Medium Format Digital Backs
The digital back is a digital photography equipment produced mainly for professional photographers. These devices use large digital imaging sensors in order to keep up with the medium format film resolution, letting way behind the 35mm format. Despite its expensive price, many photographers adopt this digital transition because of time and cost efficiency.
Manufacturers designed digital backs so that can fit in place of the film holders in medium format cameras, thus, converting the analog camera into a high resolution imaging digital system.
A photographer can attach a digital back to his medium format camera, and also to his view camera, making possible the transition from film to digital and still use the same camera system and lenses.
There are two main types of digital camera backs in the sense of how the back captures the image:
Scan backs – can be monochrome or color (multi-shot), and they use a linear sensor to capture the image. These sensors are CCD and they use a long line of pixel elements (one pixel wide) which is electronically guided up and down until captures the complete image. Just like a flatbed scanner, each pixel is used continuously while the sensor is moving, thus, eliminating the need of matrix array sensor elements.
The scan time may vary from a few seconds to a few minutes, thus, making impossible action shots with such backs. However, they can be successfully used in a studio for product shots, but only using continuous light sources.
Single-shot backs – just like the name says, these backs can take digital pictures in the same way like any digital still camera does, a single shot is needed to instantly capture the image. Single-shot backs use big CCD area array sensors (matrix) for capturing images, thus, eliminating the need of scanning the image.
These camera backs are more expensive than scan backs but are more convenient to use due to their wide shooting flexibility. Many of the actual single-shot backs can be easily used outdoors and action shots are not a problem. Also, the need of using pretentious light sources is vanished.
Common characteristics, connectivity, file transfer and ease of use.
Either scan or single-shot back, when fitted with the suitable camera, both produce images that can outmatch the quality of any other digital camera type. Also, the dynamic range of digital backs is higher, therefore, resulting pictures with smooth transitional tones.
The connection with the camera is made electronically through electrical contact pins, thus, making possible the communication with the camera.
The connectivity with the storage devices or computers are often made in special and different ways compared with regular digital cameras. Due to high resolution images that result from digital backs, image files are very big and can take really impressive storage space. Also, the transfer speed of such files can be a problem when shooting a rapid series of shots, or while the photographer transfer his files to the computer.
Though, the file writing and transfer time is reduced to a minimum because usually, a digital back uses specially designed storage units to store the resulting digital images, and these units use large capacity HDD’s that are capable of high transfer rates. The connection between the digital backs and storage units is made through ports capable of high transfer speeds like USB 2.0 Hi-Speed, IEEE 1394 Firewire or Gigabit Ethernet.
The digital backs require more power to work than regular cameras and that’s why they use only high power rechargeable batteries.
The majority of digital backs come with a stand-alone or integrated LCD display, conferring live preview and easy composition. Through the LCD display can also be changed various settings that a digital back may have.
The features of a digital back depend more of the camera being used, but are intended to satisfy the needs of any professional. Compared with regular digital cameras, some of the setting levels and features may be slightly expanded in a digital back.
– The sensor sensitivity (ISO) can be from 25 to 10.000;
– Resulted image files have increased bit depths;
– If compatible, the digital back can be used with various MF cameras.
Today sensor resolution for regular digital backs may vary from 10 to 60 MP (2006), but in the past, various manufacturers developed some of the first digital backs with even 3 MP, which was very good for those times. As the technology moves forward, the resolution and quality of digital backs will continue to grow.
When used with a manual MF camera, the digital back is dependent of the camera settings possibilities, but many other features can be implemented in the digital cameras made especially for a digital back unit, and these can be an in-camera image retouching, control over how the sensor captures the colors, shutter speeds up to 1/20.000 s, custom functions, image filters and other goodies.
The only prominent advantage is obviously the image quality. Digital backs are the digital photographic tools that can acquire images with the highest resolution and dynamic range, while cutting the expenses of using medium format film and related developing processes.
Expensive to purchase.
The system is heavy and usually dependent of additional equipment, which can be difficult to carry around.
Although uses big and powerful rechargeable batteries, the system shooting capacity is more reduced than other digital camera systems, especially in cold environments.
The set up of an old system digital back unit is rather complex and require many wires.
If the digital back uses a linear sensor to capture a color image, then the shooting possibilities are very limited.
Digital backs are not photographic tools that can anyone afford to buy. While these systems are targeted only to professional photographers who need the ultimate in image quality, as the technology continues to move ahead leaving various equipment behind, in the future the price drop for older systems will become imminent, making possible for many amateur photographers to afford the acquisition of a digital camera back.