Infinity focus with M lenses

[dsedov]

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I've bought the SL yesterday and the Leica M-Adapter T to use with M lenses. I've noticed that if I focus my 50mm lux on infinity it goes just a bit further on the SL. Is this a known problem? 

[steppenw0lf]

It is known that typically the adapters (all adapters) are a tiny bit too short, but this is intentionally.

And this is not a problem - at least not for me. I would never simply set the lens to infinity, this is a really bad idea. Just think about it - what happens to the DoF ? Exactly.

[dancook]

It is known that typically the adapters (all adapters) are a tiny bit too short, but this is intentionally.

And this is not a problem - at least not for me. I would never simply set the lens to infinity, this is a really bad idea. Just think about it - what happens to the DoF ? Exactly.

 

If you want to shoot the stars in the night sky, open wide aperture and focusing to infinity is a pretty valid method I believe.

[dsedov]

Thank you for replies. I just thought there was something wrong with my adapter.

[scott kirkpatrick]

If you want to shoot the stars in the night sky, open wide aperture and focusing to infinity is a pretty valid method I believe.

Sorry, but the infinity stop is seldom accurate with longer focal length lenses.  And adapters tend to be slightly undersized.  You can focus "beyond infinity" if you just just turn the lens to the stop.  For stars in the night sky it is best to use live view and focus magnification or to focus on a very distant building or tower first.  The classic telephotos, like the Telyt 180, 280 and longer, place the focusing limit well beyond infinity, in order to allow room for thermal expansion or contraction.

[helged]

...even for wider lenses shot wide open, the infinity mark can not be trusted. Live view + magnification, or wireless transfer of test images to an android device, or self-made marking for any specific body+adaptor+lens combo are required to nail the focus.

[dancook]

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Sorry, but the infinity stop is seldom accurate with longer focal length lenses.  And adapters tend to be slightly undersized.  You can focus "beyond infinity" if you just just turn the lens to the stop.  For stars in the night sky it is best to use live view and focus magnification or to focus on a very distant building or tower first.  The classic telephotos, like the Telyt 180, 280 and longer, place the focusing limit well beyond infinity, in order to allow room for thermal expansion or contraction.

 

I wasn't commenting on the accuracy of the marking, he was talking about DOF, I was saying that planning to focus at infinity was valid for some applications.

[pop]

There are (at least) three kinds of "infinity" involved in this discussion:

 

1. The mechanical stop which limits how close to the image plane the lens can move;
2. the ∞ mark on the distance scale;
3. the distance of something really far away in front of the lens;
4. the proper distance of the lens from the focal plane for making a sharp image of something at the distance denoted by #3.

 

I don't think there's a serious debate that the proper way of determining #4 is not by moving the lens to the end of the range but by actually moving the lens to the place where a sharp pictdure is attained, and that #1 and #2 are not usually the way to do it.

[scott kirkpatrick]

The "infinity" symbol is pretty wide, and the true infinity position on the scale usually lies somewhere within this symbol.  I try to find out and remember where that is for use in rapidly setting focus for dynamic scenes that need to be sharp all the way into the distance.  I am not a believer in scale focusing to a critical middle distance if the scene extends to far away.  It seems to me that softness at the distant parts of a scene undercuts the sharpness achieved elsewhere, unless the picture is about the objects near to the camera and the background is intended to be less distinct.  How do others feel?

 

scott

[wlaidlaw]

It is really only on super expensive professional movie lenses from the usual suspects, Cooke, Arri-Zeiss, Leica, Panavision and so on, that the distance scale markings will be guaranteed to be totally accurate. That is because that is how they are generally focussed on set with a metal tape (or laser measure), notebook and the "focus puller". When you watch these lenses being serviced, one of the main parameters that they check is focus distances matching scale. 

 

Wilson

[hmathias]

It is really only on super expensive professional movie lenses from the usual suspects, Cooke, Arri-Zeiss, Leica, Panavision and so on, that the distance scale markings will be guaranteed to be totally accurate. That is because that is how they are generally focussed on set with a metal tape (or laser measure), notebook and the "focus puller". When you watch these lenses being serviced, one of the main parameters that they check is focus distances matching scale. 

 

Wilson

 

This is true, but they are focused on the set with an expensive accurate cloth tape, you don't want to cut an actor's face if they walk into a metal tape. The lenses are individually custom-engraved with precise footage markings during manufacture and then recalibrated regularly with precision shims under the lens mounting flange. Lasers are not permitted on a set per SAG (Screen Actors Guild) union safety rules. All good film lenses focus past infinity to allow for thermal expansion.  

[FlashGordonPhotography]

I always infinity focus test my lenses on my M. And all my lenses focus perfectly at infinity. Except for my currently faulty 90mm they all stop exactly in the middle of the infinity mark. Not a single M lens I own from any manufacturer stops anywhere except exactly in the middle of the infinity mark.

 

I don't appreciate that an expensive adaptor made by Leica doesn't focus my lenses the same on my SL as they do on my M. "All adaptors are made short" screams of Leica apologism to me. They should function like they do on the M and they don't. And this isn't a long lens issue. The longest lens made for the M is 135mm and mine is also spot on on my M. Turn to infinity. Point at moon take perfectly sharp photo. I can do that with any M out lens I own on my M's. Just not on the SL.

 

Leica shim M lenses to ensure they hit infinity pretty much spot on and it's frankly just lazy that a A$500.00 dumb adaptor doesn't get shimmed by Leica. Leica are just using the excuse of the focusing aids so they can get away with a less than stellar product and a stellar price. If this was a $30.00 adaptor I could be more tolerant. But it's top dollar for bugger all benefit over an eBay special except for the IR transfer.

 

I suspect the real reason they come up short is because they're mass produced in some developing nation and not checked rigorously. It's better to have them a bit short than a bit long if you're going to dump a product on the market without checking each one for accuracy.

 

Gordon

[thighslapper]

The other issue with the SL and T you have forgotten is the fact that Leica have no need to adjust the mount flange to sensor distance to the accuracy as needed in the M ....... as there are, and will presumably never be, any native manual focus SL lenses. The M sensor is shimmed to a very high tolerance as there is a mechanical linkage that achieves focus. 

 

I had shimmed my M-L adapter to work perfectly on the T ...... it took 0.09mm (conveniently the thickness of most LCD protection film - fitted inside the adapter)....

 

...... but .... this is too much for the SL and I have had to strip it down again and use 0.04mm to get my Noctilux and 75/2 (the most finicky lenses) to focus at infinity, after a lot of trial and error.

 

I suspect this will vary from camera to camera, so Leica making the adapter to nominally focus at infinity based on 'exact' dimensions may cause more problems than it solves .....

 

If you want to do this it takes about half an hour ..... and most of that is the fiddly business of cutting the shim material pieces to fit round the shelf inside the adapter to avoid screw holes and other things. The screws were originally loctited but I can't see them coming loose if replaced without it. 

Edited October 5, 2016 by thighslapper

[mjh]

I suspect the real reason they come up short is because they're mass produced in some developing nation and not checked rigorously.

Not true. As I have mentioned before (I think – this issue comes up every couple of months), you could also get a Made in Germany adapter from Novoflex and experience the same. These adapters are designed that way. (On the other hand you could try your luck with a Chinese adapter – as these are often not tested rigorouly it might, by pure chance, fit your requirements.)

Edited October 5, 2016 by mjh

[mada9909]

On 10/5/2016 at 10:07 AM, FlashGordonPhotography said:

I always infinity focus test my lenses on my M. And all my lenses focus perfectly at infinity. Except for my currently faulty 90mm they all stop exactly in the middle of the infinity mark. Not a single M lens I own from any manufacturer stops anywhere except exactly in the middle of the infinity mark.

 

I don't appreciate that an expensive adaptor made by Leica doesn't focus my lenses the same on my SL as they do on my M. "All adaptors are made short" screams of Leica apologism to me. They should function like they do on the M and they don't. And this isn't a long lens issue. The longest lens made for the M is 135mm and mine is also spot on on my M. Turn to infinity. Point at moon take perfectly sharp photo. I can do that with any M out lens I own on my M's. Just not on the SL.

 

Leica shim M lenses to ensure they hit infinity pretty much spot on and it's frankly just lazy that a A$500.00 dumb adaptor doesn't get shimmed by Leica. Leica are just using the excuse of the focusing aids so they can get away with a less than stellar product and a stellar price. If this was a $30.00 adaptor I could be more tolerant. But it's top dollar for bugger all benefit over an eBay special except for the IR transfer.

 

I suspect the real reason they come up short is because they're mass produced in some developing nation and not checked rigorously. It's better to have them a bit short than a bit long if you're going to dump a product on the market without checking each one for accuracy.

 

Gordon

 

On 10/5/2016 at 5:00 PM, mjh said:

Not true. As I have mentioned before (I think – this issue comes up every couple of months), you could also get a Made in Germany adapter from Novoflex and experience the same. These adapters are designed that way. (On the other hand you could try your luck with a Chinese adapter – as these are often not tested rigorouly it might, by pure chance, fit your requirements.)

the arrogance become Leica's protective carapace.i bought another 2 adoptor with spending less than 10% of leica's , made in China/ made in japan, both perfectly works at infinity on SL.

Adoptor was not a high-tec products. 

Edited December 1, 2023 by mada9909

[dpitt]

On 10/5/2016 at 10:09 AM, thighslapper said:

The other issue with the SL and T you have forgotten is the fact that Leica have no need to adjust the mount flange to sensor distance to the accuracy as needed in the M ....... as there are, and will presumably never be, any native manual focus SL lenses. The M sensor is shimmed to a very high tolerance as there is a mechanical linkage that achieves focus. 

 

I had shimmed my M-L adapter to work perfectly on the T ...... it took 0.09mm (conveniently the thickness of most LCD protection film - fitted inside the adapter)....

 

...... but .... this is too much for the SL and I have had to strip it down again and use 0.04mm to get my Noctilux and 75/2 (the most finicky lenses) to focus at infinity, after a lot of trial and error.

 

I suspect this will vary from camera to camera, so Leica making the adapter to nominally focus at infinity based on 'exact' dimensions may cause more problems than it solves .....

 

If you want to do this it takes about half an hour ..... and most of that is the fiddly business of cutting the shim material pieces to fit round the shelf inside the adapter to avoid screw holes and other things. The screws were originally loctited but I can't see them coming loose if replaced without it. 

Thanks. I think you mentioned the one real reason these adapters are intentionally made too short. I can understand there is no reason to control the flange distance in the L camera's as tight as previous generations of camera's. Maybe the unibody aluminium design complicates this even more, as it is probably more sensitive to temperature changes.

These tolerances would in some cases (bad luck with tolerance on the wrong side) make infinity focus impossible if the adapter would be made too accurate. So Leica made the right decision to make the adapter short enough to make sure you can always reach infinity.

[jaapv]

6 hours ago, mada9909 said:

 

the arrogance become Leica's protective carapace.i bought another 2 adoptor with spending less than 10% of leica's , made in China/ made in japan, both perfectly works at infinity on SL.

Adoptor was not a high-tec products. 

You are responding to a seven year old thread. 
the fact that all Leica and Novoflex adapters are short by exactly the same amount proves that it is not a tolerance or manufacturing issue but a design specification. 

[mada9909]

Yes, Jaapv, indeed i just bought SL2S and noticed this issue after mounting Leica M-L adopter. 

Thanks for the reply. 

so, the solution is that using a cheaper adopter made in China instead of original Leica's if you want to get infinity focus with M lens? 

 

[Photoworks]

50 minutes ago, mada9909 said:

so, the solution is that using a cheaper adopter made in China instead of original Leica's if you want to get infinity focus with M lens? 

 

made the china adapter is good for some days, but no. ad the material expands and contracts in different temperatures you better use and adapter that goes past infinity.

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[BernardC]

12 hours ago, mada9909 said:

the arrogance become Leica's protective carapace.i bought another 2 adoptor with spending less than 10% of leica's , made in China/ made in japan, both perfectly works at infinity on SL.

Adoptor was not a high-tec products. 

There's more to it than focal distance.

I have some cheap adapters in my junk drawer that are too loose, or too tight, or that won't mount at all with certain lenses/body combinations. One thing I can say about Leica and Novoflex adapters is that they feel exactly like a native lens/body combination. They never bind, or loosen, or shed screws, or have excessively sharp release buttons.

I've standardized to the premium adapters for lenses that I use a lot, or where I have several lenses with the same mount (M and Yashica/Contax in my case), but I still use cheaper adapters if I know I won't use it much, or in the rare case where Novoflex doesn't support the mount (Rollei QBM).