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Flange focal distance Leica M-to-SL adapter


Steve McGarrett

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Hi all,

 

Just a question on native Leica adapters: they are exactly the right lenght for focusing at infinity on the hard stop (like the way M lenses work on M cameras...) or they are a little bit shorter, like many third-parties adapters, requiring the photographer to fine tune focus in the EVF to shoot at infinity?

Thank you

 

S.

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Correct ....... and I did some experiments having noticed issues with my Leica T using the M-T/SL adapter ....... adding a 0.09mm shim  (conveniently the thickness of my screen protector film) inside the adapter (easily dismantled) brings infinity and the lens stop into alignment ....... for most ..... but not all lenses ...... which is why this lee-way is built into the adapter to cope with lens variability.

 

Personally I'd prefer to be able to set the lens to infinity if in a hurry and just shoot without having to check focus ...... so my shim has stayed put. I have a couple of M lenses where infinity is very very slightly OOF ..... but they are not the ones I would be tempted to use on the T or SL

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Hate to hear this, I've thought that the Leica adapter, as pricey as it is, should keep the correct distance... then I wonder if it's better to save some cash buying a Novoflex adapter...

 

p.s.: the R-adapter is tuned the same way?

Steve, the Novoflex adapter lost functionality with my Leica T and I believe won't relay 6-bit lens information on the SL, perhaps other losses on the SL.   

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Hate to hear this, I've thought that the Leica adapter, as pricey as it is, should keep the correct distance... then I wonder if it's better to save some cash buying a Novoflex adapter...

 

p.s.: the R-adapter is tuned the same way?

 

We've had this discussion here before. This is the manufacturing approach for ALL adapters to cope with lens variation, irrespective of who makes them. 

 

It's to ensure that all lenses can be used, no matter how crappily they have been adjusted when made. 

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To me, this is non-sense (NB: not your post, but the Leica approach).

If a M lens is "crappily adjusted", and you mount it on a well-adjusted M camera, it can't be used, it must be tuned first. Same stuff for R lenses on R cameras. You have a poorly adjusted lens, you send it to Leica AG, or to a good independent technician, and have fixed it.

Otherwise you can't focus to infinity.

 

Why the hell they use a different approach for adapters? Why do they support out-of-spec lenses? We're not talking about cheap M42 adapters, we're talking about Leica lenses and bodies: using adapters on a SL is not meant to be a cheap solution to use some €25 lens salvaged from scrap (yeah, you can do that too, but it's not the point...), it's meant to be the way to use (nearly) all Leica lenses to their full potential...

 

A Noctilux or a Apo-Summicron user have his lens(es) poorly serviced? And how he can use it on a M camera, then?

Edited by Steve McGarrett
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It's not the Leica approach .... it's the industry approach and you can see the logic behind it, even it goes against what I (and you) would do. 

 

It is better that everyone can focus every lens rather and put up with a few moaners that want the infinity stop of a lens to coincide with focus on a mirrorless camera where it is basically not required. 

 

My T and the adapter went back to Leica as I was not happy ..... and was pronounced to work exactly as it was designed to.

 

After a few days of grumbling I dismantled the bloody thing and inserted various shims as spacers till it worked how I wanted it to. Took a few hours and is a non-destructive modification. 

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Why the hell they use a different approach for adapters?

 

Probably because the adapter itself expands and contracts with changes in temperature. If it was adjusted to hit infinity exactly at -40c, then it would not focus to infinity at +40c. The easiest solution is to have it be right at the highest likely temperature, knowing that it will be slightly short in more temperate weather, and thus will focus past infinity.

That's also the reason why long telephoto lenses are often painted silver (Leica), or white (Canon), and have focus scales that go past infinity.

It's a bit counter-intuitive, but, in the case of an adapter, the effect is most noticeable with wide angle lenses and not long lenses. That's because the adapter sits between the lens and camera. A change in length of 1mm (which would be a lot) is 4% of the focal length for a 24mm, but only 0.5% for a 200mm.

