This is the latest article in my column, The Numismatic Image, published in the RCNA's Canadian Numismatic Journal. As a professional coin photographer, one of the most common questions I get is unrelated to macro or lighting. It’s about smartphones. Collectors regularly struggle with this, even though the devices themselves are capable of extraordinary photography. That frustration raises a question I’ll explore here: Are Smartphones Smart Enough for Coin Photography? The answer is yes, but it’s not their intelligence that’s causing the problems. Smartphones get smarter everyday. At the same time, the physical differences between smartphone cameras and DSLR or mirrorless systems affect image quality in ways particularly relevant to coins. Understanding these differences helps explain why smartphones work well for many purposes, yet professional numismatic photography still relies heavily on dedicated cameras. Sensor Size and Light Gathering The most significant physical difference between smartphones and DSLR cameras is the sensor, which is the light-sensitive component that captures images. Image 2: Sensor size difference. A 36mm x 24mm full-frame DSLR sensor on the right and a Smartphone camera on the left, compared to a silver dollar. A typical modern smartphone uses a sensor with a format of 1/1.3 inch to 1 inch. These sensors have surface areas ranging from 80 to 116 mm². By comparison, a full-frame DSLR sensor measures 36 × 24 mm (≈864 mm²). This means a full-frame sensor can collect 8–10 times as much light as a smartphone sensor. An equally important difference is pixel size. Smartphone pixels are often 1.4 microns or smaller—a micron is one-millionth of a meter. In a DSLR, pixels are around 6.1 microns. DSLRs have larger pixels that capture more photons (particles of light), resulting in lower noise, smoother tonal transitions, and greater dynamic range. This becomes important when photographing coins because lustre and toning are subtle optical effects. The difference between an accurate representation of a coin’s surface and a flat-looking image often depends on the camera’s ability to record delicate variations in reflected light. Modern smartphones partly compensate for their smaller sensors through multi-frame processing and advanced noise reduction, but these are educated guesses. Sensor physics still gives larger cameras a measurable advantage, allowing them to capture significantly more light from the coin. Lens Size and Optical Design Another difference is the lens's physical size. For coins, the most important camera spec is not megapixels, which are often misleading in mobile devices, but macro behaviour. Image 3: Lens size difference. A high-end 105mm Macro lens on the left and a Smartphone camera and lens on the right. Smartphone lenses are tiny, typically 5–8 mm in diameter. They must fit within phones less than 8 mm thick. Many modern phones use periscope optics, directing light sideways inside the device. This enables longer focal lengths without increasing thickness. In contrast, DSLR macro lenses are much larger. A typical 100 mm macro lens for coin photography may have a 40–60 mm wide front element and contain 10–15 precisely designed glass elements. The larger size allows engineers to correct optical problems such as distortion (warping of shapes), chromatic aberration (colour fringing), and field curvature (loss of sharpness at the edges of the image). Macro lenses are designed to produce extremely sharp images across the entire frame. Smartphones compensate for their smaller lenses using software corrections. The phone automatically adjusts distortion, edge softness, and colour fringing during image processing. For everyday photography, this works well, but dedicated macro lenses still offer superior optical precision when capturing small details. Clip-on macro lenses can be excellent for photographing tiny details like die cracks or repunching marks, but most require extremely short working distances. This makes lighting coins tricky and increases the risk of shadows. Telemacro phones are a better all-around solution, while clip-on macros work best as specialized diagnostic tools like a digital loupe. Image 4: Image capture with an iPhone 14 Pro Max, shot with a loupe placed in front of the lens. Aperture Control and Depth of Field A DSLR lens lets photographers adjust the aperture, the opening that controls how much light enters the camera. Large apertures (low f-numbers like f/2.8) give a shallow depth of field, so only a small part of the image is sharp, and the background is blurry. Small apertures (high f-numbers like f/32) provide a deep depth of field, making most of the scene sharp. Image 5: Macro Lens Apertures. A large aperture, f/5.4, on the left, lets in more light while a small aperture, f/32, on