Aspheron????

[tecflms]

On the bolex 12.5-100mm lens what does the Aspheron button do and mean????

[Sam Wells]

It lets you reset the backfocus of the lens (essentially putting it in macro mode) for use with the Bolex Aspheron adaptor (a focal length converter using aspherical optics) on the front of the zoom which gives you a focal length of about 6.5mm

 

Actually you can get intermediate focal lengths by going part way on that ring, but you must carefully judge your back focus by eye, and you can't do a zoom in that mode

 

-Sam