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We had the temperature argument as well last time. 

 

Using the expansion coefficients of the metals involved and the temperature ranges the tolerance built into the adapter is at least a factor of 10x more than required. 

 

Someone has done a calculation on the back of a cigarette packet, added a fair bit for luck and settled on 0.1mm. Nice round number and easy to remember. 

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Probably because the adapter itself expands and contracts with changes in temperature. If it was adjusted to hit infinity exactly at -40c, then it would not focus to infinity at +40c. The easiest solution is to have it be right at the highest likely temperature, knowing that it will be slightly short in more temperate weather, and thus will focus past infinity.

That's also the reason why long telephoto lenses are often painted silver (Leica), or white (Canon), and have focus scales that go past infinity.

It's a bit counter-intuitive, but, in the case of an adapter, the effect is most noticeable with wide angle lenses and not long lenses. That's because the adapter sits between the lens and camera. A change in length of 1mm (which would be a lot) is 4% of the focal length for a 24mm, but only 0.5% for a 200mm.

 

Yes, but so does the lens mount itself when you put it on a M camera.

Still, you're able to focus to infinity by the hard stop.

Maybe in extreme climate conditions the infinity setting will be slightly off on a M camera, I don't know, I didn't make any specific test, but I've never noticed any misfocus in real life photography.

 

Allowing to focus slightly past the infinity settings make sense with long telephotos as you said, when the real infinity is many hundreds of meters away and it may be tricky to nail focus at long range (but not infinity yet)

Edited by Steve McGarrett
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It's not the Leica approach .... it's the industry approach and you can see the logic behind it, even it goes against what I (and you) would do. 

 

It is better that everyone can focus every lens rather and put up with a few moaners that want the infinity stop of a lens to coincide with focus on a mirrorless camera where it is basically not required. 

 

My T and the adapter went back to Leica as I was not happy ..... and was pronounced to work exactly as it was designed to.

 

After a few days of grumbling I dismantled the bloody thing and inserted various shims as spacers till it worked how I wanted it to. Took a few hours and is a non-destructive modification. 

 

Yeah, I know, but I don't like to mess with shims, I'd be worried about surface planarity when reassembled.

 

It's a problem I know because I've tried many adapters for Sony cameras, I've hoped that due to very high prices the Leica ones were built to tighter tolerances.

 

However, it seems there is a brand who makes adapters of the right lenght... at least for Sony, but maybe Kipon make 'em for Leica too...

http://blog.kasson.com/the-last-word/still-more-on-adapter-tolerance/

Edited by Steve McGarrett
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Yes, but so does the lens mount itself when you put it on a M camera.

An adapter is just a tube, whereas the elements in a lens are not attached to the mount directly, which can compensate in the other direction. As an example, the rear lens mount may get shorter with colder temps, pulling the glass back toward the sensor, but the helical also gets shorter, which pulls the glass forward.

I doubt that the compensation is as extensive as on a marine chronometer, but it is probably a factor.

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... Same stuff for R lenses on R cameras. ...

 

Not quite true for R lenses/cameras. 

 

In an R camera, you are focusing on the image produced by the lens itself.  In a mirrorless camera, the image you focus on IS the image that the sensor sees.  In an R camera, the image that you focus on SHOULD BE in the same focus plane, IF the mirror and the camera body are properly adjusted, and, in SLRs with interchangeable focusing screens, the screen is sitting properly in its mount.

 

Guy

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Oh no this was not what I wanted to hear.

I was just about to post a question on:- if there are any image quality issues with using SL + MadapterL or MadapterT (not sure if there is a difference). I have a similar issue with a M - Sony NEX adapter on my Sony A7. I also get the lens distance scale not matching the actual focus distance. But it's not that that I'm really worried about but the use of the wider apertures on the wider angle lenses, 35mm and wider. On the A7 I get nasty looking effects in the lower corners (subject distance closer than start of hyperlocal) and nasty bokeh in the upper corners , (greater than end of hyperlocal) with the 35mmF2asph so I have to use f8 for clean images.

 

I.e. is it only the DOF that is allowing us to get a sharp image on the sensor because the adapter isn't focusing the image on the Leica sensor plane correctly?

 

I guess the question is would a 35mm M lenses at F4 to F2 on an M240 have the same image quality as the same lens same aperture on the SL with Adapter? You'd hope the sensor micro lenses etc would allow you to use the M lenses and give as good image quality as when used on an equivalent M body. If not then the adapter isn't for professional use with the M lenses and you can only really use the native SL lenses.

 

If the M lenses give images that look the same(ignoring sensor colour rendition, dynamic range differences) , even in the OOF corners, on the M240 (M10) as on the SL then I'll consider getting an SL, but if they are considerably poorer on the SL + Adapter then I can get that effect with the Sony A7 + adapter. By "look the same" I'm ignoring sensor colour rendition or dynamic range difference between the different Leica CMOS 24M pixel sensors but more about seeing the lens characteristics focus DOF and OOF effects which should appear the same when using the same lens same settings but on different cameras M240/M10/SL.

 

Some of the images posted on the SL pics thread with M lenses look nasty in the OOF corners for lenses like 50 summilux asph or 35mm FLE when using wide apertures. The corners look like they have camera shake but the centre in focus is sharp (I get that on the cheap Sony A7 with cheap adapter + expensive 35mmF2Asph M). Similar image issues for some of the longer R lenses on SL have nasty distracting bokeh but as I don't have or use these particular lenses it's difficult to know if its the lens' character or the effect of the adapter on the SL.

 

As Leica photography is all about Image quality and lens character (for me anyway) we don't want to use anything that degrades that as it makes the whole think pointless. We might as well just use a phone or a small digital compact point and shoot.

 

Do I take a risk with SL + adapter or play safe with M240/M262/M10?

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Oh no this was not what I wanted to hear.

I was just about to post a question on:- if there are any image quality issues with using SL + MadapterL or MadapterT (not sure if there is a difference). I have a similar issue with a M - Sony NEX adapter on my Sony A7. I also get the lens distance scale not matching the actual focus distance. But it's not that that I'm really worried about but the use of the wider apertures on the wider angle lenses, 35mm and wider. On the A7 I get nasty looking effects in the lower corners (subject distance closer than start of hyperlocal) and nasty bokeh in the upper corners , (greater than end of hyperlocal) with the 35mmF2asph so I have to use f8 for clean images.

 

I.e. is it only the DOF that is allowing us to get a sharp image on the sensor because the adapter isn't focusing the image on the Leica sensor plane correctly?

 

I guess the question is would a 35mm M lenses at F4 to F2 on an M240 have the same image quality as the same lens same aperture on the SL with Adapter? You'd hope the sensor micro lenses etc would allow you to use the M lenses and give as good image quality as when used on an equivalent M body. If not then the adapter isn't for professional use with the M lenses and you can only really use the native SL lenses.

 

If the M lenses give images that look the same(ignoring sensor colour rendition, dynamic range differences) , even in the OOF corners, on the M240 (M10) as on the SL then I'll consider getting an SL, but if they are considerably poorer on the SL + Adapter then I can get that effect with the Sony A7 + adapter. By "look the same" I'm ignoring sensor colour rendition or dynamic range difference between the different Leica CMOS 24M pixel sensors but more about seeing the lens characteristics focus DOF and OOF effects which should appear the same when using the same lens same settings but on different cameras M240/M10/SL.

 

Some of the images posted on the SL pics thread with M lenses look nasty in the OOF corners for lenses like 50 summilux asph or 35mm FLE when using wide apertures. The corners look like they have camera shake but the centre in focus is sharp (I get that on the cheap Sony A7 with cheap adapter + expensive 35mmF2Asph M). Similar image issues for some of the longer R lenses on SL have nasty distracting bokeh but as I don't have or use these particular lenses it's difficult to know if its the lens' character or the effect of the adapter on the SL.

