TLDR; The objective of this project was to construct a basic camera lens from recovered lens elements from some wide angle lens converters. I designed and 3D printed the housing for the lens elements so that it is compatible with the Nikon F mount. I was able to take photos with it on my Z6 but photos turn out with awful aberrations. It was still great practice in design and multi part assembles but the optics are not great as can be seen in the sample photos at the end of this article.
Going into this experiment I had some experience with how lenses were assembled from restoring a few that had bad mold in them. I wanted to expand on that by trying to build a basic lens assembly from some lenses I had scavenged. As this was my first time working with optics in a project like this, I was not targeting a specific focal length or minimum focus distance with the optics just working with what I had. For this project I determined the opportunities to solve were the optics, how to mount the assembly to the camera, and the focusing mechanism.
For the optics it would be simpler to use a single element but I did not have any that would reach the 46.5mm back focal distance that my Nikon F mounts use. I found that I had a pair of lenses that worked together from a wide angle converted so I proceeded with those. For the aperture I decided to keep it simple and just place it in front of the lens elements. The aperture would typically be between elements but this added complexity so I opted for the front. I built a test rig to get rough measurements on the distances I would need the lenses to travel for focusing.
Test rig made from an SLR mechanism from a broken Nikon film camera and printed parts
It was clear to me that trying to 3D print the F mount connector would be overly complex. I opted to reuse an existing mount that I scavenged from an old teleconverter. With the mount connector simplified, I designed a part that would join the F mount connector, Back element, and the focusing assembly.
Most manual focus lens, that I have worked on, have a focus helicoid that allows for precise and smooth focusing. The helicoid is composed of two threaded components that are lubricated and threaded together to provide lateral movement with radial motion. This means that the threads must be smooth and machined/cast to tight tolerances. I have not yet solved how to accomplish this with a 3D print. To move past the complexity, I decided on a push pull design for focusing to keep this prototype moving. I used 3 metal rods to reduce the friction between the inner and outer plastic barrels so that the focusing lens can slide in and out. This “works” for testing but would cause missed shots every time in the real world.
Lens mounted to a N2020
Unmounted lens
Lens with fully extended focus
Lens with aperture discs
Lens with front removed
Disassembled lens showing rods and both lens elements
The assembled lens is less than exceptional optically and is difficult to focus but it was cool for me when I mounted it to my camera and it worked to an extent. I will need to work on designing a solution for or using something to replicate the way a helicoid functions to achieve small movements in the focusing element. Multi element lens are complex mechanisms and I need to continue to learn more for my next lens.
All this to say this is just my first attempt and I plan to continue working on refining the design and optic pairing. Below are some of the test shots using the lens on my Z6. The clear shots are with a very small aperture so the ISO is quite high. There are also a few out of focus shots that were shot using the aperture resembling a triforce from the photo set above. I wrote this to communicate that along the path to creating something new there are failures and unexpected outcomes. Those set backs are not a reason to stop creating but more of a reason to keep learning and keep creating. Thank you for reading and good luck with what ever you are creating!
Wide open aperture - Shot with lens on Z6
Closed down aperture - Shot with lens on Z6
Closed down with better lighting - Shot with lens on Z6
Olivia out of focus(Cat) - Shot with lens on Z6
Generative Space Invader Out of Focus with triforce aperture - Shot with lens on Z6
