The Yashica or Takashi FX-521 camera is marketed as the digital Holga. Basically it is a cheap plastic retro-styled fixed focus camera with a crappy slow 5MP sensor.
I want to modify the camera to take C-mount or CS-mount lenses. These lenses are very cheap and normally used in CCTV cameras. This is especially valid for the CS-mount lenses.
CS-mount lenses normal come with an adapter ring to be able to focus them on C-mount camera systems. I used such a ring to create a the camera mount. I used plastic glue to fixate the adapter ring on the sensor. The adaptor ring can be positioned straight on the lens housing. This creates enough distance to focus to eternity.
After testing that everything works as should I applied some black paint on the inside of the adaptor ring and the glue to create a light tight seal (not picutured).
The picture below shows the camera with a cheap Chinese 12mm f1.2 CCTV lens.
The mod works surprisingly well. The camera now has manual-focus and depending on the CCTV lens used you now have some sort of depth of field available. The only drawback is that the infrared blocking filter was on the lens so that is now gone. This means that colors are quite off. A future mod would be to install an IR blocking filter, but first to acquire one...
Below are some sample pics taken with this cam: