Fast 50mm lens without focus shift

[Vise]

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Hi everyone, I am writing to ask you something about fast 50mm on Leica M.

I'm looking for a fast 50mm but I'm very scared to buy one with the unfamous focus shift. I shoot only and exclusively film and I would like my images to be in focus at every apertures, as I have always done on reflex cameras. 

I mistakenly thought that the asphericity of the lenses corrected this "defect", but from what I read, even on this forum, it would not seem to be so. I was very excited about the last Voigtlander VM 1.5 Classic II.

So the question now is: If I want to be sure to always shoot perfectly focused images at any apertures, do I have to stick to a Summicron or any other ƒ2 lens? Is this "problem" real? 

Thanks!

MV

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[pedaes]

14 minutes ago, Vise said:

I shoot only and exclusively film

Is focus shift an issue on film?

[evikne]

The 50mm Summilux-M ASPH has a floating element group (FLE) and should not suffer from focus shift. It is quite expensive, though.

[FrozenInTime]

11 minutes ago, pedaes said:

Is focus shift an issue on film?

yes, for example the 50mm Zeiss C-Sonnar exhibited shift when I tested on film.

The 50/1 Noctilux is notorious for focus shift ; I lost many shots before realizing it's either f/1 or f/4...

Edited January 6, 2021 by FrozenInTime

[elmars]

The "normal" Summicron has a bit Focus shift. Lenses without are:

Apo Summicron

Summilux (FLE)

Noctilux 0,95

Voigtländer 1,2 (not 1,0 or 1,5)

[Gobert]

I have the Summilux and the Noct 0.95. I have never noticed focus shift on either.

[evikne]

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I have 50mm Summilux ASPH and pre-ASPH. The pre-ASPH has a little focus shift at f/2.0 and 2.8. The ASPH has no focus shift. 

[pippy]

2 hours ago, pedaes said:

Is focus shift an issue on film?

It has always been present, pedaes (as I'm sure you already know!), but that's not the same thing as saying it's always been an issue. Stating the obvious if, say, the 50mm v2 rigid Summicron has apparent focus shift on an M10 it would also have focus-shift with an M3.

It could be argued that with pre-digital rangefinder cameras practically no-one had ever noticed there was much of a problem. Once digital images arrived and could be examined with such minute attention to detail some people started to notice and the result was the development / modernisation of certain optical manufacturing techniques (some of which are mentioned in earlier posts) to circumvent an aspect of lens-design which hadn't seemed to trouble many photographers in Leica World from the introduction of the first model quite some time ago.

FWIW many years ago now, after there was discussion about focus-shift with the 40mm f1.4 Voigtlander Nokton, I tested a dozen lenses under controlled studio conditions and 10 of them showed noticeable shift to a lesser or greater extent. The two which didn't have any appreciable shift whatsoever were the 75mm and 90mm Summarits.

Which brings me back to the OP, so perhaps the 50mm f2.4 Summarit, having as it does a much more modern lens computation, might be worth considering as an option?

Philip.

Edited January 6, 2021 by pippy

[a.noctilux]

Philip, do you mean that f/2.4 lens is fast lens ?

Meanwhile Summarit-M lenses are stellar lenses for film or digital.

I use now three f/2.5 older 35/50/75 with pleasure.

 

For film use, decades of thousands slides using 50mm lenses as Noctilux 1.0, Summilux non-asph, Summicron

I've never notice thing as "ennoying focus shift" in real life using Kodachrome at all aperture.

 

Maybe in digital, a bit of focus shift in those Noctilux/Summilux/Summicron had never (mostly) bothered me.

I do test some to figure it out, why I'm "digital" using my lovely Noctilux 1.0 at f/1.0 or from f/4 up 😇.

 

Film (or myself ) is very tolerant concerning "focus shift" (new hobby for digital user in my view)

[Rob L]

I've been wondering about the M mount CV 40 1.2 ( and 35 and 50 1.2s, as all are similar design ). The E mount 40 1.2 has some focus shift, but not an issue with an electronic viewfinder, but this would be a big issue on a Leica.

[Pyrogallol]

How fast do you want the lens to be, f2 or f1.4 or faster ? There are lots of lenses to choose from if you are not needing to go faster than f1.4

The only lens I realised had back-focussing with on film was a Voigtlander 40mm f1.4

[pippy]

10 minutes ago, a.noctilux said:

Philip, do you mean that f/2.4 lens is fast lens ?...

It's certainly faster than my 50mm f2.8 Elmar, Arnaud.....

OK! I forgot about the 'Fast' bit!

Mea Culpa!

Philip.

 

[a.noctilux]

Philip 😇

or what a lens like Summaron-M 28mm very nice lens but not very fast if usable in dim situation (with care or tripod ! ).

"Fast" lens is subjective anyway.

Let's go on.

To the OP,

- in my "limited" experiences, Leitz/Leica lenses DO have less "aberrations" than most compatible lenses

- M compatible lenses tend to be replaced (for me) by the equivalent Leitz/Leica if this exists, I don't know why

 

 

[astrostl]

The TTArtisan 50/1.4 (probably my price/performance pick for any lens/focal/system) and Voigtlander 50/1.2 are both good.

[pedaes]

1 hour ago, pippy said:

practically no-one had ever noticed there was much of a problem.

My understanding is that the thickness of the film emulsion was deep enough to 'loose' marginal focus shift. The move to silicon removes that latitude, and hence the problem seems more apparent on digital cameras. When at such a critical focus/dof situation one always wonders if it is the lens or operator. Hey ho - all good fun!

[astrostl]

3 hours ago, evikne said:

The 50mm Summilux-M ASPH has a floating element group (FLE) and should not suffer from focus shift. It is quite expensive, though.

The main impact of floating elements is to improve performance at close focus distances. The main impact of aspherical elements is to reduce spherical aberration (the category in which focus shift resides). There are still examples of ASPH + FLE lenses that have "noticeable" focus shift, though (e.g. the latest Leica 35 FLE).

[pippy]

32 minutes ago, pedaes said:

My understanding is that the thickness of the film emulsion was deep enough to 'loose' marginal focus shift...

Hmmm... could be. I suspect the real reason was - as you mention - that we assumed it was our own slight user-error and in 99.999% of images it didn't really matter that much at all. I can't remember even a single image I've shot with my M2 in the 41 years I've owned it being discarded because of focus-shift.

Perhaps I'm just not picky enough?

Philip.

Edited January 6, 2021 by pippy

[BrianS]

Are you shooting black and white or color film?

If shooting Black and White, what color contrast filters do you plan on using?

You will find that focus shift due to chromatic aberration is often as much or more than focus shift caused by spherical aberration.

I suspect that you want the APO-Summicron to control both. Or wait until the APO-LAnthar comes out and people do some tests. Both are 50mm F2 lenses.

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Hallo,

Look here: Leica M