The Polaroid SX-70 camera is an extremely popular instant camera.  It is considered by many to be the best camera that Polaroid ever produced, as it is a true SLR (Single lens reflex) camera with a 4-element glass lens and "through the lens" viewing, which means "what you see is what you get".   It has a very unique folding design which allows the camera to be very compact when not in use.  The camera has a completely automatic exposure system with a manual override control allowing the user to "lighten" or "darken" the image for special lighting situations such as a backlit subject.   There were many models of SX-70 produced by Polaroid - below I will try to explain the differences between camera models, and also explain how to use the SX-70 with current Polaroid film.

The Original SX-70

Original Model SX-70

The camera was first released in 1972, and was designed to use the new "Integral" SX-70 and "Time Zero" film that developed before your eyes - until that time, Polaroid cameras uses a messy peel apart pack film.  The original model was chrome with tan leather inserts.  Interestingly, despite the metal appearance of the camera, it actually is made out of a dense plastic which was covered in a chrome coating.  The original model is easily identified as it is marked "POLAROID SX-70 Land Camera", and has no distance markings on the lens, and no split-prism in the viewfinder - some later original model cameras did have a split prism in the viewfinder.  For flash exposures, the camera used flashbars.  A number of third party electronic flashes were also produced for the camera, made by ITT, Nissin, and Acme.

The "Bargain" models

The SX-70 proved to be a huge success, despite it's expensive price tag of $180 in 1972.  Polaroid soon developed two less expensive SX-70's, the "Model 2" and the "Model 3".  

SX-70 "Model 2"

The Model 2 is easily identified by it's white plastic body and brown "Porvair" (a type of imitation leather) coverings.  The cheaper materials allowed Polaroid to offer this model at a lower price of $150.  The Model 2 was otherwise very similar to the original SX-70, except for the fact that it had the improvement of a split-prism rangefinder added to the focus screen, which made manual focusing much easier. 

SX-70 "Model 3"

The "Model 3" is the only SX-70 camera that is not an SLR.  It is easily identified by the large "see through" viewfinder on the front of the camera.  The Model 3 was a much less expensive camera than any of the other models, and required the user to guess the distance to the subject, instead of actually focusing through the lens.  It is often considered to be the least desirable model.

The "Alpha" Models

By 1977, Polaroid introduced a nunber of improvements to the popular original SX-70, and these were introduced as the SX-70 "Alpha" models.  The improvements were subtle but important.   A tripod socket was added to the bottom of the camera, which allowed the camera to be used with a tripod.  Strap lugs were also added to the camera, so that it could be hung around the user's neck.  The Alpha models all had the split prism rangefinder incorporated into the finder, and a distance scale printed around the front of the lens.  The other important refinement of the Alpha models is that they were given the capability to use "fill flash" in daylight - the original SX-70 would not fire the flash in full daylight. 

SX-70 Alpha 1 SE

The Alpha models were offered in a suprising array of color combinations, ranging from the original chrome and tan leather scheme, to black body and leather models, and even an "SE" (Special Edition) model which is identifiable by it's blue button.  In short, the differences between the Alpha models are purely cosmetic - functionally, they are the same camera.   The improvements made to the Alpha models make them particularly desirable to own and shoot with.  For collectors, notable versions of the camera are the "SE", the "Sears Special", and the extremely rare "Executive" models.  Many of the models were also offered with a unique "ever ready" case which would fold up with the camera.

SX-70 with Ever Ready Case

The Sonar SX-70

By the mid  1970's, Polaroid introduced a new Autofocus model of the SX-70.  This was a major innovation for Polaroid, and the camera has the unique claim of being the very first autofocus SLR ever produced.   The camera utilizes sonar waves to judge the distance to the subject, and then focuses the camera.  The autofocus system is very accurate, and not easily fooled - the only exception would be when focusing through a glass window.  The Sonar also has a focus overide switch,  allowing it to be manually focused like the other SX-70 models.  The Sonar models are not as compact and elegant as the SX-70's, as the sonar focus module looks like a protruding plastic "add on" to the camera, and makes the camera much less compact.   Furthermore, the complicated autofocus mechanism is prone to failure, so it is a good idea to make sure the autofocs is in working condition before buying one of these models.  Despite these minor drawbacks, the Sonar cameras provide a "point and shoot" experience in a focusable instant print SLR, and can often be had at less expensive prices than the manual focus models.  They have the same quality lenses and construction, and may be a good alternative for those who do not wish to manually focus their camera.

  SX-70 Sonar Onestep

SX-70 Film and Alternatives

The SX-70 cameras were designed to use SX-70 or TimeZero instant film, which came in a pack which was inserted into the camera, and had 10 exposures per pack.  The film pack also contained a built in battery which powered the camera.  SX-70 film had an ISO (film speed) rating of 125, and was prized by art photographers for a unique quality which allowed the emulsion to be manipulated by pressing on the photo using a blunt object - these "SX-70 manipulations" often have a surrealistic quality.  Unfortunately, Polaroid discontinued manufacturing SX-70 film in 2006, so the film is no longer available.  This was very sad news to the legion of devoted SX-70 users who prized their unique folding cameras. 