the right, allows less. Think of apertures as fractions, not whole numbers. In coin photography, apertures around f/8 to f/11 are used because they provide a balance between sharpness and depth of field. Stopping the lens down increases the range of distances that remain in focus, ensuring the entire surface of the coin appears sharp. Smartphones typically have large apertures, usually around f/1.7–f/2.2. Rather than changing the lens aperture, they use computational methods such as focus stacking and digital sharpening to simulate depth of field. While these methods can yield impressive results, they may also introduce digital artifacts, such as errors, distortions, or glitches, due to limitations in digital capture, processing, compression, or display hardware. Working Distance and Lighting Control Another key difference is working distance—the space between the camera lens and the coin. Older smartphone macro modes often required a distance of only 2–4 cm from the coin. At this range, the phone blocks light, causing reflections on mirrored surfaces such as proof coins. DSLR macro lenses typically allow a working distance of 30 cm, giving photographers space to position lights and diffusers. Recently, many flagship smartphones introduced telemacro lenses—telephoto lenses that focus closely. They often allow photography at 10–15 cm, a major improvement for coin imaging. This distance helps better control lighting angles, which are essential for revealing relief and lustre. Computational Photography: Help and Complication The biggest difference is computational photography. Smartphones often combine several exposures and process them with algorithms. These include HDR blending, multi‑frame noise reduction, AI sharpening, and auto-contrast. These processes can boost clarity, especially in tough light, but can also subtly alter the coin’s appearance. Two failure modes were processing can go wrong, are especially relevant. Over-sharpening artifacts Digital sharpening can create halos and exaggerate textures. It can also wipe out highlight detail—precisely where you need honest, accurate rendering on proofs and lustrous uncirculated coins. Over-noise-reduction “plastic wrap” smoothing Excessive noise reduction smears fine details, giving coins an unnatural, painted look. It also hides tiny surface clues and makes fields look smoother than they are. Image 6: Image capture with an iPhone 14 Pro Max, aperture of f2.2 with 3x optical zoom. The unnatural, painted look is evident. If your phone auto-brightens shadows and boosts contrast, it can flatten lustre or distort mirrored fields by shifting the balance between highlights and shadows. When authenticity is important, start with the most neutral image possible. Shoot in RAW if you can, limit auto-HDR, and minimize edits. Many smartphones now let you capture RAW images, which preserve authentic image data with less automatic processing. Image 7: iPhone 14 Pro Max on the left and Nikon D810 on the right, shot under identical lighting circumstances. When Smartphones Are More Than Adequate For many collectors, smartphones now fully meet their needs for everyday numismatic photography. They can capture coins well for inventory, attribution, forum posts, and most sales listings. They are especially useful for photographing reference coins at shows or club meetings. Where Dedicated Cameras Still Excel DSLR and mirrorless cameras continue to deliver for high-quality imaging, thanks to their larger sensors, macro lenses, adjustable apertures, and exposure control. These features make them suitable for private collection photography, professional auction images, dealer catalogues, academic publications, enlargements, and surface detail analysis. In such cases, capturing the most precise depiction of a coin’s surface is essential. Conclusion So, are smartphones smart enough to photograph coins? In some cases, the answer is yes. For best results, treat your phone as a real camera system. Use proven photography methods: control lighting, keep your setup steady, and avoid unpredictable processing. Unfortunately, the laws of optics still favour larger cameras for accurately showing a coin’s surface. Dedicated macro lenses and larger sensors capture subtle details like lustre, microscopic marks, and delicate toning. Smartphone macros look good on small screens, but DSLRs provide cleaner edges, sharper detail across the coin, and fewer artifacts at full size. Smartphones have not replaced professional numismatic photography. However, they have made quality coin photography more accessible. The quiet irony is that top smartphone camera photos are possible because phones now imitate DSLR macro optics. For most collectors, the phone in their pocket is already a capable tool for documenting and sharing coins.
