======Pinhole Camera ======


<WRAP right box>
**Materials: **{{$demo.materials_description}}\\
**Difficulty: **{{$demo.difficulty_description}}\\
**Safety: **{{$demo.safety_description}}\\
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**Categories:** {{$demo.categories}}
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**Alternative titles:** Simple Pinhole Viewer
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====Summary====                   
{{$demo.summary}}



====Procedure====  
  - Gather materials: shoebox with lid, aluminum foil, white parchment or tracing paper (or thin white plastic), scissors or craft knife, pin or needle, black tape, and black paint or dark paper.  
  - Darken the box interior by painting it black or lining it with dark paper to reduce internal reflections; let dry if painted.  
  - Cut a square window (about 6–8 cm per side) in one short end of the box; tape parchment or tracing paper over this opening to make a viewing screen pulled flat without wrinkles.  
  - On the opposite end, cut a smaller opening (about 2–3 cm per side); cover it with a piece of aluminum foil taped tightly around the edges.  
  - Using a pin, make a single clean hole at the center of the foil (start tiny; you can enlarge later). Aim for a circular hole with smooth edges.  
  - Close the box securely so no stray light enters except through the pinhole; seal seams with black tape if needed.  
  - Point the pinhole toward a bright scene (a window or outdoor landscape) and look at the tracing-paper screen; allow your eyes to adapt. You should see a dim, inverted image of the scene.  
  - Adjust for sharpness and brightness: try smaller or larger pinholes on fresh foil patches, move the box closer to or farther from the scene, and shade the screen from stray light to improve contrast.



====Links==== 
Pinhole Camera | English - Arvind Gupta: 
{{youtube>mBPLL01mNjA?}}\\

Using the pinhole camera as a physics practical - Physics with Simon Poliakoff: 
{{youtube>9-1BlfC9hVE?}}\\

📄 Pinhole Camera - National Geographic Kids: [[https://kids.nationalgeographic.com/books/article/pinhole-camera]]\\


====Variations====
  * Replace the tracing paper with wax paper or thin white plastic to compare image brightness and contrast.  
  * Mount the screen on a sliding inner sleeve (second box) to change the distance from pinhole to screen and observe the effect on magnification.  
  * Use photographic paper or a phone camera placed at the screen to record a long-exposure pinhole photograph in bright daylight.  
  * Make a room-sized camera obscura by darkening a room and placing foil with a pinhole over a small window opening.



====Safety Precautions====
  * Use scissors or craft knives carefully; adult supervision recommended for cutting cardboard and foil.  
  * Pins and needles are sharp; handle with care and store safely after use.  
  * Never aim the pinhole camera at the Sun or bright reflections and never look at the Sun through any viewer; permanent eye damage can occur.  
  * Keep liquids, paints, and adhesives away from eyes and mouth; use in a ventilated area and wash hands after the build.




====Questions to Consider====
  * Why is the image upside down on the screen? (Light travels in straight lines; rays from the top of the scene pass through the pinhole and land at the bottom of the screen, and vice versa.)  
  * What happens when you make the pinhole larger or smaller? (Larger increases brightness but causes blur from overlapping light cones; smaller increases sharpness but dims the image and can introduce diffraction if too small.)  
  * How does the distance between the pinhole and the screen affect the image? (Greater distance increases image size but reduces brightness; smaller distance does the opposite.)  
  * Why do pinhole cameras have effectively infinite depth of field? (Each scene point maps to a tiny region regardless of distance because focusing is set by geometry of the pinhole, not by a lens.)  
  * How do lenses improve on pinhole cameras? (They allow a large aperture to gather more light while focusing rays to points on the image plane, enabling shorter exposures with controlled depth of field.)