The film is only sensitive up to 740 nm on a good day, while my filter only allows through wavelengths greater than 720 nm. Therefore, the film was almost guaranteed to be blank as hardly any light would get through.
Armed with this knowledge, I bought two rolls of Maco 820c which, as its name suggests, is sensitive up to 820 nm.
I also read a bit about how to meter properly when using an infrared filter. I set the ISO to 12 (the lowest my AE-1 will go). I attempted most of the photos 2 or 3 times, sometimes using the camera’s TTL meter with the filter on, and sometimes metering without the filter, then adding the filter and adding anywhere between 4 and 8 stops of exposure. In most cases the TTL light meter seemed to suggest about +7 stops, so I figured I was doing it about right.
I developed the film a couple of nights ago, and was disappointed to find it totally blank except for the one frame I’d shot without the filter. I hung it up to dry anyway, but then noticed that some ghostly images were appearing! I guess this means that I didn’t fix the film properly. Nonetheless, about half a dozen of the frames are showing underexposed images – which is progress. After about ten minutes the images stopped darkening so I moved them to a dimly-lit room to dry. I scanned them as quickly as possible, in case they disappeared again.
The negatives are massively underexposed, but the scanner was able to help a bit and I also used GIMP to boost the contrast massively. They look pretty awful and the grain is very coarse, but you can make out what the pictures are supposed to be if you look carefully. You can also see that much of the foliage is white, so I guess it worked 🙂
Some of the pictures also have fingerprints or creases, where the film got jammed while I loaded it onto my developing reel. It buckled and pinged out, and I had to poke it back in.
Here are some samples (published on this, my geek blog, rather than my photo blog, since I reserve the photo blog for pictures I actually like; and I consider these photos very much a scientific experiment!)
Incidentally, it’s now been a couple of days since I developed the film, and the images are showing no signs of fading further. Goodness knows what caused the magic appearing effect, then.
I still have one roll of Maco 820c remaining. Next time I will increase exposure by many, many stops. 15, perhaps. The camera’s longest shutter speed is 2″ so this will almost certainly put me in the region of bulb exposures and stopwatches.
If this doesn’t yield decent results I’ll stop buying infrared film, because it’s not cheap!