Sohdo Solaris is a fixed-pointing, autonomous imaging installation in Ehden, Lebanon. Engineered to operate continuously for 24 months, the project will observe four complete solstice-to-solstice cycles to produce 24 curated artworks depicting the sun’s seasonal journey.
The scientific foundation of Sohdo Solaris relies on precise geodetic mapping of the horizon to align with the sun’s seasonal path. Situated at Kirset Hmaysroun in Ehden, Mount Lebanon, the observation station rests at an altitude of 1,710 meters above mean sea level. This high elevation creates a significant atmospheric dip of approximately minus 1.21 degrees, meaning the optical horizon sits lower than the standard astronomical horizon. To capture the full horizontal swing of the sun, which spans a lateral azimuth of exactly 57.03 degrees, the camera heading must be calibrated with absolute precision. Rather than using a generic center point, the system accounts for seasonal asymmetries, such as the vernal equinox sunset at 270.53 degrees and the autumnal equinox sunset at 270.67 degrees. The diagonal path of the sun descends at a steep 55.6-degree angle, and the maximum horizontal range occurs just as the sun reaches the lowest point of the apparent horizon. By mapping these boundaries, the project ensures that the solstice endpoints are framed perfectly, capturing the complete lateral swing across each six-month period.
| Coordinates | 34°17’00” N, 35°59’18” E |
| Elevation | 1,710 m AMSL |
| Lateral Azimuth Swing | 57.03° total horizontal span |
| Optical Horizon Dip | -1.21° below astronomical level |
To capture the massive horizontal drift of the sun without edge distortion, the campaign coordinates multiple camera bodies and calibrated lenses. The primary tested configuration utilizes a full-frame Nikon D3x body paired with an AF-S Zoom-Nikkor 28-70mm lens set to 28mm. This combination provides a theoretical horizontal field of view of 65.47 degrees, leaving a horizontal safety margin of 3.58 degrees on each side of the sensor. This safety buffer is critical, allowing the sun to sweep near the edge of the frame at 16.12 millimeters without clipping the physical bezel. Auxiliary contemporary digital sensor crop bodies are also under evaluation for secondary nodes, utilizing an 18mm lens to achieve a wider 66.21-degree horizontal field of view. Additionally, a secondary alternative configuration evaluates an AI AF Nikkor 28mm f/1.4D prime lens, which has a measured effective focal length of 30mm. This alternative focal length reduces the field of view to 61.93 degrees and constrains the lateral safety margin to just 2.45 degrees. The primary zoom lens configuration remains the preferred option because its tested dimensions balance high spatial resolution with a safe frame buffer.
| Primary Camera (FX) | Nikon D3x (6024 x 4016 px) |
| Primary Lens Preset | AF-S 28-70mm f/2.8D @ 28mm |
| Primary Field of View | 65.47° horizontal |
| Alternative Lens (Effective) | AI AF 28mm f/1.4D (@ 30mm) |
Achieving pixel-level clarity across a two-year exposure requires minimizing optical aberrations under extreme light variations. The lenses are stopped down to a fixed aperture of f/8, yielding a hyperfocal distance of 3.27 meters for the primary full-frame configuration and 2.03 meters for the auxiliary crop sensor setup. Stopping down the aperture restricts marginal light rays, reducing sagittal comatic flare and controlling off-axis astigmatism at the outer edges of the frame. Oblique rays traveling at a 28.5-degree angle near the edge of the sensor experience a geometric circle of confusion expansion of roughly 30 percent, which causes a subtle stretching of the light spot. However, light falloff at the frame edge remains under 0.5 exposure values, ensuring near-uniform illumination. Lateral chromatic aberration is also controlled, with the primary zoom lens showing a negligible dispersion of under two pixels at the edge, while the crop sensor prime lens reduces this dispersion to under one pixel. These controlled parameters ensure that the sun’s disk is rendered with sharp, high-contrast boundaries during its transition into the horizon.
