p.1 #2 · 50mm Summilux f1.4 Black Chrome 11688 has a front focus issue
Front focusing is tougher for the user to fix than back focusing. If a lens front focuses, you can usually correct it by adding shims at the mount. But if it back focuses, most Leica M lenses don't have shims you can simply remove, so unless you shave the mount (to reduce distance and fix the front-focusing), the lens has to be opened and the internal rangefinder adjustment located, and every design handles that differently.
Don at DAG can usually take care of it, but in my experience not always. When that happens, Leica is the one who can get it properly dialed in.
p.1 #3 · 50mm Summilux f1.4 Black Chrome 11688 has a front focus issue
Hi Fred
Thanks for your reply
I contacted Don at DAG but he just gave me a bucket full of excuses why you can only have
sharpness at one aperture range in the lens
I thought the new 50 Lux versions with FLE design are made to overcome this problem
as stated by their lens designer Peter Karbe.
Don from DAG was not helpful that much and I think he is not clued up on this design or
some other reason
Oh well
I will just keep looking for someone that will help my lens
p.1 #4 · 50mm Summilux f1.4 Black Chrome 11688 has a front focus issue
That has been my experience too. The Leica 50/1.4 Lux ASPH can absolutely be tuned to hit perfectly at f/1.4. I've owned two black chrome copies in the past, one front focused and the other was spot on, and my current classic Lux ASPH is dead-on wide open. Leica can adjust them, but they do not always get it right. Your best move is to return or sell the copy you have and try another one. If it were back focusing you could fix it with a very thin shim, but front focusing depends on how far off it is.