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Sonnar 50mm f1.5 focus shift noticeable on film?

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Hi everyone, I was wondering if anyone has used the Sonnar 50mm f1.5 on a M film body and can tell me if the focus shift is noticeable? 
I used to have this lens and loved it's small size and bokeh, but the focus shift on my digital M was too much so I decided to sell it.

Thanks in advance!

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The focus shift will be identical on film. However, as film is less focus-sensitive, due to its inherent thickness, it will be less noticeable, but still present.

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I have been using the lens on my M7 for a number of years - can't say that I have noticed any focus-shift.

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With regards to the modern Zeiss Zm 50mm f1.5 Sonnar, it depends both on when in production the lens was adjusted as well if the owner of the lens sent it in for recalibration of their choosing.  Apparently Zeiss early on adjusted focus for f2.8 .  Therefore the lens would front focus at f1.5 and back focus at f4.  By f5.6 and beyond, the depth of field would generally cover the back focus.  I believe it wasn't changed to adjusting the lens at f1.5 (although Zeiss may have implemented this, but many sent in their lens to precisely have that done and Zeiss welcomed those that wanted this optimization done at f1.5.  The most recent change going back a few years, is Zeiss compromised and adjusted focus for approx. f2 .  In my opinion, this worked best.  There is a small amount of front focus at f1.5, especially at shot subject distances and a smidgen of back focus at f2.8 but at both f1.5 and f2.8 with this latest adjustment for focus at f2, for most intents, its hardly noticeable.  I confirmed this with my own extensive testing of such a lens.  Others who have more recent lenses also confirmed this as well as did Zeiss.  My findings were done strictly on M digital as Jaap suggested, with film's thickness, it should mask even this small amount of front/back focus.

 

Dave (D&A)

Edited by DandA

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Just my input. I know what focus shift are but it must have to do with my work flow that I've not thought about that at all. Just take the picture with the aperture you think is best then focus. I can't understand how it's a problem.

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 @dickgillberg with all lenses that I use, I just shoot without thinking about any technicalities such as focus shift, but that's because all other lenses that I own this is not an issue so I never really think about it, but this lens does clearly have a focus shift issue (at least in digital), but given that I love its rendering and shoot film mostly nowadays, I've been thinking if I should buy it again. 

Thanks for everyone input so far, really appreciate it! 

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All of the RF type Sonnar lenses from the 1930's onwards also have distinct curvature of the focus field, which it is very easy to mistake for aperture shift, which although present, is less apparent than field curvature on the 50 Sonnars. I sold my 50 Summilux ASPH, as I  did not like its over-clinical rendering, purple fringing on digital due to high edge contrast and extreme sharpness of the focus tab, which together with an extremely stiff focus ring, literally made focussing a painful process (the next owner, also a forum member gave up on it as well for this reason). I then bought a 50mm ZM Sonnar, as I quite liked using my father's 1954 50/1.5 Opton-Sonnar on a Amedeo Muscelli Contax to M adapter ring, apart from the "wrong way round"  focusing. What you will excuse, as a charming feature on vintage lenses, which I  use quite a lot, can be just a plain irritation on a modern lens and that is what I found with the modern Sonnar. It was just too left field for an everyday lens. Oddly I have replaced it with another slightly left field lens, a 1999 year Summilux III 50/1.4 Special Edition LTM (used with its supplied LTM to M ring or on digital Leicas with 6 bit detectors, a coded Rayqual LTM to M ring). This lens does aperture shift a bit but as long as you have it shimmed to have a tiny bit of front focus at 2m and f1,4, the aperture shift is within the Dof of at least film. To my eyes it renders beautifully and I suppose this would apply to all of the e46 versions of the 50 Summilux III. I suspect the aperture shift would be more of a problem on the 47MP sensor of the SL2, with a much smaller CoC than the usual figure of 0.029mm for high resolution 35mm film like Ilford Ortho 80. 

Wilson

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3 hours ago, dickgillberg said:

Just my input. I know what focus shift are but it must have to do with my work flow that I've not thought about that at all. Just take the picture with the aperture you think is best then focus. I can't understand how it's a problem.

Unfortunately, that's not how it works when using a rangefinder...

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The other thing to remember when folks are discussing back and front focus, this refers to the location of the sharpest image inside the camera relative to the imaging medium and not the object being taken. 

Wilson

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4 hours ago, dickgillberg said:

Just my input. I know what focus shift are but it must have to do with my work flow that I've not thought about that at all. Just take the picture with the aperture you think is best then focus. I can't understand how it's a problem.

That is only correct if you focus through the lens with working aperture.

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1 hour ago, jaapv said:

That is only correct if you focus through the lens with working aperture.

Ok, thanks. Then I’m confused and I might got the hole thing wrong. Do you mean that you can’t focus a lens properly that has some kind of focus shift with a rangefinder? Not even at a choosen aperture?

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13 minutes ago, dickgillberg said:

Ok, thanks. Then I’m confused and I might got the hole thing wrong. Do you mean that you can’t focus a lens properly that has some kind of focus shift with a rangefinder? Not even at a choosen aperture?

Correct. That is why the f1 Noctilux is basically a "one trick pony" to take very shallow DOF shots, unless you carry a focus correction table with you. That is the reason some lenses with extreme aperture shift work better on cameras with liveview, like the M240. 

Wilson

 

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2 hours ago, wlaidlaw said:

....I then bought a 50mm ZM Sonnar, as I quite liked using my father's 1954 50/1.5 Opton-Sonnar on a Amedeo Muscelli Contax to M adapter ring, apart from the "wrong way round"  focusing. What you will excuse, as a charming feature on vintage lenses, which I  use quite a lot, can be just a plain irritation on a modern lens and that is what I found with the modern Sonnar.

