Bridge Cameras

High-end, live-preview digital cameras are referred to as either bridge or prosumer digital cameras. While DSLR cameras operate on the same mechanical principles as the autofocus 35mm film single-lens reflex camera, the key difference is that a CCD or a CMOS image sensor takes the place of the film. This allows for creation of images in-camera without the need to chemically develop an image on actual film.

The major advantage over other digitals is the defining characteristic of an SLR: the light goes directly from the main lens, instead of reflecting from an off-axis viewfinder.

The advantage of seeing an exact copy of the image has been duplicated in the LCD displays of many of the digital compact cameras. However, the SLR retains the best quality of image due to its being in real time and more detailed.

LCD displays tend to have a time lag, causing the view to be clear, but not exactly what you are looking at. If something in the shot is moving, this movement will actually be viewed a second or two later. While bridge cameras are comparable in weight and size to the smaller dSLR they lack the mirror and reflex systems which are characteristics of dSLRs.

Referred to as "bridge" cameras because they hold a place between the digital consumer compacts and the dSLR's, prosumer identifies their high-end more advanced technology.

The lines between the two are not clear-cut -- the LPD category includes both the bridges and compact cameras. Mainly they both have live-preview on an electronic screen, which is their principle means of previewing an image before taking the photograph. There are also several nonessential characteristics applying to many of the bridge cameras, but not all of them.

For instance, there is the single fixed noninterchangeable lens and a CCD sensor, which is much smaller in the bridge cameras than in the dSLRs. A few of the new bridge cameras have defied these nonessential qualities and now have larger sensors of different types that are equal in size to those found in some of the dSLR cameras.

Bridge cameras still do not have interchangeable lenses; however, this may change in the not too distant future.

Comparing Film and Digital Cameras

Digital cameras have many advantages over traditional cameras. Some of these advantages are:

* After instantly reviewing the picture, it can be retaken if there is a problem. The photographer simply changes a few settings.

* Taking many shots of the same thing using different settings and angles can be done inexpensively, and you print only the best ones. This is too expensive to accomplish with film cameras.

* Those who want to take hundreds of photos for various uses without printing them can do this at minimal cost.

* Storing large quantities of digital media on the newer computers is much cheaper than film.

* No degradation occurs when copying images from one medium to another.

* You can view pictures on your computer without having to scan them first.

* With a consumer-grade printer and a computer, you can print your own photos.

* Film cameras of equal quality are often much larger than digital cameras.

* While it is necessary to change film after 24 to 36 shots, you can store hundreds of images on the same card in a digital camera.

* With many of the new cameras, you can view your photos on the television with an AV-out function that is included.

* It is easy and inexpensive to experiment with the settings on a digital camera. With a film camera, you could use up many rolls of film trying to learn to use it.

* Some printers can communicate directly with your camera, or its memory card; you don't need a computer to print your pictures.

* Digital cameras make it easy to add information to your pictures, such as time and date.

* Sharper images are now possible with digitals due to the anti-shake tools, making tripods nearly obsolete.

* A color darkroom is as close as your computer, and you can now avoid the very expensive photo labs.

History and Early Development of Digital Cameras

Using a mosaic photosensor, Eugene F. Lally of the Jet Propulsion Laboratory wrote a paper describing the concept of producing still pictures in digital format. This was proposed for onboard navigation information during missions to the planets that astronauts would later take.

Still photos would periodically be taken during the trip, and when the planet was actually approached, addition information would be provided for orbiting and landing assistance. These were the first design elements of the digital camera. A filmless analog camera was developed in 1972, but whether it was ever built is not known.

Steve Sasson, working for Eastman Kodak, was the first to record the attempted development of a digital camera. Weighing eight pounds and using a cassette tape, it recorded black-and-white images with a resolution of 0.01 mp. In December 1975 it took 23 seconds to capture its first image. Never intended for production, the prototype was still in existence in 2005 and was merely a technical exercise.

The first handheld digital device was actually an analog camera. Demonstrated in 1981, it was based on television technology and recorded a 2x2 floppy video disc. It was basically a video movie camera that took single frames, holding 50 images per disk. At the time, the quality of the prints was about equal to current television technology of that time.

At the 1984 Olympics, an analog camera was demonstrated for the consumer, printing the images in the newspaper. Widespread acceptance was held back by several factors, including a cost of up to $20,000.00, poor image quality in comparison to film, and a lack of consumer-priced printers.

A frame grabber was one of the items needed to print the photos, the cost of which was beyond that of the normal consumer. Later, several readers were created, allowing the disks to be viewed on screen, but they were never developed into a computer drive.

Storage on Digital Cameras

The higher-end professional cameras may have microdrives; these are hard drives that are built in the form of a compact flash. With the use of an adapter, you can use SD cards in a compact flash device. Digital cameras may use a memory card or a flash memory card, which are solid-state electronic storage devices.

In October 1998, Sony introduced the removable flash memory card called the Memory Stick; this term is used to describe the entire family of memory sticks. While the original stored up to 128 MB of data, an 8 GB card is now available that holds two 128 MB banks. There is also a card specifically designed for high-definition stills and video cameras called the Memory Stick Pro-HG.

