Focus shift Nokton 1.1??

[horosu]

I have seen quite a few pictures wide open with this lens, and they seem all fine to me, that is no focus shift at 1.1 and at minimum focus distance. However, since most high-speed lenses tend to exhibit this behavior (think Summilux ASPH and C - Sonnar) , I would like to know if anyone noticed it in their copy of the lens? Could anyone provide pictures through all apertures with this lens, maybe with a setup composed of 3 objects placed in 5 cm distances one from the other and focusing on the one the middle ?

Thank a ton, Horea

 

[john_s]

I left some comments in this thread (post 17):

http://www.rangefinderforum.com/forums/showthread.php?t=76339

 

[horosu]

Thanks for your comment.

However, I feel that we haven't seen conclusive evidence about this focus shift (yet). Anybody willing to test that or shall we continue the happy party about this lens?

Horea

 

[D&A]

HI,

I respond in a more general fashion at this time, since I'm not currently at the computer that has most of my extensive test images with this lens.

I have found on an M8 body (as alluded to in another post) a small amount of focus shift that occurs from stopping down to f1.4 to approx. f4.5-5.6. It's small but noticable if you pixel peep at 100% actual pixels. At f1.1, focusing is quite accurate.. Hope this info helps.

Dave (D&A)

 

[horosu]

Thanks Dave for your info. Greatly appreciated! It is consistent with what I was expecting: high-speed lenses are prone to varying degrees of focus shift. Maybe it just takes some expensive processes (aspherical surfaces, etc) to correct this behaviour. Both the Nokton 50/1.5 and the Summilux ASPH do not exhibit this.

 

[ronazle]

Nokton focus shift

Nokton focus shift

While I did not extensively test this lens, I did carefully test focus at about 3.5 feet. When it arrived I immediately put it on a tripod mounted M8 and shot a DOF scale. Amazingly, at 1.1 the lens was dead on. Mid range and infinity photos seemed sharply in focus. However, it rather severely shifted focus as the aperture size decreased. At f16.0 the focus point of the lens shifted to about (still focused at 3.5 feet on a tripod) 50mm further away.

Depth of field seems to take care of medium to infinity shifts, but who would want the lens for general use anyway? Leica/other CV glass clearly better for general use. Also, equally impressive is the lens resistance to flare. Opinion: this is not a good avaiable light lens, it is a great one!! 🙂 ron