NiSi Pro Nano AIR UV 37 mm – UV Protection Filter with 99.9% Transmission

NiSi Pro Nano AIR UV 37 mm is a premium UV protection filter for lenses with a 37 mm filter thread. It protects the front element from dust, scratches, water and fingerprints while staying practically invisible: 99.9% peak transmission and only 0.1% reflectivity thanks to the 48-layer ULRC coating. It blocks UV light below 395 nm, keeps full sharpness on cameras over 100 megapixels and has an ultra-thin knurled brass frame that does not vignette on wide-angle lenses.

Looking for a protective filter that keeps your expensive lens safe but does not cost any image quality? The NiSi Pro Nano AIR UV 37 mm is a UV protection filter for lenses with a 37 mm filter thread. NiSi's own ULRC (Ultra Low Reflective Coating) with 48 layers gives a peak transmission of 99.9% and only 0.1% reflectivity, so the filter is as clear as air and keeps flare and ghosting to a minimum. It is made for high-resolution cameras over 100 megapixels, blocks UV light below 395 nm to reduce blue haze, and its ultra-thin brass frame is durable, easy to mount and free of vignetting even on ultra-wide lenses.

KEY FEATURES

• 99.9% peak transmission: ULRC coating, average 99.6% between 420–680 nm, only 0.1% reflectivity.
• 48-layer ULRC nano coating: scratch-, stain-, water- and oil-resistant, easy to clean.
• 100 MP ready: keeps full resolution and sharpness on cameras and lenses over 100 megapixels.
• UV cut below 395 nm: reduces blue haze and UV interference in the mountains, at the sea and in strong sun.
• Lens-grade optical glass: selected high-end optical glass, each filter tested with a Shimadzu spectrophotometer.
• Ultra-thin brass frame: more durable than aluminium, precise knurling, no vignetting on ultra-wide lenses.
• Many sizes: available in 37, 39, 40.5, 43, 46, 49, 52, 55, 58, 62, 67, 72, 77, 82, 86, 95, 105 mm.

WHEN TO USE A UV / PROTECTIVE FILTER

A protective filter is the one filter that can stay on the lens all the time. It is cheap insurance for an expensive front element.

• Travel and outdoors: dust, sand, rain and sea spray end up on the filter, not on the lens.
• Mountains and the sea: less blue haze from UV light at high altitude and over water.
• Events, street and weddings: protection against fingerprints and knocks in crowded places.
• Kids, pets and action: splashes and sticky fingers are easy to wipe off the coated filter.
• Video on gimbals and drones-on-the-ground work: a clean, protected lens when there is no time to change filters.

CLEAR AS AIR

Looking through the AIR UV – with 99.9% peak transmission the glass is practically invisible.

Reflectance curve of the ULRC coating – about 0.1% across the visible spectrum (NiSi measurement).

ADVANTAGES OVER A STANDARD UV FILTER

• Almost no light loss: 99.9% peak transmission vs. typically 96–98% with basic multi-coated filters.
• Less flare at night and against the sun: 0.1% reflectivity – fewer ghost images of street lights.
• Brass instead of aluminium: does not deform or get stuck on the lens thread.
• Tested optics: every filter is checked with a spectrophotometer.

WHICH FILTER DO I NEED?

HOW TO USE A UV / PROTECTIVE FILTER

A UV / protective filter stays on the lens all the time. It does not change the exposure or colours – it protects the front element from dust, rain, sand, sea spray, fingerprints and knocks, and a clean filter is much cheaper to replace than a scratched lens.

1. Screw it on finger-tight as soon as you unpack the lens.
2. Keep it clean – a dirty protective filter costs contrast, especially against the light.
3. Take it off for special filters – when you use a CPL, ND or Black Mist, unscrew the UV filter instead of stacking.
4. Use a lens hood – it reduces flare and protects the filter from side light and bumps.

Common mistakes:

• Cheap uncoated glass – causes flare and ghosting at night and against the sun; a multi-coated filter avoids it.
• Stacking on wide-angle lenses – a UV filter plus another filter can cause dark corners.
• Night shots of bright lights – if you see ghost reflections of street lights, take the filter off for that shot.

