lens adjustment - call for help (Brian are you there?))

[menos I M6]

Advertisement (gone after registration)

I use mainly 4 Leica M lenses on my M8.2:

 

50 Lux ASPH,

35 Cron ASPH,

90 Elmarit (latest),

28 Cron ASPH

 

I was never really satisfied with either the 50 Lux or the 28 ASPH, as normally both should deliver unreasonably sharp focus, when everything is properly adjusted

 

I therefore conducted a test at infinity, 1m and a sort of close range distance.

 

All 4 lenses behave differently, as listed in proper order above.

The 50 Lux cannot reach rangefinder alignment at infinity, while the 28 Cron overshoots the rangefinder alignment slightly at infinity.

The 35 Cron and 90 Elmarit lay in between.

 

In close focus range the 50mm does backfocus by 4 cm.

The 28mm does front focus by 5cm.

Other lenses lay in between.

 

As I see see the misalignment carefully documented for each lens now, I will have to:

 

1) Adjust infinity perfectly for the 50 Lux.

2) Adjust close focus correction for the 50 Lux

3) Shim the 35 (if necessary at all, regarding the small difference to the 50mm)

4) Shim the 90 slighly.

5) Shim the 28 the most of the 3 lenses.

 

For now (until I find the right material for shimming), I adjusted the 90 Elmarit for spot on infinity and compensate for a slight front focussing (about 1 1/2 cm @ 1m).

 

I use the 50 Lux on the R-D1, which I have matched for it.

 

All other focus errors for now do fall into the ignorable category, hidden within DOF, sharpening, printing.

Now here is the question (Brian Sweeney - are you reading ? ):

 

Do I have any failure in my concept regarding needed shimming?

Do you use a specific approach in which setting to start from?

Any failures, you experienced, which I should prevent?

 

 

Please no "send the stuff to Leica, let professional service personal conduct the work, …" comments. I am fully aware, of what I am going to do.

 

This is the first approach of work inside a lens, other than degreasing aperture blades, cleaning lenses, etc. for me.

 

I post this openly, as I think, other people could benefit from the exchanged information.

Should this exchange of information conflict with forum rules or principles here on the board, I respectfully wish, to be informed and will alter the thread accordingly.

 

Thanks - and hope, you had a Happy Easter all!

[k-hawinkler]

Many thanks for your refreshingly honest post.

 

K-H.

[treeplanter]

Now here is the question (Brian Sweeney - are you reading ?[/b]

 

Don't believe Sweeney's on LUF. Try RFF, he does hang out there.

 

Jim B.

[menos I M6]

Don't believe Sweeney's on LUF. Try RFF, he does hang out there.

 

Jim B.

 

Thanks for the tip Jim!

I posted the above questions at RFF now here and will try to give a heads up, when work moves on:

 

http://www.rangefinderforum.com/forums/showthread.php?p=1298523#post1298523