This form of storage has outlived all other types of digital storage devices, and it isn't known if this is due to the manufacturers continued support of the device, or because of the technology it contains as a storage format.

Gradually taking the place of the memory stick is the flash memory card SD/MMC. Originally they were limited to 2 GB of storage, but are now being replaced with 4 GB cards. A revision was made to the SD standard, which means that all cameras don't recognize the larger storage capacity of the 4 GB cards.

In addition, these cards are formatted in the FAT32 file format, and the older digital cameras use FAT16 format, which contains a 2 GB limit. Camera phones use a MiniSD Card, which is about half the size of the standard memory cards used by digital cameras.

Also available in camera phones is the MicroSD Card, which is about ¼ the size of those in digital cameras. An even smaller format was the XD-Picture Card developed in 2002. Smart Media, containing 128 MB of memory, at one time competed with the Compact Flash; it is now obsolete and was replaced by the xD picture card.

Can Film Cameras be Converted to Digital?

One of the first questions asked by professional photographers at the development of digital cameras was, "can we convert our film cameras to digital?" The resounding answer was "yes and no."

Most of the 35mm cameras can not be converted to digital; the cost would be too high, especially since lenses must evolve as well as the cameras. The only means of allowing this would be to remove the back of the camera and replace it with a specially built digital back.

While many of the early professional digital cameras were developed from 35mm film cameras, conversion meant that rather than a digital back, the body was actually added onto a large, bulky digital unit. This was often larger than the part that was actually the camera! These were not, however, after market conversions; they were actually built this way in a factory.

One development was the EFS-1. This was inserted into the camera in place of the film, giving the camera storage for 24 images and 1.3-megapixel resolution. These units were developed from about 1998 until 2001, when the company began developing a true digital back.

Included in the category of professional modular digital camera systems are some of the highest-end equipment costing up to $40,000.00. These cameras can be assembled from components and are seldom found in the hands of the normal consumer.

Developed for medium- to large-format film, they capture greater detail and therefore the prints can be enlarged more that your standard 35mm film. These cameras are normally found in studios and are used for commercial production; they are very large and seldom used for action or nature type photography.

The terms "digital back" or "film back" came from the ability to change the backs of these professional cameras to either digital or film use.

File Formats for Digital Cameras

Digital photography uses three basic file formats.

* JPEG -- JPEG stands for Joint Photographic Export Group. It is the most common format used in digital cameras. This is a compressed file allowing more storage than other formats. JPEG changes an image into a thumbnail that is available immediately for viewing. This format is recognized universally by all software programs and the majority of digital cameras.

* RAW -- The RAW format is unprocessed data. This format is not recognized by all types of cameras or software like JPEG is. Using specific software, the data can be retrieved and developed. Only data that will be processed later using software can be stored in a RAW format.

* TIFF -- Short for Tagged Image File Format, these files take up more space because they are not compressed. Thumbnails can also be created for viewing on your camera. Better pictures are one of the advantages of the TIFF format, but there will be less storage. A 1.9 JPEG formatting camera can provide the same quality as the TIFF format.

Storage can be provided by media cards, which are miniature computer chips that store data until it can be processed into a photograph. Your digital camera's memory is the media card, which comes in different sizes to fit a wide range of cameras. The larger the card, the less it costs to store each print, and you can save more photos on a larger card. Organizing your prints is easily done on the smaller cards.

Media card formats change constantly and continue to evolve to fit smaller cameras. Most digital cameras come with a standard card that can be exchanged for a larger one or a different brand. In some instances the camera has an input for a media card, but do not come with one. You will be limited to the number of photos you can store if you store them only on the camera.

Batteries for Digital Cameras

The power need for digital cameras is very high. As they get smaller in size, the challenge has been to come up with a battery that would meet those requirements and still be small enough to fit into the smaller digital cameras.

No one would be happy with a camera that didn't have enough power to run it for a reasonable amount of time. There are two divisions of batteries for digital cameras, and these divisions are very broad:

* Off-the-shelf batteries While a few cameras have AAA batteries, AA (or CR2 batteries) are the more common in use. These are lithium-based and are intended for only single use; they are also commonly seen in camcorders. The alkaline battery, which is nonrechargeable, provides only enough power for a very short time in most digital cameras. Most photographers have moved to the AA nickel metal hydride batteries along with a charger; these provide the necessary power and can be easily recharged. Mid-range and low-end cameras may use off the shelf batteries, but only a few cameras (DSLR) accept them.

* Proprietary battery formats These are the second type of battery. Specifically built to the manufacturer's specifications, they can be either OEM or aftermarket replacement parts. Most of the proprietary batteries are lithium ion. The battery life begins to degrade after a certain number of charges, usually about 500 cycles; yet they are very powerful for their size. Because of this, both high-end professional cameras and consumer models at the low end have lithium ion batteries.

Digital photographers, both professionals and amateurs, will find many types of batteries available; all will be within the two categories mentioned above. It is possible to find as many opinions about the type of battery to use as there are photographers using them. Only the consumer can actually make the decision about which they choose.