Why are Summilux 35mm series 3659XXX so prone to back focus?

[Stephen.s1]

Advertisement (gone after registration)

And is this fixable?   If it is correctable, why was that not done.  Or is it correct for film and not so much digitally?

 

 

[lct]

Back focus i don't know but focus shift is documented on this lens. Rumour says it's been fixed or reduced on the titan version from 1996 but i have no experience with this lens.

[Stephen.s1]

Thanks.  The guy who sold it to me didn't bother giving me that info*.  The lens is on the way back to him.

*Guess I didn't do due diligence. 

Edited April 27, 2024 by Stephen.s1
typo

[250swb]

Focus shift according to the aperture is an inherent characteristic with many lenses, and not just Leica. Given you’ve sent it back within 60 minutes of your first post I’ll put this down to simple buyer regret. But it begs the question why a seller should disclose the inherent characteristics of a lens especially as you are then assuming everybody has specialist knowledge just because they’ve bought it. So if you didn’t know why should the seller?

[dpitt]

AFAIK all Summilux 35 pre-ASPH suffer from some focus issue. Not sure if it can be corrected. I think that if you correct it for one distance and/or aperture, it will be off for another.
At the time a F1.4 lens was at the limits of what was possible for any manufacturer. The 'faults' when used wide open seem to be one of the main selling points for this vintage lens. i.e. the very different character it shows wide open compared to stopped down.

If you want a more technically perfect lens, try a Summilux F1.4 that is designed 20 years later like the ASPH versions, or try an old vintage Summicron 35 F2.0 from the same period. The vintage Summicrons are very consistent in performance from wide open to stopped down.They are also easier to focus and calibrate perfectly on all apertures.

[lct]

The OP's lens is a Summilux 35/1.4 asph. For better results at same focal length and aperture, better choose a Summilux 35/1.4 FLE or perhaps the titan version i was referring to above but i'm not sure about that.

[35photo]

Advertisement (gone after registration)

I had a focusing issue with mine, had DAG look at it, at first he said it was focusing fine but recommended the focus assembly is reworked... Sure enough that did the trick wherever I put the focus at any F stop focus is bang on. I'm very happy with the lens now!

[UliWer]

vor 6 Stunden schrieb lct:

The OP's lens is a Summilux 35/1.4 asph. For better results at same focal length and aperture, better choose a Summilux 35/1.4 FLE or perhaps the titan version i was referring to above but i'm not sure about that.

Good that you mention which lens belongs to „a series 3659xxx“.

Has there ever been a titan version of the Summilux asph? And even if such a lens was ever produced it never would have changed anything about the focus shift of this lens. Since focus shift is inherent to - guess what - glass. It is just the spherical form of optical glass projecting light on a plain surface which causes focus shift and it is never the material of the lenses housing, whatever the material might be.

That’s the reason Leica changed the optical design of the 35mm Summilux asph with the so called „FLE“ version in order to control focus shift better than before.

Since the time of the „old“ 35mm Summilux asph this forum is full of talk about focus shift, and most of it is just nonsense. Though even in 2010  - before the FLE version came to the market - there was an explanation in this forum which explains it all:

I often wish people would take more notice of the - rare - good parts of this forum. 

[lct]

1 hour ago, UliWer said:

Has there ever been a titan version of the Summilux asph? And even if such a lens was ever produced it never would have changed anything about the focus shift of this lens [...]

Looks like that and a reviewer found different results actually but as i said above i have no experience with this lens. For those reading French, see http://tinyurl.com/6bjmngt

 

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!