When you hear the word “slr” you’ll immediately think of a camera, but what does it really mean? In fact, there are many different types of cameras that are labeled as SLR’s. These include cameras that have interchangeable lenses and those that are equipped with Through-the-lens (TTL) metering.
Pentaprism vs Rectaflex
Pentaprisms are a type of optical device that allows a camera to view the image as it is being taken. Compared to a pentamirror, a pentaprism is less expensive to manufacture, lightweight, and usually found in high-end cameras.
The first pentaprism 35mm SLR was the Rectaflex. It was introduced in September 1948. However, the real pioneer was the Contax S, which was released in 1949. This was a more sophisticated design, with a focal plane shutter, a rapid return mirror, and an eye level finder.
While the Rectaflex is a great camera, it was plagued by some issues. Some of the problems were caused by a few incremental changes. These included a slow speed shutter dial that was removed from the front of the camera, an A/R lever that was modified, and a triple sync plug.
Despite the Rectaflex’s shortcomings, it was a landmark camera. With a wide bayonet lens mount, interchangeable lenses, and a focal plane shutter, it was a technologically advanced model. And it had a very fast top shutter speed. Unlike some of the later models, the Rectaflex had a fully flash synchronized shutter.
Pentaprisms were a major development in the history of SLR cameras. While the earlier prototypes corrected from top to bottom, a new prism corrected side to side. In the early 1950s, Zeiss Ikon applied for a Syntax patent in Italy.
Although the pentaprism was a major advancement in camera technology, it took several years to perfect. Initially, a pentaprism was a small wooden mock-up. Once it was ready, it was presented to the Prince of Liechtenstein.
Although Rectaflex was the first camera to use a pentaprism, it did not sell well. It was also plagued by some conditional issues. For example, the film compartment was not accessible until releasing a lock on the bottom of the camera. Moreover, the Pentaprism was not a very bright unit.
Pentaprisms have become more prevalent in the higher end DSLRs. However, you can still find entry-level DSLRs with mirrors. But, they do not have the same benefits of a pentamirror. Also, they are a little bit harder to use.
Through-the-lens (TTL) metering
Through the lens (TTL) metering is a technique that helps photographers achieve proper exposure. Before the camera is turned on, it measures the amount of light that comes through the lens. This information is then sent to the flash unit to fire at the correct power level. It is a very useful underwater photography tool. In addition, it also determines the amount of depth of field that can be achieved.
TTL metering is used by most digital point-and-shoot cameras, and some DSLRs. It is also employed by some compact cameras. Depending on the type of camera, there may be multiple modes for TTL metering.
A camera’s metering system can be built into the body or can be a separate unit. In most cases, the metering circuit is located inside the body. The IDM (Integrated Direct Metering) system in Canon DSLR cameras is one example of a built-in metering circuit.
Some TTL systems use a meter coupling shoe to send a signal to the meter. These meter coupling shoes can be installed on the front of a variety of interchangeable lens systems.
One of the advantages of using a meter coupling shoe is that the camera no longer needs to set the maximum aperture index before taking a picture. The information from the meter is then transmitted directly to the flash unit.
In the past, through the lens (TTL) metering was only found in film cameras. Film cameras could only measure light that hit the film. However, the camera could read light that was reflected from the film surface and the lens.
Some digital cameras, such as those from Sony, have an image sensor that can be used for exposure metering. As image sensor technology advances, real-time TTL flash metering will become more common.
Cameras can meter light in a scene by either using an external light meter or by reading the light that is reflected by the subject. Both methods are accurate and help the camera take a good exposure.
A more advanced form of metering is the use of an internal light meter, called an IDM. IDM uses a silicon photo diode to measure the light on the film plane.
The Single Lens Reflex, or SLR, is a camera that provides a direct view of an image. This is in contrast to other cameras that only allow you to view the subject through the viewfinder.
As a result, SLRs are used by professionals and amateur photographers. Some cameras even include autofocus systems to automatically adjust focus. However, auto-exposure is not always included. In the past, SLRs didn’t have many features.
Some early SLRs offered removable pentaprisms with optional viewfinder capabilities. Others featured an automatic fill-flash. Although these features weren’t unique to SLRs, they were more widespread than in other types of cameras.
Another notable feature of a camera is the shutter curtain mechanism. While it’s not unique to SLRs, some manufacturers report that their professional models can hold up to 300,000 shutter cycles.
Aside from the lens, another interesting feature of an SLR is the viewfinder. Most modern SLRs include a matte focusing screen, which is especially helpful with lenses with a wide open aperture.
The SLR also comes with a lot of buttons. This makes it easier for users to control their camera and to switch lenses. Traditionally, SLRs have been heavier, although some modern models are sleeker. Many offer more buttons to allow photographers to perform various functions more quickly.
It’s also worth noting that in the past, many photographers preferred the look of film over digital. Though digital cameras have made some strides in this department, the appeal of film cameras is still strong.
Some models are designed with low-light noise in the viewfinder. For example, the Linhof SuperTechnika V is a triple-extension bellows 4″ x 5″ camera that corrects for distortions and other errors.
Although these aren’t exactly new, DSLRs are the most popular type of camera today. They provide users with a live preview, as well as a variety of other features. Compared to other types of cameras, the DSLR is cheaper and more versatile. You can edit and exhibit your photos in digital formats, and you don’t have to waste any film.
Dedicated electronic flash units also exist. These units communicate with the camera, and send wireless signals to other off-camera flash units.