Photography for Rhinoplasty

Abstract

The importance of consistent and high-quality photographic documentation of rhinoplasty patients cannot be understated. Herein we will review important concepts in medical photography and discuss how one can alter the quantity and quality of light that is captured by the camera. Equipment selection will be discussed, including camera, lens, and external lighting sources. We will also discuss other key components for consistent medical photography in rhinoplasty including patient preparation and positioning.

Introduction

Photography is an essential tool to assess the quality of interventions and demonstrate proven benefit, since in facial plastic surgery there is a relative lack of quantifiable outcomes, and surgeons are often relegated to subjective data such as patient satisfaction and attractiveness to gauge results. Even when objective outcomes are used, they tend to rely on measurements taken from photos or observer opinions thereof.^1–3 As such, accurate photographic documentation for rhinoplasty has become increasingly important for preoperative planning, measuring and comparing quality of work, counselling patients, medicolegal documentation, and for providing proof of benefit to patients and payers.

Although there has been increased attention to photo consistency and quality in facial plastic surgery over the years, it is still relatively common for photos to be taken under inconsistent conditions and/or with suboptimal equipment. This can result in misrepresentation of rhinoplasty results, and can be misleading when such photos are used for pre-operative planning or intraoperative guidance. For instance, it has been demonstrated that minimal variations in head tilt can result in the appearance of a shortened nasal dorsum shortening by over 30% (p<0.001) among other notable facial distortions with position and lighting changes.^4–6

Standard photography for rhinoplasty has been well described, and includes at least a frontal view, right and left lateral views, right and left three-quarters oblique views, basal views, and a smiling view.^7–9 Some also advocate for the addition of a “bird’s eye” frontal view with the chin tucked at 45 degrees.¹⁰ Although obtaining the standard views seems relatively straightforward by following the templates previously set out, there are many critical details for obtaining consistent quality photos that can easily be overlooked. Several issues we will discuss at length within this chapter include equipment choice followed by adjustment of lens aperture, camera shutter speed and ISO. Furthermore, the patient should be consented, prepared and positioned appropriately. These concepts, as they relate to rhinoplasty, have been reviewed numerous times since the 1980’s, with a gradual transition in popularity from 35 mm film to the introduction and progression of digital photography as the new standard.^11–19 We will focus solely on the digital platform.

Equipment Selection

Cameras

The first step towards obtaining consistent quality images is to select the appropriate camera. Today, the vast majority of photographers are using digital cameras over standard film given numerous obvious advantages. There are generally two categories of digital cameras to choose between: fixed lens compact “point-and-shoot” cameras (e.g., smartphones) or interchangeable lens cameras (e.g., digital single lens reflex (DSLR) and interchangeable lens mirrorless). Fixed lens cameras are often smaller, more convenient, affordable, and easy to use compared to interchangeable lens cameras. However, they offer less flexibility with regard to manual focus, focal length, and resolution among other settings which work to reduce distortion and improve consistency. Additionally, the advantages of the fixed lens camera (primarily size and convenience) are not particularly important in the medical setting. Therefore, we recommend an interchangeable lens camera for rhinoplasty photography.

If one chooses an interchangeable lens camera, the next decision point is whether to use a DSLR or an interchangeable lens mirrorless camera, both of which have various advantages. In a DSLR camera, light enters the lens and reflects off a mirror to a prism, which directs the light through the optical viewfinder (OVF). When the user depresses the shutter button, the mirror lifts and the shutter snaps open allowing light to fall upon the digital sensor. On the other hand, for mirrorless cameras, light is transmitted directly to the sensor which displays a reconstructed image on the electronic viewfinder (EVF). As a result of the less complex mechanical design of the camera, mirrorless cameras are often times smaller than their DSLR counterparts. Quality of image is dictated in part by sensor type, size, and pixel number. In essence, the viewfinder of the DSLR is an optical pathway, where as the viewfinder of a mirrorless camera uses an electronically reconstructed image.

