Nokton 50mm F1 backfocusing on M240?

[SimonV]

I just recently got into the M-system for the first time with a M240. At the moment I'm trying to decide between the Voigtländer Nokton 50mm F1.2 and the Nokton 50mm F1, I'm currently testing both to decide which to keep. Naturally I'm aware of the differences in weight and such, but I got the F1 just for the better sharpness wide open at minimum focusing distances, even though it's 90cm vs the 70cm on the F1.2.

It seems though that the 50mm F1 is clearly backfocusing on my camera, and I'm trying to find out if it's a fault with the lens or the body, perhaps a calibration issue. I realize the plane of focus is shallow, but the 50mm F1.2 doesn't seem to have this issue, so I'm confused, since both lenses have very shallow DOF. I've tried the Summicron 50mm F2 and the Voigtländer Color Skopar 50mm F2.2, which are slightly more forgiving. The Summicron did seem to slightly backfocus as well, so perhaps the problem is indeed with the camera. How much does calibration of a Leica body and lenses normally cost? Is it something you have to do all the time or does it stay good as long as you don't mishandle the camera?

What confuses me about the 50mm F1 though is that it seems to backfocus even when using the LCD. At longer distances the lens is somewhat accurate even at F1, but closer up (MFD to a few meters) not so much. I have a VF2 EVF as well, but I didn't get into rangefinder cameras to use EVFs.

A very old thread here on DPReview mentioned something about the Nokton F1.1 (I assume? They still called it the F1) being back focused by design. Could it be something similar with the modern F1?

Any tips would be appreciated!

 

[Franz Kerschbaum]

You cannot have backfocus on your screen. It shows the sensor data as in the resulting picture. But both noktons show some field curvature. So be sure to zoom into the right spot that you want to have in perfect focus.

 

[SimonV]

You cannot have backfocus on your screen. It shows the sensor data as in the resulting picture. But both noktons show some field curvature. So be sure to zoom into the right spot that you want to have in perfect focus.

This is what I'd say too. I'm just zooming in to the center where I'm focusing as well.

Normally I would find it most likely that I happened to move a few mm forwards when taking the shot, but then it should show up more in the F1.2 shots too, I'd imagine. Naturally F1 is shallow, but I must say I'm not sure how much shallower it is than F1.2. With the F1.2 I have much less problems getting things I'm trying to get in focus. I'm inclined to believe I'm the culprit here, but maybe that just tells me I should go with the F1.2 instead.

 

[David Kieltyka]

How much does calibration of a Leica body and lenses normally cost? Is it something you have to do all the time or does it stay good as long as you don't mishandle the camera?

I can't say anything about possible lens calibration issues as I've never owned any of the Voigtländer fast 50mms. I do have a 50mm f/1 Noctilux, though, and accurately focusing that lens at f/1 with any of the sensor-based M cameras via the rangefinder is tough. And I've been using M cameras for over 50 years now. I also own a 7Artisans 50mm f/1.1, and focusing it wide open isn't any easier. I don't much like using EVFs on M cameras, but for those two lenses I make exceptions.

I'd recommend making things easier for yourself by starting with a 50mm f/2. A v4 (focus tab) or v5 (focus ring) Summicron would be a great choice. The v5 is still in production if you prefer buying new instead of used.

The currrent Voigt 50/2 is part of their APO lineup and is a highly-corrected lens…I'm guessing this isn't what you're going for. A used f/2 Heliar might be a better choice.

The Zeiss 50/2 ZM Planar is a fine lens, very similar to the Summicron but a little wider…somewhere between 47 & 48mm. I've owned one since the lens was introduced, ~20 years ago, and it's seen lotsa use.

Oh…as for rangefinder calibration, the only M I've ever had calibrated (as part of a general Clean, Lubricate, Adjust procedure) was my M3 and that was at least 15 years ago. I treat my cameras pretty gently, though. If I were bangin' 'em around I'd likely be sending 'em off to Leica every few years.

-Dave-

 

[SimonV]

How much does calibration of a Leica body and lenses normally cost? Is it something you have to do all the time or does it stay good as long as you don't mishandle the camera?

