What’s the Best Aperture Setting for Portraits?

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Watch enough online tutorials or read enough marketing copy and you might be convinced that a successful portrait requires cranking the aperture of your lens to its widest setting. While the “wide-open” approach to portraiture is far from new, its usage has surged in recent years, leading to a surplus of photos flaunting extremely shallow depth of field. As polarizing as it is popular, whether this phenomenon is viewed as a scourge or a blessing depends on the audience. Plenty of striking portraits have been made using this technique but, like any creative decision, moderation is key. This article considers the pros and cons of making portraits at the maximum aperture of your lens before exploring an often under-discussed topic: when to stop down.

Photographs © Cory Rice

To stop down or shoot wide open? That is the question. Read on for the answer.
To stop down or shoot wide open? That is the question. Read on for the answer.

Why shoot wide open in the first place? There are practical and aesthetic reasons behind this trend. Let's start with the basics: When you open up your lens’s aperture you are allowing more light to enter your camera. This provides two immediate benefits for portraitists. First, more light means you can shoot at a faster shutter speed, granting greater freedom to you and your sitter. This can be a godsend for fidgety subjects like children or pets. More light also means you can work in darker environments than you would be able to when stopped down. This adds flexibility when using available light indoors or when working outside later in the day. This benefit is especially noticeable when using “fast” prime lenses (e.g., f/0.95, f/1.2, f/1.4) that can provide an immediately noticeable boost in brightness when opened up, compared to slower lenses.

When focused on the eyes of your sitter, shooting wide can lure viewers into your portraits.
When focused on the eyes of your sitter, shooting wide can lure viewers into your portraits.

How does this affect the way your portraits look? The aesthetic appeal of shooting wide open revolves around selective focusing and subject-background separation. At a very shallow depth of field, you can make in-focus areas “pop” out of their surroundings. This technique has gained considerable traction in the engagement, wedding, family, and senior portrait photography industries. If you have ever seen a photograph of a couple in razor sharp focus surrounded by an indistinguishable blur of colors, you have seen the results of this phenomenon. Smartphone camera makers have been quick to jump on this trend, developing shallow focus “portrait” modes for consumers eager to simulate this effect with their phones.

A well-constructed lens will provide smooth, non-distracting out-of-focus areas. Captured with FUJIFILM GF 110mm f/2 R LM WR Lens (left) and Sony FE 135mm f/1.8 GM Lens (right).

When working at close range, shooting wide open can produce dramatic portraits. In these scenarios, focusing on the eyes of your subject can really make an image stand out. This can also serve as an optical means of gently softening the complexion of your sitter’s face as focus falls off from their eyes. Be aware, however, that working close and shallow can be an unforgiving process if you miss focus. Luckily, many newer cameras incorporate Eye-AF functionality, which can be extremely helpful when shooting with such a narrow focal plane. Be vigilant about keeping the firmware on your cameras and lenses up to date to take advantage of such technologies as they expand and improve.

The image on the left was shot at f/1.8 and the image on the right was shot at f/8. Note the dramatic difference in how the flowers are rendered.

Another frequently touted aesthetic effect associated with shooting wide open is bokeh. This buzzworthy term describing the out-of-focus areas of a photograph popped up in the late 1990s and has since come to dominate the marketing language around lenses. While the physics behind bokeh is a topic warranting its own article, it is worth noting that the greater the area of your image that is out of focus, the more relevant bokeh becomes. Personally, bokeh is something I only think about when it becomes distracting. The primary purpose of focusing your lens is to direct your viewer where to look in a photograph. If the out-of-focus regions of your image look weird or unnatural, that is going to compete with your subject in a detrimental way.

Introduce an object near someone’s face and watch your camera’s brain implode. Stop down or focus manually if consistency matters to you. Compare leaf-in-focus (left) vs. eye-in-focus (right).

