One of the defining characteristics of a photographic image is "film speed," an attribute, since carried forward to the digital world, to describe the sensitivity of a film or digital sensor to light. Higher "ISO" speeds of a film or sensor setting allow for faster shutter speeds and narrower apertures to freeze action and increase depth of field to better guarantee focus.
Most digital cameras now START at ISO 200 on the low end, and many promote usability at ISO ratings of 25600 or higher. This is quite a change from even the recent past of both film and digital photography, where ISO 100 was generally considered "baseline" with ratings of ISO 800 or 1600 considered to be the extreme high end. It is now typical for a digital camera user to routinely shoot in ISO400 or ISO800 in broad daylight.
Recently however, I had the opportunity to experiment with a film that was extreme in the opposite direction from the typical starting range of digital ISO ratings. Not half the speed of 200 at 100. Not half the speed of 100 at 50. Not half the speed of 50 at 25. Not half the speed of 25 at 12. Not half the speed of 12 at 6. Not half the speed of 6 at 3. But about half the speed of that ISO, at a rating of ISO 1.6, about 7 stops slower than ISO 200.
The film is a repackaged product of the Film Photography Project, using Kodak stock 2254 low speed duplicating film packaged into 35mm cassettes. Though the original film is not typically intended for camera use, there is certainly nothing prohibiting its use in the world at large, and the availability of it in 35mm rolls allows one to use it creatively.
What purposes might one use such a super slow color negative film? A few things come to mind. First, use of really slow film allows for shooting in full sun at wide open apertures, particularly when shooting older film cameras whose fastest shutter speeds are typically in the range of 1/250 to 1/1000. An f/2 lens can be shot at about 1/100 of a second wide open, allowing daylight photos taken with minimal depth of field and enabling one to see the lens' bokeh characteristics.
As well, one can also stop the lens down to smaller apertures like f/16 in daylight or overcast and take exposures of several seconds to deliberately blur subjects, or to make them vanish almost entirely, leaving only a transparent smear. It's all part of the fun of photography, and something I wanted to try, so I did, and here are my results.
One use of such a slow speed film: taking shots under full sun wide open to get the most use of aperture. Here, a Schneider lens with a wide open aperture of f/1.9 provides very shallow depth of field in this view.
Shooting wide open for a pair of shots provides an interesting study in depth of field. In the image above, the image is focused at infinity to provide focus to the horses in the backdrop. The second shot was taken with the focal point on the fence in the foreground, and as a result, the distant trees blur and the horses disappear.
Stopping the lens down, time exposures are possible, though unlike evening ones in which moving cars turn into light trails and people disappear, the result is a frenetic looking image such as seen above.
Another example of the shallow depth of field possible with the film. This was taken under intense noon day sun.
The film can be used in a pinch for some pictoral situations in bright light. The result looks something like this, with a rather odd color cast.
Even semi-distant subjects can attain a degree of separation from their backdrops when taken at such wide apertures. There is clearly a lack of focus on the old library in the backdrop.
One of my favorite results from the roll is this one. The lens pulled down a razor sharp image on the banner in the foreground, but left an interestingly muted result in the backdrop.
Another short focusing distance shot reveals a backdrop of almost donut shaped bokeh in the traffic signals in the distance.
A time exposure taken under overcast skies allows a longer exposure of about 6 seconds, and results in something more closely resembling a night bulb exposure.
One significant restriction to using this film for serious color replication of a scene is the odd cast as well as the contrasty rendition, seen here in this image.
All in all, this made for an interesting experiment, though the color balance is pretty unpredictable and not terribly appealing. I could see trying this again as a fun experiment for subject matter that isn't specifically desired for precise color rendition. All in all, it was worth the fun and effort.