Depth of M42-Fuji mount adaptors compared to other brands

[Christ the Merciless]

Hello,

I am currently adapting a Konica Hexanon 45mm f1.8 to Fuji X mount and the final piece in the process is obviously the adaptor to the X mount. The one tutorial video on YouTube about adapting the Hexanon 45mm https://www.youtube.com/watch?v=__alAfOcMs4 is to adapt to a Sony NEX and advises on using M53-M42 ring superglued to the back of the lens, an M42-M42 12-17mm helicoid, and then a 1mm M42 to NEX adaptor on the helicoid. I'm following all of this up to the last part, obviously. But when browsing M42-Fuji X adaptors, I find that they are all a lot deeper than 1 or 2mm, while M42 to other brand mounts can be that slim.

So my question is whether there is a technical reason for Fuji X mount adaptors being longer than other brands?

Thanks.

[BobJ]

The distance between the sensor and the lens flange is different for each make of mirrorless camera.