I can't say anything about possible lens calibration issues as I've never owned any of the Voigtländer fast 50mms. I do have a 50mm f/1 Noctilux, though, and accurately focusing that lens at f/1 with any of the sensor-based M cameras via the rangefinder is tough. And I've been using M cameras for over 50 years now. I also own a 7Artisans 50mm f/1.1, and focusing it wide open isn't any easier. I don't much like using EVFs on M cameras, but for those two lenses I make exceptions.

I'd recommend making things easier for yourself by starting with a 50mm f/2. A v4 (focus tab) or v5 (focus ring) Summicron would be a great choice. The v5 is still in production if you prefer buying new instead of used.

The currrent Voigt 50/2 is part of their APO lineup and is a highly-corrected lens…I'm guessing this isn't what you're going for. A used f/2 Heliar might be a better choice.

The Zeiss 50/2 ZM Planar is a fine lens, very similar to the Summicron but a little wider…somewhere between 47 & 48mm. I've owned one since the lens was introduced, ~20 years ago, and it's seen lotsa use.

Oh…as for rangefinder calibration, the only M I've ever had calibrated (as part of a general Clean, Lubricate, Adjust procedure) was my M3 and that was at least 15 years ago. I treat my cameras pretty gently, though. If I were bangin' 'em around I'd likely be sending 'em off to Leica every few years.

-Dave-

Thanks for the detailed reply, very informative! I actually have the Summicron v5 too but it's going back, I can't justify the price vs. the look from the lens, it just isn't for me I guess. I couldn't tell it apart from shots I took on any cheap 50mm I've used before. I don't know if that's sacrilege in the Leica community, but maybe I just can't appreciate it, it seems very low contrast at F2 and bland compared to the Voigtländers, for instance. If it was even close to the image quality I'd absolutely keep it, since the form factor, balance etc. on the Leica body and looks of it are way ahead of the Voigtländers. The Color Skopar 50mm F2.2 I'm keeping though, it's brilliant in every way except for the comparatively small aperture. Sharper and more contrasty too, and super light.

My main confusion about the 50mm F1 is that the focus is so off vs. the 50mm 1.2. The 1.2 I can focus quite easily wide open with the rangefinder and hit focus, but the F1 just seems to be behind the subject almost every time, except when using the LCD. Sure, F1 is shallower than F1.2, but I don't think the difference should be this significant.

I will check out the Planar though, thanks!

 

[Rodenmg]

As far as the rangefinder is concerned both the camera body and the lenses are calibrated to a standard. The calibration adjustment in the body is possible for the user to do. The Leica M lens must be dissembled to adjust.
In your case it would be possible to calibrate the body to the lens that is back focusing but then it would be off with any other lens that is properly calibrated. I do not know if Voigtlander lenses can be calibrated like the Leica M lenses.

--
... Mike
... https://www.flickr.com/photos/198581502@N02/

 

[David Kieltyka]

Thanks for the detailed reply, very informative! I actually have the Summicron v5 too but it's going back, I can't justify the price vs. the look from the lens, it just isn't for me I guess. I couldn't tell it apart from shots I took on any cheap 50mm I've used before. I don't know if that's sacrilege in the Leica community, but maybe I just can't appreciate it, it seems very low contrast at F2 and bland compared to the Voigtländers, for instance. If it was even close to the image quality I'd absolutely keep it, since the form factor, balance etc. on the Leica body and looks of it are way ahead of the Voigtländers. The Color Skopar 50mm F2.2 I'm keeping though, it's brilliant in every way except for the comparatively small aperture. Sharper and more contrasty too, and super light.

My main confusion about the 50mm F1 is that the focus is so off vs. the 50mm 1.2. The 1.2 I can focus quite easily wide open with the rangefinder and hit focus, but the F1 just seems to be behind the subject almost every time, except when using the LCD. Sure, F1 is shallower than F1.2, but I don't think the difference should be this significant.

I will check out the Planar though, thanks!

The v4 & 5 50mm 'Crons are meant to be basic workhorse lenses. Since that doesn't sound like what you're going for you should return it. Note: the Zeiss Planar is a touch contrastier but only a touch.

My own favorite 50 on M cameras is a late 1950s Topcor-S f/2 in Leica Thread Mount, made by Topcon only for 2–3 years and apparently never exported. Until a few years ago I'd never even heard of it. Cost me ~US $300 including shipping from Japan. The lens likely doesn't have the contrast you're looking for, but it's surprisingly modern in its rendering for an optic 65+ years old. (I lucked into one that had just been CLA'd and didn't suffer from a common drawback: element separation.)

