This is probably the smallest SLR twin rig available.


This setup uses twin Pentax 110 Auto cameras with interchangeable lenses (normal, wide angle, tele).  The camera's are auto exposure, manual focus.  The stereo base is normal. The film is 110 size.

The shutters are synch'd by a sliding square tube/rod assembly with adjustment screws over each shutter button.  This design works well.

Of course, this design is for prints only.  They used to sell slide film for these, but not any more (?).  If they did sell slide film it could be used for Viewmaster format.

The results: Using print film I wasn't very satisfied with the overall print quality, mostly due to the film grain being prominent. It would have been a more satisfying camera rig project in the days of 110 slide film I believe.






















This is two identical Yashica 'A' twin lens reflex cameras permanently fastened together and linked for single knob film advance and single knob focus, as well as linked shutters synchronized for flash.  The stereo base is 3", very near normal.

Focusing is by ground glass in the viewfinder.

It takes two 12 exposure rolls of 120 film, yielding 12 stereo pairs.  The flash is X synch. already built in the cameras.  I use a flash bracket  and handle with two screw knobs to attach to the camera bottoms.  Extra long standoffs are attached to the camera bottoms to allow the camera to sit on a table.

Since the cameras are old, the leatherette on the sides was brittle, and I had to destroy it to remove the side covers.  I made new solid mahogany wood sides.

This is not a weekend project, and presented many challenges.  The following photos show some of the items that have to be addressed to make this a workable camera.  Note that my requirements before I started were to have linked focus and film advance, and a near normal stereo base.

 I had already used these two cameras on a twin bar, where the cameras were not connected.  This produces a hyperstereo setup, and the two focusing adjustments and two film advance knobs made for a miserable time.  It was not a fun setup.  Now that the cameras are connected and linked I am having much more fun.  I especially like the full size ground glass focus system.


This photo shows the film advance and focus knob shaft side of the camera.  The wood cover has been removed.  The camera body is made of die cast aluminum, a very nice product.  The focus knob is attached to the brass shaft shown, which goes all the way through the camera body, guided by brass bushings.  Two cams are attached to the shaft on each side of the camera.  One cam is for the outward focus motion and the other for inward motion.  It is a very positive, zero free play focus system.

The standard film advance is a view through window type, reading the film paper backing for the frame number.

To make this twin camera work I had to figure a way to link the film advance knob to both cameras, and also link the focus knob through both cameras.

The film advance was the first challenge.  Part one of the challenge was to make the knob spring loaded so that the roll of film could be inserted.  The standard knob was fixed to the body, and a spring loaded pin was on the opposite side.  On a twin camera the spring loaded pin has to be eliminated, so the advance knob had to be made spring loaded.   In the photo the new spring loaded knob is in the upper left corner.  You can see the three springs around the three attachment screws.  The springs are from a ballpoint pen, and three new longer metric screws are locktited in place so they won't back out.   The three longer screws work like shoulder bolts, with the spring contained under the heads by washers.  The knob can now be retracted and a roll of film inserted.

The focus attachment was accomplished on the other side of the camera, where they are joined together.  I used a 5/16 hex socket from a ratchet wrench set to bridge the gap between the shafts.  The socket is the same size as the knob hex nut on one camera.  The socket is screwed and epoxied to the other shaft.  When the cameras are moved together for joining the socket engages the hex nut and completes the link.  I used a long set time epoxy to allow me enough time to adjust the infinity focus after joining the cameras together. Once it is adjusted the glue cures, and the socket is permanently set in the correct angular orientation.  There is zero free play in the focus system.


This photo shows the camera backs open and the film advance shown.  On the far right is the spring loaded knob for advancing.  On the far left is the spring loaded pin for inserting one roll of film.

In the center is the link for the two film rolls.  It is attached to one camera body, and passes through a hole in the other.  Both sides of this short shaft have a tab for driving the film spool.



The shaft was made from the left over film advance knob shaft.  One side already had a tab, so the other side of the short shaft was slotted for a new tab.  The photo shows the new slot being cut.  I found that using three Dremel cutting discs together on one mandrel made the correct slot width.   A brass tab was made and pressed and glued into the slot.  This assembly was screwed into one camera body, and the hole enlarged in the other body for pass through.








This photo shows the milling of the body casting where the center film advance shaft passes through.  The casting has to milled down in this area to allow the two camera bodies to fit flush.


To finish the twin rig the two bodies are fastened together by drilling three holes through the sides.  Machine screws and nuts are installed and moderately tightened, so you don't crack the thin wall aluminum casting.  The exposed screws are painted flat black.

One focusing hood and ground glass and mirror is removed, and the hole covered with a wood plate.

Next on the project list for this camera is a magnifying hood to go over the ground glass.  The standard magnifier is a flip up DCX lens and is not shrouded from surrounding light.  A magnifying hood will block out the surrounding light and allow me to put in a much better achromat lens to focus through.

To make the image on the ground glass brighter place a fresnel lens on top of the ground glass.  It makes a big difference.



I've had a lot of fun with this instant stereo setup.  I developed it to sell "holiday" pictures (Santa, Easter Bunny, etc.) , but as usual the public doesn't understand what I'm doing.

This setup is still viable for making money for someone who has the  right business connections in a shopping mall.  The "holiday" picture business is very tough to break into as an individual.

I used a Pentax beamsplitter attached to a converted 108 pack film Polaroid Model 110B camera.  I did the pack film conversion of the camera myself, a real challenging project in itself.  Total investment in camera was $85 (not including splitter of course).

The viewer is a Taylor Merchant print viewer cut and mounted on a folded card.  It folds up flat and stores in an envelope. A mailable viewer and print. Think of the possibilities!

I really like the quality of the image with Polaroid pack film cameras.  This camera has a high quality adjustable lens and takes very crisp pictures.  The film is still easily available.

You can also do this with the cheaper ColorPack cameras that have glass lenses and auto exposure.  I started this way.  I glued a 52mm empty filter ring around the lens, screwed on the beamsplitter, attached two angled mirrors to point the auto exp. eye outwards, and presto.  The cheaper cameras take very sharp pictures too!

The most expensive part of this project is the beamsplitter.  From what I have read , a beamsplitter and viewer were available in the 1950's for the Polaroid camera.  I have never seen one.


This is what happens when you are between projects.  You look at the pile of parts that resulted from stripping cameras for stereo projects and you start to hallucinate.

The rangefinder on the Color Pack Polaroid camera is an excellent design.  I had some of these left over and decided that it was a shame to not do something with it.

Here it is........ the pocket rangefinder.  Just like the expensive accessory rangefinders costing dozens of dollars, this one is just as good.  You just turn the screw until the split images lineup, then read the distance at the tip of the screw........instantly!

COPYRIGHT 2002 by Alan Lewis