￼3D Printed Panoramic 6×14 Camera
Camera Geekery: ￼3D Printed Panoramic 6×14 Camera
I was hoping to have this up a bit sooner, but it has been rather busy at JCH HQ lately. John Kossik returns to us, this time with a fantastic piece on how he has engineered a 3D printed 6×14 camera. And he shows us how you can make one too!
A panoramic, medium format, 6×14 film camera the weights only 1.625 lbs (737 grams)! Can it be true? Yes it can with compact 50+ year old wide angle large format lens and a 3D printer.
The initial goal was a lightweight medium format camera that I could take up on mountain hikes here in Washington State to capture the tremendous panoramas available. Sure you could paste together panoramas from your digital camera and yes I have done this in the past, but I have found that medium format film has the added resolution that simply does justice to the beauty of the mountains. I have lugged my Mamiya RB67 up in the mountains as the resolution of that camera is tough to beat, but this is a very heavy camera that takes up significant room in your pack and the 6×7 format still would require either significant cropping of stitching of images to produce the panoramic feel.
Another option is my Agfa Record III as it is very light and compact and has a nice 6×9 format. Unfortunately, the 105 mm lens (45 mm equivalent for a 35mm camera) and 51 degrees of coverage really does not make it a panorama. Couple this with the fact that the Record III’s lens though sharp is not as sharp as the RB67 and there was room for a new image capturing device in my camera bag.
Seeing that even the lenses on old folding cameras would not cover the 6×14 or 6×17 format I was looking for I started looking for some compact large format lenses to fill this task. I settled on a 3in. Goerz Rectagon I got off Craigslist. This lens will give me a 90 degree field of view at 6×14 format and a whopping 100 degree field of view at 6×17 format, perfect for those wonderful mountain-top panoramas.
But how to house this lens? As you know there are Houseman and Linhof of this type but these cost upwards of $7000 and weigh significantly more. There are also used Fujifilm G617 and number of cameras from China that are cheaper but still run in the $1000’s and are are heavy. A 3D printed housing has the advantage of having minimal infill (something far more difficult when injection molding) so that the weight of the camera can be low. One very good DYI panoramic camera design can be found at: http://www.instructables.com/id/DIY-6×17-Panoramic-Film-Camera/. This design by mattthegamer463 is a very good starting point.
The main difference in my design was that it is made of 3D printed plastic and the film advance design is reversed so as to be more like that on my RB67 providing a better opportunity to keep the film perfectly flat.
￼￼The initial design done in OpenSCAD (http://www.openscad.org/) is shown above. The final design ending up being slightly different but the basic parts are the same.
Starting from the back left hand side you have:
1 The film back with winding knob.
2 The film pressure plate
3 Light seal
4 Front bellows (lens to film plane distance fixed at infinity focus)
LENS TO FILM DISTANCE
Since this camera will be used for landscape panoramas the lens to film focus distance will be set to infinity, but how to determine this value for an old lens with no documentation available on the web and no access to a large format camera assembly? What I do have though is a Nikon DSLR and some extension tubes. I 3D printed an adapter to go from the DSLR to the large format lens. Using that with the extension tubes and some circular shims I was able to ￼take images at various lens to image plane distances.
￼￼The images below are the results at different flange back distances viewed at 100%.
￼As you can see somewhere between 71.28 mm to 72.36 mm gives the sharpest image of the tree at infinity. Taking the average this gives us 72.22 mm which is the value we will design the bellows for in our 3D printed model. One great advantage of 3D printing is that the resolution of many printers can go down to 50 micron or 0.05 mm. I personally have my printer set at a resolution of 200 micron or 0.2 mm as this is standard for reasonable printing speeds.
Of course plastics change dimension with temperature and might warp slightly so the final print will most likely not have a 0.2 mm accuracy, but it should be within 0.5 mm. This is far better than I could do in my shop using metal and wood and hand tools.
Surprisingly, the sharpness at this flange back distance and this lens is almost the same as when I mount my Nikkor 70-200 f2.8 on this camera.
Now we move onto the film back. The design here was generally based on the film backs on my RB67. In this case the spools are mounted behind the film plane instead of in front of it as in typical medium format folding cameras and traditional SLRs. This configuration gives a better chance of getting a perfectly flat film plane as you are pulling the film back against the Backing Plate instead of away from it.
The OpenSCAD images and image of the start of the 3D print of this film back are shown below. Note that the film back takes up the whole printing area of my MakerFarm Prusa 8″ i3v (http://www.makerfarm.com/index.php/prusa-8-i3v-kit-v-slot-extrusion.html). For this reason I had to settle for a 6×14 image format as a back that could cover 6×17 simply would not fit on my printer. This is fine though as the 3in. Goerz Rectagon probably could not cover the whole 6×17 format anyway.
￼￼Because of the constraints of printing “bridges” (printing in thin air between two points) inherent with 3D printing a model of this configuration and the need for accuracy in some areas, I split this print into a top and bottom half. This allowed me to add straightening rods on each end of the film back to assist with the spooling and travel of the film. To make sure that the two halves lined up perfectly I added reinforcement fiberglass rods in the body. These rods are really not needed for strength as the PLA this is printed out of is very strong, it is mainly needed to ensure that the two halves lined up perfectly.
