Silverbased

The collapsing Polaroid SX-70, introduced in the 1970s, may be one of the coolest cameras ever made—and it’s definitely my favorite Polaroid. So in our final few months before the company stops making film, I’m determined to get the maximum use out of mine.

Aside from a few price-gougers on eBay, there are no supplies remaining of the Time-Zero film packs created for the SX-70 cameras. However, there are many descriptions on the web of how to adapt a Polaroid SX-70 camera to use 600 film packs—even Polaroid has one.

The basic problem is that the original Time Zero film packs for the SX-70 had a speed of ISO 75; while 600 film has a speed of… well, 600. There are a couple of ways to solve this, and I won’t repeat all the information available elsewhere.

I wanted a solution that left the camera in unmodified, original condition, and didn’t rely on the “lighter/darker” dial for adjustment. The simplest answer is to add a 2-stop neutral-density filter over the lens. (Admittedly, this makes the viewfinder image rather dim.)

Originally I had high hopes for holding a regular Hoya screw-in polarizer in front of the lens: This cuts out about two stops, plus would have sometimes helped deepen colors by rotating it to different angles.

But it turned out to be a real fumble to hold the polarizer in the correct place; and worse, the image seemed a bit washed-out and greenish.

Flexible gelatin filters are a better choice: They can be taped permanently in place while allowing the camera to collapse normally. So I wanted to report success in adapting my SX-70 using filters taken from a swatchbook of Roscolux theatrical gels.

You only need about 30mm square to cover an SX-70 lens. Perhaps some friendly theater tech will let you snip out what you need from their samples or scraps. I got my swatchbook by requesting it from a form on the Rosco website—but perhaps too many photographers were abusing this, because the page has vanished now (I blame Strobist readers!)

Roscolux filter samples have handy light-transmission info included right in the swatchbook. So it was an easy choice to start with #98 “Medium Grey,” which claimed 25% light transmission (that is exactly two stops). I found the exposure was almost perfect—perhaps just a shade light on my camera. However there was a slight greenish tinge to the image which bothered me a bit.

I tried sandwiching the gray filter with #3318, a pale magenta “1/8 Minusgreen.” That worked great, but still gave a slightly bluish color palette. Finally I tried the #98 gray plus #05, “Rose Tint.” This seemed like the best combination overall—slightly warmer grays but still neutral. Having said that, the color casts were pretty subtle and you might be happy with any of them.

Polaroid 600 film shot in SX-70

The other issue with fitting 600 packs into an SX-70 is that there are four little plastic nubs on the bottom of the pack whose purpose is to stop you from sliding them into the “wrong” camera. It’s possible to use a stiff card to slip those over the obstructions in the SX-70’s film compartment; or even to force the pack into place by tipping it in at an angle.

But it’s no real problem to shave the nubs away with a sharp blade. According to Polaroid, it’s only the two middle nubs which hang up on the opening to the film chamber.

With these two mods, you can take that sleek SX-70, in all its folding, close-focusing grooviness, and put it back to use again!

[See another Polaroid project: the Pack-film Pinhole]

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UPDATE: June 20, 2008

Thanks to Megan, commenting below, for noting that you can buy the Roscolux sample book for $4—good tip!

Contrary to the instructions widely posted on the Internet, my original silver SX-70 did not have a neutral density filter over its photocell; hence I needed a 2-stop filter over its lens for proper exposure (the Roscolux #98).

However I just snagged an SX-70 model 2 (in stylish cream & tan), and successfully modded it too. This camera did have a 1-stop ND filter over its photocell; removing it (see photos at the link above) allows you to get correct exposure with only a Rosco #97 ” Light Gray” gel over the lens.

Conveniently, the first gel in the Rosco sample book is a completely clear one. It’s much easier to cut a new cover for the photocell from this than from a brittle CD case as often suggested. Another bonus of this solution is that the viewfinder image becomes one stop brighter too.

I still found that sandwiching a #05 “Rose Tint” along with the gray gave a more neutral color balance; but I will continue experimenting.

Thus continues my bittersweet Polaroid love affair…