The internet is pretty sketchy on the EXACT differences, but from what I hear is that the cartridges will physically fit either camera. That’s good news! The main difference appears to be the film speed: SX-70 is a 100 ISO film, whereas the 600 is a 640 ISO film (i.e. it’s more sensitive to light).
It shouldn’t be too difficult to get some arty results out of a 100 ISO film with a 640 ISO camera – all we need to do is to tell the camera to put two stops of extra light on the film and we’re good to go. Wouldn’t be a problem with manual exposure of course, but Polaroid cameras are a bit sketchy when it comes to that chapter: everything works kind of “magically automatic”, and the only influence the user has is a “lighter/darker” slider with no scale on it.
What we need to do then is to trick the camera into “thinking” our subject is darker that it actually is. But to do that, we need to know…
How a Polaroid Camera measures light
Again, your guess is as good as mine when it comes to 600 series cameras. There seems to be virtually no documentation on this subject on the web.
So let’s guess… According to the history section on http://www.savepolaroid.com, the SX-70 had some very complictaed yet ingenious internal workings. If you can spare 10 minutes, the following film is well worth watching:
This film explains how the exposure on an SX-70 works:
- user presses shutter button
- shutter button triggers electronic shutter to expose the picture
- at the same time, the shutter opens ANOTHER shutter to expose the light meter thingy
- light meter thingy continuously measures incoming light and closes the picture shutter when it’s had enough
- picture gets ejected
- happy faces all round – the end
Simple yet amazing! No pre-measure is needed, and everything is done via shutter speed. Very clever!
Even though the SX-70 has a variable aperture, and the Integral 600 Series cameras only have a fixed aperture, it’s highly likely that they work exactly the same. Polaroid probably never changed that winning formula.
What we can safely assume is that the light metering thingy underneath the viewfinder is responsible for the correct exposure. Covering that “eye” with a pair of Neutral Density Shades (i.e. stick a filter in front of it) *should* trick the camera into seeing two stops less and exposing SX-70 film correctly. You with me?
I happen to have a free Lee Filter Swatch here that surely contains a piece big enough…
[flicks through filters]
Eh voila: Lee Filter No. 210 is a .6 Neutral Density that reduces light by 2 stops. Just in case, I also found the same enumaration on my Rosco swatch. Groovy!
All we need now is some film
Lucky for me, the Photographer’s Gallery on Ramilies Street had an “exclusive preview batch” of the new Impossible PX100 in stock, even though £19.99 is a tad hefty for only 8 black and white pictures. I understand they may well increase that number to 10 once they reach full production capacity.
They also had a few packets of SX-70 colour film called “TZ-Artistic – Paul Giambarba Edition”. This is original Polaroid film in a fancy sleeve, designed by the same man who was responsible for Polaroid’s package designs between 1957 and 1977 before he got fired: Mr. Paul Giambarba (applause applause applause).
Paul has a couple of blogs that are worth checking out if you’re into the history of “behind the scenes of Polaroid” and how the format gets a facelift via The Impossible Project. Check it out!