Hacking a Vintage Lens
Can I hack an old film-camera lens using 3D printing, to mount it on a modern digital camera?
My dad’s Pentax K1000, a 35mm SLR released 40 years ago, was gathering dust in a shelf. I used to love the pictures he had clicked with it!
Pentax K1000 with a 50 mm prime lens.
That’s me, in 1997, clicked by the Pentax camera.
Unsurprisingly, I also got into photography, and in my sophomore year of college, I was able to buy my first Digital SLR, a Nikon D5300. Coincidentally, right around that time I also got access to a 3D printer for the first time—so it is not hard to connect the dots on why I decided to take on this challenge of reviving the 50mm Pentax prime lens
First, I noticed the lens had dirt and humidity inside it which could not be wiped from the outside, so decided to open it up. There were five lens elements inside it, assembled with perfection! Thankfully, I could clean up the dirt that was on one of the inner elements and everything fit right back in.
All the lens elements laid down to be cleaned.
The steel ring is the K mount adapter
Now, the steel ring was the K mount adapter, and this was the part that needed to be replaced by a 3D-printed F mount adapter.
Challenges:
I could not find CAD files of mounts online
This meant spending a lot of time in carefully measuring the mount dimensions with callipers.
Different Flange Distances
“Flange Distance” for a camera is the distance between the flange of the lens mount and the camera sensor—not maintaining this distance would mean out of focus pictures. Now, K mount’s flange distance is ~1 mm less than F mount’s. Since the flange distance follows the lens, this means that I had to design the mount such that the lens gets pushed in 1 mm more into the Nikon body, compared to its original Pentax body. This meant carefully trimming the mount features so that the mount mechanism lowers down by 1 mm. This was much trickier than had it been the other way around, where the flange distance was 1 mm more than normal, where I would just have to design the mount thicker.
Result
I used ABS filament on an FDM printer to print this hoping it would be a bit stronger, but it would be totally fine with PETG or even PLA. Surprisingly, it fit perfectly on the first try—measure twice print once!
3D printed F mount Adapter
Old lens, new camera!
My friends were kind enough to use them as test subjects, and here are the unedited shots. There’s always something magical about making old technology work! 😊