Just as there are practical and aesthetic reasons for cranking open the aperture of your lens, there are plenty of reasons to stop down when making portraits. As noted above, the greatest challenge when shooting at a lens’s maximum aperture is nailing your desired focus. The margin for error is slim and mistakes become increasingly noticeable when less and less of your subject is in focus. If you are relying on a camera’s autofocusing system, it can be difficult to communicate the exact plane of focus you want when shooting at very shallow depth of field. Placing your subject in a crowded environment and hitting focus this way becomes even more challenging.

It is much easier to achieve the exact slice of shallow focus you want when using a tripod and working with a cooperative sitter.

Manual focusing is a potential workaround to this problem, although this approach comes with its own limitations, namely the need for your subject to remain still. Manual focusing while shooting a moving subject at f/1.4 isn’t going to work for most of us mortals. A seated portrait taken with a camera on a tripod, on the other hand, would be much more manageable. However, this entire scenario can be avoided by simply stopping down to give either your camera’s autofocus or your own manual focusing a wider margin for error.

Making portraits off-angle and wide open can create an impossible focusing scenario for eyes. Note how only one of the model’s eyes is in focus at f/1.8 (left) compared to both eyes at f/3.5 (right).

While achieving the exact shot you want of a moving subject when shooting wide open is technically possible, there are scenarios in which shooting wide open will not work no matter how much luck is on your side. One of the most frequently encountered limitations for portraitists in this regard—once again—involves eyes. As soon as the angle of a sitter’s face changes relative to the camera, the distance between each of their eyes and the camera starts to vary. If you are shooting wide open from a close distance, it can become physically impossible to keep both eyes of the sitter in focus at the same time. Add a second or third sitter and now you are juggling multiple pairs of eyes. As is true of everything in this article, the extent to which having the eyes of your subject fall out of focus is deemed a mistake will depend upon your creative vision. Again, this problem can be mitigated by simply stopping down your aperture to expand the focus area of your image. When working in-studio, stopping down and boosting light on set can be done to ensure uniform focus if you are shooting a group portrait or commercial images.

Shooting wide open is impractical when you are trying to keep more than one subject in focus.

Another factor to consider when selecting an aperture for making portraits is the fact that the resolving power of a lens is not uniform across aperture settings. You may have heard photographers mention the “sweet spot” of a lens. This refers to the aperture setting that produces the least amount of distortion, fewest aberrations, and most uniform sharpness in an image. This is different from depth of field because it describes sharpness across in-focus areas. Generally, the sweet spot of most lenses is somewhere between 2.5 and 3 stops down from their maximum apertures. For a more scientific approach to testing and determining the sharpness of your lenses, check out this article.

Like any creative decision, shallow depth of field works best when it contributes to the meaning of an image.
Like any creative decision, shallow depth of field works best when it contributes to the meaning of an image.

A quick jaunt through the history of photography will reveal that shallow focus portraits are not nearly as common as the loudest voices online might lead you to believe. There are plenty of reasons for stopping down when making portraits, and aperture setting plays just one role out of many in the portrait photographer’s bag of tricks. Experiment with different settings to see what works best for you.

Do you have a preferred aperture setting when making portraits? Let us know in the Comments section, below!

2 Comments

When shooting multiple subjects, stopping down becomes mandatory in order to expand the range of lens-to-subject distances that are in sharp focus.  I use "TrueDoF-Pro (iPhone app) to give me a good starting point for just how far stopped down I need to be.  What do you use?

Cory's point to take everything in moderation is so important.  It's something long-time photographers learned the hard way back in the bad old days.  Then, common films actually had ISOs of 25 and "kit lenses" were 50mm f1.8.  With such glacially slow film and a fast lens, far too many shots were made wide open with predictably disastrous results.  So, for photo geezers these days there is often an aversion to shooting wide open and a bewilderment as to why anyone would want to.   Even though the eyes may be in focus,  the eyebrows and tip of the nose won't likely be.  By stopping down to the lens' sweet spot the bokah won't be as "creamy".  But, it also won't look like a messed-up out-of-focus "nice try" either. ;^)

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