By numerous reader request, in this week’s Troubleshooting your photography we discuss portraits with Christmas lights. Controlling your ambient light and flash exposure to get Christmas lights that pop while keeping a proper exposure on your subject can be confusing. Let’s talk about it…
Using a strobe, whether on-camera or off to light your subject is a straightforward process, but when you mix a secondary light source like Christmas or fairy lights into a portrait, things can get wonky. We have all taken those photos where the flash completely overpowers everything, and you end up with a brightly lit subject and everything around and behind them is black. With this method, you isolate your subject using the flash to control where the light is landing in your image – on your subject. What if you want more ambient light? Say your subject is standing in front of a Christmas tree, you want to see all those points of light and your subject.
When looking at the exposure triangle – ISO, Aperture and Shutter speed we traditionally are told that ISO should always stay at the lowest possible – otherwise we get a super noisy image, aperture controls how much of the background is in focus and shutter speed is instrumental in freezing movement. The reality is that each part of the triangle also controls ambient light. In terms of camera mode, you can work along with me on these examples using either aperture priority or preferably manual mode. Since we are creating a portrait, we will start by setting our aperture to the biggest opening which is the smallest number, in my case I started at 4.0 or f4, but my lens is capable of f2.8. With a larger opening, more light will enter the lens, allowing you to use lower ISO and faster shutter speeds. The added benefit of a wide-open aperture is the lights in the image blur out (called Bokeh).
With our aperture set to one stop above its largest opening, we have three options to adjust the ambient light in our image, raise the ISO, drop the aperture to f2.8 or slow down the shutter speed. In example 1, I have opted to raise the ISO from the base value of 100 to 400. With the quality of sensors in most cameras today, 400 ISO is well within the “safe” range – well before undue noise is introduced into the image. At a shutter speed of 1/100 @ f4, we can see our ambient light is at about a medium level of exposure, adding overall brightness to the capture. The issue introduced by raising the ISO is you can clearly see the strands of the Christmas lights, and a lot more detail in my background than I want. We are going for an image where the lights are fading into the background – so this is not a viable solution. It should be noted that turning the light source away from the model more (called feathering the light), or moving the model away from the background would have also been a viable solution, but I wanted to solve the problem keeping the location and distances intact.
When working with off-camera lights, whether constant or a flash, I always recommend building your scene one light source at a time. To dial in the brightness of the Christmas lights, I started by turning off my main light (the Profoto B10), returning my ISO to 100, and opening my aperture as far as my lens would let me – f2.8, with my Shutter at 1/100 you can see in example 2a, how the ambient light level is looking relative to the lights in the background. The decrease in ISO immediately brought the overall brightness of the image down closer to where I want it to be, but I would like the lights a bit brighter.
In example 2b, I reduced my shutter speed (called dragging the shutter) to 1/50 – which is stretching the limits of hand-holding for many cameras without introducing undue blur, so I opted for a tripod (truth be told, with the image stabilization switched on for my lens, I can comfortably shoot at 1/25 hand-held but your mileage may vary). Looking at this example, I am happy with the amount of bokeh from the lights, and the ambient light and the light from the Christmas lights is looking good. So now, it is time to switch the main light back on and see where we are at. It should also be noted at this point, that shooting at shutter speeds less than 1/100, you are very likely to see blur if your subjects are not holding still. Even with the pop of the strobe, any movement from the subject will produce an unflattering blur – potentially widening their faces or appendages that are moving – be careful.
With the changes in aperture and shutter speed, we have gotten a handle on our ambient light in example 3, the balance between the Christmas lights and ambient light is more pleasing. With the current light in the background, there should be enough detail in the branches and ornaments if you opted to shoot your subject in front of a decorated Christmas tree. Speaking of the light, the subject was lit by a single Profoto B10 strobe with a 36-inch octabox. The strobe was in TTL mode, and did a good job sorting out the exposure on the subject once I had all the other attributes dialed in to my liking. If your subject is adept at holding still, you could easily consider dropping your shutter to 1/25. With the settings dialed in, it is easy to fine-tune the look you want from this point.
I hope you found this information helpful for your holiday portraits, feel free to post some images on Instagram or Twitter and tag me @nedskee I’d love to see your work using this method!
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My Photography site: http://www.tahquechi.com/
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