More than just windows
Window light, of course, is a great way to shoot indoors. But that’s really only part of the equation. Don’t forget your doors—especially if you’ve got glass storms that can remain closed to keep the cold out but still let the light in. I have a north-facing door in my home and it produces great light—with the bonus of a bright red door as a background. Here, as is the case with any window light type source, you can position the subjects in relation to the source so that it produces side lighting or front lighting. If you’re going to position the subject’s back to the window, you’ll need to use some frontal fill by way of a white card or silver reflector to tamp down the contrast from the backlighting. In the “cat ears” portrait shown here, the window light is above the subject’s head and the frontal illumination is provided from a Flexfill with a matte silver finish.
Any direction will do
What do you do, though, when instead of nice soft light that comes from a north-facing window, you have direct southern exposure? You make the most of it, of course. South facing doors and windows can be helpful too, by producing a different look with stronger shadows and typically quicker falloff to a darker background. North facing windows produce beautiful light, but don’t discount the stronger, more direct light of southerly or even east/west exposures. If you’ve only got south facing windows but you want a softer illumination, consider using a popup diffusion to soften the direct light, or bouncing it off of a large white reflector to give it some softness that takes off the edge compared to direct light. Or, as in the “singing” portrait here, position the subject deliberately and expose for the brighter direct light and let the periphery and background fall into shadow. This helps put the focus more squarely on the subject, too.
Kill the overheads
You might think it doesn’t matter if you have interior lights on, but depending on the intensity of the window light you’re working with, indoor lighting can definitely influence the white balance making pictures too warm and orange/yellow compared to neutral daylight or even the slightly cool hues of open shade. So to be on the safe side and nail the perfect white balance, turn off any indoor lighting that might influence your exposures. This is especially true with tungsten or warm white CFLs or LEDs, whereas a true daylight balanced fluorescent or LED would, of course, match the color well enough. Besides the color influence, these additional lights can throw off your lighting pattern as well as the contrast of the scene, muddying the waters of the lovely window light.
Keep it tele, but just barely
In an outdoor portrait scenario where you’ve got plenty of room to work, you might like a 135mm, 150mm or even a 200mm lens for separating the subject from the background, isolating them from clutter and filling the frame with their head and shoulders or for a waist-up portrait. But it’s likely that working in your home, squeezed close to windows and doors in order to get just the right angle and the most beautiful light, you’re going to be working in close proximity with your subject—closer than usual for a typical portrait. That means your telephoto zoom is likely too long. Those 150mm and 100mm lenses are going to be too tight, so instead you’ll need a slightly shorter lens—likely in the neighborhood of 85mm, 70mm or even 50mm. I don’t typically like to get wider than that for portraits unless absolutely necessary. If you don’t have a superfast portrait prime, consider the long end of your 24-70mm zoom which will likely work great in this scenario.
Open up the lens
Unless you’re fortunate enough to have a true studio in your home, the background in your indoor pictures is going to be normal living spaces. To help these from being a distraction—as well as to put the focus sharply on the subject and provide a natural aesthetic—open up your lens and shoot at the maximum aperture or close to it. The largest opening on the lens is its maximum aperture, and it’s indicated by the smallest f-number—like ƒ/1.8, ƒ/2 or ƒ/2.8, depending on the lens. The smaller the number the wider the opening (relatively speaking) and the shallower the depth of field will be. If you can manage to focus well enough, don’t fret shooting wide open. But if you’re having a hard time nailing focus at ƒ/1.4, consider stopping down a bit to ƒ/2 or ƒ/2.8 to improve your chances of tack-sharp focus. If you’re comfortable with manual exposure modes, pair this maximum aperture with a fast shutter speed such as 1/250th or 1/500th in order to eliminate any camera shake. Adjust the ISO as necessary until the exposure works just right. If you’re not comfortable in manual mode, consider Aperture Priority in which you set the aperture (ƒ/2, for instance) and the camera will adjust the shutter speed accordingly. Just ensure you’re using a high enough ISO to keep the shutter speed fast enough for handholding.