Nikonos RS 13mm Sony Conversion I have developed a procedure for converting the legendary Nikonos RS 13mm (the sharpest underwater wide angle lens) to modern Sony E mount. This is achieved by removing the optical elements from a Sony 50mm f/1.8 donor lens and replacing them with those from the 13mm. After the conversion, the lens has native Sony autofocus and aperture, but with the optics of the 13mm. It is also possible to use the converted lens on Nikon Z cameras with the Megadap Sony E to Nikon Z adapter. The converted lens is a full native Sony E mount lens without the glitches that can sometimes affect adapted lenses (other than recording as a 50mm lens in the metadata). It has a larger maximum aperture of f/1.8 compared to the f/2.8 of the stock lens. It can also focus closer than the stock lens (basically to the dome). Autofocus speed is fast and accurate in AF-C mode (it is a little slower in AF-S mode). For the port, I separate the 13mm dome from the rest of the lens and install it on a port I 3D print in PETG plastic. I pressure test the port to 100m/330ft. I am currently producing ports for Nauticam (N100 and N120), Marelux, and Isotta. In the future, I will likely add ports for Seacam, Ikelite, and perhaps others. Additionally, I have developed a CRC (close range correction) system that can be used to significantly improve edge sharpness over the stock lens when shooting at close distances (closer than 12in/30cm). It includes a dial that can be set to the approximate shooting distance to optimize sharpness for that distance. A gear can be used to adjust the CRC setting while in the water. For those who only shoot large subjects or do not want to deal with the added complexity of the CRC system, there is the option to leave it off. The conversion fee is $1000 USD (or $750 if you only want me to convert the inner lens and get the port made elsewhere). Adding the CRC system is an additional $100. There is also the cost of the Sony 50mm f/1.8 donor lens (~$200), which I am happy to source if the customer desires. I also ask that the customer cover the cost of return shipping and any customs fees, if applicable. I am located in Harrison, Arkansas, USA. Feel free to send me an email if you have any questions or are interested in ordering a conversion.