lights will be 2 stops brighter than one, and 8 lights 3 stops brighter.

This is assuming, as you stated, that the flashes are set to manual, and that they illuminate the same area (i.e. are the same distance from the subject and aimed at the same point). That would not be the case if the strobes are aimed differently, for example, to provide wider lighting for a group shot, to evenly illuminate a whole room, or split between the subject and background, etc.

Gerry

  

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M_Jackson Silver Member Nikonian since 28th Oct 2005Wed 03-Apr-13 05:57 PM
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#2. "RE: Multiple SB910s in Manual?"
In response to Reply # 1


Jackson, US
          

gvk,
Thanks. I just wanted to double check the math regarding the fractional settings of multiple strobes when they are set to Manual.

Four at 1/2 power = two at Full Power
Four at 1/8 power = one at 1/2 Power
Four at 1.4 power = one at Full Power
Two at 1/2 power = one at Full Power
Etc..?

Manual: All set to the same zoom, all without diffusers or filters, and all pointing at the same subject.

If the math above is incorrect, please correct me.


M. Jackson
Jackson Hole, WY

Blog: www.bestofthetetons.com
Web Site: www.tetonimages.com

  

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gvk Silver Member Nikonian since 16th Feb 2006Thu 04-Apr-13 03:26 AM
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#3. "RE: Multiple SB910s in Manual?"
In response to Reply # 2
Thu 04-Apr-13 04:35 PM by gvk

Mystic, US
          

Your calculations are correct. The same ratios can be also applied when diffusers are used as long as the flashes are treated in the same way. For example, I often mount 2 x SB-800s to fire through the same umbrella for my main light either to increase the illumination by a stop, or to reduce recycle time by decreasing the power of both speedlights.

Gerry

  

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Forums Lobby MASTER YOUR TOOLS - Hardware & Software Nikon Speedlights & Lighting topic #61165 Previous topic | Next topic


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