By John Harris | we got information from https://www.bhphotovideo.com/explora/photography/tips-and-solutions

It would be foolish to claim that there is only one way to take a portrait, but there are some accepted norms and basic camera settings that you should understand if portraiture is to become your area of photographic interest. Remember though, as you walk down your creative path, that a portrait is more than a headshot, more than a beautiful photo of your subject; it is an opportunity to get to know someone, to have a visual conversation with a person, and to use your photographic skills to pass that understanding of the person on to the viewer.

Cameras

Cameras are a fluid piece of gear when it comes to portraiture—Nan Goldin used a beat-up 35mm Nikon in her early work and Richard Avedon used an 8x10" Deardorff camera, among others. For some photographers, high resolution is critical to a good portrait, while others prefer a dreamy softness. In general, full-frame mirrorless, DSLR, or medium format cameras are the choices of experienced portraitists. But do not limit your creativity because of the camera you don’t have; find ways to interact with your subject and get to the moment where they are showing you their true self and be ready to capture it. Andy Warhol did it with a Polaroid Big Shot camera.

ISO

ISO is a calibration carried over from the days of film photography, and on a digital camera it indicates the light sensitivity setting of the sensor. A high ISO enables brighter image capture in low-light situations, but the downside is that this brighter image can be “noisy” or, using another word from the film days, grainy. These digital artifacts that become noticeable at high ISO settings are not conducive to flattering portraits. It is considered best practice to use as low an ISO setting as your light source will allow, creating smooth and consistent color tones. Depending on your lighting and camera stability and presuming your subject is stationary, try to keep the ISO below 400. That type of low sensitivity may not be possible in all lighting situations, but if you are using strong continuous light or daylight or have a strobe setup, consider an ISO of 100 for the best skin tones and overall image clarity.

Shutter Speed

Shutter speed is a measure of the time your film or digital sensor is exposed to light. Short shutter speeds are good for freezing movement while long shutter speeds allow more light but may introduce blur. Even momentary gestures like a glance sideways or a blink of an eye can result in enough blurring to ruin the portrait you were hoping to make. The same goes with the movement of the camera at slow shutter speeds.

So, what is an ideal setting for shutter speed when taking a portrait? Again, this is as subjective as the day is long and dependent on the type of portrait you want to take. Think of Avedon’s portrait of Killer Joe Piro or blurred smoke from a cigarette in classic Hollywood portraiture or, conversely, a dancer suspended in mid-leap. But because this is an introductory article, consider a shutter speed of at least 1/60 of a second as the minimum to avoid blur. Many photographers will push this even slower in the right conditions, especially when using a tripod or other support. However, the shutter speed is not the be-all and end-all of your setting decisions because the other camera settings, particularly the aperture opening, will determine how fast your shutter speed can be. And remember, during a portrait session, you can control the movement of your subject to some degree and can place the camera on a tripod or other stable support.

We will get to the aperture setting momentarily, but a final word on shutter speed—your light source, whether it be a corresponding flash duration or the golden light of sunset, will also dictate what your shutter speed should be. Be flexible with this setting and adjustment as you photograph. There is a rule of thumb that suggests the slowest shutter speed usable when shooting handheld should correspond with the focal length of the lens you are using. If, for example, you are using an 85mm lens, the slowest shutter speed to avoid blur would be approximately 1/85 of a second. In general, it seems better to me to err on the side of underexposure (a faster shutter speed, in this case) rather than overexposure, which could create a washed-out tone and/or display movement blur.

Aperture

Aperture setting determines the size of the opening in the lens or camera allowing light in. The aperture is normally adjustable and measured as an f-number, which is colloquially called an “f-stop.” F-stops on most portrait lenses range from f/1.4 to f/22 but can go higher or lower. A lower f-stop number is a setting for a larger aperture opening and vice versa. An aperture setting of f/22 is a tiny hole that lets minimal light in the frame and an f/2.8 is a relatively large opening that allows in more light. The trick of photography is balancing the ISO sensitivity, the shutter speed, and the amount of light coming through the aperture, so that the image is exposed well—neither too dark nor too bright.

