The ultraviolet filter is one of those curious photographic relics that somehow managed to outlive its original purpose. In the early days of color film, when emulsions were less sophisticated and more sensitive to ultraviolet light, these filters had a real and measurable function. They reduced the bluish haze that appeared in mountain landscapes or on the open sea, where invisible ultraviolet light could trick film into recording a milky veil over distant subjects. In those days, the filter was not a fashion accessory. It was a modest but functional part of a photographer’s kit.
With the arrival of digital sensors, that need disappeared. Every modern sensor sits behind a multi-layered assembly of protective glass and coatings that already block ultraviolet and infrared light. The UV filter quietly lost its function, but not its place in the shop window. Manufacturers and retailers simply changed the story. What had once been an optical aid became a “protective filter” – a kind of insurance policy for anxious photographers. The argument was simple: better to scratch or break a ten-euro filter than a multi-element lens.
It sounds reasonable until you look more closely. The front element of a good lens is not fragile. It is made from hardened optical glass, often coated several times over, and can tolerate a surprising amount of abuse without any visible or measurable effect on image quality. A fine scratch on the surface has almost no influence on the optical performance of a lens. Light scatters so little over such a narrow groove that the sensor – or film – simply ignores it.
What does affect image quality, however, is the addition of another piece of glass, particularly a cheap one. Each extra surface introduces the possibility of internal reflections, veiling flare, and those telltale rainbow-coloured ghosts when sunlight hits at a certain angle. The filter, which once improved the purity of an image, now risks degrading it. The irony is hard to miss.
The idea of protection is itself slightly misplaced. A rubber or metal sun hood offers far better physical protection than a wafer-thin piece of glass ever could. A hood shields against impact, stray light, and the photographer’s own fingers – and, when it is deep enough, it absorbs the kind of knocks that would simply shatter a filter. The lens itself remains unharmed, its coatings intact, its front element safely recessed.
It is also worth remembering that glass, in its most basic form, is nothing more than hardened sand. Photographers often fear scratches on the front surface as though a few microns of glass could decide the fate of an image. Yet the rear element — the one part of the lens that genuinely matters most for image quality — is rarely given a second thought. That is where even the smallest imperfection can alter sharpness, introduce ghosting, or change contrast. The fear of damaging the front is largely symbolic; it speaks more to psychology than to optics.
In the end, the ultraviolet filter has become an artifact of habit. It lingers because it gives a sense of safety, and perhaps because it makes the lens look complete. There are still moments when one might justify its use – during chemical work, or in a saltstorm on a pier — but for most photographers it has become little more than a pane of glass between the image and the world.
Those who value their lenses, and their images, might consider letting the air touch the front element again. A clean piece of glass, unfiltered, remains one of the most honest instruments in photography.
