Sony FE 100mm F2.8 STF GM OSS – The new underwater benchmark for Sony shooters

A flagship macro lens – now in a completely new league underwater

The Sony FE 100mm F2.8 STF GM OSS is renowned for its outstanding sharpness, unique STF (Smooth Trans Focus) bokeh and the optical precision of Sony’s G Master series. Underwater, this lens raises the bar even further and, combined with Nauticam’s MFO and SMC optics, becomes a tool unlike anything we’ve seen before.

The reference combo: Sony 100mm + Nauticam MFO-1 + MFO-3 + SMC-3

For Sony underwater photographers, this setup is the new benchmark in macro performance. In terms of sharpness, focus behaviour and overall macro versatility, it sits in a league of its own – from classic macro to extreme super macro and blackwater work.

Mid-range Focus Optimizer MFO-1 – optimized focus range & improved image quality

MFO stands for Mid-range Focus Optimizer. The Nauticam MFO-1 is designed to optimize the focus range of popular macro lenses and significantly improve performance in the mid-focus distances.

• Enhanced image quality: reduces lens aberrations and improves clarity and color accuracy compared to a simple flat port.
• No focus hunting: the converter adjusts the effective focus range so that autofocus runs smoothly with far less visible hunting.
• Focus range conversion: shifts the useful working range into distances that make more sense for underwater macro shooting.
• Increased magnification: slightly boosts maximum magnification for more detail at close range.

For lenses like the Nikon 105mm VR and Canon RF 100mm, detailed focus range and magnification data are specified. In practice, the Sony 100mm benefits from the same design goals: more stable AF, better image quality and a far more practical working range for macro underwater.

Mid-range Focus Optimizer 3 – MFO-3 for 90/100/105mm full-frame macro lenses

The Nauticam MFO-3 is specifically optimized for longer focal length full-frame macro lenses such as 90mm, 100mm and 105mm – making it an ideal match for the Sony 100mm macro underwater.

• Approx. “60mm behaviour” underwater: transforms long macro lenses so they behave more like a 60mm underwater, with much better close-focus capability.
• Improved close focusing: dramatically enhanced “focus-to-the-glass” performance, while still keeping usable working distance when needed.
• Perfect for blackwater & wide-angle macro: excellent for mid-range macro and open-water environments where flexibility and quick focusing are essential.
• Outstanding image quality: water-contact optic delivering high sharpness and clean rendering across the frame.
• Lower in-water weight than SMC-3: despite its physical size, the MFO-3 is lighter in the water than the SMC-3, making the system easier to handle and balance.

From thumbnail-sized nudibranchs to frogfish the size of a grapefruit, the MFO-3 gives the Sony 100mm an extremely wide range of usable working distances and subject sizes without swapping lenses or ports.

Nauticam SMC-3 – the super macro booster

The Nauticam SMC-3 Super Macro Converter is Nauticam’s most powerful super macro optic and perfectly complements MFO-1 and MFO-3 whenever extreme magnification is the goal.

• very high super macro magnification
• excellent sharpness for the tiniest subjects
• comfortable working distance despite the high magnification

Combined with the Sony 100mm, the MFO-3 and the SMC-3, you get a system that is extremely sharp, very fast in response and offers a level of macro versatility that is hard to match.

Key features of the Sony FE 100mm F2.8 STF GM OSS

• G Master optics – maximum resolution and contrast
• STF (Smooth Trans Focus) – beautifully smooth, creamy bokeh
• Fast, accurate autofocus – ideal for moving or shy subjects
• Optical SteadyShot image stabilization – added stability, even underwater
• F2.8 aperture for creative depth-of-field control
• Rugged, weather-sealed construction – ready for demanding environments
• Perfectly compatible with Nauticam MFO-1, MFO-3 and SMC-3 for maximum macro performance

Why this lens stands out underwater

1. Cinematic bokeh & subject separation

The STF element produces exceptionally smooth backgrounds, strong subject separation and very pleasing highlights – ideal for artistic macro work and refined underwater imagery.

2. Precision for creative macro & snoot lighting

With MFO-1 or MFO-3, the usable focus range becomes far more practical. Paired with snoots such as Backscatter OS-2, Nauticam Aperture Card systems or Retra LSD, the Sony 100mm is perfect for:

• spotlight-style macro shots
• clean black backgrounds
• high-contrast, visually striking macro lighting

3. From classic macro to extreme super macro

Thanks to MFO-1, MFO-3 and SMC-3, this system covers the entire range – from classic macro portraits and mid-range macro to blackwater and extreme super macro – all with a single core setup.