M8 Summicron 50mm focus

[SiOnara]

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Hi everyone,

 

Quick question about a new lens I have.

 

Basically my fairly new M8 went back to Solms for repair as the shutter was sticking and it had the coffee ring. When it was there as far as I understand it was overhauled and calibrated etc.

 

I recently bought a brand new 50mm Summicron 6bit lens and when I use it on the M8 I can see that the focus seems soft at f2. If I stop down to f2.8 / f4 etc the focus seems spot on.

 

I tested it shooting a ruler at 45 degrees on a tripod and focused at 4" on the ruler. The focus came out at 3" at f2 (1 inch closer to me) and bang on 4" at f2.8 right through to f16.

 

I bought the 50mm Summicron as I thought it would be perfect across all f stops.

 

Is there anything I can do to correct this issue or is it something I will have to live with? I am not a pixel peeper BUT I kinda like focus to be spot on.

 

Thanks J

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[johnloumiles]

Hi Mega

 

I think every Leica lens should be spot on focus at every aperture if properly aligned. Maybe the rangefinder needs adjusting because it got bumped in the shipping process? I have a 50 Summicron non-ASPH and it splits hairs at every f stop on my M8. The picture below (f.2) I focused on the bottom of the "e". I know it sucks but might want to shoot Leica an email explaining the problem if haven't already.

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[wda]

J, assuming your test has been repeated with similar errors, there seems to be a fault. Try or borrow another lens to check rangefinder performance. If your Summicron is a current model and new, I doubt it would be delivered with a focusing fault. I would suspect your rangefinder accuracy, despite its recent sojourn in Solms.

[jvan01]

My 50mm Summicron wouldn't focus correctly on the M8. Turns out the rear glass element had come loose in its thread. Tightening it carefully with a spanner did the job.

[luigi bertolotti]

Just a question J...maybe I didn't read right... how did you focus at 4 inches ? Of course, surely not by Rangefinder... And why did you make a test at such short distances ? Is not a typical usage of the Summicron.

[Holybasil]

Just a question J...maybe I didn't read right... how did you focus at 4 inches ? Of course, surely not by Rangefinder... And why did you make a test at such short distances ? Is not a typical usage of the Summicron.

 

He ment he focused on the 4 inches mark on a ruler at a 45 degree angle.

[ho_co]

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The lens should focus properly wide open. Don't bother trying other apertures unless you're looking for focus shift. If it doesn't focus accurately wide open, it's out.

[Jeff S]

I think every Leica lens should be spot on focus at every aperture if properly aligned.

 

Not possible given optical design properties of many lenses. I'm not an expert, but I think all spherical lenses exhibit some focus shift when stopped down. Harder to see in a slower lens, but technically it's there. And even some aspherical lenses, even some with floating elements (like the new 35 Summilux asph) still shift to some degree; just not as much as older designs.

 

Even my 35 Summicron asph, which has been checked by Leica along with my camera, exhibits some shift at f2.8 and f4, consistent with reports from Sean Reid and others. Until there's a better design (and possibly even then), it will always be there.

 

As a practical matter, however, it's immaterial to me. The final print is all that I care about.

 

Jeff

[SiOnara]

Well I have an 28mm Elmarit ASPH and a CV 40mm 1.4 and they both spot on, especially the Elmarit.

 

The CV suffers a bit of focus shift from f2 onwards but I kinda knew that would be there and it doesn't bother me.

 

I would have thought the Summicron 50mm would have been perfect being such a standard lens. I really do need it spot on at f2 and feel it should be for the price.

 

Apart from that its an amazing lens to use and I love the way it renders.

 

I will drop Leica an email and see if they can help me out with this.

[SiOnara]

The lens should focus properly wide open. Don't bother trying other apertures unless you're looking for focus shift. If it doesn't focus accurately wide open, it's out.

 

Do you get focus shift on this lens? I thought that mainly effected faster lens.

[ho_co]

You shouldn't get focus shift on the 50 Summicron. That's my point.

 

Just do a through-focus test wide open to see whether the lens focuses accurately.

 

Testing it at smaller apertures isn't likely to give you any more information, will just tend to cover any error with increasing DoF.

 

The only time one needs to test at various apertures is when one is looking for focus shift. (Or for other aberrations, which aren't the subject here. )

 

 

BTW, you might find the Nikon D70 Focus Chart easier to work with than a ruler, since it has a clear, wide black line for focusing. Turn the camera vertical on the tripod, of course.

[SiOnara]

You shouldn't get focus shift on the 50 Summicron. That's my point.

 

Just do a through-focus test wide open to see whether the lens focuses accurately.

 

Testing it at smaller apertures isn't likely to give you any more information, will just tend to cover any error with increasing DoF.

 

The only time one needs to test at various apertures is when one is looking for focus shift. (Or for other aberrations, which aren't the subject here. )

 

 

BTW, you might find the Nikon D70 Focus Chart easier to work with than a ruler, since it has a clear, wide black line for focusing. Turn the camera vertical on the tripod, of course.

 

 

Thanks Howard.

 

I will give this a go. I am pretty sure I am getting focus shift off this lens for some reason. I am guessing it's because my body is not set up correctly rather then the lens itself.

[pklein]

I've been able to detect very small focus shift in my tabbed 50 Summicron, which is the same formula as the current lens. It's not enough to matter for practical photography, but it's there.

 

One thing we learn with the M8 and M9 (compared to film) is that there is no such thing as perfection. There are matters of degree. Fortunately, when that degree gets small enough (as with the modern 50 Summicron), it's perfect enough for our purposes. Some lenses are usually adjusted so that the wide-open point of focus is a gnat's eyebrow closer to you than absolutely optimum. This makes the point of focus fall within the depth of field at other apertures. This is not something you'll notice unless you pixel-peep at 100%. So the lens is perfect enough for most photographers.

 

Others lenses--like the Noct f/1 and the Zeiss Sonnar 50/1.5--must be adjusted to be right either wide-open or at f/2.8 and wider. For the Noct, the choice is obvious. For the Sonnar, it's a matter of what you prefer. The old 35/1.4 ASPH falls into that category, too, though not as drastically as the other two. You just learn to focus on people's noses rather than their eyes at f/2.8-5.6.

 

Megadust: If your 50 Summicron is truly and repeatably focusing nearly an inch closer at f/2 than optimum, it might benefit from adjustment. It probably can be adjusted so that it would do better. Some people have sent both their camera and a problem lens in to Leica together. Leica can then adjust them both to digital M standard, which is tighter than film.