 

As Leica photography is all about Image quality and lens character (for me anyway) we don't want to use anything that degrades that as it makes the whole think pointless. We might as well just use a phone or a small digital compact point and shoot.

 

Do I take a risk with SL + adapter or play safe with M240/M262/M10?

Huh? You come up with “we may as well just use a phone...” based upon speculation on problems that may or may not even exist?

 

Try the M to L adapter on an SL. Or check out the huge number of available images online. I don’t see what you are stating you see in the corners of the images I’ve looked at. Or check out Sean Reid’s site where he tests on both the SL and M.

 

The adapter works just fine with my 35 and 50 Summiluxes at all apertures on the SL. I can see no noticeable difference between the SL and the MP240 with these lenses. I have not set up rigorous tests like Reid has because I have seen no issues with my normal workflow. The choice between the same lenses on the two cameras comes down to other considerations besides IQ for me.

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Good lord ...... what a lot of fuss about nothing.

 

Does anyone actually look at the distance marking on the lens these days or for that matter regard them as anything other than a vague estimation of range anyway ???? 

 

With an SL you can get perfect focus with the EVF, EVF+magnification and or Focus Peaking with any lens. What else do you want ?

 

The SL sensor is configured specifically to give excellent results with M and R lenses ...... the only poor performers are the few older M designs which which have now been updated ..... and even then we are talking marginal softening of extreme corners in wide angle lenses (I know ..... I did the tests and posted the results 18months ago). 

 

There is a minor irritation with adapted lenses that idle folk like me cannot just set the lens to infinity when wide open and expect it to be exactly in focus. That's it. The only other occasion with problems would be star field photos at night ..... but even then the DOF of a sub 24mm lens is likely to prevent trouble. 

 

If you are that distressed with this appalling lapse on Leicas (and other adapter makers) part then by all means throw your dolly out of the pram and complain about it, but it's hardly a sane reason not to buy an SL. 

 

I spent half an hour dismantling the adapter, cutting out a 5mm wide ring of 0.09mm thick screen protector, stuck it in the adapter and reassembled it ensuring all the screws were equally tight. That solved the problem rather than moaning about it. 

Edited by thighslapper
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Good lord ...... what a lot of fuss about nothing.

 

Does anyone actually look at the distance marking on the lens these days or for that matter regard them as anything other than a vague estimation of range anyway ???? 

Actually, I do.  From 75 mm down, it's nice to have the infinity stop be correct to let you shoot fast, but I have older lenses and long lenses that can't be trusted and in some cases are used with digital backs that only permit checking focus after a test shot.  So I test carefully to see where "infinity" lies today, extract how much rotation is needed from the marked distance for a good picture, and make that correction at other distances.  And shooting an event recently I couldn't get the rangefinder to respond on my M, so I scale-focused and everything pretty much came out OK.  (The problem was that I had not seated the lens fully, and it backed out so far that the RF cam had nothing to respond to, but it was dark and I didn't have time to trouble-shoot.)  And finally, working in video with the SL, the focus peaking sparklies are not very reliable.  If you have to pull focus, the scale is the gold standard.  With real cinema lenses, the scale IS a gold standard.

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LD_50

Thanks for your reassurance about the SL + Adapter. As an amateur Leica M film photographer who has seen issues with my ~£1000 Sony A7 + adapter for M lenses, moving to the Leica SL + adapter (~£4000 used) is a big outlay so forgive me for being cautious and asking the forum for their experience with SL+ adapter when considering moving to SL.

 

I'll probably have to visit Leica in London to test the SL + Adapter and see for myself. If the only minor issue with the adapter is the distance scale on the lens doesn't match but you always need to use the focus peaking then I suppose that's acceptable. If you know it's there you can work with it.

 

Regards, Lincoln

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