The SX-70 was a folding single lens reflex Land Camera produced by the Polaroid Corporation in the 1970s. It was the first instant SLR in history, and the first camera to use Polaroid's new integral print film, which developed automatically without the need for intervention from the photographer. The SX-70 utilized a folding body design, a 4-element 116mm F/8 glass lens, and an automatic exposure system. The lens could close focus to a distance of 10.4 inches, and had shutter speeds ranging from 1/175 to more than 10 seconds. There were a variety of models beginning in 1972 with the original SX-70, though all shared the same basic design. Later models were often equipped with a sonar autofocus system, and the Model 3 departed from the other models as it was not an SLR, instead using a viewfinder cut into the mirror hood - though all other mechanics were identical.
Though expensive, the SX-70 was popular in the 1970s and retains a cult following today. As such, many unique accessories, from close-up kits to underwater camera cases, were produced for the SX-70.
One feature of the SX-70's integral print film is its ability to be manipulated while still developing. Because it is an instant film and develops over a period of several minutes, artists are able to "push" the emulsion material around the photograph to produce effects somewhat like impressionist paintings.
SX-70 "Time-Zero" film is no longer in production. Though it can be found it is quite expensive. Polaroid stopped producing it early in 2006. For these reasons, many SX-70 owners modify their cameras to use Polaroid's more recent 600 film, which is readily available and relatively inexpensive. SX-70 and 600 film are not exactly the same shape however, the 600 having a some extra little 'nubs', so photographers must either use a playing card or dark slide from a used Polaroid film case to help slide the 600 film into the camera or slice the nubs off of the cartridge.
The problem with using common 600 film is that it is significantly faster than SX-70 film, causing overexposure. To address this issue, some photographers simply set the exposure dial all the way to "darken" and replace the small Neutral Density filter over the electronic eye with a similar clear filter. Polaroid itself recommends placing a 1-stop ND filter over the lens, and replacing the small ND filter over the electronic eye with a clear piece of plastic (as from a CD case). Even with these modifications, SX-70 users may find they need to set the exposure controls fully to "darken." Perhaps the most effective, yet difficult, modification is to modify the SX-70's exposure electronics to accept the film's higher speed.
Announced in early November 2006, a new type of SX-70 film has been released: SX-70 Blend. This film comes with a ND filter stuck over the top of the film pack, allowing the use of SX-70 cameras without the need to apply lens-based ND filters or risk damage to the camera by opening taking it apart. This film seems to be exclusively available at unsaleable.com