You might want to consider a 50mm f/1.4 Summilux ASPH. This lens has more pizzazz than the v4/5 'Cron but isn't as highly corrected as the later APO lenses. I'm mostly not a wide-open lens guy but this is one I do enjoy using at f/1.4.

It's certainly possible your Voigt f/1.0 is miscalibrated. That it's repeatably off in the same direction suggests this. At the same time, though, the lens is pushing your camera's rangefinder a bit beyond its focusing capability, particularly at closer distances. An M3 with its .91x VF magnification can handle a 50/1.0, as can the later film Ms with .85x mag. An M240 with its .68x mag, or even the current Ms with their .73x…different story.

-Dave-

 

[Geniet]

“SimonV wrote:
Thanks for the detailed reply, very informative! I actually have the Summicron v5 too but it's going back, I can't justify the price vs. the look from the lens, it just isn't for me I guess. I couldn't tell it apart from shots I took on any cheap 50mm I've used before. ...”
Possibly of interest:

YouTube:
“...The Real Reason Your Photos Aren’t Sharp (and how to fix it)...”.

Also, it is remarked kindly, that the vocabulary/language(s), one has command of, influences.

Kind regards,

 

[ffabrici]

I just recently got into the M-system for the first time with a M240. At the moment I'm trying to decide between the Voigtländer Nokton 50mm F1.2 and the Nokton 50mm F1, I'm currently testing both to decide which to keep. Naturally I'm aware of the differences in weight and such, but I got the F1 just for the better sharpness wide open at minimum focusing distances, even though it's 90cm vs the 70cm on the F1.2.

It seems though that the 50mm F1 is clearly backfocusing on my camera, and I'm trying to find out if it's a fault with the lens or the body, perhaps a calibration issue. I realize the plane of focus is shallow, but the 50mm F1.2 doesn't seem to have this issue, so I'm confused, since both lenses have very shallow DOF. I've tried the Summicron 50mm F2 and the Voigtländer Color Skopar 50mm F2.2, which are slightly more forgiving. The Summicron did seem to slightly backfocus as well, so perhaps the problem is indeed with the camera. How much does calibration of a Leica body and lenses normally cost? Is it something you have to do all the time or does it stay good as long as you don't mishandle the camera?

What confuses me about the 50mm F1 though is that it seems to backfocus even when using the LCD. At longer distances the lens is somewhat accurate even at F1, but closer up (MFD to a few meters) not so much. I have a VF2 EVF as well, but I didn't get into rangefinder cameras to use EVFs.

A very old thread here on DPReview mentioned something about the Nokton F1.1 (I assume? They still called it the F1) being back focused by design. Could it be something similar with the modern F1?

Any tips would be appreciated!

It sounds like the f/1 lens is not perfectly calibrated.

 

[SimonV]

Thanks for the detailed reply, very informative! I actually have the Summicron v5 too but it's going back, I can't justify the price vs. the look from the lens, it just isn't for me I guess. I couldn't tell it apart from shots I took on any cheap 50mm I've used before. I don't know if that's sacrilege in the Leica community, but maybe I just can't appreciate it, it seems very low contrast at F2 and bland compared to the Voigtländers, for instance. If it was even close to the image quality I'd absolutely keep it, since the form factor, balance etc. on the Leica body and looks of it are way ahead of the Voigtländers. The Color Skopar 50mm F2.2 I'm keeping though, it's brilliant in every way except for the comparatively small aperture. Sharper and more contrasty too, and super light.

My main confusion about the 50mm F1 is that the focus is so off vs. the 50mm 1.2. The 1.2 I can focus quite easily wide open with the rangefinder and hit focus, but the F1 just seems to be behind the subject almost every time, except when using the LCD. Sure, F1 is shallower than F1.2, but I don't think the difference should be this significant.

I will check out the Planar though, thanks!

The v4 & 5 50mm 'Crons are meant to be basic workhorse lenses. Since that doesn't sound like what you're going for you should return it. Note: the Zeiss Planar is a touch contrastier but only a touch.

