2 Weeks in BangkokI recently spent 2 weeks in Bangkok with a new [to me] Stereo Realist 3D camea. Following are notes on lessons learned while using this camera for the first time...
There is, simply, nothing else like slide film for the Stereo Realist. Today, the once mighty slide film processing infrastructure has basically vanished, making it a real pain to deal with slides. I was very lucky to find that IQ Lab in Bangkok still does run slide processing every weekday. In San Francisco, the once rich landscape of processing labs has totally dried up, leaving only one lab that will probably stop processing within the next few years. But aside from the headache and cost of processing, the visual impact of using slides with a Stereo Realist provides an experience everybody remembers - remarkable in today's barrage of over-abundant digital images. Transparencies have so much more luminance than print media. Scenes in the soft light of dawn or dusk are so much more enchanting than can be printed on any kind of opaque media. Back-lighting the slides really brings out the experience - almost a 3D effect in itself.
The Realist slide viewer has fully adjustible optics, good design and construction. The diffusion chamber provides smooth, even illumination. You'll probably want to find a high intensity bulb for the viewer, to provide whiter color balance than the default flashlight bulb.
Avoid faster slide films. I've seen that Fuji Velvia 50 is being re-introduced (year 2007), though I would tend to buy 100 speed going forward. In case you haven't used slide film before, you'll probably find that 400 speed is just too contrasty.
Check your Realist to make sure the guide rail over the sprocket counter wheel rides the film low across the wheel's teeth. If the guide rail doesn't press the film down well, the sprocket counter may skip, causing the images frames to alternately skip and overlap.
The loading / unloading sequence is basically:
OK, here we go... After detailed analysis with the Stereo Realist viewer, eye loupes, and a Nikon Coolscan 5000 film scanner, I've decided that the Realist optics can be sharp, but only if used properly. I killed a lot of otherwise good images due to over softness. You really have to stop this lens down, way down. That's not for the depth-of-field, but to obtain decent sharpness.
Conventional photographic thinking says that the heart of your lens is right in the middle of the f-stop range, with optimum performance around f 8. But the 3-element Realist lenses are so soft that the whole opimal curve is pushed much higher - peaking at around f 16 for "optimum" performance. In fact, I haven't seen that f 22 is on the declining curve, except that the f 16 and f 22 settings are physically tight and difficult for accurately setting the iris mechanism.
The problem with the higher f-stops is that shutter speeds take a huge hit. This is especially true when using slides, where the best artistic effects happen in soft light, such as evening scenes, and film speeds won't be higher than 100 ASA. You'll find yourself down at fifth or even half second speeds, where the detrimental effects of camera shake then dominate. The solution, as I found in Bangkok, is to use at least a monopod. Unfortunately I discovered this after killing a lot of great images due to softness, either from wider f-stops (f 5.6 to f 8) or camera shake.
In particular, the softness comes from both a general defocusing across the image, with nasty, uneven smear in the image corners at f 4. However, chromatic aberation is under control, and rectalinear correction is good. Shooting images below f 8 is a very bad idea.
Contrary to popular opinion, I've found that depth-of-field isn't a significant issue - selection of DOF is really up to the photographer, and a shallow DOF can be beneficial if at least something is in focus. It's the general softness that really kills faster apertures on the Realist.
For slide film in the Realist, it is a good idea to meter a third stop faster than the rated film speed, for exposures that tend to deeper tones than "normal". (Example: the film is 50 ASA, so the meter is set to 64 ASA.) Remember that you'll be looking straight into what amounts to a flashlight (the Realist viewer) at close range. This guarantees that your shadows will be well lit, so a tendancy toward deeper shadows (under-exposure) is appropriate for this media.
There are two good reasons to avoid open, daytime sky with the Realist:
Slide film gives you only about 5.5 stops of usable range, which is a lot less than a sunny scene provides. Shadows can go black, and sky can wash out. You have to choose what in your scene you want to preserve. Here's what I re-learned about metering for slide film:
There's no point going overboard on expensive slide mounts. The Stereo Realist isn't a precise art form and there are many limiting factors, making good cardboard mounts an optimum choice. For Bangkok I used heat-sealed cardboard mounts, which have a thin sandwich layer with cutouts that make it very easy to position the film chips. The lower edge of the cutout is sufficient for aligning the chips along their bottom edges. The mounts seal with a clothing press iron at mid temperature setting, such as "permanent press".
The Stereo Realist frame intervals will be slightly uneven. This can be due to fluctuations of film tension over the sprocket wheel as film advances through the camera, or from uneven cutting, or parallax effects at variable subject distances. It's difficult to escape this, as the images are crammed, edge to edge without any spacing, to balance the spacing of human eyes and consumption of film. There isn't any margin between the images, making it difficult to decide exactly where to make a cut.
After running through 10 slides, you may notice that some need their pairs spread apart, while others need the pairs brought together. The symptom is not a poor stereo image, but simply that the left and right vertical edges don't align (a double edge is visible). Before mounting the film chips in a slide mount, compare them at the left and right edges and make the appropriate compensation.
In general, mounting is quite easy. The human eye will automatically adjust for positioning horizontally and vertically, with the only limitation being rotation. As long as the two images are aligned along an edge, viewing will be fine.