M9 & Zeiss ZM Lens Focus Error?

[Keith (M)]

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Before I took the plunge into the world of Leica late last year, I did quite an amount of research and reading. One article I came across made extensive comparisons and tests between the ZM 50mm f2 Planar / Summicron 50mm and the ZM 35mm f2 Biogon / Summicron 35mm. In both cases the Zeiss lenses were given glowing reports. Partly on that basis, partly on reading users first-hand experiences and on other reports, I bought both Zeiss lenses and have been delighted with the results.

 

So what, I hear you ask. Well, I have just come across another test which describes finding that both the ZM 50mm f2 Planar and the ZM 35mm f2 Biogon badly front-focused on an M9.

 

Hmmm, can't say as I have ever noticed either of mine front (or rear) focusing, but I have just run a quick test. To set the scene, in all images the point of focus is on the right shoulder of the pear. The images are:-

 

 

1. 75mm Summarit at f2.5, uncropped (for comparison)
   
2. ZM 50mm Planar @ f2, uncropped
   
3. 100% crop of the 50mm @ f2
   
4. 100% crop of the ZM 35mm Biogon @ f2
   

 

Looking at the results, I cannot see any particular evidence of front (or rear) focus error, so I wonder if other ZM owners have had any experiences of focus error?

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Not long ago I decided to try the 35 f2.8 ZM and had good results, but the nagging feeling persisted that i should have spent more on a 35 Summarit. And first comparisons suggested I should keep the Leica lens. Having sold the Zeiss I now think that was a mistake, and that although the ergonomics etc of the Summarit are preferable, in fact resolution with the Zeiss was very marginally superior. Both are of course virtually flare free, and the performance of the cheaper Zeiss is everything declared in Sean Reid's comparative testing. Colour rendering indistinguishable.

[John Ricard]

35mm Zeiss F2.8 ZM - best 35mm lens from any manufacturer that I have ever used. If you don't want F2 then this lens is awesome.

 

Isn't the Zeiss 35mm an F2 lens, and not F2.8?

 

And, as I indicated (with photos) in a thread on this board titled, "Is this acceptable sharpness for Zeiss 35mm lens", my Zeiss 35mm wasn't sharp at F2. It was great at F2.8 however. I sold the lens and I am now using the Summicroin 35mm, which is sharp at F2.

[MarkP]

Note this comment in the Popflash Photo info regarding the 1.5/50 C Sonnar ZM:

 

all production since 1997 is focus optimized at f/1.5 for film based cameras to a FFD distance at 27.86mm.

 

this adjustment works well for film based cameras, but causes a noticeable shift on digital rangefinder cameras - since their FFD is longer than film-based M-mount cameras (basically they do not meet the standard M-mount spec). When the optimized lenses are tested with digital rangefinder cameras at a close focus distance of 0.9m and at f/1.5, they front focus by about 2cm

 

because of the differences between film and digital rangefinder cameras - which we cannot control - it is impossible to have a focus optimized C Sonnar for both systems.

 

for customers who want their lens adjusted for digital rangefinder cameras, Zeiss Germany have set the FFD to a distance of 27.90. This provides good results on digital cameras, but will cause a focus shift on film cameras for the reasons mentioned above

 

If an individual customer wishes to have their C Sonnar optimized for use with a digital camera, the customer can send the lens into Zeiss Germany for adjustment.

 

I wonder whether this may apply to a lesser extent to the lenses discussed above.

 

Mark

[lars_bergquist]

Mis-adjustment can occur with any lens. No production process is faultless. I use two ZM lenses. An early 18mm arrived with a mis-focusing of several meters! Zeiss themselves fixed this in no time on the warranty. My 25mm is perfect. I have also had a mis-focusing 90mm Elmarit-M. I still have it, but it's not mis-focusing anymore.

 

I would suspect either the reviewer's camera, or the reviewer ...

 

The old man from the Age of Scale Focusing

[lars_bergquist]

No Zeiss make two 35mm lenses - the Biogon F2 and the Biogon C 35mm F2.8. The 35 F2.8 is a superb lens. Don't swallow the old myth that just because a lens has a sexy wide aperture it is automatically a great lens.

 

Right – like half a century ago, the 35mm Summaron 1:2.8 versus the Summicron 1:2. Guess which one got the headlines? Guess which is the 'cult lens' even today? But the Summaron was better even at 1:4.

