Retratos

How to Shoot with TTL When the Weather Keeps Changing

11 septiembre, 2014

Escrito por: Jared Platt

On September 17, Profoto and photographer Jared Platt will host a free webinar on how to shoot with TTL when the sun comes in and out of the clouds. To get you in the mood for the webinar, Jared has written an article on the topic. Enjoy!

 

Although I learned flash in a completely manual world, complete with light meters and distance charts, TTL (Through The Lens) flash metering has been around for a while now. We have come to expect it on any on camera flash and with the help of radio and infrared, some companies have even taken the TTL metering off camera.

Basically, TTL technology allows the camera and the flash to have a conversation about the appropriate power of the flash for any given exposure. Not all TTL systems are excellent at this, but the Profoto B1 off-camera flash and the Air Remote TTL-C (for Canon) and the Air Remote TTL-N (for Nikon) do a fantastic job communicating with the camera and come up with very accurate results.

On September 15, 2014, Profoto is releasing Air Remote TTL-N for Nikon, so we took it on location with a Nikon D800 and two B1 off-camera flashes for a 100% TTL photo shoot on location in the desert lakes of Arizona.

 

In most cases, for a portrait, TTL is completely unnecessary and unadvisable. Because of the nature of the system, the camera and flash are devising a flash power solution for each individual shot, which means that based on a slight change in composition, a stray reflection could inspire a completely different power from the flash and ruin the shot.

Whereas, exposing the flash manually would maintain the power of the flash regardless of how much sky you might include in the camera frame. I would normally advise that on a portrait shoot, you should find your exposure and lock it in to the camera and the flash manually.

However, there are times where auto camera modes and TTL flash exposure metering are warranted.  We sought out those scenarios for this shoot.  Having a highly accurate TTL system like the B1 and Air Remote TTL is very helpful.

As you can see in the first image, we were enjoying some monsoon cloud cover, but it was not completely overcast.  We had intermittent moments of sun and shade throughout the photo shoot. This would require constant changing of both the camera exposure settings and the power of the flash. Rather than deal with that, we chose to shoot the entire job in shutter priority with TTL flash metering.

 

Shutter Speed: Because we are trying to fit our flash within the sync speed of our camera’s shutter, we must maintain a shutter speed of 1/250 or below (on a Nikon D800). By choosing shutter priority, I am able to maintain the fastest shutter speed available to me, which helps me avoid camera shake.

Depth of Field: Because the shutter speed is locked in pace, the aperture will fluctuate. How can I then maintain a depth of field that will be appropriate for my shot? At 1/250 of a second on a sunny day, the aperture required can get annoyingly small and focus heaps of sharpness and focus on me that I don’t want.  So, in order to force my aperture open, I first drop my ISO to 50. This doesn’t pull the exposure down far enough to give me the shallow depth of field I am looking for, so I also add a neutral density filter to the lens.  This brings me to f2.8 – f 5.6 which is the right general area. As the sun dances through the clouds the exposure will fluctuate, and therefore the camera will be forced to change f-stops, but they will stay in those lower f numbers, which suites my purposes for the shot.

Exposing the camera: With my ND filter on, my shutter speed locked and my f-stops in the right general vicinity, I test the ambient exposure. Always test the ambient exposure first.  The dark cliffs behind the model and the dark clouds above fool the camera.  Remember, the camera is looking for middle grey. So the clouds and the cliffs are too bright and the model’s dress is blown out! So an exposure compensation of minus one stop is applied. This puts the dress in the range of white, and makes the cliffs dark grey. I know that no matter what the sun does now, I will want the cliffs and the clouds to stay somewhat dark, so I should be able to shoot the entire thing at -1EV and get a pretty accurate ambient exposure with perhaps a slight adjustment here or there.

Exposing the Flash: When lit by the ambient light, the model is either extremely contrasty in the full sun, or she blends into the cliff in the softer, overcast light. So either way, she needs to be lit by other means. Because the ambient light will fluctuate throughout the shoot, TTL is a great way to go. Fortunately, the Profoto AirTTL system is extremely accurate, so it will do a great job at judging the flash exposure. Our first shot with the Air Remote on TTL-N yields a pretty accurate shot, but a slight adjustment on the Air Remote TTL-N to bring our “hair light” flash up by one stop separates her nicely from the cliffs and an adjustment of minus 1/3 stop tones down the fill light on the model’s face to maintain the drama of the ambient light without looking too flashed.  The flash will now make an educated calculation in communication with the camera and then alter those calculations by +1 and -1/3 respectively.

Light Shaping Tools:  Our “hair light” flash on the left is just out of frame was using absolutely no light modifiers and our “fill light” on the model’s face (with a Softlight Reflector White AKA Beauty Dish) is being held by my assistant on the end of a monopod and has been removed digitally from the final shot.  The Beauty Dish was an excellent Light Shaping Tool for the shot. I might have preferred a small softbox, but the Beauty Dish, was less cumbersome for my assistant to hoist in his precarious position in the lake and provided a softer light than a bare head.

 

Looking at the final shot once again, it is hard to tell that flashes were employed.  With the correct values dialed in to maintain the dramatic look of the ambient light but to soften the harsh edges of the merciless Arizona sun, we were able to achieve something that looks both natural and beautiful.

For those of you who are shooting Nikon, your wait for powerful and accurate TTL flash is over.  The Profoto Air Remote TTL for your B1 Off Camera Flash is available on Sept 15, 2014.

In our free webinar on September 17, we will be talking more about this shot and others captured on our 100% Auto Exposure and TTL photo shoot.  Click here to register!

If you have any questions, leave a comment below and I’ll do my best to reply!

Ps. We needed a Nikon camera for this shoot because I shoot Canon.  So a big thanks to Lens Pro to Go for sending us a Nikon D800 for this shoot!

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Escrito por: Jared Platt