￼￼Now the holders for the spools need to be added. For the top on the undeveloped side a simple male spool holder was printed right into the film back. On the take-up spool side a knob with a spindle through the top of the film back was printed with the appropriate male “key” at the end. For the bottom of the spool holders I initially envisioned a traditional spring mechanism but this proved problematic. Instead I just used a nylon bolt with a hex-head nut screwed into it. The hex-head being chosen to fit a typical spool hole. A nut trap was printed into the bottom of the film back to accept the nut for this bolt and thus allow it to be moved up and down.
All these connections were made with simply SuperGlue which is more than adequate for PLA. Matter of fact if a primer is used prior to gluing the joint is far stronger than the layer to layer adhesion of the printed PLA.
￼￼Now there is just a few finishing touches for the film back. First the viewing window in the back was covered with some red plastic (formed out of a file folder label). This was then covered with a thin pad of closed cell foam from the craft store. On top of this was attached with double-sided tape a 3D printed pressure plate. This pressure plate was printed such that the side to face the back of the film was perfectly flat. To finish the interior of the back treaded inserts were screwed and glued into the holes in the film back and then short treaded rods were screwed in and glued in place. These will be used to secure the film back to the bellows front of the camera.
Turning the film back over printed clips were installed so that a cover could be inserted over the frame viewing window when not in use and to hold paper denoting the film type currently in the camera.
With the film back complete now it was time for the printing of the front bellows and lens mount. In a like manner as with the film back the front bellows was designed in OpenSCAD in two parts.
￼￼After printing these two halves were SuperGlued together using fiberglass rods to ensure that the alignment was correct.
￼￼To complete the bellows assembly light seals were added. These were glued into a slot in the bellows. When the bellows is clamped to the film back these seals nest into slots in this back to form a convoluted path to keep out light leaks.
Film guide rails were printed into the bellows to hold the film as flat as possible. The distance between these film rails and the outer front of the bellows formed the flange back distance determined earlier as 72.22 mm . This configuration allows the flange back distance to only be dependent on the bellows print and thus independent of the film back. After all this was done the inside of the bellows was spray painted flat black to minimize any light reflection during exposure.
Now that the body is complete the 3in. Goerz Rectagon can be mounted in the hole provided for it in the front of the bellows using a simple retaining ring. The bellows can then be attached to the film back by inserting the threaded rods through the holes in the bellows and securing the two together using 5 Brass Knurled Nuts. To finish the assembly a simple viewfinder is printed up with a 90 degree field of view and mounted the top of the film back. A clip is also printed to hold a release cable attached to the 3in. Goerz Rectagon lens so that the whole camera can be hand-held like a traditional SLR.
￼￼I also added film tighteners on the take-up spool and the supply-spool.
After a few tries I finally found some spring steel that could be bent but still had enough strength to bounce back to its original shape under the pressure of the widening roll on the take-up spool. A tightener was also installed on the supply-spool side though I do not think that is as critical.
The first two rolls of film through this camera were a disaster with completely fogged images. This was due to the fact that the black 3D printed camera body was simply not opaque enough.
￼￼To solve this problem I used some High Build (high solids content) Auto Primer. There are some speciality ones that are probably better than what I used but they are difficult to purchase locally so I settled on Filler Primer from Rust-oleum because it was easily available at Home Depot. After 7 to 8 coats, I lost count, I tested it with a flashlight and it passed. So far so good.
I then added a few coats of flat black inside and out. Eventually I will probably add some leatherette to cover some of the seams and make it look nicer.
￼￼FINALLY SOME IMAGES
With the fogging problem finally solved I was able to get some images as seen below. The first image was taken from a Washington State Ferry leaving Friday Harbor, WA imaged at 1/400 sec and ~f19. At this high of a shutter speed I was hoping for a little sharper tree line but I was on a moving ferry after all. The vignetting at the corners is also noticeable but to be expected.
￼￼The second image, at least to me, could stand some improvement. This is taken at the top of the Heybrook Fire Lookout just outside of Index, WA. The image was captured at 1/100 sec and f11. At 100% the softness of this image is obvious.
I attribute this to three items; (1) hand- holding this camera at 1/100 sec, (2) an f-stop of f11, which subsequent tests have shown this lens to be soft at, (3) a flange back distance that is not optimized. The incorrect flange back distance is the biggest problem as this intensifies the softness at f11.
First and foremost the flange back distance of this camera body needs to be optimized. Further tests showed that I need to add about 0.5 mm to 1 mm to this distance. This can easily ￼be done (probably before this article is even published) using some circular shims created on the 3D printer. Lucky I needed to add distance instead of take it away as that would involve printing a whole new bellows section. Then again in the initial design the bellows was slightly on the short side for just this purpose. In addition to this I will probably stick with a tripod while using this camera and keep the f-stop no lower than f16.
If anyone is interested in the 3D files for this project they can be found at http:// www.thingiverse.com/thing:1721178. I have included the OpenSCAD files along with the STLs to allow users to manipulate them as they need to especially to accommodate the different large format lenses that will obviously require different flange back distances.
The files may not be totally complete as this was and is a work in progress, but if you are a 3D printer you know quite well what I am talking about and would know how to modify them for your personal requirements.
John Kossik (firstname.lastname@example.org) graduated in 1983 with a degree in Chemical Engineering from Michigan State University, he currently works for Beacon Engineers, Inc. (www.beaconengr.com) a small industrial engineering firm in Bothell, WA, USA and is co-founder of Steadfast Equipment (www.steadfastequipment.com). Some of his images can be found at http://63alfred.smugmug.com/. You can also see John’s other articles on JCH by clicking here.
Thanks to John for taking the time to put this process together. The sheer ingenuity and passion that you see in projects like these is inspiring. Excellent work.