|Round and around|
|Like all high-end digital cameras, the Panoscan is costly - but Adam Woolfitt is nonetheless enthusiastic about its abilities.|
|Top: Infra-red picture captured using a Lee #87 filter Above: Captured as a 233 MB file, this image shows the effect of moving people, and the variation in sky bnghtness that the camera must accommodate.|
|The Panoscan Rotational Digital Panoramic camera is a real heavyweight. It weighs a great deal, it costs a great deal - but it also does a great deal. In a Pelican flight case with an accompanying Mac G3 laptop and a tripod, the Panoscan weighs nearly 601b. In fighting trim with one basic lens it costs auound f20 000 bwt in the right conditions it can make a 360" digital file, of over 560MB (enough resolution to let you read the fine pnnt on the back ofthe moon). As more and more QTVR panoramas are commissioned for the web and for print advertising, more and more cameras, work-arounds and devices appear. Each method of shooting 360s' has its strengths and its weaknesses! By far the simplest way is to use an indexed panning head like those made by Manfrotto, Kaidan or Peace River and capture 6 to 18 images on film. These images must then be processed and scanned before being "stitched" with software such as Apple's QTVR Authoring Studio or PhotoVista.
The same result can be achieved even more quickly with a single-shot digital camera, many of which now offer fully automatic stitching software as part of the bundle. But beware: many low-end digital cameras have very limited wide angle performance and all low-end digital cameras use compression to store images, so each image may well end up with density and colour variations that will make for patchy panoramas.
Rotational 360" panoramic cameras that do the whole thing in one shot on a single piece of 220, 70mm (or even 5 inch!) film are strictly for perfectionists and masochists. As the lens tums round its nodal point, it exposes through a narrow slit onto a roll of moving film. If all goes according to plan, the moving image and the moving film are perfectly synchronised and a sharply focused picture is produced. With rotational film cameras, close focusing is a tricky problem because the movement of the image and the film makes the plane of focus extremely shallaw and contrary to normal optics, stopping down the lens has little effect on depth. The second great problem is banding which occurs due to minute fluctuarions in speed of rotation and is especially visible in clear blue skies. Film has some major drawbacks forpan~ mas. High on the list is the high cost of shooting and processing 70mm, 220, or (God forbid) 5 inch film. The dynamic range of transparency material is also seriously challenged by the wide variations in light levels at varying angle around a 360 shot. And on an advertising corporate shoot, there is no way of showing an art director a Polaroid or preview, Lastly, images, which can be about 6x24cm will need expensive drum scans to get the best results. All of which adds up to some very strong arguments for a digital 360 panoramic camera.
Enter the panoscan, brain-child of American panoramic photographer Ted Chavalas. The heart of the Panoscan is a Phase One medium; format scanning back with a 7072 pixel tri-colour CCD locked in position behind anarrow slit. The camera housing carries a wide, threaded barrel with a Nikon lens mount at the front (but other mounts can be specified when ordering).
This barrel unscrews to clean the CCD and to fit either a daylight or tungsten balanced. infra-red filter, which is essential when shooting colour pictures. Because the CCD sees a long way into the infra-red end ofthe spectrurum the Panoscan can make very nice infra-red landscapes when a suitable filter is fitted over the lens.
On the top ofthe camera's casing there is a 25-pin SCSI connector, and undemeath is a heavy chamfered rail for quick attachment to the motor base. A spring loaded lug prevents the camera sliding straight through and dropping out the other side - evidence that the Pansocan was designed by a working photographer,not a salesman or a designer. A short cable links the motor to the camera housing. The SCSI connection can then be made between camera and G3 laptop, with a r' spur going to the battery to power the motor. Using an additional cable, it is also possible to use the cameq battery to power the laptop.
All the cables and connectors are ofa quality' and sturdiness that would impress the SAS. An elegant stainless steel hook screws into the side ofthe camera to keep the SCSI cable from fouling the tripod as the camera head rotates.
