words Onur Baştürk

Lighting designer Ali Berkman grew up around luminaires in his father’s shop in Istanbul. Today, he leads the Istanbul-based ON·OFF Lighting Design Consultants and Studio DIM. His work is shaped by a careful reading of light and shadow. For Berkman, lighting is not an accessory to design, but one of its structural elements.

What makes a space powerful — its design, or its lighting?

Design and lighting are not separate disciplines. Each can stand alone, yet a compelling spatial experience depends on their alignment. A beautifully designed interior can feel flat — even uncomfortable — under the wrong light. Equally, a modest architectural setting can gain depth through considered illumination. Every space has a psychology, and vision shapes it more than we tend to admit. Light is not a technical afterthought; it defines atmosphere.

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Jonathan Speirs was once asked in Copenhagen, “What is good lighting?” His answer was direct: “If a user walks into a space and says, ‘What beautiful lighting,’ we’ve probably done something wrong.” 

Light should not call attention to itself. It should reveal — the space, and the people within it.

‘HIDE THE LIGHT SOURCE’ IS A PRINCIBLE THAT DEFINES OUR APPROACH

Why should lighting be seen as foundational rather than a finishing touch?

When lighting is introduced at the end, it must adapt to decisions already made. But light and darkness need to be considered from the outset. To fully understand a project, a lighting designer should witness how materials are selected, how volumes shift, how intentions take shape. Atmosphere begins long before fixtures are installed. “Hide the light source” defines our approach. The source should recede; the effect should lead. When involved early, we can integrate light into architecture — concealed within ceiling details, embedded in furniture, or positioned discreetly behind objects. The result is not decorative illumination, but something embedded in the space itself.

How do you evaluate architects’ and interior designers’ approach to lighting today?

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In larger practices, lighting designers are increasingly involved from the beginning — not merely as technical consultants, but as part of the design dialogue. The challenge is not only timing, but understanding. Investors and clients need to recognise what lighting design contributes and why it matters.

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How does ON OFF guide its clients through the process?

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Design today is saturated with digital tools. Simulations and modelling software can predict performance with impressive accuracy. Yet no software replaces physical presence. Our approach is defined by involvement — from concept to completion, and critically, on site. Early conversations often influence interior decisions themselves. Materials, hierarchy, spatial distribution and even ceiling design are reconsidered through the lens of light.

On-site testing remains essential: mock-ups, adjustments, observing how materials react, measuring reflections. Fine-tuning follows. In lighting, small shifts can alter perception dramatically. A slight change in angle, a minimal relocation, a calibrated contrast — these can transform the experience. Such precision only emerges at full scale, in real conditions.

GOOD LIGHTING DEPENDS LESS ON AESTHETIC FASHION THAN ON PERCEPTION AND BALANCE  

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Are there trends in lighting, or is good lighting inherently timeless?

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Technology evolves. Light sources improve. Control systems become more refined. Lighting design itself, however, is not driven by fashion. It is grounded in human vision and psychology — and that makes it timeless. Good lighting depends less on aesthetic trend than on perception and balance. The Seagram Building in New York, where Richard Kelly developed the lighting design, remains a compelling example. Nearly seventy years on, it still feels current. Kelly emphasised vertical surfaces, concealed sources and movement guided through contrast rather than brightness alone. What draws you toward the elevator lobby is not sheer illumination, but orientation and contrast. Its endurance lies in its alignment with how we see.

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Lighting is also contextual. Cultural and geographic differences shape preference. In parts of the Middle East, cooler tones are common in residential settings; in Northern Europe, warmer tones dominate. These choices reflect climate, habit and cultural perception rather than fashion.

How do you approach lighting in your own home?

Lighting at home was not a solitary decision. My wife, Juanna, is an architect, and from the outset we developed materials, colours and furniture details together. This dialogue allowed for a restrained and largely invisible lighting strategy. Our home receives generous daylight; artificial light is rarely needed during the day. We value observing how natural light shifts over time. In the evening, we rely on layered lighting. All sources are dimmable, allowing the atmosphere to adapt to different moments. Artworks, plants and objects create distinct layers. Reading, dining, hosting — each activity shapes its own tone.

Where possible, light sources remain concealed, aside from decorative fixtures. They are integrated into furniture, hidden within planting, or positioned discreetly beside seating. We chose not to use visible ceiling-mounted sources.

Collectible lighting is becoming increasingly sculptural and expressive. How do you see it?

Collectible and decorative lighting should primarily be understood as design objects. When tasked with illuminating an entire space, they often compromise visual comfort. In our projects, we position decorative fixtures as compositional elements rather than primary light sources. The general lighting scheme is resolved independently. In some cases, these pieces become strong focal points. We still engage with how their light is controlled — colour temperature, dimming, glare — but their role remains expressive rather than functional.

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At Studio DIM, even when designing sculptural pieces, we carefully construct the light–shadow balance. Form may lead, but it is the dialogue between illumination and darkness that ultimately gives the object presence.