Shadows in Photography

By: Austin Dorr
Pictured below is a photo by Ansel Adam, one of the most famous photographers that used light and shadows extensively to enhance his photos.

Ansel_Adams.jpg
One of the most famous pictures taken by the renowned photographer Ansel Adams. This photo uses shadows to add a mysterious quality to the landscape being displayed


Shadow - an area where direct light from a light source cannot reach due to an obstruction by an object


Facts

The cross-section of a shadow is a two-dimensional silhouette, or reverse projection of the object blocking the light.Shadow.jpg


The sun causes many objects to have shadows and the length changes throughout the day.

Here is a video example of this:





The length of a shadow is porportional to the cotangent of the sun's elevation angle - relative to the horizon. Near sunrise and sunset, when θ = 0° and cot(θ) is infinite, shadows can be extremely long. If the sun passes directly overhead, then θ = 90°, cot(θ)=0, and shadows are cast directly underneath objects.


sun-shadow.jpg

The only astronomical objects to produce visible shadows on Earth are the sun, moon, and with the right conditions, Venus.



Parts of a Shadow

  • Umbra - the innermost and darkest part of the shadow

  • Penumbra - Outer par of the shadow, only part of the light is obscure

Umbra_and_Penumbra.jpg
Overlapping_Shadow.jpg
Overlapping Shadows



The wider the light source, the more blurred the shadow. If two penumbras overlap, the shadows appear to attract and merge. This is known as the Shadow Blister Effect. If there are multiple light sources there are multiple shadows, with overlapping parts darker, or a combination of colors.


The farther the distance from the object blocking the light to the surface, the larger the silhouette will be.




A shadow cast by the Earth on the moon is a lunar eclipse
A shadow cast by the Earth on the moon is a lunar eclipse
A shadow cast by the moon on the Earth is a solar eclipse
A shadow cast by the moon on the Earth is a solar eclipse



History

  • In ancient times, an unattended shadow was thought to be that of a ghost

  • Early eastern beliefs are that shadows were representations of the gods

  • They were also used in sundials to show the time of day




Uses in Photography

  • In photography "highlights" and "shadows" are the brightest and darkest parts of an image
  • Photographic exposure must be adjusted to allow the sensor, which has a limited dynamic range, to record detail in the highlights without being washed out and in the shadows without becoming undifferentiated black areas
  • Light and shadows establish correlation of one object to another and their place in the full scene
  • Shadows set the mood of the scene depending on placement and add a mysterious quality to them


Ansel Adams: a famous photographer known for photographing many national parks, used a large format camera to better capture light and shadows
Ansel Adams: a famous photographer known for photographing many national parks, used a large format camera to better capture light and shadows

A large format camera
A large format camera

Large Format Camera

  • Has a much higher resolution

  • Allows better control of rendering of perspective and increases apparent depth of field

  • It has a front and back called "standards" that allow the front and/or back of the camera to be shifted right/left or up/down

  • This shift and tilt allow it to solve otherwise impossible depth-of-field problems, change perspective rendering, and create special effects that would be impossible with a conventional camera





Social Impact

  • Ansel Adam's photos became the foremost record of what the national parks were like before major tourism

  • He helped expand the national park system and used his photos to promote the goals of the sierra club and the nascent environmental movement

  • Many of his stirring images are still popular in calendars, posters, and books today

  • He developed a "zone system", still in use today, that gives photographers better control over finished photographs

  • He helped elevate photography to an art from comparable to painting and music, equally capable of expressing emotion and beauty




Conclusion

Shadows are an essential element of photography. The science behind them is relatively simple, but they greatly enrich photographs. They add a mysterious quality to them as well as establish the correlation of an object with the entire scene. Shadows are an example where the physics behind light is used to create a magnificent work of art.



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