STC Optics Clip Filter Review

2021.01.28

Taiwanese manufacturer STC Optics makes a series of filters using German glass and Taiwanese silicon. Their lineup covers a range of protectors, circular polarizers, neutral-density and infrared filters. They specialize in high-end optics that deliver additional benefits rather than competing on price.

One of the most unique STC Optics product is the Sensor Protector Clip-Filter. This diminutive ultra-transparent filter goes inside a camera. It clips around the internal edge of the lens mount to fit right between the mechanical-shutter and rear lens element. Similarly to a Lens Protector filter, this one is designed to pass light straight through unchanged. The difference is that a Lens Protector filter protects the front of a lens, while the Sensor Protector Clip-Filter protects the sensor.

Unlike a lens, the main enemy of a sensor is not impact but dust, so a sensor protector does not need to be extremely sturdy but it must be far more precise. Alignment is key to avoid color-shifts and chromatic aberrations. Some camera sensors, like the one in the excellent Sony Alpha A7R IV reviewed here are dust-magnets! This 61 megapixels sensor attracts dust more often than most cameras and so changing lenses, even carefully indoors, is likely to introduce stubborn sensor-dust. Its builtin sensor-cleaning system is incredibly ineffective.

STC Optics makes the Sensor Protector Clip-Filter in different shapes for a long list of digital cameras, mostly mirrorless models and a decent number of DSLRs. There no official internal filter-mount standard, so even very similar cameras from the same manufacturer often require a different variant. The model for the Sony A7R IV also fits the A7C, A9 II and A7S III but not the original A9 or other A7-series cameras, for which a different filter must be purchased.

A thin layer of optical glass with nano-crystal coatings on both sides gives the filter anti-smudge plus grease and water-repellent properties. This is far more protection than the sensor has. More importantly, the gap between the clip filter and sensor minimized the impact of dust that does not reach the sensor. Larger dust particles would still be visible but luckily, the STC Optics Protector Clip-Filter does not statically attract dust.

The Clip-Filter series is made of a sturdy aluminum frame with no magnetic properties to keep dust attached. The glass itself can hang on to dust sometimes but much less than the camera sensor. Plus, its nano coatings on it make it very easy to clean with a standard lens brush. Installing the filter takes a few seconds as it clips into place. A metal tab at the top makes it simple to remove using a provided magnetic tool.

At a cost of $90 USD plus shipping, the Sensor Protector Clip-Filter is not cheap but not expensive either. Compared to the difficulty and sensitive nature of cleaning sensor dust, it is really worth the price. As it does not modify incoming light, this filter can be kept permanently inside the camera body. STC Optics makes specialized clip-filters with NR, IR and spectral properties for specialized uses but accessing them exposes the sensor to dust and so those are not recommended when a front lens filter is an option.

The STC Optics Sensor Protector Clip-Filter is highly recommend to anyone who experienced frequent sensor-dust with their camera.

• Review