Rangefinder Magazine
August 2002

First Exposure by John Rettie
Kodak DCS Pro Back 645M

Just think that a few years ago a studio photographer who wanted to capture images digitally had to pay somewhere around $50,000 for a digital capture back. In addition, the camera had to be tethered to a computer and could only be used to capture still images—very still images—as the camera had to make three scans to capture a full color image.

Nonetheless, many high-end studio photographers especially catalog shooters, readily switched to digital. The high up-front cost of the camera back and the related computer equipment was not of concern as the costs saved in film and processing were significant. But more than these savings it was the vastly improved workflow that encouraged adoption of digital camera backs. Photographs could be imported directly into an art director’s computer and incorporated into the page layout program in real time. The savings in color separations were enormous but more than anything it was the time savings that lead to the wide adoption of digital camera backs.

Gradually, over the past few years the initial purchase price of digital camera backs has dropped, while at the same time their versatility has improved substantially. Take the newest Kodak DCS Pro Back (645M and 645C)—it costs just $11,995 and does not need to be tethered for operation. It is completely self-contained with its own power supply, storage card slot and playback LCD, all contained in the back, which is not much bigger than a film magazine.

Regular “film” users of the Mamiya 645 camera will find that the use of the Kodak DCS Pro Back 645M digital back hardly changes usage of the camera body.

Currently this back is only available for use on a Mamiya 645 AF or AFD and the Contax 645 camera. If you own one of these systems this new portable digital back could be the system that sways you to the join the digital revolution if 35mm-based systems do not meet your requirements.

I’ll admit that I have not been a user of medium format camera backs for many years. My style of photography does not lend itself to the slow operation of medium format cameras—I found the slow operation of the cameras and the need to change film after 12-20 shots to be a limitation. Over the years I have tried several medium format cameras with digital backs but they have always been tethered or if “portable” still needed an external storage system and battery pack.

To me one of the biggest advantages of a digital camera is the ability to view an image immediately after capture and to keep shooting for much longer than in a film camera without having to change film. Obviously in a tethered studio situation these positive aspects of digital image capture have always been available. But a tethered camera does not work on location and certainly does not work for weddings.

The Kodak DCS Pro Back 645M overcomes the shortcomings of earlier digital camera backs and delivers an ideal fully portable solution. Thanks to the use of Kodak’s newest 16-megapixel (4080x4080) CCD, the camera produces an image with quality that should meet the requirements of just about any wedding or portrait photographer.

The chip used in this back is the same one that Kodak uses in the DCS Pro Back Plus that fits the Hasselblad and other 21⁄4 square cameras. This, of course, means that a 645 camera in effect becomes a square format camera capable of producing a 48MB to 128MB post-processing image file that’s identical in size to one captured by a larger camera.

Apart from the LCD screen and the battery pack, the DCS Pro Back 645M does not look any different from a regular film back on the Mamiya 645	The single card slot accepts regular Compact Flash cards as well as the I GB MicroDrive, allowing the camera to be completely self contained for location work.

The CCD has a physical size of 36mm by 36mm, which is smaller than the size of frame captured on film. Consequently there is a multiplier effect of approximately 1.5X so that a 50mm lens is equivalent to a 80mm lens if the camera had a film back. Logically, as the sensor size is the same as the long side of an image captured on 35mm film, a lens on the Mamiya with the digital back has the same effective focal length as that on a 35mm film camera. The viewing screen on the Mamiya is marked so the boundaries of the captured image can be viewed accurately. The back can also be programmed to capture a smaller image, either vertically or horizontally with a 4:5 aspect ratio instead of square. This can be useful if square format is not needed and as the image size is smaller, more images can be captured on any given memory card.

Anybody who is used to operating a Mamiya 645 camera will immediately feel at home with the Pro Back 645M attached to the camera body. In non-tethered operation it’s no more difficult to operate than a Polaroid back or just switching from one film back to another. The back clips on to the camera body in the regular fashion and the camera’s built-in electronic contacts are used to operate the digital back without any need to plug in extra cords or sync cables for operation. A small battery pack clips underneath the back to provide power while a CompactFlash or MicroDrive is inserted into the single card slot for storing captured images.

Overall weight of the back with the battery attached is about two pounds and it fits nicely to the rear of the camera underneath the viewfinder, making for a well balanced, albeit somewhat heavy, unit. Pictures can be captured at a rate of once every 1.63 seconds until the buffer is filled after five images. Then one has to wait a few seconds as the images are written to the storage card before the next image can be captured. Each file is saved in Kodak’s raw DCR file format and is around 17 to 19MB in size, so you are able to capture about 55 images on a 1GB MicroDrive.

The optional anti-aliasing filter covers the CCD for better protection and lessens moiré patterns but it does lead to some softening of images.	The large square CCD is somewhat vulnerable to collecting dust, especially if the filter in front is removed.