 

The old man from the Age of the Meniscus Lens

[Xmas]

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Right – like half a century ago, the 35mm Summaron 1:2.8 versus the Summicron 1:2. Guess which one got the headlines? Guess which is the 'cult lens' even today? But the Summaron was better even at 1:4.

 

The old man from the Age of the Meniscus Lens

 

Hi Lars

 

The summaron was better when both lenses were at f/2.8...

But the my lens is bigger and more expensive than yours school won out.

tusk tusk.

 

Noel

[glenerrolrd]

Keith

 

Your example shows “mild” front focus . I don t remember the exact ratio ..but starting at the absolute plan of focus ....DOF should be slightly greater ..behind the pear than in front (say 60/40) . (it varies by focal length).

 

First test ..which is sharper ..apple in front or behind the pear ? Looks like the apple in front. Second test ..what area is sharp on the wood ....all in front of the pear none behind (yes angle affects this so most should be in front but not all.

 

If you did a ruler test ..bet you would find a slight front focus bias. Looks small at table top distance ..but how about at 2M,7M and infinity?

 

The best fast test for front/back focus is shot at 2M . I draw a chart on a white board like this &--&--&--&--&. (actual size is about 18inches). Focus on the middle but look at the front and rear & s. Shoot and refocus 6 image and view on your MacBook. This is one of the tests thats done at Leica NJ and one they use for a quick reference. They have a printed chart about 3 feet wide (you can find it on one of my old posts) . Be sure to inspect the images on your computer as you can easily see the start and end of the zone of focus . Sharp on the screen doesn t mean its in the middle of the zone.

 

The Zeiss glass is calibrated for “Film” ...Diglloyd confirmed this directly with Zeiss. It is very close but not perfect. He has a review site and specializes in Zeiss reviews.

 

I got around this by having my zeiss lenses 6 bit coded and calibrated thru an independent Leica repair business.

 

Achieving perfection especially with the wide angles can be frustrating,expensive and generally not worth it . I wouldn t touch your lenses or that body unless a distance test shows an issue.

 

 

 

 

 

 

 

 

 

 

 

Before I took the plunge into the world of Leica late last year, I did quite an amount of research and reading. One article I came across made extensive comparisons and tests between the ZM 50mm f2 Planar / Summicron 50mm and the ZM 35mm f2 Biogon / Summicron 35mm. In both cases the Zeiss lenses were given glowing reports. Partly on that basis, partly on reading users first-hand experiences and on other reports, I bought both Zeiss lenses and have been delighted with the results.

 

So what, I hear you ask. Well, I have just come across another test which describes finding that both the ZM 50mm f2 Planar and the ZM 35mm f2 Biogon badly front-focused on an M9.

 

Hmmm, can't say as I have ever noticed either of mine front (or rear) focusing, but I have just run a quick test. To set the scene, in all images the point of focus is on the right shoulder of the pear. The images are:-

 

 

1. 75mm Summarit at f2.5, uncropped (for comparison)
   
2. ZM 50mm Planar @ f2, uncropped
   
3. 100% crop of the 50mm @ f2
   
4. 100% crop of the ZM 35mm Biogon @ f2
   

 

Looking at the results, I cannot see any particular evidence of front (or rear) focus error, so I wonder if other ZM owners have had any experiences of focus error?

[Viv]

I have three Zeiss and one Leica lens.

 

No focus error with any of 'em on my battered M9.

[Keith (M)]

Keith

 

The Zeiss glass is calibrated for “Film” ...Diglloyd confirmed this directly with Zeiss. It is very close but not perfect. He has a review site and specializes in Zeiss reviews.

 

I got around this by having my zeiss lenses 6 bit coded and calibrated thru an independent Leica repair business.

 

Achieving perfection especially with the wide angles can be frustrating,expensive and generally not worth it . I wouldn t touch your lenses or that body unless a distance test shows an issue.

 

Thanks for the comprehensive reply. I subscribe to the DigLloyd site and it was reading his latest report that triggered my test. Due to it being a subscription site I cannot quote his results but one has to wonder at the size of the reported errors. My lenses are the ZM 21 f2.8 Biogon, 35mm f2 Biogon, 50mm f2 Planar and Summarit 75mm f2.5. The results I obtain on my M9 and M7 have never given me any concerns at all, in fact I continue to be highly delighted by them but I was just curious to compare them with his test results.

[Guest #12]

...This is one of the tests thats done at Leica NJ and one they use for a quick reference. They have a printed chart about 3 feet wide (you can find it on one of my old posts)...