The Panoscan software is based directly on the Phase One package that runs the company's scanning and one-shot cameras. It is one of the simplest and most forgiving packages around. It is extremely simple to work with and understand - and the grey balance, unsharp masking, crop tools, histograms and preset tone curves are all idetltical or at least very similar. Panoscan's dedicated plug-in provides extra features such as resolution tables and the black calibration facility, which must be used before any capture. With the lens cap on this takes only a few seconds, but the software will not permit capture without it. If anything is amiss, pop-up dialog boxes alert the user to the fault or omission, including a waming if the camera is not visible on the SCSI chain.
|Taken using a 28mm PC Nikkor lens set to W1 ). To judge the level of detail recorded in this 125MB file, the area boxed in red has been reproduced separately, and (right) close-up detail contained within the marked area of the garden picture. Below: Panoscan 360" digital camera. All pictures by Adam Woolfitt.|
In a scanning back, resolution is govemed by the ISO speed: the higher the speed, the lower the resolution. At IS01600, the maximum possible file size with a 16mm lens under 10 MB (though this is still much more than is needed for a good web panorama). With a 50mm lens at IS0100, a massive 560MB file is possible. The focal length ofthe lens also affects the image dimensions. Two of the recommended 35mm Nikkor lenses (the 28 mm PC Shift and the 50mm f/1.8) offer such a wide image-field that they cover the whole 2.25 inch height of the 7072 pinel CCD.
In preview mode, the camera scans around rapidly and the preview unrolls down the monitor window. The preview is then cropped to the desired angle of capture. This feature is used if you need to re-scan an area such as a window, for exposure compensation, or to re-shoot an object at higher resolution.
The time taken to complete a final 360 scan is govemed by a combination of the exposure time and ISO setting. At each line position the CCD must stop to record the image for the duration ofthe chosen shutter speed. A window in the software interface indicates total exposure time remaining to complete the image scan.
For the novice, setting up the camera is a cumbersome process, made worse by the lack of any obvious method of supporting the laptop computer, battery or power block, other than at ground level on the canying case. In normal light levels outdoors, seeing an image on the laptop screen is very difficult indeed, and there is a special accessory hood to ease matters in this respect. The writer, however, rigged up a work surface between the tripod legs and clamped a darkcloth around it to make a sort of 'wigwam obscura'.
Focusing is done by determining the maximum contrast level in the image with a software tool. There is no focusing screen, and in practice the accuracy ofthe Panoscan mount is sufficient to rely on the distance scale ofthe Nikon lens.
Much the most intractable problem inherent in all scanning backs is subject movement. Because the CCD contains three lines ofpixels (one each to record the red, green and blue information), the mildest subject movement leaves a pronounced colour halo or fiinge, even at quite high shutter speeds. Rapid subject movement produces results that look positively psychedelic as people and vehicles are transformed into coloured slices.
A 360" digital camera offers several major advantages. First - and always the prime argument for digital - is that you see the image at once and can instantly spot if anything has gone wrong.
Second, the exposure latitude of digital backs exceeds that of transparency film, so exposure and lighting contrast problems are minimised. The possibility ofre-scanning small areas of over- or under-exposure, and combining these elements into the full image, is very straight-forward with digital capture. Thirdly, because a digital panoramic camad makes numerous still pictures on a stationary recording medium, all the normal rules offocus and depth-of-field apply.
In practice, this very particular camera can be easily tamed - as the superb examples on Ted Chavalas's demonstration CD prove. So for interiors where movement is no a problem, fantastic quality is possible. In addition, it is feasible to adapt it for peripheral photography of the surface ofcylindrical objects.
For shooting five star hotels, world class architecture, car interiors or super-detailed museum galleries, nothing else would come close. While f20,000 is a hell of a lot of money, you must reckon the life-long savings on film, scanning and heartache into your business plan if you want to see the true benefits of such a purchase.
Fortunately the Panoscan camera can also be hired on a daily basis from Cinebuild Europe, the system's UK importers. Training is provided to hirers and purchasers alike. Furthermore, Cinebuild itself is a veritable Aladdin's Cave of lighting, film skills and experience that should be in every serious photographer's address book. If you plan to hire the Panoscan specifically, talk to Tony Neal.
Cinebuild Europe can be contacted on 020 7582 8750.