The primary advantages for mirrorless cameras are that they are more compact, can have more advanced autofocus and in-body stabilization capabilities, and provide a real-time preview image on the electronic viewfinder. However, some photographers have complained that the smaller bodied mirrorless cameras are more difficult to use with larger lenses or for those with bigger hands. Alternatively, DSLR cameras are excellent for capturing moving objects since the OVF has no lag. The DSLR OVF also produces a sharper raw image compared to the mirrorless EVF since it is a reflection of the true image rather than a digital reconstruction, and for that same reason performs better in bright light. Additionally, the autofocus on some DSLR cameras can be faster when compared with their mirrorless counterparts.

The mirrorless camera EVF has much more functionality built in, and will display essentially a preview of the image being captured exactly as the digital sensor sees it. In essence, once can see a “real-time” preview of what the image might look like prior to taking the image while adjusting aperture, shutter speed, ISO, and exposure compensation. The technology is analogous to the “live-view” feature on DSLR cameras. Additionally, because there is no reflective mirror, there is no associated temporary blackout through the image finder such as is found in DSLR cameras. Moreover, because mirrorless cameras are newer technology, there are generally more lenses available for DSLR cameras when compared with mirrorless cameras. Some manufacturers have developed adapters to permit use of DSLR lenses on mirrorless camera bodies. For the medical photographer, this is typically not an issue since one or two different lenses should suffice for this purpose. Both DSLR and mirrorless cameras are suitable options, but mirrorless cameras are quickly becoming the most popular option among professional photographers for several reasons, and would be our recommendation for medical photography as well.

Lens Selection

Interchangeable lens cameras permit the photographer to use different lenses for different situations, rather than being confined to the use of a single lens. Lenses are in part defined by their focal length, or the distance from the optical center of the lens to the digital sensor. The shorter the focal length of the lens, the wider the field of view will be, and vice versa.²⁰ The ideal lens focal length for portrait photography varies with the size of the camera sensor.

Digital camera sensors are the modern replacement for photosensitive 35 mm film. Such sensors contain millions of photosites or “pixels” in a grid which detect light color and intensity and convert them into a digital signal. Sensor size and lens focal length are the two variables used to determine angular field of view per the following equation.

The above is key for selecting the appropriate camera lens, and understanding how that can lead to distortion in your photographs, which will be discussed in a subsequent section.

Previously in the age of 35 mm film, the recommendation for portrait photography was a 90 to 105 mm focal length lens to obtain the least distortion and most appropriate depth of field, i.e. the distance between the farthest and nearest objects in focus.^13,19 The modern analog to 35 mm film is the “full frame sensor” and thus with this platform it is still valid to use a 105 mm lens for pre and postoperative photography. However, modern cameras will often have smaller sensors such as an advanced photo system type-C (APS-C) sensor or a “cropped” sensor. Here focal length of the selected lens is actually magnified roughly 1.5 times depending on the camera manufacturer. Thus, with a 105 mm lens and an APS-C sensor, the 35 mm film equivalent is of a lens with 157 mm focal length, resulting in a narrower angular field of view, and requiring the photographer to stand farther away. Therefore, when using an APS-C sensor we recommend using a 60 mm focal length lens, or a 105 mm focal length lens with a full frame sensor.

Finally, we recommend against using an adjustable focal length lens as this can introduce added variability in photography between sessions. The better choice for achieving consistency is a fixed focal length lens. Macro lenses are in particular are optically suitable for close focusing distances, and with proper lighting can be used to demonstrate excellent detail for intraoperative photography (figure 1).

Light Sources

Pre and postoperative photos should ideally be shadowless. Built-in flash units are not useful for this purpose, and can create the effect of flattening the face and nose, and causing overexposure. The optimal lighting set-up includes two flash units on either side of the camera with horizontal angles of incidence (angle between patient-camera axis to flash unit) of 45-degrees. Height of the flash units should match the patient’s face and camera height. The author also recommends the use of light modifiers to soften the light created by the flash units. Additional external lighting sources can also be used to help reduce shadowing and enhance portraits, but these are out of the scope of this chapter. If a studio set up is not possible, then the author recommends using an on-camera speedlight pointed towards the ceiling (figure 2). This effectively creates a softer light by increasing the size of the light source, resulting in a more even light. This is the author’s technique of choice, since he does not have an in-office photography studio.