I don't understand what you mean here about 'wrong way round focussing'. Surely the modern ZM Sonnar focusses in the standard way.

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13 minutes ago, dickgillberg said:

Do you mean that you can’t focus a lens properly that has some kind of focus shift with a rangefinder? Not even at a choosen aperture?

Grossly speaking that is correct. The camera RF mechanism has no way of knowing what lens is mounted or whether it has focus shift and how much at what aperture. The RF has to assume that all lenses focus correctly at all apertures.

However, as mentioned above, a given lens with focus shift can have its connection to the camera (the focus cam) factory-adjusted for correct focus at a specific aperture.

And focus shift varies in amount from lens design to lens design - it is present in a Zeiss 50mm f/1.5 Sonnar, but not the same as the shift in a Voiglander 35 f/1.4 Nokton.

As to adjustment, one can have that set for a given aperture one uses a lot (say, f/1.5) or for a compromise location (say, f/2, with minor shifts at f/1.5 and f/2.8). And always remember that at some aperture the focus shift goes away anyway, since the defocused rays from the outer edge of the glass (spherical aberration) are cut off.

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6 minutes ago, sinjun said:

I don't understand what you mean here about 'wrong way round focussing'. Surely the modern ZM Sonnar focusses in the standard way.

Read wlaidlaw's sentence this way:

Quote

"I quite liked using my father's 1954 50/1.5 Opton-Sonnar on a Amedeo Muscelli Contax to M adapter ring, apart from the "wrong way round"  focusing."

It is the 1954 lens for Contax mount that has the "wrong-way round" focusing. Not the modern Sonnar.

 

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But his next sentence implies the same thing applies to the ZM Sonnar.

2 hours ago, wlaidlaw said:

...What you will excuse, as a charming feature on vintage lenses, which I  use quite a lot, can be just a plain irritation on a modern lens and that is what I found with the modern Sonnar. It was just too left field for an everyday lens.

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44 minutes ago, dickgillberg said:

Ok, thanks. Then I’m confused and I might got the hole thing wrong. Do you mean that you can’t focus a lens properly that has some kind of focus shift with a rangefinder? Not even at a choosen aperture?

Correct. The camera does not look through the lens to focus. Thus the lens setting of the aperture cannot influence the focusing. Normally such a lens will focus correctly at the aperture that it is adjusted to. All other apertures will misfocus to a certain extent, but at smaller apertures DOF will hide the effect.

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14 minutes ago, sinjun said:

I don't understand what you mean here about 'wrong way round focussing'. Surely the modern ZM Sonnar focusses in the standard way.

Yes but older Contax mount Sonnars focus the other way infinity to near focus compared with Leica lenses. The Amedeo Muscelli adapters for Contax RF to Leica M, copy the focus direction of Contax RF cameras. I have my father's Contax IIA Colour Dial Camera with the 50/1.5 Opton Sonnar, which he bought on a business trip to Germany in I think 1954 or 55. He could never get used to the "wrong way round" focus either, being like me a dyed in the wool Leica RF user, so the camera is basically unused. When I  had a CLA done a few years ago on the Contax, the repairer said it was just like it had come out of the Stuttgart factory yesterday. 

Wilson

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There are two types of Amedeo adapters for either Contax or Nikon: the original version indeed focuses in the "wrong way", whereas the helical of the most recent version for 50mm lenses turns in the "right (Leica) direction". The "recent" version has been available for at least a couple of years now and also has a focus tab.

I'm not affiliated with Amedeo, but he's a great guy, - who has now moved to the US,  but manages to keep making adapters in his Venezuelan workshop despite the situation his home country finds itself in - so here's a link:

https://www.ebay.com/itm/Zeiss-Contax-Sonnar-50mm-rangefinder-to-Leica-M-M9-M240-adapter/133226303286?hash=item1f04e80f36:g:yVgAAOSwP~tW3VtL

Time to put that Opton Sonnar to good use perhaps 😉?

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4 hours ago, Ecar said:

There are two types of Amedeo adapters for either Contax or Nikon: the original version indeed focuses in the "wrong way", whereas the helical of the most recent version for 50mm lenses turns in the "right (Leica) direction". The "recent" version has been available for at least a couple of years now and also has a focus tab.

I'm not affiliated with Amedeo, but he's a great guy, - who has now moved to the US,  but manages to keep making adapters in his Venezuelan workshop despite the situation his home country finds itself in - so here's a link:

https://www.ebay.com/itm/Zeiss-Contax-Sonnar-50mm-rangefinder-to-Leica-M-M9-M240-adapter/133226303286?hash=item1f04e80f36:g:yVgAAOSwP~tW3VtL

Time to put that Opton Sonnar to good use perhaps 😉?

Mine was I think the first M mount adapter Amedeo made, quite a long time ago, his earlier ones being LTM. I have so many classic and modern Leica lenses in 50mm, LTM, M, R and L, that I really don't need to rob my Contax IIa of its lens. I also have a very nice 1953 LTM Canon Serenar "Hiroshi" Sonnar clone 5cm/f1.8, the all chrome one with the infinity lock, that I think is at least as good as my 1950's Leica offerings and has the advantage of hard coating, so there is not a mark on the front element. I bought it for a Leotax, which I acquired, as it came with three of the superb Leotax spring loaded wind on spools. I am using two of these in my IIIa and Reid and Sigrist Model 3 Mk.2 (a IIIb clone). They are so much easier to use than the Leica spools - no more broken finger nails! I was going to sell on the Leotax which in total cost me less than the two spare and much sought-after Leotax spools would have cost but it was so nice, I decided to keep it. 

Wilson

Edited by wlaidlaw

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