Summicron M 35mm ASPH - soft center image at mid-aperture

[Frits]

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I recently got a 35mm Summicron ASPH for my M9 (2012 serial number).

I am surprised and disappointed to see definite softness in the image center at the f 4 - 5.6 range. The image is fine away from center all the way into the corners. At larger apertures it seems OK and it is fine again at f8.

The MTF chart does not seem to reflect this softness at all, nor did I expect it at what is rated to be an excellent lens.

 

I would appreciate comments on your experience with this lens, as I suspect (hope?) that the issue is an isolated one.

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[Tonki-M]

it is highly unlikely that the lens performs as you described, unless the lens is a defect (which is very rare) have you tested it on a tripod? or is your M out of alignment? my 35 cron asph is extremely sharp, even at f2, as is most of the user's reports of owning this lens.

[IWC Doppel]

It's certainly not the design, the MTF's are better for each f stop in centre and across the frame as you go down from f2 to f5.6. The best aperture being 4 from memory. I can't think of an obvious answer and suggest popping into a Leica shop and A-B another sample.

 

I had a copy of this lens and only changed as I preferred the bokeh and rendering of others and has zero issues with sharpness

[lincoln_m]

Frits,

Can you post an example image, because I have 2 copies of this lens and I agree with the others on it's sharpness. The only thing I could imagine that would do this is if the focus was out and you were actually focusing a little further away. I must admit I've only used these lenses on film Ms with 0.72x and 0.85x rangefinders.

Regards, Lincoln

[malsop]

Your problem is likely Focus Shift...

 

I have 10 Leica M lenses, mostly post 6-coding, from 21mm to 90mm. I have carefully tested all these lenses on an M9-P for, among other things, focus shift as aperture is stopped down.

 

Of all my Leica lenses the 35mm Summilux-M ASPH and the 35mm Summicron-M ASPH have the greatest amount of focus shift. For all of my Leica M lenses the focal plane is dead on at full aperture for the lens. For my two 35mm M lenses the target focal plane is OOF through the middle apertures.

 

For the 35mm Summicron-M the target focal plane is right on the edge of the DOF at f/2.8, it is OOF at f/4 and f/5.6. The target focal plane is back within the DOF at f/8. The 35mm Summilux-M, which is the latest FE design, has even more focus shift than the Summicron!

 

These 35mm lenses need to be used wide open or stopped down to f/8 or f/11 for best results. Alternatively they can be used in the middle apertures if the rearward (away from the camera) focus shift is compensated for ...which is not easy.

 

I mostly do landscape work and the 35mm Summilux-M is my primary lens, it is the lens I leave on the camera, it is a great lens when you know how to use it.

[tobey bilek]

1.4 are known for focus shift. 2.0 ASPH are not. Send it in to be checked. But before doing that, make sure the RF is operating properly. The two calibration points are infinity and 1 meter from sensor.

[malsop]

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My Summicron-M 35mm, purchased used, was pre 6-bit coding.

 

It went to Leica repair with my M9-P (for a different issue). Leica 6-bit coded the Summicron-M and calibrated it to my M9 last year.

 

On return it was (and is) dead on and very sharp at f/2. Indeed, it is very sharp throughout the aperture range but it does focus shift enough to put target focal plane OOF at f/4 and f/5.6.

[IWC Doppel]

Interesting I never found any focus shift issues with my ASPH 35, I do with other lenses and work round, the worst is my pre ash Summilux 50, my M9-P went back for calibration as well

 

If you are shouting with images central then something like the Summaron f2.8 at f4, f5.6 is stunning in the central and medium field , plus small, cheap and beautifully constructed.

[Frits]

Thanks all for your comments.

By now I have confirmed that the issue is front-focusing by a fair bit. I need to back off the focusing ring by several degrees to get things properly in focus.

I understand that it can be sent to Leica for adjustment, but then I am out of my equipment for a period of time.

 

Rats!