Controlling The Light

There are three parameters the photographer can adjust in a camera to change the quantity of light that is captured by the camera. These three parameters are completely adjustable in most modern DSLR and interchangeable lens mirrorless cameras and include aperture, shutter speed, and ISO. Each of these parameters contributes to the exposure of the image. Achieving the proper exposure requires balancing each of these three parameters.

Aperture

Aperture is defined as the diaphragmatic opening within the lens, which can be adjusted to allow more or less light to pass and reach the sensor. Aperture is measured in f-stop, shorthand for “focal stop.” A larger f-number correlates to a narrower opening, and vice versa. This setting is also one of the main adjustable determinants for depth of field. The depth of field is defined as the distance between the closest and furthest objects in a photo that are in focus. A lower f-number, which allows more light to hit the sensor through a larger aperture, results in shallower depth of field. This can function to direct the viewer’s attention to a focal point, such as the eye. Decreasing the distance between the camera and the subject will also work to decrease the depth of field for this purpose. For pre- and postoperative rhinoplasty photography the author uses an aperture of f/9-f/11 (figure 3). This gives the image a suitable depth of field, keeping the eye and nose in focus, while keeping the background out of focus. This is preferable compared to figure 4 where the eye is not in sharp focus. If one desires, the f-stop can be increased (to a higher number) to achieve greater depth of field. In general photography, if the depth of field is not important, the author recommends using an f number between f/9-f/11, which is where commonly used lenses are the sharpest.

When taking intraoperative photos, it is often beneficial to blur the areas of the photo that are not of interest. For instance, the patient in figure 3 desired an improvement in symmetry of the nasal tip and base. The intraoperative photo (figure 5) of the same patient demonstrates the post-operative result on the table. An aperture of f/2.8 was used for this image to create a shallow depth of field, making the nasal base in focus and keeping the remainder of the subject out of focus, As a result, your attention is brought to the base of the nose, and the background is blurred nicely to reduce distraction. One might imagine that if the elements in the background were in focus, the image would take on a busy appearance, and lose its three-dimensional feel.

Shutter Speed

The shutter speed is defined as the length of time the image sensor of the camera is exposed to light during a particular exposure. Shutter speed is measured in seconds, or fractions of seconds, with lower numbers representing faster shutter speeds. Faster shutter speeds “freeze” moving objects and can also reduce the effects of camera shake from the photographer’s unsteady hands when not using a tripod (figure 6). Moreover, when taking a photograph without a tripod, a general rule is that shutter speed should be at least as fast as 1/focal length. For instance, if using a 200 mm lens, shutter speed should be about 1/200th of a second or faster. If you have vibration reduction capability built into your camera body and/or lens, you can typically use slower shutter speeds without a tripod. Alternatively, in order to display some element of motion, a slower shutter speed should be used (figure 7).

ISO

ISO can be thought of as the sensitivity of the image sensor to light. A lower ISO means that more light is required to achieve the proper exposure. Correspondingly, higher ISO settings mean less light is required to achieve proper exposure. Each camera has a native ISO where it typically performs best, filtering out the most noise and optimizing dynamic range. Raising ISO, for example to 800 or greater, can be beneficial in low light settings or when using fast shutter speed and narrow aperture. Unfortunately, by using higher ISO settings, the noise in the photograph increases. While this noise is often negligible in medical photography at settings less than or equal to ISO 800 (figure 8), noise can become noticeable at higher settings depending on the type of camera one is using. For this image of the Galactic Center of the Milky Way, the author used an ISO of 2000 to capture the very faint light (figure 9). The viewer should note the substantial amount of “graininess” or noise in the image. In the image taken of the moon, the author used a much lower ISO setting of 64, because of the bright light reflected from the surface of the moon (figure 10). There is a great deal less noise in this image as a result. For medical photography, ISO is an excellent tool to use to optimize exposure. Modern cameras can use very high ISO settings and still produce medical photographs of high quality. The author routinely uses and ISO setting of 800 for medical photography.

