A good photographer takes pictures. A great photographer makes them.
Monday, March 14, 2011
Sunday, March 13, 2011
Shutter
Like the aperture, the shutter is a method of exposure control. However, unlike the aperture, which controls the amount of light that strikes the sensor within a given period of time, the shutter is what determines what that period of time is.
There are actually several different types of shutter. These types include the focal plane shutter (also known as a curtain shutter; the type found in SLR and other cameras), the leaf shutter and the diaphragm shutter. Do know that most of these principals are universal regardless of your camera because they all accomplish the same thing with different methods.
Shutter Speed
Shutter speed is usually expressed in a fraction. A shutter speed of 1/30 means the sensor is exposed to light for one thirtieth of a second. However a shutter speed of 30/1 means the sensor is exposed for thirty seconds.
However, on most digital cameras, any shutter speed above one second will be expressed as a whole number. (i.e. instead of 1/30 it will simply be 30). Shutter speeds of one second or lower are expressed with a whole number and a " after the number. A shutter speed of one second looks like 1".
Focal Plane/Curtain Shutter
The focal plane shutter is called that simply because it is very close to the focal plane. It's also known at a curtain shutter which as also a very descriptive name as it's made up of two curtains.
Let's take a look at a crappy animation of my own making to understand how a curtain shutter works.
What you may not know is that SLR cameras actually have two shutter curtains. As you can (hopefully) see, the first curtain opens, exposing the sensor (or film). Then, the second curtain closes. In this way, the whole frame is exposed evenly. If there was only one curtain, going up then down, the top of the frame would be too dark and the bottom would be too bright. This animation shows what the shutter would look like in slow motion at a very slow shutter speed. At higher shutter speeds (usually greater than 1/60), the two curtains will actually be in motion at the same time, one right after the other. At speeds like 1/4000, there will only be a slit between the two curtains. This, of course, presents a problem for flash photography which is why your flash won't fire above a certain shutter speed but I'll get to that on another article.
Central Shutter
The central shutter is the main alternative to the focal plane shutter. The shutter, in this configuration, is almost always located in the lens rather than the camera body. This type of shutter is very popular in medium and large format cameras like Mamiya studio cameras, and Cambo large format camera lenses.
This type of shutter was also commonly used in cameras without removable lenses like twin lens reflex (TLR) cameras and rangefinder cameras.
Many low-end point-and-shoot type cameras also employ a central shutter in the form of a simple (and cheap to manufacture) leaf shutter.
Effects of Shutter Speed
The faster your shutter speed, the easier it is to "freeze" motion. In this photo, you can see an example of the shutter speed being too slow. While it's not imperative to eliminate all motion blur completely, this photo has too much because at first glance, it's a bit difficult to tell just what's going on.
I'll go into detail about good use of motion blur in a later post but a general rule is that motion blur should be merely used to "introduce the idea of motion." In this photo, however, the player's foot looks like it's made of rubber and the football is hardly visible.
There are other issues with the photo too, of course, but the blur is the big problem.
Let's look at one more example in which motion blur is used constructively.
In this photo of the Criminal Justice Center in downtown Fort Worth, Texas, a long shutter speed produces a very blurred vehicle driving down the street. Because the vehicle is not the center of attention, it doesn't matter and actually adds the idea of motion. The building, which is the subject is in nice sharp focus.
This ties in nicely with the other problem of slow shutter speed: shake. If you are hand-holding your camera, you may introduce blur that way as well. This problem only gets worse at longer focal lengths.
To simulate this, hold a pen at one end in your hand. If your hand shakes, the deflection of the end of the pen is only a few millimeters. However, if you hold a long stick in your hand, if your hand shakes, it produces a deflection of (perhaps) several inches. In the event that it doesn't, perhaps you should be a surgeon.
In other words: use a tripod.
There are actually several different types of shutter. These types include the focal plane shutter (also known as a curtain shutter; the type found in SLR and other cameras), the leaf shutter and the diaphragm shutter. Do know that most of these principals are universal regardless of your camera because they all accomplish the same thing with different methods.
Shutter Speed
Shutter speed is usually expressed in a fraction. A shutter speed of 1/30 means the sensor is exposed to light for one thirtieth of a second. However a shutter speed of 30/1 means the sensor is exposed for thirty seconds.
However, on most digital cameras, any shutter speed above one second will be expressed as a whole number. (i.e. instead of 1/30 it will simply be 30). Shutter speeds of one second or lower are expressed with a whole number and a " after the number. A shutter speed of one second looks like 1".
Focal Plane/Curtain Shutter
The focal plane shutter is called that simply because it is very close to the focal plane. It's also known at a curtain shutter which as also a very descriptive name as it's made up of two curtains.
 |
| © Nic Neufeld/Photo Basics |
What you may not know is that SLR cameras actually have two shutter curtains. As you can (hopefully) see, the first curtain opens, exposing the sensor (or film). Then, the second curtain closes. In this way, the whole frame is exposed evenly. If there was only one curtain, going up then down, the top of the frame would be too dark and the bottom would be too bright. This animation shows what the shutter would look like in slow motion at a very slow shutter speed. At higher shutter speeds (usually greater than 1/60), the two curtains will actually be in motion at the same time, one right after the other. At speeds like 1/4000, there will only be a slit between the two curtains. This, of course, presents a problem for flash photography which is why your flash won't fire above a certain shutter speed but I'll get to that on another article.