Fortunately, there are alternatives that allow one to use Polaroid 600 film in an SX-70 camera - 600 film is widely available at drugstores, so this is indeed good news.  Furthermore, because 600 film is much faster than the original SX-70 film, much faster exposures can be obtained which allow the user to take photos in dim lighting conditions without the use of flash. 600 film and SX-70 film are the same physical size, so a 600 film cartidge will fit in an SX-70 camera.  Polaroid put small tabs on the bottom of the 600 film cartridge to prevent people from accidentally using the wrong film, so those tabs must be removed to insert the pack into the camera.  Alternatively, one can place a playing card or similar under the film pack to aid sliding it into the camera - the card must be removed before closing the camera to allow it to operate. 

The larger problem with using 600 film in an SX-70 is that it has a much faster film speed rating of ISO 640, and the SX-70 cameras were designed to expose for the original film which had an ISO of 125.  What this means is that simply using 600 film in an SX-70 camera will cause the photos to be overexposed.  Fortunately there are ways to make the SX-70 expose 600 film correctly.

Method 1 - Using a Neutral Density (ND) filter over the lens

This is most likely the easiest way to use 600 film in an SX-70 camera.  Polaroid produced a two stop ND filter which can be placed over the lens of your SX-70.  This filter basically acts like sunglasses for the camera, and darkens the image by two stops so that the camera exposure is correct.  These filters are available to order from various vendors through Ebay.  The advantage of using this type of filter is that it is a very simple modification to the camera, as the filter simply sticks on the front of the lens.  The disadvantage to this method is that the viewfinder becomes much darker, making focusing difficult, and making it difficult to see the subject.  Also, the filters are not made of glass, but are made of a thin plastic film which cannot be cleaned, and is not very durable.  Furthermore, placing the plastic filter degrades the quality of the image to some extent.  This method causes the camera to expose at the original ISO 125,  so the benefit of faster exposures from 600 film will not be obtained.

Method 2 - Using an ND filter over the film:

This is a similar approach to method 1, where the exposure is corrected with a 2 stop ND filter.  Unlike method 1, this approach involves placing the filter directly over the film pack, instead of over the lens.  Sheets of ND film can be purchased, cut to the size of the film pack, and taped or glued on top of the film pack prior to loading it in the camera.  The advantage to this method over method 1 is that the viewfinder remains bright, and so focusing and composition is easy.  The disadvantage to this method is that there is still some image degradation resulting from placing a filter over the film.  Also, it is easy to damage the film when sliding the filter into place.   If you do not have the expertise to do this yourself, you can purchase film from a third party manufacturer which already has an ND filter placed over the film.  This third party film is known as "SX-70 Blend" film, and is a ISO 640 film with a filter placed over the pack - it is not manipulatable like the original SX-70 film, and is also very expensive compared to standard 600 film, but is a good alternative if you do not wish to do modifications yourself and can afford the expense of purchasing this film.  

Method 3 - Removing the Electric Eye filter:

This approach is favored by many SX-70 users, since it requires no added filter in the light path of the camera, and is one of the easiest methods to use 600 film in the SX-70.  Be aware, however, that it does not work on all SX-70 cameras.  To use an SX-70 this way requires two steps - the first step is to remove the filter in front of the electric eye on the camera.  This is easily done by prying off the chrome ring which surrounds the filter using a thin pocketknife or similar object.  One the ring is removed, the filter falls out.  The chrome retaining ring can simply be snapped back into place, and the filter should be stored in a safe place in case you ever want to restore the camera to normal.  This procedure is reversible (i.e. not a permanent modification),  and takes only a few minutes to do).  The second step involves setting the camera's exposure control all the way to the "darken" setting whenever taking photos.  Using the camera in this manner will give correct exposures except in very bright sunlight, which may cause the photos to still be slightly overexposed.  You must be aware, also, that the camera resets the exposure control every time the camera is opened, so one must be mindful to set the camera all the way to "darken" every time the camera is opened.  Furthermore, the exposure cannot be darkened if it is too bright, since the camera is already set all the way to the "darken" setting.   This method has the advantage of providing much faster exposures (allowing photographs to be taken in dim lighting conditions without flash), and also does not degrade the image quality with a filter in the lightpath.

Method 4 - Electronically modified cameras:

This is by far the best type way to use 600 film in an SX-70.  The SX-70 camera can have it's circuits modified so that it correctly exposes 600 film normally, and can have it's film chamber modified so that a 600 pack fits without trimming off the tabs.  These modifications are very difficult to perform except by experienced camera technicians, and are beyond the scope of this article.  However, these modified cameras are sometimes offered on Ebay and are very desirable cameras.  If you see one advertised as "modified for 600 film", look closely to make sure that the camera has been electronically modified, and is not simply an SX-70 with an ND filter added onto the lens.   The advantage to this type of camera is that it will expose the film correctly without the use of filters, and the 600 cartridge will fit without having to trim off the tabs.  Full exposure control is retained, and one does not have to worry about forgetting to set the exposure to "darken" each time the camera is opened.  Furthermore, this type of modification allows the camera to benefit from faster exposures, as it causes the camera to function at a true ISO 640 film speed.