Nokton 50/1.1 on the Leica M8- test photos.

Sonnar Brian

Sonnar Brian

Product of the Fifties
Staff member
Local time
11:28 PM
Joined
Jan 12, 2004
Messages
19,780
View My Gallery
Okay, I generally buy old lenses. Broke that rule and bought the Nokton 50/1.1 and Ultron 35/1.2. Given the prices of other super-speed optics for the M-Mount, these lenses are "enticing".

Got them in, did some quick tests on the M8. Both back-focussed. Fixed the back-focus with two layers of copper tape, 0.05mm thickness.

After reading this note on Tony Rose's site, it makes sense:

http://www.popflash.com/zeiss-lenses/zeiss-50mm-f/1.5-zm-c-sonnar-t-lens-black-usa-new/

Manufacturers have to make certain assumptions regarding film flatness and other factors. And with Digital Sensors, microlenses, Mosaic Filters, sensor elements, lions, tigers, and bears, hard to get things down to 0.01mm.

From the first walk with the Nokton, usual test patterns.

Wide-Open at F1.1, minimum Focus. Leica M8 with 1.25x magnifier.



100% crop:


F4:
\

Tight Crop:


SO: significantly sharper, and significant focus shift. About like an F1.5 Sonnar.
 
Flare test, Hot Mirror Filter used, lens is in sunlight for this shot.

F1.1


At F4:


Distance test, at F1.1:



Tight Crop, 100%
 
19th Century Gravestone, in the neighborhood.

At F1.1:


At F4:


At some point, I'll check out the Canon 50/0.95 on the Canon 7 vs this lens. This lens is much sharper wide open. It is about 1/2 the weight. And these days, a Bargain price compared with what the 50/0.95's are going for.

One quick observation: The performance of this lens really improves a bit farther out from Minimum Focus. Lenses are optimized for distance. "Speculation", choice for 3ft minimum focus may have been partially due to this.
 
Last edited:
In the first 4 shots, the focus is on the leading edge where the fence slat is nailed into the post. The image at F1.1 is within my tolerance for focus. The same point is used for F4, and the focus shift of the lens looks to be slightly over 1". This amount of shift is about the same as in a pre-war Sonnar going from F1.5 to F4. So: using at F4, focus slightly in front of the desired point.
 
Last edited:
All of these shots are after adding 0.05mm thickness of copper tape to the RF Cam. Before doing so, the focus at F1.1 was about 1" behind the RF. So- the shot at F1.1 as shown is as close as I can get with the M8 finder and 1.25x finder. I used the same arrangement for the Canon 50/1.2. The Nokton is substantially sharper than the Canon 50/1.2 wide-open. I could add another layer of tape to the cam, so that it was optimized for F2.8 or so: but I go for close-up and wide-open.

On the tall grass, the focus is on the grain dead center- coming from the stalk. I was happy with the focus. On the headstone, focus is on the letter "D".
 
Last edited:
Pine Needles, F1.1:


100% crop:


focus is dead center, right where I put it. The resolution is high enough to introduce some aliasing artifacts.

At F4:


100% crop:

Focus shifts backwards again, but with a 3D subject: just focus a little bit on the near side. Tip of a nose to get eyes in sharpest focus at F4.
 
Brian,
thx for the test comparisons and info about the copper tape and how to correct the back focus problem. I still dont fully understand how it all works, or how to correct it myself, but I would have to do a more thorough search of how to DIY this at home.

But since the Leica lenses, and especially the Lux's, have jumped in price seemingly overnight, I think many of us may have a renewed interest in the CV 35/50 Noktons.

But to clarify: if the Nokton back-focusses out of the box at f1.1, does that presume that the focus @ f4 or greater would NOT have focus issues?
Or: if the focus is optimized @ f2.8, how does that affect f1.1 focus? or f4 or greater focus?
 
Last edited:
1) Actual focus shifts back to infinity as you stop down. So if F1.1 focuses behind the RF, F4 wil be worse.

2) Lens manufacturers make assumptions about their cameras when making lenses- one is film flatness in the camera, which applies to Voigtlander and Zeiss cameras, but not to the M8 and M9.

3) Building up the RF cam has the same effect as thickening the Shim of the lens.
 
You must log in or register to reply here.
Back
Top Bottom