Henry Peach

ISO stands for International Organization of Standards. I don’t know why it’s not IOS, but what it refers to in photography is the level of light sensitivity of the sensor or film. It’s often called “film speed“, even when talking about digital cameras.

A higher ISO number means more light sensitivity; more sensitivity means less light is necessary to get a good exposure. Besides shooting a low light scene, a photographer might need to use a very fast shutter speed to freeze action, or a small aperture (large f/#) to get a very deep DOF. These situations may require getting the exposure with less light.

ISO 100 is typically used for bright, well lit scenes such as outdoors on a sunny day.

ISO 400 would be used in situations with less light, when photographing action, and/or with flash.

ISO 1600 would be used in very dim situations or with extremely fast moving subjects.

Generally higher ISO settings mean the photos will have more noise with digital or more grain with film. Whether noise is going to be an issue depends on how much magnification or enlargement the finished photograph requires. Noise won’t show as much in small prints or web friendly sized photos. On the other hand it becomes much more evident in large prints.

Currently available DSLRs have extremely low noise if the exposure is good. The difference between ISO 100 and ISO 400 is barely noticeable if at all, and even at ISO 1600 the noise is comparable to the grain of ISO 400 film. Underexposure is usually the culprit for excessive digital photo noise.

It also depends on the photographer’s opinion and vision of the finished photograph. For instance I think coarse noise/grain often works well with the subject of live music. Noise/grain is sometimes assumed to always be undesirable, but as my Photo 101 professor said “Grain is not evil. It’s just grain” (at least it was something like that). It is true that people do like sharp, smooth grained or noise free photos, but there are plenty of examples of great photos that have extremely coarse noise/grain. I think the detrimental effects of grain and noise on photographs are often over-emphasized in discussions among photographers. The rest of the world is mostly concerned with content.

Here’s a photo taken at ISO 100 or 200

Here’s one taken at ISO 3200 (no noise reduction used)

At these sizes it’s pretty hard to see the difference, but they would be obvious in an 8″x12″ print.

There are ways to decrease noise and grain. Film photographers can choose tabular grain films and fine grain developers. Digital photographers can use noise reduction software. With both there are exposure and processing techniques that can be used by the photographer to decrease or increase grain/noise.

The aperture is the hole in the lens.  It’s a ring of interleaved metal blades called an iris diaphragm which allows the size of the hole to be changed.  The size of the aperture is measured in f/stops.  It is written f/#, like f/4 or f/5.6.  The formula for f/stops is lens focal length divided by aperture diameter equals f/#.  For example a 50mm lens set at f/2 has an aperture 25mm wide:  50/25=2.  At f/10 the aperture would be 5mm wide:  50/5=10.  You don’t have to remember the math as long as you remember that a small f/# like f/2 is a larger hole than f/8, and f/8 is a larger hole than f/22.

Aperture size controls two things.

1)  Exposure:  The larger the hole the more light is allowed through (increasing exposure).

2)  Depth of field:  DOF is the area of the photo that is in focus.  DOF can be shallow like is often seen in portraits where the subject is in focus and the background is out of focus; the larger the aperture (smaller f/#) the shallower the DOF.  DOF can be deep like in a landscape photograph where everything from the foreground to the far background is in sharp focus; the smaller the aperture (large f/#) the deeper the DOF.

This photo was taken with the camera set to a large f/# (small aperture size).  Everything from the front of the car to the back, as well as the light pole and building in the background is in fairly sharp focus.

With the camera set to a small f/# (large aperture size) the DOF is shallow, and the background is not in sharp focus.

DOF is also controlled by lens focal length and distance to subject.  A very small f/# combined with a long focal length and close subject can completely obliterate backgrounds.   The closer the focusing distance the shallower the DOF.  The longer the focal length the shallower the DOF.  So to increase DOF (deeper) use a large f/#, increase focusing distance, and/or use a shorter focal length (wide angle).  To decrease DOF (shallower) use a small f/#, decrease focus distance, and/or use a longer focal length (telephoto).

Aperture Assignments

1)  Demonstrate shallow DOF using a small f/#.

2)  Demonstrate deep DOF using a large f/#.

Most DSLRs have focal plane shutters. A focal plane shutter is a curtain made of interleaved metal blades directly in front of the sensor. The shutter is set to open for a particular amount of time usually measured in fractions of a second such as 1/125th. In your camera display this might be abbreviated to 125. Since normal use shutter speeds usually range between 1/30th and 1/4000th of a second the fraction is just assumed. One second is usually designated with an apostrophe such as 1′. So when you see 2 in the camera display it probably means 1/2 sec, but 2′ would mean 2 seconds.

The amount of time the shutter allows light to reach the sensor controls two things.

1) Exposure: The amount of time the sensor is exposed to light is one control for exposure. More time (slower shutter speeds) means more exposure.

2) Motion: How motion is rendered in the photo. For instance if taking a photo of a galloping horse a very fast shutter speed like 1/1000th and higher might be able to freeze the horse sharply in mid-gallop, while a slower shutter speed would render the motion as blur. How high of a shutter speed is needed to freeze action depends on a number of things including how fast is the subject moving, which direction is it moving in relation to the camera, how far away the subject is, etc… 1/125th of a second is usually a safe shutter speed to freeze normal, casual, human movement.

A high shutter speed, something like 1/2000th, freezes Maisy mid-jump.

A slow shutter speed, like 1/10th, shows subject movement.

In this photo the camera was on a tripod, and the shutter speed was 30 seconds. The movement of the LED lights is fairly sharp because they were so bright. The movements of the people holding the LED lights is more ghostly because they were not brightly lit. The trees were pretty still throughout the long exposure so they were rendered sharply.