Central Shutter
The central shutter is the main alternative to the focal plane shutter. The shutter, in this configuration, is almost always located in the lens rather than the camera body. This type of shutter is very popular in medium and large format cameras like Mamiya studio cameras, and Cambo large format camera lenses.
This type of shutter was also commonly used in cameras without removable lenses like twin lens reflex (TLR) cameras and rangefinder cameras.
Many low-end point-and-shoot type cameras also employ a central shutter in the form of a simple (and cheap to manufacture) leaf shutter.
Effects of Shutter Speed
 |
| © Nic Neufeld/Photo Basics |
I'll go into detail about good use of motion blur in a later post but a general rule is that motion blur should be merely used to "introduce the idea of motion." In this photo, however, the player's foot looks like it's made of rubber and the football is hardly visible.
 |
| © Nic Neufeld/Photo Basics |
Let's look at one more example in which motion blur is used constructively.
In this photo of the Criminal Justice Center in downtown Fort Worth, Texas, a long shutter speed produces a very blurred vehicle driving down the street. Because the vehicle is not the center of attention, it doesn't matter and actually adds the idea of motion. The building, which is the subject is in nice sharp focus.
This ties in nicely with the other problem of slow shutter speed: shake. If you are hand-holding your camera, you may introduce blur that way as well. This problem only gets worse at longer focal lengths.
To simulate this, hold a pen at one end in your hand. If your hand shakes, the deflection of the end of the pen is only a few millimeters. However, if you hold a long stick in your hand, if your hand shakes, it produces a deflection of (perhaps) several inches. In the event that it doesn't, perhaps you should be a surgeon.
In other words: use a tripod.
Tuesday, March 1, 2011
Aperture
One of the most difficult things to understand about photography is the aperture. The aperture may also be referred to as the iris or the diaphragm.
Simply, a photographic aperture is the means of controlling the amount of light that strikes the sensor (or film). Aperture is basically a fancy word for a hole.
Exposure Control
The main use of the aperture is to control exposure. As you probably know, the smaller your aperture is set, the less light it will allow through. However, a smaller aperture is represented by a larger "f-number." I'll go into more detail on "f-numbers" or "f-stops" later. For now, just know that an aperture of f/1.4 is much larger than an aperture of f/22.
In early box cameras, such as the Kodak Brownie, a photographer had the ability to choose between two apertures: one for daylight (a small aperture) and one for darker subjects (a larger aperture). One would literally push or pull a small metal tab on the camera body to move the correct hole into place behind the lens.
Today, the aperture is much more advanced but still operates on the same principal.
The lenses on modern SLR cameras have what's called an iris diaphragm. The iris diaphragm is a mechanical means of creating an aperture. Because photographers face widely varying lighting conditions, from very bright to very dim, a mechanical iris diaphragm is an efficient method to change the aperture.
The iris diaphragm uses "blades" to create an opening that can be made larger and smaller.
Depth Of Field
Another effect that the adjustment of the aperture has on the final image is the depth of field. I'll go more into depth on DoF in another article but here's the gist.
Below is a little mock-up of a simple studio setup. The camera is in the center, our subject stands right in front of it. The field of view (what the camera can see) is represented by the red lines.
In the first image, the green lines represent our field. The field is the area in front of the camera that is in focus. So, the depth of field is the depth of the area that is in focus. In this diagram, the depth of field is large. The subject could move forward or backward and still remain in focus.
To achieve this, the aperture is set to a high aperture value (small aperture size).
Simply, a photographic aperture is the means of controlling the amount of light that strikes the sensor (or film). Aperture is basically a fancy word for a hole.
Exposure Control
The main use of the aperture is to control exposure. As you probably know, the smaller your aperture is set, the less light it will allow through. However, a smaller aperture is represented by a larger "f-number." I'll go into more detail on "f-numbers" or "f-stops" later. For now, just know that an aperture of f/1.4 is much larger than an aperture of f/22.
In early box cameras, such as the Kodak Brownie, a photographer had the ability to choose between two apertures: one for daylight (a small aperture) and one for darker subjects (a larger aperture). One would literally push or pull a small metal tab on the camera body to move the correct hole into place behind the lens.
Today, the aperture is much more advanced but still operates on the same principal.
The lenses on modern SLR cameras have what's called an iris diaphragm. The iris diaphragm is a mechanical means of creating an aperture. Because photographers face widely varying lighting conditions, from very bright to very dim, a mechanical iris diaphragm is an efficient method to change the aperture.
The iris diaphragm uses "blades" to create an opening that can be made larger and smaller.
Depth Of Field
Another effect that the adjustment of the aperture has on the final image is the depth of field. I'll go more into depth on DoF in another article but here's the gist.
Below is a little mock-up of a simple studio setup. The camera is in the center, our subject stands right in front of it. The field of view (what the camera can see) is represented by the red lines.
In the first image, the green lines represent our field. The field is the area in front of the camera that is in focus. So, the depth of field is the depth of the area that is in focus. In this diagram, the depth of field is large. The subject could move forward or backward and still remain in focus.
To achieve this, the aperture is set to a high aperture value (small aperture size).
 |
| © Nic Neufeld/Photo Basics |
In the next diagram, we see a shallow depth of field. If the subject were to move forward or backward, he would be out of focus.
 |
| © Nic Neufeld/Photo Basics |
The depth of field also varies depending on focal length. Further, the aperture has a direct affect on the appearance of the bokeh. I'll get to both of these at a later time.
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