Achieving Proper Exposure

Obtaining proper exposure requires balancing the three parameters discussed above. If the aperture is opened (i.e. using a lower f-number), more light enters the image sensor, so a faster shutter speed, and/or lower ISO can be used. On the other hand, if the photographer desires more depth of field and increases the f-number (resulting in decreased opening in the aperture and less light reaching the image sensor), achieving proper exposure will require using a slower shutter speed and/or a higher ISO. Keep in mind that external lighting sources can also be used to increase the amount of light that reaches the image sensor of the camera. Conversely, neutral density filters can be used to decrease the amount of light that reaches the image sensor of the camera. A thorough discussion of these two concepts is out of the scope of this chapter.

Other Important Concepts In Photography

Focus

The focal point is the area of the photo in sharpest focus. While it is important to keep the anatomic structure of interest in sharpest focus, when taking pictures of animals (including human beings), the eye should always be in sharp focus to create a pleasant image (figure 11). On the other hand, poor focus on the eye of the subject results in an unpleasant image and can even create confusion as to the subject of the photograph. In this image of a bald eagle, the eye of the eagle is out of focus, and the eye of the fish is in focus, which can result in drawing more attention to the fish rather than the eagle (figure 12).

Depth of Field

As discussed earlier, depth of field is defined as the distance between the closest and furthest objects in a photo that are in sharp focus. Depth of field is controlled primarily by aperture size and distance from subject to the lens. However it is also inversely proportional to lens focal length when keeping the subject to lens distance constant.²⁰ Camera lenses with short focal lengths, using smaller apertures, or standing further from the subject will generally capture images with a large depth of field.

Distortion

There are generally two types of distortion, optical and perspective. Optical distortion or “lens distortion” is dependent upon characteristics of the lens itself. For instance, when using a wide angle lens the field of view can be larger than the camera sensor and result in “barrel distortion” with the edges of the image appearing compressed causing physically straight lines to bend in towards the center of the photo. Alternatively, when there is a narrow field of view paired with a large sensor the result will be “pincushion” distortion where edges of the image appear expanded and physically straight lines bend outward. Optical distortion is usually of small magnitude in medical photography, and so it is incorrect to choose a particular lens under the assumption that it will cause less distortion.

Alternatively, perspective distortion can cause a more significant problem. Perspective distortion is independent of the lens characteristics, and instead correlates to the distance between the subject and the image sensor (figure 13). For instance, when standing too close to the subject, the nose and lips will appear magnified while the ears will be minimized (figure 14). For this reason, the author recommends the use of a 60 mm focal length lens on a cropped sensor camera or a 105 mm focal length lens on a full-frame camera to achieve optimal distance from the subject for rhinoplasty photography.

Patient Preparation

Next, the patient should be prepared so there is the least distraction and most consistency between pre and postoperative photos to include hair style, make-up, and clothing. The hair should be retracted so that both ears and the forehead are exposed. Make-up, if excessive, may need to be removed. Clothing should be the same, with a bland neck line, or the patient can be placed in a standard hospital gown if needed. The patient’s jewelry should be removed.

The patient should be positioned roughly with their eyes at camera level. Background is typically medium blue, which is complimentary to all skin tones, reduces glare, and provides good contrast. Regardless of background color, the background material should be free of wrinkles and generally not in focus to reduce distraction. The patient should also be sitting upright with good posture looking directly at the camera without any head tilt unless required.^6,19 The author uses a darker blue background because of personal preference, but feels that a lighter blue is also a reasonable option.

Achieving consistency

Consistency is absolutely critical when photographing for medical purposes. Similar to the concept of eliminating or controlling for covariates in a research study, variables in photography need to be controlled to help bring the attention of the viewer to the change of interest. That is, the only difference between the pre and postoperative photos should ideally be due to the surgical intervention (figure 8). As such, the author uses consistent patient positioning, and completely manual settings on the camera to eliminate any changes in aperture, shutter speed, and ISO that may result if the camera is permitted to determine these parameters. If exposure or positioning is varied, the resulting photographs can be less useful because of the distracting variables (figure 15).

Conclusion

With the right tools and technique it is easy to produce useful photographs of rhinoplasty patients. We recommend an interchangeable lens mirrorless camera system with an appropriate lens based on the sensor of the image size of the camera. The author generally uses an aperture of f/9-f/11, shutter speed of 1/60-1/100 second, and ISO of 800. Other important considerations include focus, depth of field, distortion, consistency, external lighting sources, and well as patient preparation and positioning.