Friday Headlines – June 5, 2020 – #BlackLivesMatter

Friday Headlines, March 6, 2020

PEOPLE OF COLOR IN THE GEOSCIENCES

In light of the recent death of George Floyd and the following #BlackLivesMatter protests, I feel it is appropriate and necessary to highlight geoscientists of color.

I do not fully understand the struggles that are faced by people of color in this country, but I’m listening. Your pain is real. Your protests are valid.

Paleontology

Geology

Environmental Science and Climate Change

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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.

I is for ISO – #AtoZChallenge – 2020

I is for ISO

ISO is a measure the sensitivity of film to light, or “film speed.” Higher ISO films are more sensitive to light and therefore better for taking photos in low-light conditions. (However, as noted in an earlier post, more sensitive films tend to have larger grain.)

ISO stands for the International Organization for Standardization, located in Geneva, Switzerland. While many different classifications for film speed have been used (e.g. DIN and ASA), in 1974 the universal ISO system became the standard.

A 36 exposure roll of ISO 400 35mm black and white film. It’s what Penny is shooting with lately.

Typical film speeds are 100, 200, and 400. ISO 100 is best used under sunny conditions. ISO 400 (or the even faster ISO 1600) are best used in low-light conditions like indoors or outdoors at night. ISO 200 is a general purpose film that does well in sunlight and in the dark.

H is for Hot Shoe – #AtoZChallenge – 2020

H is for Hot Shoe

Frequently on top of cameras is a clip of sorts. Most frequently, there is a flash unit pressed into the clip for taking photos under low-light conditions.

This clip is called a shoe. I have no idea why.

When hand-held cameras became popular, manufacturers provided additional equipment (typically flashes, but also rangefinders and light meters) that could be bought to go with that camera. Each add-on was specific to that camera, and most times could not be used with any other camera.

The standardized shoe on top of the camera made it possible for the extras to be moved between different cameras of different makes and models. It became possible for companies to specialize in devices that would work with any camera (provided it had a shoe) and not have to also make a camera as well.

Shoes on many different makes and models of camera.

The “Hot” shoe took the concept one step further. It has an electrical contact that is triggered when the shutter is activated, making it possible for a flash placed into the shoe to strobe simultaneously with the shutter.

Hot shoe on a Minolta SLR.

Suddenly, manufacturers could make elaborate flashes that would also work with any camera and always be synchronized with the shutter for the optimal photograph.

Modern camera shoes are far more complicated and have gotten back to being more specific to the camera. Today’s cameras are computerized with sensitive electronics. Extra contacts allow the camera’s computer to communicate with and control the attached flash as needed.

Hot shoe on my Nikon DSLR. The middle contact is the synchronize the flash, but the other three allow the flash to communicate with the computer inside the camera.

Because of the new complexity, one has to exercise caution when switching flashes between cameras. The wrong flash can destroy the sensitive electronics of a camera. So be careful.

G is for Grain – #AtoZChallenge – 2020

G is for Grain

Grain is used in photography as a measure of the size of the photosensitive particles (generally silver) on film or photographic paper. With modern digital photography, one might compare it to the resolution of the image in pixels per inch.

Film with large grains will appear to be at lower resolution and less focused than those with smaller, finer grains.

Examples of different grain size and distribution on photographic plates (i.e. glass negatives). Plate VII from “The Silver ‘Grain’ in Photography” by Robert James Wallace, The Astrophysical Journal, Vol. XX, No. 2, Sept. 1904, pp. 113–122, Chicago.

The sensitivity of film to light is related to grain size. Films with low sensitivity to light work best in bright situations, like outside on a sunny day. These films have very fine grain structures and yield a sharp image. But, if one wishes to take photographs in low-light conditions, say around a campfire at night, a more sensitive film is needed. These films tend to have larger grain sizes resulting in a less-sharp image.

Grain can also be used for photographic effects.

Halicki uses coarse grains to produce an interesting effect. CC By 3.0