Hello and thank you again Claire,
Yeah! you nailed it! Once manually focused, it keep the focus all the way (incredible!). I will need some years to understand how it does the trick, but it does it! .
I didn't knew that L900 were from the 70's it looks like a little bit more modern... It seems so strong and professional... compared with my former Krokus Mini M enlarger...
Your memory works fine! I just don't want to bother you with such enlarger questions... but... thank you again!