Thanks

 

Was that the chart they were shooting handheld, and it had 8's on it?

 

They must have something a little more exacting ... ?

[Schafreuter]

Hi Keith, I have exactly the same problem as you! In May I bought a M9 with a Biogon 2/35 and a Planar 2/50. Both lenses showed a frontfocus (don't mix it up with focus shift) of about 5 cm at maximum aperture and minimum focus distance. This makes it impossible to use the planar for low light portraits - if you focus on the eyes, the tip of the nose is sharp! I called Leica in Solms and Zeiss in Oberkochen and decided to send the camera first to Leica - obviously the sensor is not in the correct position. Now I am waiting since four (!) weeks for the camera. Hopefully I will be able to take sharp pictures after that, otherwise I have to send the camera including the lenses to Zeiss. The guys there told me, that every rangefinder lens has a focus tolerance of about percent. In my case of course it is much more. But it is possible to calibrate the lenses for each camera - says Zeiss.

[Keith (M)]

Hi Keith, I have exactly the same problem as you! In May I bought a M9 with a Biogon 2/35 and a Planar 2/50. Both lenses showed a frontfocus (don't mix it up with focus shift) of about 5 cm at maximum aperture and minimum focus distance. This makes it impossible to use the planar for low light portraits - if you focus on the eyes, the tip of the nose is sharp! I called Leica in Solms and Zeiss in Oberkochen and decided to send the camera first to Leica - obviously the sensor is not in the correct position. Now I am waiting since four (!) weeks for the camera. Hopefully I will be able to take sharp pictures after that, otherwise I have to send the camera including the lenses to Zeiss. The guys there told me, that every rangefinder lens has a focus tolerance of about percent. In my case of course it is much more. But it is possible to calibrate the lenses for each camera - says Zeiss.

 

Hi 'Schafreuter',

 

Actually, I do not think that I have a problem as such with front-focus with my M9/ZM35/ZM50 combinations. Without pixel-peeping to the n'th degree, the results from my quick test seem to be acceptable and certainly when I have taken the occasional portrait at f2, there has not been loss of sharpness in the near-eye of the subject.

 

I would be interested in the outcome of your M9's trip to Solms and whether or not they need to adjust anything.

[Schafreuter]

I got my m9 back from Leica - the sensor was out of tolerate, but still the Biogon showed almost the same front focus of 5cm. So I decided to send it to Zeiss in Oberkochen: Zeiss admitted, that the M9 has a different back focal distance than film Leicas, so they have to adjust their lenses for digital use. Now the focus of the Biogon is perfect even at f2!

[Nick_S]

...this adjustment works well for film based cameras, but causes a noticeable shift on digital rangefinder cameras - since their FFD is longer than film-based M-mount cameras (basically they do not meet the standard M-mount spec)

 

What is the reason for the difference between the FFD of the film and digital Leica M bodies --- would this not also cause consistent problems for a number of Leica lenses?

 

Nick

[Rick in CO]

I have the 25 ZM f2.8 Biogon, 35 Biogon-C f2.8 and 75 Summarit f2.5 and they focus spot on (tested them all). Every 135 Elmarit F2.8 I have tried (3) front focused. So does my 50 f1.4 Canon, but my 5DMkII allows me to compensate for it, even though I have to go to -20 to get it right. I am looking at the 50 Summilux ASPH and would have to say that I would not purchase an f1.4 (or faster) lens that does not have at least one ASPH element because of the (out of) focus issues. I mostly shoot travel, landscape and portraits under controlled lighting.

[Bobu]

The 50 Summilux ASPH is the only fast (more than f/2.8) optic that I have tested and consider usable for landscape shooting and display prints wide open. It's, of course, much better stopped down (outstanding by f/4) but at the wider apertures -- including f/4 -- it's a unique fast lens in my experience, which includes the Canon 50 EOS f/1.4, 85 f/1.2 (older FD), ZM 50 f/2 and others. Some of the others have reasonable wide aperture sharpness in the center, and can be outstanding in the center at f/8, but the Summilux even has good (sharpen nicely) edges at f/1.4. Only an ASPH can to this.

 

The non-Asph Zeiss 2.0/50mm MP (ZE/ZF not ZM) is at least as good as the 50 Summilux Asph. But this lens is a SLR lens with a max aperture of 2.0 and a sometimes nervous/swirly bokeh. So the performance of the Summilux is quite remarkable, but there are alternatives at f/2.0.

 

Boris