My own favorite 50 on M cameras is a late 1950s Topcor-S f/2 in Leica Thread Mount, made by Topcon only for 2–3 years and apparently never exported. Until a few years ago I'd never even heard of it. Cost me ~US $300 including shipping from Japan. The lens likely doesn't have the contrast you're looking for, but it's surprisingly modern in its rendering for an optic 65+ years old. (I lucked into one that had just been CLA'd and didn't suffer from a common drawback: element separation.)

You might want to consider a 50mm f/1.4 Summilux ASPH. This lens has more pizzazz than the v4/5 'Cron but isn't as highly corrected as the later APO lenses. I'm mostly not a wide-open lens guy but this is one I do enjoy using at f/1.4.

It's certainly possible your Voigt f/1.0 is miscalibrated. That it's repeatably off in the same direction suggests this. At the same time, though, the lens is pushing your camera's rangefinder a bit beyond its focusing capability, particularly at closer distances. An M3 with its .91x VF magnification can handle a 50/1.0, as can the later film Ms with .85x mag. An M240 with its .68x mag, or even the current Ms with their .73x…different story.

-Dave-

The Topcor sounds fun, I've been enjoying my Super Takumar 50 1.4 as well as the Minolta 58mm 1.2, despite them being less contrasty or sharp (still good for their age) than modern lenses.

The Summilux is kind of what I look for in a lens, I just haven't been able to justify the price so far. But maybe it's a buy once, cry once kind of deal. Then again, the Thypoch Simera 50mm 1.4 seems to be quite close to it for a much lower price. It does sometimes feel like you should use a Leica lens on a Leica camera, but time will tell what feels the best.

It is indeed difficult with a smallish viewfinder to get accurate focus, although this is kind of part of the charm I was prepared for with the M-system. But when it looks sharp and comes out back focused, it's tricky. But, I will continue to test to find out how much of it is me vs. the lens.

Thanks again!

 

[DenverSteve]

It sounds like the f/1 lens is not perfectly calibrated.

Perfect (short) answer. If one lens works and the other doesn't, it doesn't matter why. Unnecessary distraction is a waste of time. Get rid of the lens that's not focusing for you and use the other.

 

[pavel_k]

Perhaps you’re seeing focus shift.

Nokton 50/1.0 has a focus shift. Some users report their copy calibrated to 1.0 and some 2.0. If yours is calibrated to 1.0 it should look good at 1.0 and backfocus at smaller apertures. If it’s calibrated to 2.0 it will show front focus at 1.0 and look perfect at 2.0.

 

[JDLaing50]

Perhaps you’re seeing focus shift.

Nokton 50/1.0 has a focus shift. Some users report their copy calibrated to 1.0 and some 2.0. If yours is calibrated to 1.0 it should look good at 1.0 and backfocus at smaller apertures. If it’s calibrated to 2.0 it will show front focus at 1.0 and look perfect at 2.0.

Focus shift is an anomaly on an auto focus lens. If it’s a manual rangefinder lens it’s either front or back focus.

 

[Franz Kerschbaum]

no its an optical property. Esp. with strong spherical abberation the outer light rays have a different focud. That leads to a focus shift when stopping down.

 

[Rodenmg]

Perhaps you’re seeing focus shift.

Nokton 50/1.0 has a focus shift. Some users report their copy calibrated to 1.0 and some 2.0. If yours is calibrated to 1.0 it should look good at 1.0 and backfocus at smaller apertures. If it’s calibrated to 2.0 it will show front focus at 1.0 and look perfect at 2.0.

Focus shift is an anomaly on an auto focus lens. If it’s a manual rangefinder lens it’s either front or back focus.

From what I’ve read focus shift (focal plane shifting at different apertures) can happen with manual focus lenses. Of course, the rangefinder doesn’t see what the lens does. Some Leica M lenses are known to suffer this. Leica tried to correct for this by producing FLE (floating element) models. The Noctilux M 0.95 was the first Noctilux to use this design.

 

[JDLaing50]

no its an optical property. Esp. with strong spherical abberation the outer light rays have a different focud. That leads to a focus shift when stopping down.

The last thing anybody does before they press the shutter is focus. I know of no one else that does any different on a rangefinder.
Focus shift is when an auto focus camera opens up the lens to set focus and then closes down to the aperture you have chosen to capture the image.

 

[JDLaing50]

Perhaps you’re seeing focus shift.