| Optimal Aperture | f/8 (fixed target) |
| Primary Hyperfocal Distance | 3.27 meters |
| Off-axis Spot Distortion | ~30% tangential CoC expansion |
| Max Edge Illumination Falloff | < 0.5 EV (vignetting control) |
Operating a fixed-pointing system in Mount Lebanon requires exceptional structural rigidity to survive heavy seasonal snowfall and wind load. The camera is mounted on a heavy, thermalized magnesium and aluminum chassis designed to prevent thermal contraction and bayonet flex during sharp temperature drops. This rigidity keeps the camera alignment locked within a heading yaw tolerance of plus or minus 1.2 degrees for the primary 28mm configuration, preventing the solar disk from hitting the camera frame. The system is also highly sensitive to camera roll, as a tiny roll error of just 0.5 degrees displaces the horizon by approximately 24 pixels on the sensor. By maintaining absolute structural stability, the project avoids frame misalignment and tripod leg creep across the 24-month deployment. This structural defense is essential to compile thousands of individual daily sunsets into a single, seamless visual continuum that honors the rugged and sacred landscape of Ehden.
| Maximum Yaw Tolerance | ±1.2° before bezel clipping |
| Roll Displacement | 24 px vertical shift per 0.5° roll |
| Chassis Stabilization | Thermalized magnesium and aluminum |
| Environmental Threshold | ΔT = 10°C drop stabilization |
The campaign relies on a fully autonomous hardware architecture designed to operate continuously without manual intervention. At the core of the installation, a discrete analog timing chip manages the capture queue and triggers the shutter electromechanically, bypassing software-based operating systems to ensure bulletproof reliability. An Nvidia Jetson Nano node operates in tandem with this timing chip, handling image extraction, sensor data streams, and database archiving. All telemetry is logged locally into an on-device PostgreSQL database, which aggregates real-time weather logs, astronomical algorithms, and image color analysis. Situational awareness enables the system to dynamically optimize the capture cadence and automatically trigger auxiliary sub-projects, such as tracking planetary alignments during twilight. To guarantee data safety, the installation is protected by a redundancy matrix, featuring dual camera nodes, secondary triggers, backup batteries, and smart charging policies, while the outer enclosure can be replaced without disrupting the camera’s optical alignment.
| Trigger Architecture | Discrete analog hardware timing chip |
| Edge Processor | Nvidia Jetson Nano |
| Local Database Engine | On-device PostgreSQL |
| Redundancy Level | Multi-node parallel hardware cameras |
The altitude of 1,710 meters offers a unique vantage point to capture rare atmospheric refractions, including the elusive green flash. Because the air density at this elevation is lower, the standard horizontal refraction is scaled down by approximately 18 percent compared to sea level. This prevents the solar disk from flattening, retaining a circular shape of approximately 0.53 degrees as it sets. The green flash is caused by dispersion, which acts as a prism to separate the green and blue upper limbs of the sun from the red lower limb. The system uses a predictive meteorological index to identify prime conditions for this phenomenon, scanning for vertical thermal inversions greater than 1.5 degrees Celsius, high barometric stability, and low aerosol optical depth. When these conditions are met, the edge controller initiates a high-frequency capture sequence of one frame per second, adjusting the sensor’s exposure levels to keep the green color channel below 90 percent capacity to prevent highlight clipping and preserve the flash.
| Atmospheric Refraction | 0.82 of sea-level value (at 1710m) |
| Capture Interval (Event) | 1 frame per second (1.0 Hz) |
| Meteorological Inversion | > 1.5°C lapse rate delta threshold |
| Exposure Safety Ceiling | < 90% Green channel highlight headroom |
Through this synthesis of sub-second astronomical precision, robust structural stabilization, and redundant autonomous edge systems, Sohdo Solaris translates complex geodetic calculations into a serene, uninterrupted testimony of time and light.