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The Digital Predictor: previewing your digital and film work by: R.A. Glidewell
It is frustrating to be "almost" sure how film work will turn out. It is especially frustrating since most studio photographers have
a digital camera, capable of giving instant feedback on the selection of lights, reflectors, gobos, etc. If only it could be made to match
what a larger-format film camera produces.
There are, of course, sophisticated digital studio systems with real-time preview capabilities, but I wanted a system that could "preview"
the results of both digital and film cameras, was sufficiently portable to be used for remote "studio" setups, and made use of a digital camera
that could be carried to other assignments.
The promise of such a system is its power. To be able to preview effects such as depth-of-field effect, judge the intensity of a fill-flash,
spot unwanted reflections, assess the effect of reflectors or gobos, or the intensity of a gel, it is both assuring and liberating. Especially
when doing new tasks, or on location, where one's tried-and-true setups can't be used, a preview system is security. Plus it is liberating.
Digital previewing is so fast, and so cheap, that one has more freedom to explore: to try ideas that, without the preview system, you
wouldn't otherwise "chance."
My initial experiments used inexpensive digital cameras. Although many of these sub-$1000 units have adequate resolution, I generally found the
focus imprecise and the zoom functions awkward. And without the through-the-lens viewing of an SLR, depth-of-field judgments are impossible.
Many don't offer a full range of f-stops. Finally, most current digital cameras simply won't work with studio flashes. Problems such as
the lack of an external flash interface, an undefeatable internal flash, proprietary hot shoes (or no hot shoe at all), pre-flashes for exposure
calculation or red-eye prevention are all common. And most don't focus well under the low light output of studio modeling lights.
Nikon Dx1
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Already accustomed to the Nikon system, I decided to try the D1x digital camera as the basis for the system. It has worked out remarkably well.
Here is what I found. To match the imaging of a film camera, a zoom lens is almost essential on the digital camera. It must duplicate the chosen framing of your film shot, compensate
for the smaller-than- film digital sensor size (1.5x compensation on the D1x), and it must match the depth-of-field of its film counterpart, even
when the film is a larger format. On the D1x, a Nikkor 24-120mm f/3.5/4 gives me the 35MM equivalent of a 36-180mm zoom. This is able to match
almost any framing I use in 35MM and medium format studio work. One's first inclination, to use the "video out" port on the D1x to drive a monitor,
won't work. What you will get is an NTSC (television) version of the 130,000 pixel output spread across a large monitor. On the 2" display on
the back of the D1x, it looks fine, but on a large monitor, this roughly 400 x 300 resolution is unusable. Fortunately, the D1x maintains full
operational status while in "PC" (file transfer) mode, through its 1394 (FireWire) port. Attached to a computer running Nikon Capture software,
the camera/computer combination becomes a formidable image management system, through which almost every camera function can be adjusted and
setting stored. Picture taking can be operated either remotely or at the camera. In fact, while the D1x is a spectacular camera, the real key to
the preview system's operation is Nikon's $225 Capture software. This preview setup is very much a software-driven system.
Samsung 171MP Monitor
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For viewing the digital image, I found the combination of the D1x and an IBM a30p laptop works beautifully for location work. The laptop's 15"
display has remarkable resolution and, unlike many laptops I've used, has a trouble-free FireWire port. In the studio, I found conventional
monitors too large. I want the preview monitor within a few feet of the camera stand, so an LCD flat panel display was a must. The 17" Samsung
SyncMaster 171MP proved to be ideal. Driven by a conventional PC, it produced clear, bright, easy to evaluate pictures and features a very
flexible array of inputs. Unlike Apple MAC computers, PCs usually lack FireWire ports. In my case, I used an ATI Radeon 8500DV AIW video board,
which features both a FireWire port and very fast photo editing capability, to drive the display.
Nikon Capture allows you to configure and save profiles that define the white balance, color balance, tone compensation, hue adjustment, and
individually adjustable curves for each color channel. An unsharp mask, exposure compensation, and custom cropping can also be included in the
shooting profile. It is these tools, more than any other feature of the preview system, that allow one to fine tune the digital output to match
the results of your film exposures. The greatest challenge was matching the wider tonal range of film. It can be done, but it took repeated test
cycles using typical studio subjects, starting with some tabletop still-life work and then on portraits.
I usually rely on Portra NC for negative and Ektachrome S or SW for chrome work. I now have digital Capture profiles for each of these films
in several formats that very closely match my film results. Bracketing can give you a dozen bad shots. A good preview system can
lead you to the shot you want. The ability to snap off a picture, look to your side, and see a 15" "print" within two seconds, takes one
light-years beyond the old system of preview prints from a Polaroid back. And, I confess, it is great fun.
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Playing With Preview
One of the virtues of a big-display preview system is that small, but crucial, details are so easy to see and manipulate. Here are some
samples from a shoot with Nicole Niles - omp model #15561.
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Set 1:
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Multiple problems here: the hairlight hitting the nose, unattractive highlights on cheek, neck and chest. Her hand is a distraction.
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Better, but hand and torso still add nothing. Hair light is still
hitting chest, and her cheekline is lost in the shadows of her hair.
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Got it. A tighter shot with the hand and torso gone, hair light goboed off her chest, and a reflector - which you can see in the
catchlight in her eyes - fills in and defines her cheekline.
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Set 2:
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This was one of a dozen shots that didn't quite "have it"; nice idea, nice pose, but... so we tried a lot of variations.
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Finally... having her crouch lower and spread her feet wider, outside the chair rungs, made the pose more playful and opened the picture up. The
smile didn't hurt either.
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Set 3:
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Again, this first shot represents dozens of head shots that were "just OK." So, we experimented.
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Bringing the hands in did it. This is where I would switch to a larger-format chrome.
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Set 4:
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This is the kind of subtle point that a large preview display can catch. Her nose is visually merging into her face and the highlights
on her neck, just under her chin, are awkward.
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Bring the hairlight around to her side just a bit, and voila.
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To contact R.A. Glidewell with suggestions or comments email him at: doc@onemodelplace.com
© copyright R.A. Glidewell 2002
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