Saturday
Jun022012

Control The Power of the Sun

Auto FP High Speed Sync

 

In this post I'll explain how you can shoot directly into the sun, and still get a great exposure.  This is a technique used by many commercial photographers, and giving credit, I stumbled across it while reading about the work of Joe McNally, then adapted it to my style.

The article directly applies to the Nikon D700, though it can be applied to your preferred camera manufacturer and model.

 

What high-speed sync does...

 

Auto FP High-Speed Sync is a mode that allows you to shoot in extreme daylight situations, like the Mojave desert in the case above, and combat lighting conditions that either would blow out or underexpose most scenes.

When shooting a subject in front of a bright background, typically we're faced with two options: Save the background and silhouette the subject, or save the subject and blow the background.

 

In the situation above-- it's a common trade-off every photographer faces-- do I expose for the foreground, blowing out the background?  Or do I expose for the background and send the subject into darkness?  In this case-- it's a lose-lose.  Neither solution is particularly attractive.

FILL 'ER UP


Suppose you want to put the Sun in the same frame as your subject.  Let's look at the options:

The above left is without any fill.  As you can see, the image is completely useless.  There isn't an aperture/shutter speed/ISO combination that will make this shot work.

In the middle is the most common solution: Fill Flash.

All light to the sensor is additive.  This is important to note.  You can't pump up the foreground and expect the background to be diminished, it doesn't work that way.  Any strobes you add to a scene will be added to your current exposure.

Fill is great.  It can balance a typical outdoor shot in daylight.  But when you move to extremes, like the above middle, I can get the subject exposed, but to control the Sun, I need to either close way down on the iris, or increase shutter speed dramatically.  

F/Stop U

If you close down to f/22, you might stand a chance of getting that background under control, but your strobe probably won't be sufficient to punch the subject with enough light to balance the subject.  Plus-- you lose control of the shot.  Everything will be in focus at f/22.  And more than that-- you will lose sharpness!  The sweet spot for sharpness is usually between f/5.6 and f/11, depending on the choice of lens.  As you close down, the image develops lens abberation.  This is not a good thing!

Shutter Me Timbers

In order to open up, you need to increase shutter speed.  And here's the rub with fill flash and shutter speed:  On most camera bodies-- the limit for shutter speed is 1/250 or slower.  In the middle image above, 1/250 doesn't begin to control the background.  I'm looking at 1/1000 or faster before that background is tamed.

Why is 1/250 a speed limit?  Because if you introduce a strobe at a shutter speed higher than 1/250 you catch the shutter of the camera in the frame (represented as a black line across the image).

More Power

What the above right shows is we need a way to speed up that shutter-- to 1/3200 or so, but still have the freedom to punch the subject with a whole bunch of light, to compensate for the super-fast shutter speed.  How do we do that?  Auto FP High-Speed Sync.

 

The above shots were taken in quick succession.  On the left-- without a strobe.  On the right-- using Auto FP High Speed Sync.  In the shot on the left, the sensor is finding a decent median or average to the exposure.  It's doing the best it can to average out the light in the scene and produce something useable.  In the image on the right, I've taken full control of the camera.  I'm setting the camera to darken the exposure, and I'll provide the pop for the subject with flash.

Auto FP High Speed Sync turns strobe control over to the computer chips in the camera and strobe.  The two units communicate to not catch the shutter in the frame at speeds over 1/250.  The trade off is you need POWER.

A LOT of power.  The above left is what I call FrankenFlash.  Three strobes bongo-bungied together, positioned at relatively close range to the subject.  Small speedlights need not apply.  On Nikon, you must use a strobe of SB-600 or higher.  These units fire at full power in most of the the shots.  You're fighting the power of the Sun with AA batteries.  

Enough!  Tell me how to do it!

You’re going to the custom settings menu on the camera. 

e Bracketing/flash

 

e1 Flash sync speed

-> Set to 1/320 s (Auto FP)

 

e3 Flash cntrl for built-in flash

->Set to C Commander mode and arrow right

 

->Set built-in flash to “--”

->Set Groups to “TTL”

->Channel “1”

 

If you have a D3 or D4, obviously you don’t have an internal flash, you will need an SU-800 IR trigger or an SB-600 or better mounted on the camera.

 

Put all your strobes on Channel “1” and REMOTE.  

 

To set remote on an SB-800, hold the “SEL” button for 3 seconds.  The top right box is the remote select.  Highlight and click, scroll down to REMOTE and push “SEL”.  

 

The SB-900 is much easier.  Rotate the on/off switch to “Remote”.

 

You can assign the strobes to different groups if you’d like.  This would allow for tweaking their output from inside the camera.  They MUST be on the same channel, however.

Let's Shoot!

Time to make some frames!  Pop-up your flash.  Set the camera to M and select the aperture you wish to shoot for depth of field, without concern for exposure.  Use your shutter speed to control the background exposure.  Crank it up.  The camera's computer will do the math.

Move the strobes in close to the subject, and fire!

What you’ll notice immediately is the flashes start beeping like CRAZY!  You just completely drained them-- and they need to refresh before you can go again. 

 

Conclusion

 

The cool thing is Auto FP High Speed Sync will take an ordinary photo and take it to the extraordinary.  And who wants to take ordinary photos?  Tame the Sun! 

 

 

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