[IWC Doppel]

You may have done so already but do check your M9 my M9-P went back for adjustment

[Frits]

You may have done so already but do check your M9 my M9-P went back for adjustment

My other lenses are spot-on, which makes me suspect this lens.

[michali]

A couple of years ago I bought a new 35mm Summicron ASPH and straight out of the box it exhibited the same symptoms as yours. I sent it to Solms for adjustment and it came back after a few weeks with a note that the lens was fine and within spec. At that point I gave up I sold it and bought a 35mm Summarit which I use even more than my 35mm Summilux ASPH.

 

FWIW of the 12 Leica lenses that I own, the 35mm Summicron was the only one that exhibited focusing issues.

[jrh68uk]

I'm in agreement with malsop.

 

I bought my 35 'cron ASPH new and pretty soon discovered the focus shift, which was confirmed many times over on testing. So, around middle apertures I noticed that the edges of the frame would be noticeably sharper then the centre. Wide open, things were OK as they were when well stopped down, for obvious reasons.

 

The differences between edge and centre are down to curvature of field. I figured that, if the lens were adjusted so that it's at the front-most point of acceptable sharpness when wide open, the shift backwards when stopping down wouldn't be so apparent and would later be masked by depth of field. Indeed, I had read that some people were actually requesting this adjustment for the same reason.

 

I sent the lens to Leica U.K. (as it existed then) who sent it back, unchanged, saying that it was within spec. Shortly afterwards Leica U.K. restructured and so I took the opportunity to send the lens to Solms. I explained fully what I was seeing and I think I emailed a couple of examples. They took note and sent it back with a very slight front-focus bias (bias as in, within the limits of acceptability) which I find totally usable. Of course, any human errors I make may be made more obvious if I err on the side of front-focus but, when I take good care, it's sharp every time.

 

From going from a lens I was about to sell in favour of the 35 Summarit, it's now my most frequently used lens and a favourite.

[lct]

Never got significant focus shift problems with my 35/2 asph at any aperture. Less so than with my 35/2 v4, which is hardly visible at medium apertures due to DoF anyway. My advice is the same as Tobey's above. I would check the RF accuracy at infinity to begin with as it is often the only fix needed. Takes hardly more than 5 minutes to fix with a 2mm allen key.

[Luke_Miller]

Sean Reid in his review of 35mm lenses on the M9 speaks to the focus shift of the 35 Summicron ASPH at mid (f4-f5.6) apertures. That said, he believes it is one of the best 35mm lenses to use on the M9.

[lct]

No focus shift reports by J.M. Sepulchre though. I would not be put off by any review unless it is confirmed by other serious reviewers personally.

[charby57]

Well, I did find the very same phenomenon on my sample of 35 summicron Asph.

 

At first, I thought I was focusing incorrectly. After reading this post, i have done testing on the lens at various distance. Indeed, on any distance of focusing, the center of the image is out of focus, from 2 to 5,6. It looks to me more as a case of strong field of curvature than front/back focusing. Unless I am very much mistaken.

 

In any case, I have sent my lens few weeks ago to NJ service. My retailer who send it just told me that he knew what to write on the repair way bill.

 

We shall see what is this all about.

[tashley]

1.4 are known for focus shift. 2.0 ASPH are not. Send it in to be checked. But before doing that, make sure the RF is operating properly. The two calibration points are infinity and 1 meter from sensor.

 

Sorry, not true: the 35 Cron is indeed known for focus shift... just not as much as the last gen 35 lux

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Hallo,

Look here: Leica M

[lct]

None is known for that.

[tashley]

None is known for that.

 

Well, pretty much every review I have ever seen of the 35 Cron and the one I had (possibly two, I can't remember, it was four or five years ago) showed it quite clearly though not as bad as the last generation 35 Lux, which was by Leica's own admission affected by residual spherical aberration and was replaced after they 'went digital' with the FLE, which also has focus shift but it is minimal and so the POF remains within the DOF as you stop down. So whether you believe it or not, and whether it matches your own experience or not, I am afraid it is simply not the case that ' none are known for it'!