N is for Negative – #AtoZChallenge – 2020

N is for Negative

The negative. For those of you too young to remember, it used to be when you got a roll of film developed, you’d get a pile of prints plus the film from which the prints were made. But the image on the film was the opposite colors from real life. Reds in real life are green on the negative. Dark places are light on the negative.

Why are they reversed?

Photographic film itself is a thin strip of plastic upon which is coated some light sensitive chemicals. There are complex layers of chemicals each sensitive to different colors (for color film), or more simply sensitive to light and dark for black and white film. When these chemicals are exposed to light, they become darker. Thus, the brightest areas in the scene will be the darkest on the film.

This same sensitivity of greater light making for darker exposed chemicals is fine, because the printing process works the same way. Bright patches on the negative will become dark on the print. The reversal of color and brightness from scene to negative will be undone from negative to print.

A: The scene to be photographed; B: A color negative of A; C: The scene in black and white; D: A negative of picture C. Credit: rjt CC By-SA 3.0

See the other 25 letters of the 2020 A to Z challenge from Animal’s Place by clicking here! All about how cameras work!

M is for Macro – #AtoZChallenge – 2020

M is for Macro

Macro as a word has many meanings. It often stands as the opposite of ‘micro,’ and refers to things that are large enough to see without assistance.

In photography, macro refers to photographic techniques used to make small subjects large enough to see easily. Basically, it’s magnification.

Macro photography often requires a special macro lens. But with this lens, it is possible to take close-up images of very small objects.

Macro photo of a tiny insect in a flower.

See the other 25 letters of the 2020 A to Z challenge from Animal’s Place by clicking here! All about how cameras work!

L is for Lens – #AtoZChallenge – 2020

L is for Lens

The lens is among the most fundamental components of the camera. It is the lens that collects light and focuses it onto the film to capture the image.

The most basic lens is a piece of clear glass or plastic with at least one curved side which then bends the path of a light beam. A lens with a convex surface (curved out toward the light source) will cause the light rays to bend toward each other. A concave surface will cause light rays to diverge from each other.

The original camera obscura did not have a lens. Instead there was a tiny hole through which light passed and was bent. This made an image, but it was faint.

The addition of a glass lens meant that the opening could be larger, allowing more light to enter. It also provided better control on the focus of the image.

Today, cameras have elaborate lens systems with multiple, movable lenses of various shapes.

A camera objective in double-gauss design. Engineered by Leica ~1935. Typical design for Leica III lenses like Summitar or Summar. Credit: Foreade CC By-SA 4.0

These more complex lenses allow for differing depths of field, adjustment of focus, and make it possible to allow more light into the camera. Professional cameras allow the user to change lenses on their camera for different effects and purposes.

See the other 25 letters of the 2020 A to Z challenge from Animal’s Place by clicking here! All about how cameras work!

K is for Kelvin – #AtoZChallenge – 2020

K is for Kelvin

Most people, ok, maybe just me, associate the term Kelvin with temperature. Zero degrees Kelvin is ‘absolute zero,’ the coldest possible temperature when molecules cease to vibrate.

However, Kelvin – and temperature – are terms also applied to the quality of light.

“Temperature” can be applied to color because both relate to the radiation of light from ‘black bodies’ of particular temperatures. [A black body is a hypothetical object that absorbs all electromagnetic radiation, including light, that strikes it.]

While a black body absorbs all radiation striking it, it will also radiate light depending on its temperature.

A black body at a temperature below about 4000 degrees Kelvin (K) appear reddish. At temperatures greater than 7500 K, black bodies appear bluish. Daylight has a color temperature of about 5600 K.

Modern digital cameras and photo software can adjust the temperature of an image, which will enhance blues or reds in a photo to make it feel cooler or warmer.

J is for Joule – #AtoZChallenge – 2020

J is for Joule

A joule is a unit of energy measured in Newton-meters (Nm).

That sounds like physics. Physics is important in photography, but how does the joule, as defined above, apply to photography?

Flashes. Flash units are rated in Watt-seconds, which happens to be equivalent to Newton-meters, which means that joules can be used to rate flash units.

Flash units of higher joules or watt-seconds ratings produce more light and a brighter flash.