Silverbased

Sadly, we are all counting down the days now, until Polaroid stops making all their instant films.

I must confess that in the past, I rarely used Polaroid cameras, finding the “$1 per image” aspect a little daunting. But also, most of their plasticky, auto-exposure consumer models seemed rather lacking aesthetically. (I do make an exception for the SX-70 camera—which still seems as futuristic today as it did when it came out in 1972.)

But in the spirit of savoring our Polaroids while we still can, recently I bought some type 669 film packs.

These peel-apart films are an older technology than Polaroid’s “integral” types like 600 or SX-70 Time-Zero. But the peel-apart pack type was adopted for so many professional and technical uses that demand remained high until digital arrived. So there are several packfilm emulsion types still available. Even Fuji has now started making a line of compatible film packs.

I’m skeptical that another manufacturer will start up making Polaroid’s integral films: It’s a much more complex technology (each pack includes a unique flat PolaPulse battery). But it’s nice to feel I’ll have the Fuji backup option, if I end up falling deeply in love with my pack-film projects.

Anyway, as I mentioned, I was never that fond of Polaroid’s own cameras. This started me thinking about “alternative” ways I could expose images onto 669 film. So today I’ll show the first of two Polaroid camera hacks: The PackPola Pinhole.

This one is so ridiculously easy that it barely deserves the name “DIY project.” Here is the executive summary:

STEP 1: Find a Polaroid microscope camera
STEP 2: Tape an 0.4mm pinhole behind its dark slide
STEP 3: Take pinhole photos

But, oh all right—if you insist on making things more complicated, here are some additional details.

While most of the later pack film cameras were plastic-bodied, Polaroid did manufacture a stout cast-metal body which was used for certain products—in complete cameras, or as a dedicated Polaroid back for technical uses. The model shown (which I was told was a microscope camera) has a rigid cast-metal “pyramid” where a civilian Polaroid model would have bellows, with a custom attachment flange on the front.

Aside from the nice brushed-metal finish, this camera has two useful features. First, it has a real live tripod socket on the bottom (vital for long pinhole exposures). More importantly, its microscope fitting comes equipped with a dark-slide—we can reuse this without modification as the shutter for our pinhole camera. (I gather microscope photos must require long exposures too.)

Now you could build a Pola-pinhole by hacking a regular bellows style camera too—and these models are practically being given away today. You’d need to remove the front of the lens/shutter assembly, and attach a pinhole behind the bare lensboard. (See the excellent step-by-step disassembly photos here—also getting a chance to practice your Italian!) But in that case, you would need to improvise a shutter, and the focal length will be about 30mm longer (and hence less wide-angle-y) than with the microscope camera.

The pinhole is pierced in a thin sheet of metal—the sidewall of a beer or pop can is ideal—and taped inside the “pyramid” behind the shutter. This gives a focal length of about 74mm. (The diagonal of a packfilm image is about 120mm, so this yields a wide-angle coverage similar to a 28mm lens on 135 format.)

For that focal length, the optimum pinhole diameter is roughly 0.4mm or 0.015 inch. This equates to a pretty tiny f/stop: the nearest whole stop value is f/181. That’s 7 stops smaller than f/16—useful to know when trying to translate light-meter readings into pinhole exposure times.

Back up your pop-can metal against something firm like a phone book, then just barely pierce the metal with the tip of a sewing needle—don’t poke all the way through! Sand away any rough burr around the edge of the hole using fine 320 or 400 grit emery paper. Twirl the needle tip in the hole to smooth any raggedness—you want the hole to be nice and round.

You can measure the diameter of your pinhole exactly, by placing it on a flatbed scanner and scanning at the highest possible resolution. Knowing the exact DPI of the scan, and reading off the dimensions of a selection just including the hole, you can see if its diameter is in the right ballpark.

I often start with a bunch of metal blanks of 50mm square, a size that will fit inside a cardboard 35mm slide mount. By setting up a slide projector at a known magnification, I can quickly go back and forth between checking sizes and roundness and gently enlarging holes with the needle to reach the desired diameter.

Of course, one great advantage of a Polaroid pinhole is that you can just wing it. Try an exposure at what you think your equivalent f/stop is. If it’s too light or too dark—next time use a revised guesstimate of your f/number when you figure the exposure.

Polaroid 669 is well-known for “interesting” color shifts when developed in cold temperatures; but also when using the kinds of longer exposure times needed for pinhole work. With a multi-second-long exposure under open sky light, you can have quite a strong blue/cyan cast:

You might enjoy this effect—or, you can tape a warming filter in front of the pinhole.

In direct sun, start by trying one of the #81 series filters. But for longer exposures or in cooler light you may need a stronger orange/salmon colored filter, like one of the #85 series. If you can get your hands on a swatch-book for theatrical gels (like Roscolux), that would offer a huge range of colors to try (with pinhole work, you’re not exactly worried about the optical flatness of the sheets).

Personally, I raided my cache of oddball Series VI filters, and found a perfect Harrison brand color-correction filter, designated “C3.” This filter loses a little less than one stop of light; I used exposures of about 3 seconds in full sun, up to 30 seconds in darker shade. The color palette of 669 seems to give a nice pastel softness, thought without much saturation in the reds & yellows.

If you have never used pack film before, you may be flummoxed by the profusion of weird tabs that sprout from the end of the camera (from a slot helpfully labeled “4″). This becomes easier to explain when you understand that pack film is actually negative and positive sheets stored separately, which need to be sandwiched together to start development.

The first black tab pulls a light shield out of the way, and uncovers the top negative sheet. After you make an exposure, pulling a white tab slides the exposed negative around into contact with the positive print paper. However both are still dry at this point, and nothing happens yet.

Pulling out the wide arrowed tab bursts a pod of chemical paste, and the two chrome rollers smoosh a uniform layer of this goo between the positive and negative, starting development. After 60 seconds, the image is fully transferred and you can peel the print away. It stays a little tacky for a few moments, so don’t accidentally get it stuck to another print.

I discovered pretty quickly that my microscope camera pack-holder had a couple of quirks—possibly the reason why it had been retired and discarded in the first place. The first is that its rollers seemed to have gotten tired, and weren’t spreading the developer goo all the way to the far edge of the print. But actually, the white blobs caused by this were one of those serendipitous creative accidents that I ended up liking.

The other issue was that there was a serious light leak somewhere in the camera body. Now, remember that a pinhole (like a lens) forms its image upside-down. So this radiant splash of light at the bottom of the print was coming from somewhere on the top of the camera.

Eventually I realized there was a tiny gap at the seam where the pyramid cone attached to the film back—perhaps the camera had gotten dropped once. A bit of electrical tape fixed that up. But as light leaks go, this may be one of the more beautiful ones I’ve seen!