If you ask me, the greatest benefit of natural light portraits is that they look and feel much more authentic.
That isn't to say that artificial lighting is bad or that it doesn't have its uses, because it does.
But I'd much rather head outside and use natural lighting for portraits than stay in the studio and fiddle with strobes, softboxes, and umbrellas.
Besides, I like to shoot lean and mean, and natural light portraiture is precisely that - just you, your camera, and the subject!
Natural light portraiture is also a great introduction to shooting portraits.
Without the worry of how to set up your lighting (or the expense of buying artificial lighting), you can focus on things like composition, framing, and using the light that's naturally occurring to make your subject look his or her best.
To get the best natural light portraits, you need to understand the camera settings that are needed. That's where this guide comes in...
Shooting Mode
If you've got some experience under your belt, natural light portraiture is best tackled in manual mode.
Manual gives you the most control over what the camera does, particularly when it comes to aperture, shutter speed, and ISO.
If you're a bit newer to photography (or to portraiture, for that matter), try shooting in aperture priority mode.
What's nice about aperture priority is that you set the desired aperture (say, f/4 to get a nice, blurry background) and the camera selects a shutter speed to match.
This helps you get well-exposed images without having to worry about manipulating all three exposure settings.
Learn more about advanced shooting modes.
Shutter Speed
There are two things to consider regarding shutter speed.
First, the shutter speed you choose should be fast enough to eliminate camera shake.
As a rule of thumb, the slowest shutter speed you can use is the inverse of the focal length of the lens.
For example, if you're using a 50mm lens on a full frame camera, you can shoot at around 1/50 seconds without blur.
But if that same 50mm lens is on a crop sensor camera, you have to take the crop factor into account.
Some cameras have a crop factor of 1.5x, 1.6x, 2x, and so forth. Simply multiply the crop factor by the focal length (i.e. 50x1.6), and you'll get an approximate minimum shutter speed.
Secondly, also think about the creative presentation of the portrait.
The suggested settings above are for instances in which you want to freeze motion.
If you want to blur motion, you'll need a much slower shutter speed, say, 1 second.
Remember, if you're in aperture priority mode, the camera will determine the shutter speed for you. If you want to extend the shutter speed, you can use a smaller aperture or use a neutral density filter to force a longer shutter speed.
Learn more about shutter speed.
Aperture
There are several factors at play when choosing an aperture value, primary among them, the depth of field.
Aperture is just one of many elements of depth of field, but the larger the aperture, the shallower the depth you'll have in the image.
This is typically preferable for portraits as it allows you to blur the background, which helps isolate the subject in the shot.
Fast lenses - those with a maximum aperture of f/1.4-f/2 - are great for this.
If you don't have a fast lens, you can use other factors to help you get a blurry background, as explained in the video above by Phillip McCordall.
As the distance between you and the subject increases, the depth of field narrows and the background is blurrier.
Likewise, the larger the distance between the subject and the background, the blurrier the background will be.
Learn more about aperture and depth of field.
ISO
When it comes to ISO, a good idea is to use the lowest value your camera allows.
For most cameras, this will be ISO 100, though some cameras offer ISO 50.
By minimizing the ISO, you also minimize the sensitivity of the camera's sensor to light.
This means less digital noise in your images for a cleaner, sharper look.
However, if you find that your shutter speed is just too slow to freeze movement or avoid camera shake, you can boost the ISO to make the sensor more sensitive to light, and then select a faster shutter speed as a result.
This process will take some practice, but with time, you'll develop an understanding of how to use ISO to get around shutter speed issues.
Shoot in RAW
A last camera setting to consider for natural light portraits is shooting in RAW.
RAW files retain all the details captured by your camera, unlike JPEGs, which are compressed and lose some of that data.
That means RAW files are much larger, and therefore have much more information for you to work with when it's time to process your images.
In other words, a RAW file makes processing your images much easier because you can account for a wider margin of error.
For example, if you overexpose the image, you can more easily correct that problem in RAW than you can with a JPEG.
However, a trick to use for natural light portraiture is to underexpose your images ever so slightly.
Underexposing your portraits helps prevent any parts of the shot from being overexposed. This is preferable because it's much easier to restore detail in dark areas than it is in bright areas.
Putting It All Together
There's other things to consider when creating natural light portraits.
That includes metering, focusing, and lens choice, among other things.
However, regardless of those factors, you still need to understand the basic settings to use to get a solid shot.
Give the settings outlined above a try next time you're out shooting with your favorite subject.
I think you'll find that these recommendations give you a good starting point for taking awesome natural light portraits!