Advice on buying a digital camera back
by John Henshall
Digital camera backs enable you to shoot digitally using your existing professional camera system. You can continue to use the same camera and lenses to shoot film. They clip onto the back of a medium format camera, just like a film magazine, or slide into the back of a 5 x 4 just like a dark slide.
Produced mainly for professional use and in relatively small quantities, digital backs tend to be quite expensive. Despite this, most adopters of digital imaging find that it is cost effective and that there are advantages. Some photographers - especially of food - could never go back to the days of pulling Polaroids and getting the stylist's OK, only to find that things have changed slightly before and during the exposures of the transparencies. Only you can decide whether it's right for your work, though the fact is that clients who are now demanding images in digital form are pushing many photographers.
Digital backs come with one of two main types of image sensor: linear and area arrays. They have a big impact on what you can shoot, and how. Both are capable of producing images that match or exceed the quality obtained from film.
LINEAR ARRAYS
Scan backs use linear sensor arrays and work like flatbed scanners that fit to the back of your camera. They use a long line of CCD elements, just one pixel wide, which is driven across the image plane by a motor and lead screw, sensing and analysing the image-forming light at each point as it goes. The movement across the image plane is like the movement of a slit between the blinds of a focal plane shutter in slow motion. Scan times can be anything from thirty seconds to a few minutes, which makes them suitable for product shots and other inanimate objects but not for live subjects - unless you still have the Daguerreotype neck brace stored away in the studio loft.
SPECIAL LIGHTING
Scan backs also need continuous illumination, so you can't use your existing flash. High frequency fluorescent lights are one solution, though such lights do not have a continuous spectral emission, so colour rendition may be affected adversely. HMI lights, used extensively in motion picture and television, but now also made especially for still photography are a good but expensive solution.
Linear arrays tend to be the less expensive option and, because each pixel is used many times as it steps across the image plane, can build up into huge image files. Kodak is one of the major suppliers of linear CCD arrays for these backs, though you will not find a digital back in the Kodak catalogue. Instead, they supply to manufacturers such as Dicomed and Betterlight. Kodak themselves did supply a digital back, the DCS465, which used the same 6 megapixel chip as the DCS460, housed in a 35mm body. But although this chip is large in a 35mm body, it looks like a mere postage stamp on the imaging envelope of a 5 x 4 back.
AREA ARRAYS
Area arrays have a mosaic made up of millions of picture elements, enabling them to capture the whole of an image at once. Most of the suppliers use the 2048 x 2048 element (4 megapixel) CCD442A full frame image sensor made by Loral Fairchild Imaging Sensors. Leaf, Megavision, Carnival and Eyelike use this 30.72 x 30.72mm sensor. Another Loral sensor, with 4096 x 4096 element (16 megapixel) is exclusive to Dicomed. It is a massive 60 x 60mm - more than big enough to cover the 55 x 55mm image plane of a Hasselblad body. Note that other digital backs all restrict the angles of view of your lenses because of their smaller sensor sizes - for example, the 30.72mm square sensor effectively doubles the focal length of your Hasselblad lenses.
ANALYSING COLOUR
CCDs are monochrome devices so colour is sampled by putting filters in front of them. Scan backs usually have trilinear arrays - three linear arrays in very close proximity, each with a red, green and blue filter in front of it. There are two options for area arrays. One is to make three exposures, a few seconds apart, through red, green and blue filters. The filters are carried on a filter wheel, which the software controls. Filters may be in front or behind the lens. The other option is by 'striping' the CCD - in effect putting a colour filter in front of each tiny element - and analysing and interpolating the resulting file in software. This is the method used by most digital cameras that capture colour images instantaneously.
COST
Expect to pay somewhere in the £7,000 to £30,000 price range. There can also be other costs in going digital, for example the considerable cost of purchasing the new lighting equipment required by some digital backs. You may also need peripheral items such as a powerful workstation, calibrated monitor, CD writer and photographer's proofing system, to be sure that you know that what you hand to your clients matches your existing high standards. With investments of this size the value of your existing Sinar or Hasselblad kit can seem like a drop in the ocean, so it pays to get sound advice. These are one-off costs, however, against which must be set the obvious savings on Polaroids, film and processing - and less obvious costs such as repeat ordering, book keeping, couriers and even the running of the film freezer.
SPECIALIST SUPPLIERS
In the UK we have some specialist suppliers who can take you through the maze of equipment before you sign that fat cheque: KJP, The Studio Workshop and Silicon Imaging. They are all agents for one or more digital backs.
BETTERLIGHT
Little known West Coast US company, headed by Mike Collette who designed the original Dicomed scan back. Fast, high resolution backs for 5 x 4 cameras. Model 4000 produces 3750 x 5000 pixel images and a 53MB RGB file, Model 600 gives 6000 x 8000 137MB files and Model 8000 gives 8000 x 10640 244MB files. A 137MB file can be scanned in as little as 66 seconds.
