Smartphone accessories specialist Sandmarc has unveiled what it says is the first add-on telephoto lens designed specifically to mount on iPhone's periscope-style tetraprism camera, rather than the main wide-angle lens.
Available from Sandmarc's website for $269.99, the Telephoto Tetraprism Lens for iPhone is a 48mm attachment that provides 2x magnification of the built-in telephoto lens. This allows the iPhone 17 Pro models to achieve 8x optical zoom at full 48MP resolution, or up to 16x magnification at 24MP (384mm equivalent). On iPhone 16 Pro models and the iPhone 15 Pro Max, meanwhile, it can reach 10x optical zoom (240mm equivalent).
While add-on lenses for phones aren't new, Sandmarc's strategy of targeting the dedicated telephoto camera rather than the main sensor is a big departure. Most third-party smartphone lenses mount over the primary wide-angle camera, which limits their effectiveness when trying to extend telephoto reach.
Unique design
This approach follows similar thinking from Chinese manufacturers Oppo and Vivo, which have recently showcased add-on telephoto attachments for their flagship phones. However, Sandmarc's lens seems to be the first commercially available product designed specifically for iPhone's tetraprism periscope system.
The tetraprism telephoto camera, introduced with the iPhone 15 Pro Max and now featured across the iPhone 16 Pro and iPhone 17 Pro lineup, uses a folded light path to achieve longer focal lengths within the constraints of a thin smartphone body. Apple's native 5x optical zoom (120mm equivalent on iPhone 17 Pro Max) provides the starting point for Sandmarc's magnification boost.
The Sandmarc lens features multi-element, multi-coated glass construction designed to minimize flare and maintain color accuracy across the extended zoom range. At 143g, it adds noticeable weight to the phone, although this is obviously typical for add-on lenses.
The mounting system uses a dedicated case that aligns the lens precisely with the iPhone's middle telephoto camera. Sandmarc has designed the attachment to work with its existing filter system, allowing photographers to add polarizers or neutral density filters when needed.
Importantly, you can only use it with recent Pro and Pro Max models (iPhone 17 Pro and Pro Max, iPhone 16 Pro and Pro Max, and iPhone 15 Pro Max), as these are the only iPhones equipped with the tetraprism telephoto system. Each iPhone model requires its own specific case for proper alignment.
Practical issues
It's an intriguing approach that holds a lot of promise. The 52-degree field of view and true optical magnification should theoretically deliver sharper results than digital zoom alone, particularly for subjects like distant architecture, wildlife or sporting events.
On the downside, adding an external lens will increase the phone's bulk, and the 57.3mm height means it will protrude significantly from the device. Stabilization becomes increasingly critical at longer focal lengths, and while recent iPhone models feature impressive sensor-shift stabilization, handheld shooting at 16x magnification will test both the technology and your own technique.
Could there also be a trade-off in image quality? Adding glass elements inevitably introduces potential for aberrations, vignetting or light loss, though Sandmarc's multi-coating should mitigate some concerns.
A review unit is currently with our testers, so watch this space and we'll soon let you know what it's actually like to use in practice.
Check out our guide to the best add-on lenses for iPhones and Android phones
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