But aperture also has a secondary phenomenon and function that is specifically important to portraiture. The aperture size also determines the depth of focus, also called the depth of field, and what that describes is how much of your image—front to back—is in focus. An image with deep depth of field will be in focus from foreground through background, and shallow depth of field will create images in which the focus is only on a specific point within the frame. Adjusting the aperture for the look you want is fundamental to portraiture. For an environmental portrait, in which the background and physical space of your subject are important to an understanding of the person, you want an aperture setting no lower than f/5.6 so that much of the items in the composition are in focus. When you want the eyes of your subject to be in focus and the rest to become a beautiful haziness or contain “bokeh,” set your aperture to f/2.8 or lower, if your lens allows. As a rule of thumb, an open aperture is often considered a setting conducive to beautiful portraits.

When you establish your aperture, then you can set your ISO and shutter speed settings. Most cameras have some form of light metering built in, but to best measure light and determine these camera settings, photographers often use light meters.

Lenses

Certain lenses are often called “portrait lenses” and are considered tools of the trade but, as with cameras, great portraits have been made with every kind of lens, from wide angle to telephoto and all in between. And of course, the lenses ideal for portraiture can also be used for a range of photo disciplines.

Focal length is the most common way we describe and categorize lenses. A long focal length is from 85mm to 600mm and upward, and is called telephoto; short focal length lenses are from 8mm fisheye to 35mm and are referred to as wide angle. While there is some gray area and, of course, disagreement, the general area in-between—from 40mm to 70mm—is considered a standard focal length. These standard and shorter telephoto lenses, specifically the focal lengths between 85mm and 105mm, are often used for portraiture. Whether using a zoom lens, which provides a range of focal lengths, or a “prime” lens with just one focal length, it is this set of focal lengths that is considered optimal for capturing facial features.

A significant reason that wide-angle lenses are not the choice for portrait work is because they create distortion that is not flattering to human subjects—a nose will seem extra big, the eyes set apart, and the overall shape of the face odd, especially if captured from the side. This does not mean that a portrait cannot be made with these distortions; at times it adds to the understanding of a character, but it can be problematic. With a long telephoto lens, an image is compressed within the frame, making the background and foreground seem unnaturally close. There is an element to this that is useful to portraitists, but too much is not recommended.

Another reason to avoid telephoto lenses is simply practical; unless you are at a great distance, you will be too close to your subject and cannot achieve focus or cannot include enough of their face and body in the frame. Likewise, with a wide-angle lens, you may have to get uncomfortably close to have the face be primary within the frame. Wide-angle lenses are more often chosen for the above-mentioned environmental portraits, which incorporate (and keep in focus) items within the entire frame.

When using portrait lenses within that middle set of focal lengths, the subject’s head and face appear more naturally shaped and realistically scaled. With a mild telephoto effect, they place the subject in a comfortable spot in relation to their background, not overly compressed, but separate enough to focus on the face with the background slightly out of focus. This out-of-focus aspect points to another important part of lens selection and camera settings. As discussed above, lenses that offer a large maximum aperture (below f/2.8) enable shallow depth of field, and this is useful for portraiture. To be able to pull focus to the face, specifically to the eyes, while keeping the background in soft focus, is often the most critical aspect of portrait photography, and a short telephoto lens, with a wide maximum aperture, is the best way to do this.

Taking creative and interesting portraits is more than just proper camera settings, and there is much to discuss in future articles about light placement and control, about the use of shadows and contrast, about locations, and certainly about interaction with your subjects, but if you are shooting in full-frame or 35mm format in natural light, consider these as practical introductory settings to get you started: an 85mm focal length, with an f/2 aperture, using ISO 100 and a corresponding shutter speed setting that maintains the overall exposure of the image—not too dark, not too light.

If you have any questions or comments about basic camera settings for portraiture, please comment in the section below.