Monday, June 6, 2011

Week 23 (June 4th - June 10th) | Pictures 36 & 37

I wanted to experiment a little bit this week with shutter speed and flash. When using flash, shutter speed does not affect exposure on the object being lit by the flash. (Did your brain just explode? Mine did when I really started learning about lighting.) Take everything you ever learned about your exposure triangle and throw it out the window. Aperture, ISO, and flash power control exposure provided by the flash. Shutter speed controls only one thing: ambient light - that is, the light falling on all objects not directly lit by the flash.

Super awesome Amy has a wonderful blog tutorial about this phenomenon and why "dragging the shutter" when using your speedlight is a wonderful way to have a properly lit subject and background (in the absence of strong ambient light). I promise if this concept is new to you, then her blog post is infinitely more valuable than this one.

Obviously the fundamental concepts will also apply when you are using your flash to light something other than your subject. And this questions arose several days ago on a forum where someone was trying to light their background and get more exposure on their subject with only one speedlight.

Neither of these pictures are mind-blowing OCF. In fact, I've done the same setup before with similar results on my margarita glass experiment. But I do think they are good examples of how the same flash principles apply regardless of their application.

Image 1:


Camera: Nikon D700
Lens: 105mm f/2.8 macro
Aperture: f/4.0
Shutter Speed: 1/250
ISO: 200
Flash: SB-800 off camera, manual, 1/128th power
Exposure: manual

Image 2:


Camera: Nikon D700
Lens: 105mm f/2.8 macro
Aperture: f/4.0
Shutter Speed: 1/25
ISO: 200
Flash: SB-800 off camera, manual, 1/128th power
Exposure: manual

You can see clearly that the part of the white background being lit by the flash is identical in both images - despite a shutter speed difference of over 3 stops of light. It is only the areas not affected by the flash (the subject and the further areas of the background) that change when you adjust shutter speed.

Can you tell I'm struggling with creative ideas? I need to find some new lighting projects (or get another light)!

1 comment:

  1. This is such a great illustration! Wrapping my head around when to alter shutter speed vs. when to alter flash power has been a bit of a slow concept for me to grasp, thanks for posting these pics!

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