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To witness the true impact of ultra-low reflectance, we staged a high-contrast test: a factory at night illuminated by intense artificial light sources.
Factory at night under a clear sky with no filter attached
The Benchmark: No filter
This image represents the lens’s original optical performance. Without additional glass, there are no extra surfaces for light to bounce off, resulting in zero filter-induced ghosting. This is the baseline every protector aims to match.
The goal of any lens protector is to match this baseline while providing physical security.
While protectors are essential for guarding against physical damage, dust, dirt, water, and oils, adding glass on the top of the lens has traditionally meant accepting a slight compromise in image purity.
A Legacy of Evolution
Full-frame 4-way comparison "No filter/Prime II LP/EXUS LP II/Standard MC filter"
(You can right-click and open the picture in a separate window for an enlarged view)
These four images above demonstrate how different classes of Multi-Coated (MC) filters handle extreme light.
In the early 2000s, at the dawn of the digital camera age, a 0.6% reflectance (found in standard MC filters –picture on the far right) was the industry's top quality. However, multiple ghosting artifacts caused by surface reflections are visible (circled in red below).
with a standard MC (Multi-Coated) filter
On the other hand, the EXUS Lens Protect Mark II, released in 2019, refined the original EXUS 0.3 down to 0.2%, offering excellent image clarity. Compared to the Prime II LP, nonetheless, subtle artifacts still remain.
with EXUS Lens Protect Mark II/Reflectance 0.2%*
To see the impact of pushing reflectance down to 0.08%, we must look more closely in comparison.
Magnified 4-way comparison showing the details of the light sources and ghosting
(You can right-click and open the picture in a separate window for an enlarged view)
The Proof is in the details
Magnification reveals the clear distinction in ghosting (internal reflections).
Standard to High-End (0.6% – 0.2%):
Even at the 0.2% level, faint green ghosting and light leakage are visible around intense sources.
Prime II (0.08%):
By reducing reflectance below 0.1%, ghosting is virtually minimized. The Prime II is visually almost indistinguishable from the "No Filter" benchmark, offering the highest level of protection without an optical penalty.
Shooting Data:
Camera: FUJIFILM X-T5
Lens: FUJINON XF70-300mmF4-5.6 R LM OIS WR
Settings: ISO 500, f/5, 1.8 sec
The following link demonstrates how ultra-low reflectance affects the visual appearance of the glass.
Achieving both ultra-low reflectance below 0.1% level and reliable anti-static performance has traditionally been a significant technical challenge. In practice, however, even microscopic dust or particles adhering to a filter surface can become a source of unwanted ghosting and image degradation.
Marumi’s Ultra-Low & Anti-Static (ULA) coating overcomes this trade-off. By reducing surface reflectance to as low as 0.08% while maintaining effective anti-static properties, it minimizes the attraction of dust and airborne particles. This helps keep the optical surface clean and significantly reduces the risk of contamination-induced ghosting.
The following shows the quantitative anti-static performance.
The flatness of an optical filter directly affects the resolving performance of the lens. Any surface deviation can introduce wavefront distortion, leading to a loss of image sharpness.
The PRIME II LP is manufactured using precision-polished glass, achieving excellent surface accuracy. Transmitted wavefront measurements show no observable Newton’s rings, indicating minimal distortion. In addition, despite using a high-retention ring mounting structure that firmly secures the glass, the filter maintains outstanding flatness.
As a result, the filter preserves the lens’s inherent optical performance, ensuring that resolution and focus accuracy are not compromised.
The flatness of an optical filter directly affects the resolving performance of the lens. Any surface deviation can introduce wavefront distortion, leading to a loss of image sharpness.
The PRIME II LP is manufactured using precision-polished glass, achieving excellent surface accuracy. Transmitted wavefront measurements show no observable Newton’s rings, indicating minimal distortion. In addition, despite using a high-retention ring mounting structure that firmly secures the glass, the filter maintains outstanding flatness.
As a result, the filter preserves the lens’s inherent optical performance, ensuring that resolution and focus accuracy are not compromised.
We have completely redesigned the frame structure to eliminate internal reflections, typically triggered by flat and vertical surfaces.
In conventional frames, flat and vertical surfaces can cause stray light to reflect inside the frame, degrading image contrast. By replacing these with precision-engineered light-blocking ridges, we have thoroughly neutralized the impact of stray light.
This structural innovation, combined with our ultra-low reflectance coatings, minimizes flare and ghosting to an unprecedented level —delivering a shooting experience virtually indistinguishable from using no filter at all. As a result, we have surpassed the conventional 0.1% reflectance barrier and achieved an industry-leading 0.08% reflectance in our new lens protector.
In addition to its anti-static capability, the ULA coating features excellent resistance to water, oil, and fingerprints, helping to keep the surface clean in demanding environments. Its durable structure also provides enhanced scratch resistance.
Together, these properties ensure that the optical surface remains clean and stable, preserving image quality by minimizing contamination and unwanted reflections.
| Water repellent | Oil repellent |
| When shooting near the waterfront or in the rain, the lens repels water droplets for stress-free use. | This coating prevents fingerprints from sticking to the surface, and even if it does, it can be easily wiped off and is scratch-resistant. |