Shutter speed not only deals with subject movement, but also movement at the camera by the photographer holding it. There is a limit to how slow of a shutter speed a photographer can use while hand holding a camera and still get sharp photos. This is called camera shake, and it’s influenced by a variety of factors. There is anecdotal advice such as use a shutter speed of 1/focal length of the lens or faster, but it’s really best to do personal testing.

In this photo I used a flash combined with a slow shutter speed and intentional camera movement. The flash provides enough light in a very short amount of time (1/10,000th sec) which freezes the subject in the foreground. The flash doesn’t reach the background though, and it exposes from the ambient light with a slow shutter speed as I twist the camera. This is called shutter drag or slow sync flash.

Flash sync speed: At slower shutter speeds the curtain that makes up a focal plane shutter opens all the way. Higher shutter speeds (less exposure) are attained by only opening a portion or slit in the curtain and moving it across the sensor area. Because a modern, electronic flash occurs in about 1/10,000th of a second if the shutter curtain isn’t all the way open only the part or slit that is open when the flash goes off will be properly exposed, and the rest of the photo will be dark and underexposed. This means unless you have special equipment, such as flashes with a high speed sync feature, there is a maximum shutter speed that can be used when using flash.

Shutter Assignments

1)  Demonstrate freezing a fast moving subject with a high shutter speed.  Choose a subject that looks different moving than standing still.  For instance a frozen, speeding car looks remarkably similar to a parked car.

2)  Demonstrate rendering motion as a blur with a slow shutter speed.

3)  Try panning.  Track a moving subject while using a slower shutter speed (try 1/2 to 1/15th).  As long as the moving subject is panned evenly it should come out fairly sharp, while the background will blur.

For Erin, and anyone else with a new DSLR.

“The camera is an instrument that teaches people how to see without a camera.” -Dorothea Lange

There are many kinds of cameras for different uses. Point-and-shoot cameras are compact and as easy as possible to use. Most 35mm SLRs and DSLRs are designed to be very flexible and useful in a variety of shooting situations. View cameras, TLRs, rangefinders, pinhole cameras, etc… are other types of cameras, but fundamentally they are all the same. A simple description of a camera would be: a light proof enclosure with light sensitive imaging materials (film, digital sensor, photo paper, etc…) inside, and a hole to let light in.The basic parts (systems) of most modern cameras (built in the last 100 years or so) are:

Camera body: a light proof enclosure.

The light sensitive imaging materials/device: film or digital sensor.

Lens: shaped glass or plastic lens elements that can sharply focus the image on the light sensitive materials/device.

Focusing control: moves the entire lens or parts of it to focus at different distances.

Aperture: the hole that lets the light in is created by an iris diaphragm so it’s size can be adjusted.

Shutter: precisely controls the amount of time light is allowed to shine on the light sensitive imaging device/materials.

Viewing system: some sort of viewfinder that helps the photographer aim the camera.

A new DSLR can seem pretty complicated, but most of the many controls, buttons, menus, and features have something to do with one of the basic systems above. Also remember that DSLRs are designed to suit everyone’s needs, and depending on subject matter, shooting situation, the photographer’s style, etc… particular features may or may not be advantageous to everyone. Learn the basic controls first, and then it’s easier to understand which features each individual photographer will find useful.

“…People ask me what lens do I use? I don’t even know most times. They’ll ask what films I use? Well, it depends where I buy the film! If I’m in Japan I use Fuji because it happens to be readily available in Japan. If I’m in France I’ll buy Agfa, Ilford or Kodak. I find that when one has worked long enough, technical know-how becomes almost irrelevant. In photography, it’s not difficult to reach a technical level where you don’t need to think about the technique any more. I think there is far too much literature and far too much emphasis upon the techniques of photography. The make of camera and type of film we happen to use has little bearing on the results.”  -Michael Kenna

From The Devil’s Dictionary by Ambrose Bierce

PHOTOGRAPH, n.

A picture painted by the sun without instruction in art. It is a little better than the work of an Apache, but not quite so good as that of a Cheyenne.

PICTURE, n.

A representation in two dimensions of something wearisome in three.

PAINTING, n.

The art of protecting flat surfaces from the weather and exposing them to the critic.

ART, n.

This word has no definition. Its origin is related as follows by the ingenious Father Gassalasca Jape, S.J.

One day a wag — what would the wretch be at? –
Shifted a letter of the cipher RAT,
And said it was a god’s name! Straight arose
Fantastic priests and postulants (with shows,
And mysteries, and mummeries, and hymns,
And disputations dire that lamed their limbs)
To serve his temple and maintain the fires,
Expound the law, manipulate the wires.
Amazed, the populace that rites attend,
Believe whate’er they cannot comprehend,
And, inly edified to learn that two
Half-hairs joined so and so (as Art can do)
Have sweeter values and a grace more fit
Than Nature’s hairs that never have been split,
Bring cates and wines for sacrificial feasts,
And sell their garments to support the priests.

Some of my photos, along with live music photography from Joe Montgomery, Anne Tangeman, and Mary King, will be hanging at Love Garden at 936 1/2 Massachusetts in downtown Lawrence, KS. The exhibition will be up until Thursday, August 21. Stop in and see it!

Saturday, July 26th will be the Matt Pryor CD release party.

The Spook Lights at The Jackpot Saloon, Lawrence, KS 10/9/2007

The artists’ reception for the Lawrence Photo Alliance show at Kansas Secured Title will be from 5:00 - 7:00pm, Friday, July 18th.  Kansas Secured Title is at 544 Columbia Drive, Suite A.  I can’t even remember what photos I have in the show, but I think it might be these. 

at the Farmers’ Market, Lawrence, KS

More pics.

The Wiseacres’ Myspace page.

at the Replay Lounge, Lawrence, KS

More pics from the show.

The Wilders’ Myspace page