BetterLight, 1200 Industrial Road, Unit 17, San Carlos, CA 94070-4129, USA. Telephone +1 650 631 3680 Fax +1 650 631 2915. Website www.betterlight.com
DICOMED
Minneapolis based company headed by a Lancashire ex-patriate, Trevor Howarth. Emphasising "Digital photography without the compromise", Dicomed's products are some of the very finest. The giant 6 x 6cm 16 megapixel chip is exclusive to their BigShot 4000 (instant capture) and BigShot 3000 (sequential filter) backs for Hasselblad 553ELX bodies. Also supply the StudioPro series of scan backs and a FieldPro portable version, including versions for the budget minded starting at $9,995.
As of autumn 1998, a new back -- the LittleBigShot -- using a 24 x 36mm 6 megapixel chip and fitted to a Mamiya 645 is imminent.
Dicomed Inc, 12270 Nicollet Avenue, Burnsville, MN 55337, USA. Telephone +1 800 888 7979 or +1 888 DICOMED Fax +1 612 895 3258. UK sales manager Richard Burke 01703 276476 or 07771 645902. Website www.dicomed.com
EYELIKE
German company Jenoptik makes eyelike backs. The Eyelike Basic uses an area array to capture 2048 x 2048 pixel images and can capture both single shots for live subjects and four shots for inanimate objects. The Eyelike Scan uses the same chip but produces up to 6144 x 6144 pixel images by using a special technique which effectively moves the chip to build up an image which does not involve interpolation. Distributed in the UK by KJP.
Jenoptik Laser, Optik, Systeme GmbH, Oskar-von-Miller-Str.1a, D-85386 Echling, Germany. Telephone +49 8165 77 475 Fax +49 8165 77 503. Website www.eyelike.com
LEAF
Now owned by the Israeli Scitex Corporation Ltd, Leaf were an American company that designed the first professional digital backs to use the 2048 x 2048 Loral sensor, showed at Photokina way back in 1992. The DCB-II is the latest version, with adapters available for SinarCam, Sinar p2 and e, Hasselblad 553ELX and 500EL series, Mamiya RZ67, Fuji GX680 and Cambo Master/Toyo. A DCB-II Live variant adds a video preview window. Both are for triple exposure colour capture. The CatchLight is a single exposure version for instant capture. Supplied in the UK by Silicon Imaging.
First shown at Seybold SF98 on 31 August 1998, the new Leaf Volare uses a 24 x 36mm 6 megapixel chip.
Website www.scitex.com/products/leaf.htm
MEGAVISION
Megavision's CEO, Ken Boydston, is a digital camera veteran with immense experience. He was making the Tessera camera, which used a vidicon tube, way back in 1991. (We reviewed it in the November 1991 issue of The Photographer.) The MegaVisionT2 is a three shot back, whilst the S2 is the single exposure version. Both use the Loral 4 megapixel area array. The T2 will fit any 5 x 4 camera. The S2 is an instant capture version for Hasselblad, Mamiya 645 and RB. Versions for Bronica, Mamiya RZ, Fuji GX680 and Rollei are expected. A BatPac storage unit weighs 3 pounds and allows the S2 to be used in the field. Up to 51 images can be stored on a standard 340MB PC(MCIA) card. Based in the USA, MegaVision's products are distributed through Calumet Digital Solutions - KJP in the UK.
A new back, using a 24 x 36mm 6 megapixel chip in a Mamiya 645 body, was shown as a prototype at Photokina 98.
Website www.mega-vision.com
PHASE ONE
Danish company which makes high quality scan backs, The PowerPhase is a 6000 x 8400 pixel (144MB file) device for 5 x 4 and is also available for Hasselbad 201F, 203FE, 205FCC, 500, 501C, 503Cxi, 903SWC and Mamiya RZ67, Rollei 6008, Fuji GX680, Bronica SQ-Ai and ETRSi. The PhotoPhase vII is a high resolution (103MB files) back for 5 x 4 costing. A full listing of all PhaseOne's many options - and a price list in US dollars - may be found on their website.
Phase One showed the LightPhase, a new back for the Hasselblad incorporating a 24 x 35mm 6 megapixel chip, at Photokina 98.
Phase One A/S, Roskildevej 39, DK-2000 Frederiskberg, Denmark. Telephone +45 36 46 0111 Fax +45 36 46 0222. Website www.phaseone.com
SCANVIEW
Another Danish company who makes the Carnival 2020 back with area array for single shot or multiple exposure colour. Fits Hasselblad 553ELX and 503CW, Mamiya RZ67 and 645PRO, Fuji GX680, Sinar, Horseman and Linhof M679.
Scanview A/S, Meterbuen 6, DK-2740 Skovlunde, Denmark. Telephone +45 44 53 61 00 Fax +45 44 53 61 08. Website www.scanview.com
This article first appeared in "The Photographer" magazine, June 1998.
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