Turning over a new Leaf
by John Henshall

The Leaf Digital Camera Back showing the RZ mount and CCD.

The Leaf Digital Camera Back showing the RZ mount and CCD.

When it comes to new technology, it's all too easy for salesmen and engineers to pull the wool over our eyes. This simply may be through the careful choice of subject, avoiding anything which shows the product in its true colours, or the crafty application of computer enhancement to make the picture look sharper. Or maybe it's that the equipment is so difficult to operate that they, having known the product from "birth", are the only ones ever likely to have the necessary know-how.

These are some of the reasons why I am so emphatic about testing equipment myself, at leisure - if that's what you can call working through the night at The Chip Shop!

The Leaf Digital Studio Camera back fits medium format cameras, such as Hasselblad and Mamiya. It has made only fleeting visits to Britain from its home in the USA, or parent company Scitex's European headquarters in Belgium, or Hasselblad in Sweden, until Johnsons Photopia imported the first camera for sale in Britain recently. Until now, it has been impossible to test this camera without an engineer hovering nearby. At Photokina I managed to take an image on the camera and bring it back to the UK in digital form, for publication in The Photographer, but this is not the same as having it in your own studio.

I collected the Leaf, together with a Mamiya RZ67 body and 60mm lens, from Johnsons Photopia in Newcastle, Staffordshire, on 2 March 1993.

The Leaf kit is housed in a large, but not heavy, flight case which gives the delicate CCD back and all the other hardware considerable protection. There is quite a lot of peripheral hardware, and also special software needed to control the camera, 'develop' its images, and to apply gain and blemish corrections to each CCD chip.

Hardware includes the camera back itself, power supply, serial interface converter box, tri-colour (RGB) front-of-lens motorised filter wheel, Atto Silicon Express NuBus card and lots of special cables.

The Kit Unpacked Installing the Atto card
Attaching the Back
Mounting the filter wheel Ready to shoot

Setting up the Leaf Digital Back for the Mamiya RZ67
Top left: the kit unpacked. Top right: installing the Atto card in the Mac Quadra (note anti-static strap!)
Centre: Ready to attach
Bottom left: mounting the filter wheel. Bottom right: ready to shoot,

The camera needs an Apple Macintosh Quadra 950 or 800 computer with 64 megabytes of random access memory, a 300 megabyte (or larger) hard drive and 24-bit video (which makes it able to display 16,777,216 colours), together with a nineteen inch colour monitor. The NuBus card speeds the rate of transfer from the camera to the Macintosh.

The Leaf digital camera is called a 'Studio Camera', and that is really all it can be as the camera must be controlled by powerful mains powered computer equipment. This is a serious amount of equipment: just the 64 megabytes of RAM for the Quadra costs £1800.

The camera back itself is very chunky, mainly due to its large cooling fins which are necessary to keep the CCD at the right temperature. Temperature control is important: CCDs are apt to give very 'noisy' (grainy) pictures if they get too hot.

The square CCD chip itself is the real star of the show, the biggest I have ever seen. It has 2048 by 2048 pixels giving a total of 4,194,304 individual picture elements. A problem with all CCDs is that not all the pixels actually work. A great number of CCDs must be made in order to get just one which is good enough for use. Even this must have special individual correction applied, to compensate for the 'dead' elements which would otherwise show up as black or white spots in the picture.

The Leaf CCD

The Leaf CCD measures 2048 by 2048 pixels.

The Leaf back was fitted to the rear of the Mamiya RZ67, the motorised filter wheel to the front of the 60mm lens. Despite the large amount of hardware and software, the camera was readied for shooting without any problem. Installation of the NuBus card in the Quadra was the trickiest part: note the special wrist strap to avoid static electricity damaging the chips on the card.

The Leaf is a monochrome camera which takes 'instantaneous' pictures. It does not need continuous light and works very well with electronic flash. To take colour pictures the Leaf takes three sequential exposures, using a motorised filter wheel which has clear, red plus 0.6 neutral density, green plus 0.8ND and blue filters. The three exposures are combined in the computer to make a full-colour photograph. The disadvantage is that this sequence takes 24 seconds, so only subjects which do not move may be photographed - unless a neck clamp is used!

The Leaf CCD is approximately half the height and half the width of the 6x6cm film format, so the 60mm lens on the Leaf acts as a 120mm would on 6x6cm. A special viewfinder mask aids framing.

I wanted to choose one of the most difficult subjects I could find and I did not need to look any further than home. My wife, Paulien, is a knitwear designer. She spins her own wool from fleece which she dyes using natural substances. The colours are brilliant but fall in difficult areas of the spectrum, the fleece provides very fine detail at random angles. We arranged the fleece in a wicker basket, to get some specular highlights in the picture. This sat on a bed of finished knitwear, the patterns of knitting in which might cause interference patterns with the regular laid out serried ranks of pixels on the CCD.

Left: the cover shot set-up. Right: "developing" the wool photograph.

The camera has an ISO equivalent of 300 for black-and-white imaging and only 14 to 16 for colour. I used softlight from studio flash, with a single bare tube as backlight, to achieve a stop of 11.5. This gave a quite precise zone of focus, with soft background. I used Adobe Photoshop to apply an unsharp mask of 150% at 1 pixel radius. The result looks quite superb on my computer monitor and on an 11 inch square print, produced on the Kodak XL7700 printer. The photograph is reproduced on the cover direct from the digital image file.

Cover shot for 'The Photographer'

Brilliant colours from the Leaf back.
Originally produced as a cover of The Photographer, this picture proved that electronic images can compete with conventional film in terms of colour fidelity, sharpness and freedom from unwanted grain or 'noise'.

The camera is '14 bit' per colour (42 bit overall), which means it can produce 16,384 discrete levels for each colour, a staggering total of nearly 440 billion colours. These are sampled down by the software to the usual 256 levels produced by 8 bit per colour (24 bit overall) systems. What these staggering figures mean is that this camera has a nine stop dynamic range. This actually beats film. The software allows you to 'develop' the image and select which 8 bits per colour you wish to 'export' to programs such as Adobe Photoshop. You can save the full 14 bit image and 'redevelop' it time and time again - just as though you were redeveloping the same latent image on film.

Some of the other pictures we made included classic cameras, with fine detail and nickel plating, and a model truck, giving broad areas of saturated colour. All potentially difficult subjects which the Leaf camera handles quite superbly.

Contaflex camera Model truck

This report is peppered with big numbers. This camera gives us thousands of pixels and billions of colours for its price of around £25,000. It costs thousands of pounds for the biggest Macintosh computer, its memory and hard drive. I have used nearly 400 megabytes of disc space, just for the pictures for this column. To photograph the illustrations for a catalogue would take many gigabytes. Yet, if you are in this or a similar specialisation, it could well prove cost effective.

The Leaf is billed as a 'Digital Studio Camera'. 'Digital' and 'Studio' it is but camera - like the Mamiya or Hasselblad it fits onto - it is not. The Leaf is more like a film. And a very good film at that.

Leaf logo

This review first appeared as "John Henshall's Chip Shop" in "The Photographer" magazine, April, 1993.
This document is Copyright © 1996 John Henshall. All rights reserved.
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