HOW TO FIND YOUR FILTER SIZE

The filter thread is printed on the front of the lens barrel or inside the lens cap, marked with the ø symbol (for example ø37). The filter size must be exactly the same – this filter is 37 mm. The table below shows typical sizes, but always check your own lens.

Tip – one filter for several lenses: buy the filter for your largest filter thread and use step-up rings for lenses with smaller threads, for example a K&F Concept step-up / step-down ring set. A step-up ring goes from a smaller lens thread to a larger filter (e.g. 67 → 77 mm) and does not cause vignetting; a step-down ring (larger lens, smaller filter) usually does. The only drawback: the standard lens hood and lens cap may not fit with the ring attached.

ULRC COATING – CLEAR AS AIR

NiSi ULRC (Ultra Low Reflective Coating) is a 48-layer nano coating developed by NiSi. It reduces reflectivity to 0.1% and gives an average transmission of 99.6% between 420 and 680 nm. The surface is scratch-, stain-, water- and oil-resistant, so rain and fingerprints wipe off easily.

BRASS FRAME

The ultra-thin brass frame is more durable and resistant to deformation than aluminium. Precise knurling makes mounting and removing easy, and the slim profile prevents vignetting even on ultra-wide-angle lenses.

COMBINING FILTERS

• CPL + ND: for long exposures of water with the reflections removed. Put the ND filter on the lens first and the CPL in front, so you can still rotate it.
• Two filters at most: every extra layer of glass adds risk of flare, reflections and loss of sharpness; more than two filters on a wide-angle lens almost always cause vignetting.
• Slim frames for wide angles: on lenses wider than about 24 mm (full frame) use slim filters and check the corners at the widest focal length.
• One filter instead of two: combined filters such as ND + CPL in one frame avoid stacking altogether.
• Systems for faster work: filter systems with an adapter ring (magnetic or press-fit, e.g. NiSi Swift) let you add or swap filters without unscrewing them each time.

USE IT WITH

• Step-up rings: K&F Concept step-up / step-down ring set – one filter for lenses with smaller threads.
• Cleaning: Lenspen cleaning pen and K&F Concept microfibre cloths.
• Filter storage: Moment filter case or Lowepro GearUp Filter Pouch 100.

WHICH NiSi UV FILTER TO CHOOSE?

NiSi makes several UV / protective filters. All block UV light below 395 nm; they differ in glass, coating and frame.

AIR UV VS OTHER NiSi UV FILTERS

• AIR UV vs Armor FX: AIR UV has the highest transmission and lowest reflectivity; Armor FX is built for maximum impact protection.
• AIR UV vs SMC UV L395: SMC is the affordable everyday option; AIR UV is for high-resolution cameras and premium lenses.

CARE AND CLEANING

1. Blow off dust first – a blower or a soft brush removes sand and grit that could scratch the glass.
2. Clean fingerprints and drops with a Lenspen cleaning pen or a dry K&F Concept microfibre cloths; wipe from the centre outwards.
3. Do not breathe on the glass and do not use household cleaners – they can damage the coating.
4. Store filters in a case, such as the Moment filter case or Lowepro GearUp Filter Pouch 100, not loose in a bag.
5. Do not over-tighten – if a filter gets stuck, a rubber filter wrench or a rubber glove helps; never use tools that bend the frame.
6. Cold to warm – after coming in from the cold, let the filter warm up in a closed bag before cleaning to avoid condensation.

FREQUENTLY ASKED QUESTIONS

Which size do I need?

The size of your lens filter thread (marked ø on the lens or inside the lens cap). This product is 37 mm.

Does a UV filter reduce image quality?

With the AIR UV practically not – 99.9% peak transmission and 0.1% reflectivity. NiSi designs it for cameras over 100 megapixels.

Do I need a UV filter on a digital camera?

Sensors are less sensitive to UV than film, but the filter still reduces blue haze at altitude and over water, and above all it protects the lens.

Can I put a lens cap on it?

Yes, the filter has a front thread for a standard lens cap.

Can I stack another filter on it?

It is possible, but on wide-angle lenses we recommend removing the UV filter before using a CPL or ND to avoid vignetting.