Once the image has been saved to the storage card it can be viewed on the LCD screen on the back. This can be used to check the focus or view a histogram plus it will provide pan and spot “exposure meter” readings where the readout is the luminance percentage relative to an 18% gray card. As with all Kodak professional digital cameras and backs the DCR file is treated as an original “negative.” It contains enough detail that an image can be adjusted for under- and over-exposure latitude as well as color balance in post processing once the file is downloaded to a computer.

This does mean that there is an additional step before images can be edited in another program such as Photoshop or e-mailed as a JPEG file. Kodak provides three software applications to compliment the camera into a photographer’s workflow. DCS Photo Desk allows one to browse and manipulate the raw DCR files after capture. Exposure and white balance can be adjusted, noise reduced, moiré patterns removed and the image can be sharpened before being saved as a TIFF or JPEG file. The original DCR file is left untouched so that it is always available later if further manipulation is required.

Kodak supplies several programs to help improve a photographer’s workflow, including this capture module that allows images to be transferred directly form the camera to a Mac or PC.

On my two-year-old Mac G4 it took approximately 30 minutes to convert 55 DCR images (1 GB) to 55 JPEG files. Each JPEG file was about 2MB in size, which opened up to a 64MB file in Photoshop. The DCS Pro Back 645M is capable of producing TIFF files in four settings: 8- or 16-bits in RGB or CMYK. I found post processing of images was not such a hassle as the workflow is somewhat different from 35mm—one tends to shoot slower and make every image count. It should be noted that newer versions of the DCS Pro Back 645M are capable of saving files as JPEG images in the camera but this function was not operational when I tested the camera.

Naturally in a studio setting the camera can be tethered to a computer via a FireWire cable, which will power the camera back as well as transfer image files. The DCS Camera Manager program allows one to control the camera from the computer and capture images to a specified location on the computer. Actual remote operation capabilities are dependent on the camera model.

DCS Capture Studio is the third Kodak application included with the camera. It is an image editing program with powerful color management tools that can be used to edit images captured in Kodak’s own ProPhoto RGB color space, which Kodak claims has a wider color gamut for extensive retouching without worrying about running into out-of-gamut problems.

Another unique feature of Kodak digital systems is the ability to use removable infrared and anti-aliasing filters. The back comes with the anti-aliasing filter as standard, which helps reduce color artifacts but it does reduce the image sharpness slightly. The infrared filter on the other hand produces better color saturation but does introduce some artifacting. The camera back has an ISO range of 200 to 400.

Because the CCD has to be located to match the film plane of a regular film back, it is fairly exposed to the elements, meaning dust can be a problem. Of course it is much easier to visually check for dust and clean than on a 35mm based digital camera body where the CCD is buried in the depths of the camera body.

Considering the DCS Pro Back 645M has the same chip as the much more expensive ($14,995) DCS Pro Back Plus for the Hasselblad, you might wonder what the differences are. Basically there is no discernable difference in image quality, given equal lenses. The Plus back has a rear LCD screen that can be flipped up for easier composition with the camera mounted or held at a low level. There are two slots for CompactFlash cards and/or MicroDrives. On the other hand, the DCS Pro Back 645M is powered by a battery pack attached to its base whereas the DCS Pro Back Plus has to be powered by an external battery pack, a FireWire cable or an AC adaptor. All in all the DCS Pro Back 645M is much better value than the Plus, so there may well be a price drop before long.

As stated, I do not use medium format cameras very often. However, I must admit that I found the combination of a Mamiya 645 AF with the DCS Pro Back 645M to be very convenient to use as long as I did not want to shoot a lot of images quickly. I was able to clip the back on the camera body turn on the camera and back and begin shooting without having to read the manual. The menus were pretty intuitive for default settings. I transferred the captured images from the MicroDrive to my computer via a Lexar FireWire card reader and was able to open them in DCS Photo Desk for saving as JPEG files for editing in Photoshop.

Regular readers will know that I have been impressed by the quality of images captured by the newest five and six-megapixel 35mm based cameras. Yet there is no doubt that a 16-megapixel CCD provides even better quality. I guess it’s like comparing an image captured on 35mm film with a 21⁄4 square image captured on 120 roll film.

As far as camera operation I found the combination of the Mamiya 645 and the DCS Pro Back 645M to be easy to use. It was not intimidating at all. This compares well with the complicated setup procedures required in the past with many high-end digital backs for medium format cameras.

John Rettie is a photojournalist who resides in Santa Barbara, CA. Readers can contact him by e-mail at john@johnrettie.com or by snail-mail c/o Rangefinder.

Further Information:
DCS Pro Back 645M
Eastman Kodak Company
343 State Street
Rochester, NY 14650
(800) 235 6325
www.kodak.com/go/proback645