Prompt
One subject: a single adult chest-up portrait seated and lit solely by a smartphone screen held just below chin height, creating upward catchlights and soft rim highlights on the jawline and lower cheekbones. Frame in a 3:2 crop with the head occupying roughly the upper half of the frame, slightly left of center, and leave about one head-height of negative space above the crown while the lower chest fills the lower third. Background remains deep and uncluttered, occupying the upper two-thirds of the image as soft, nearly black negative space so the phone light reads as the only light source. Use a shallow plane of focus that renders the eyes and nose bridge sharp while the ears and collar blur into gentle falloff. Skin texture is natural and matte with visible pores and subtle specular glints from the screen, and clothing is simple dark fabric with minimal pattern. Lighting effect is hard-edged from a small source with crisp shadow shapes under the nose and chin and a cool neutral tint balanced by a warm skin tone accent from slight color crossover. Maintain a candid, relaxed expression with micro-movements frozen, no props besides the phone, and composition guidance explicitly tied to the 3:2 ratio for final cropping and layout.