Nokton 50/1.0 has a focus shift. Some users report their copy calibrated to 1.0 and some 2.0. If yours is calibrated to 1.0 it should look good at 1.0 and backfocus at smaller apertures. If it’s calibrated to 2.0 it will show front focus at 1.0 and look perfect at 2.0.

Focus shift is an anomaly on an auto focus lens. If it’s a manual rangefinder lens it’s either front or back focus.

From what I’ve read focus shift (focal plane shifting at different apertures) can happen with manual focus lenses. Of course, the rangefinder doesn’t see what the lens does. Some Leica M lenses are known to suffer this. Leica tried to correct for this by producing FLE (floating element) models. The Noctilux M 0.95 was the first Noctilux to use this design.

That would be front or back focus at a specific aperture. It would not be prudent to focus a rangefinder and then change aperture to capture the image without checking focus again. As I said to Franz the last thing you do before pressing the shutter release on a rangefinder is focus.

 

[Rodenmg]

Perhaps you’re seeing focus shift.

Nokton 50/1.0 has a focus shift. Some users report their copy calibrated to 1.0 and some 2.0. If yours is calibrated to 1.0 it should look good at 1.0 and backfocus at smaller apertures. If it’s calibrated to 2.0 it will show front focus at 1.0 and look perfect at 2.0.

Focus shift is an anomaly on an auto focus lens. If it’s a manual rangefinder lens it’s either front or back focus.

From what I’ve read focus shift (focal plane shifting at different apertures) can happen with manual focus lenses. Of course, the rangefinder doesn’t see what the lens does. Some Leica M lenses are known to suffer this. Leica tried to correct for this by producing FLE (floating element) models. The Noctilux M 0.95 was the first Noctilux to use this design.

That would be front or back focus at a specific aperture.

That is pretty much the definition of focus shift.

It would not be prudent to focus a rangefinder and then change aperture to capture the image without checking focus again. As I said to Franz the last thing you do before pressing the shutter release on a rangefinder is focus.

Looking through the rangefinder has nothing to do with the light passing through the lens. You can spin the aperture ring all you want but can’t see anything different in the rangefinder. That is exactly why it can be an issue with rangefinders.

 

[aknyc]

It seems though that the 50mm F1 is clearly backfocusing on my camera, and I'm trying to find out if it's a fault with the lens or the body, perhaps a calibration issue. I realize the plane of focus is shallow, but the 50mm F1.2 doesn't seem to have this issue, so I'm confused, since both lenses have very shallow DOF. I've tried the Summicron 50mm F2 and the Voigtländer Color Skopar 50mm F2.2, which are slightly more forgiving. The Summicron did seem to slightly backfocus as well, so perhaps the problem is indeed with the camera. How much does calibration of a Leica body and lenses normally cost? Is it something you have to do all the time or does it stay good as long as you don't mishandle the camera?

Since everyone is suggesting calibration and other lenses, let me clarify the facts.

The 50mm F1 has a focusing issue in the minimal focus distance up to 1.2m; the rest is fine.
I assume you would get the f1 for the look and speed.
I noticed the same issue on the first day of testing. The lens was returned right after.

Comparing the 50mm 0.95 to the 50mm f1, the problem was very evident.

50 f1.2
This lens is a bit older, and the image wide open has a very low-contrast look to it.
Version II has improved and is still sharp but has lower contrast and microcontrast. If you like that look, it is a good lens. It improves by stopping down, like most lenses. You can add some contrast in post, too.

As a budget option, I would also consider the Voigtlander Nokton 50mm f/1.5 Aspherical II.
It is a lens with great character, but good. Wide open, there is a bit of chromatic aberration visible.

 

[David Kieltyka]

no its an optical property. Esp. with strong spherical abberation the outer light rays have a different focud. That leads to a focus shift when stopping down.

The last thing anybody does before they press the shutter is focus. I know of no one else that does any different on a rangefinder.
Focus shift is when an auto focus camera opens up the lens to set focus and then closes down to the aperture you have chosen to capture the image.

Focus shift, as the term is commonly used, is an optical property. Sonnar lenses are particularly notorious for shifting the point of focus as you stop down or open up the aperture. This in inherent in the Sonnar optical formula and has nothing to do intrinsically with autofocus camera behavior. But some AF cameras will adjust the point of focus to compensate for this when you're using a shift-prone lens.

-Dave-