Hours of Idleness-A Photographer's Journey in St. Louis


Posted in Uncategorized by Jason Gray on July 4, 2010

“To me, photography is the simultaneous recognition in a fraction of a second of the significance of an event, as well as the precise organization of forms that give that event its proper expression.” -Henri Cartier-Bresson

It is one thing to recognize the potential in a single fraction of a second versus any other fraction of a second, and it is quite another to have the right tool in place in order to register that fraction of a second to the rest of the world. William Fox Talbot, a British photographer and inventor, produced the world’s first negative around 1839 (a mere 13 years after Niepce’s first photograph). The chemistry that Talbot pioneered meant that the result of the photographic process, the print, was made after the exposure occurred. This order of production meant that photographs could be mass-produced, for use in newspapers, advertisements, etc. In other words, what Talbot had stumbled upon was film.

I assume that, if you are reading these articles, than you are probably using either a 35mm SLR or a DSLR. Therefore, I intend to taylor this essay toward information relating to 35mm film. Film for medium- and large-format cameras is a different beast, though most of the ideas carry over.

For 35mm cameras, there are three main types of film available on the market:

1. Black-and-White Negative Film
2. Color Negative Film
3. Color Reversal Film (Slides or Transparencies)

In regard to each of these, there are four characteristics that affect what each will look like and how they should be used:

1. Speed- the amount of time required for the film to react to light and produce an exposure. This should not be confused with shutter speed; speed refers to the light sensitivity of the film and not the amount of light entering the camera (though they are obviously related). In other words, a shutter speed of 1/250th of a second will produce a different exposure on slow speed film than on fast speed film (assuming that all other settings remain constant). This is a feature that is important to know for both digital and film photographers, since both formats allow you to adjust “film” speed.
A fast film (800->3200) reacts sensitively to light, meaning that it needs little exposure time to produce an image. These types of films are ideal for subjects in dim light, or for high shutter speeds (ie. fast action shots, large interior spaces, sunset/sunrise, under >20′ of water, etc.)
A medium film (400-800) is manufactured for latitude to a wide degree of uses. Its sensitivity is moderate, and so it is ideal for most normal conditions, or for when you don’t know if a high or slow speed film would be a better fit (ie. indoor/outdoor transitions, when not under direct sun, indoor environment with flash, under <20' of water, etc.)
A slow film (<200) is relatively insensitive to light, and is used in situations requiring/featuring bright light (ie. direct sun, in the studio with flash/strobes, etc.), or for taking extremely long exposures on a tripod (ie. constellation photography)

Because many manufacturers produce and sell film, it became quickly apparent that there needed to be a standardized system for measuring film speed. The result were two systems that made it possible for photographers to purchase film from different manufacturers and to understand what they were paying for, in terms of its sensitivity. They are:

DIN system- used in Western Europe
ISO/ASA- used globally. The higher the ISO (International Standards Organization) or ASA (American Standards Association) number, the faster the film. Many SLRs in/after the 1990’s possess technology for automatically detecting a film’s ISO/ASA rating, if the film is DX encoded. A common trick to achieving more saturated colors with slide film is to set the ISO at a higher number than actual. This will underexpose the image, so you don’t want to go more than a half to full stop max (ie. if the ISO is 50 set it to 100).

2. Grain- the speckled or hazy appearance of some photographs. In film, this is caused by by the presence of clumps of fine silver grains, and it is much more noticeable in faster films. In digital photography, this chromatic aberration is known as “noise”, and because it generally appears as garbled “pixels”, it is less pleasing than film grain. Digital noise is the result of extraneous electrons being produced and interpolated while an image is being recorded. This phenomenon occurs as light reaches the digital sensor, at which point, the electrons generate an analog signal that is converged visible by the analog to digital (A/D) converter within the camera. This aberration has been the bane of digital photography since its inception by photographers, and this is because it has the tendency to render shadows or highlights as pixelated, which because it is hard-edged, rather than smooth like film grain, is analogous to “ugly” in the minds of most viewers. As technology has improved, camera manufacturers have made advancements on controlling digital noise, but it is still a reason for concern when shooting in low light.

In digital cameras, there are two elements that make up digital noise. They are:

Chrominance- colored blocks
Luminance- contrast blocks

The two causes of chrominance and luminance are:

Heat Generation- As the shutter remains open, heat is emitted. The longer that the shutter stays open, the more heat is generated. This heat can cause the electron reaction mentioned above, although the electrons generated by heat are in addition to those that are generated by light striking the sensor. It is important to understand that the hotter your sensor gets the more electrons are freed to wreck havoc upon your images. This is why using the “live-view” function for all of your shooting is a bad idea (the LCD screen, which is close to the sensor, generates undo heat).

High ISO Noise- When you up your ISO setting to shoot in low-light situations, this causes an increase in the degree of latent, background electrical noise; the more background electrical noise there is, the more prevalent noise will be in your photograph.

Color Sensitivity- This refers to a black-and-white film’s ability to score differences in color. A panchromatic film records all colors, converting them to tone, while an orthochromatic film records all colors save red. While on the subject of black-and-white film, it is probably important to speak for a second about contrast. Contrast, in short, is the degree of variation between shades of gray or in color value; contrast, therefore, enables the eye to make clear distinctions between objects within a scene. That said, different films possess different capacities for handling contrast. For instance, ISO 100 slide film can handle 6 steps of contrast variation, ISO 100 color negative film can handle 7steps, and ISO 100 B/W film can handle 8-9 steps. Many people find black-and-white images more “real” than color ones, and this is because black-and-white film can handle more complex and subtle variations in contrast.

Color Balance- The human eye corrects color from different light sources, so that an object that is understood as white will look fairly consistent under differing lighting circumstances. Because of its inception in light, what is “written” on film is sensitive to all colors, including those from different light sources. This means that color film will display the degree of color variation in light from different origins. Film manufacturers have gotten around this problem by varying the emulsions in different films in order to optimize them for compatibility with how the human eye sees. They do this by making certain films less sensitive to certain colors, so that when the photographer is using them in circumstances where a light source emits that certain color, it will be registered closer to natural in the print. For more techniques on how photographers control color balance, see the essay on using filters.


One Response

Subscribe to comments with RSS.

  1. […] Cameras 2. Film 3. Lighting Equipment 4. Filters 5. Lenses Tagged with: Basic of Photographic Equipment, Jason […]

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: