Nokton 50mm f/1.1 Backfocus

[dNorm]

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Just got a response from Gandy. His advice - try using this lens on a film camera due to the magnitude of problems with correct sensor placement of the M8's. So, I am basically sitting on a $900 paperweight at this point. :mad:

 

Hi BigLouis. Thank you for the feedback and I've tried to take in your comments with an open mind. But is my thinking flawed that I should expect the focus be within the DoF even at f/1.1 after testing it on a tripod to mitigate any sort of unsteadiness on my part? And even when stopped down to f/4, the focus is off. I've also noticed that the further away the subject is, the more it back focuses. I had sent DAG an email and I am told that he can not adjust it because of it's design. I've not yet heard back from Stephan Gandy. But at any rate, thanks for taking the time to respond. -Norm

[jaapv]

That is nonsense by Steven - the film solution works because film is more forgiving in focussing- and film is not 100% flat, being closer to the lens in the middle than it should be, thus compensating for the focus problem of the lens. There is no "correct sensor placement problem" on the M8, if anything it is too precise.....( it wouldn't work on Noctiluxes and Summiluxes either if he were right:rolleyes:) So in the upshot his advice "use it on film" is correct.

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[wlaidlaw]

Just got a response from Gandy. His advice - try using this lens on a film camera due to the magnitude of problems with correct sensor placement of the M8's. So, I am basically sitting on a $900 paperweight at this point. :mad:

 

I cannot believe that someone like Stephen said that. As Jaap says that is a total load of bull pucky and a very feeble excuse for poor manufacturing standards. I would send a personal email to Hirofumi Kobayashi, the president of Cosina, setting out your problems and attaching a copy of the incredible response of Stephen Gandy. I hope that "losing face" might enter into the picture and you will be offered a brand new replacement lens, direct from Cosina. You would need to get the customs side sorted for a guarantee replacement, so that you do not pay duty on any incoming lens.

 

I keep hoping that Zeiss might bite the bullet and design a fast 50 at a higher price point than the hit or miss Nokton but more affordable than the Noctilux. I know they do the 50/1.5 Sonnar but that is rather a specialist lens.

 

Wilson

[k_g_wolf ✝]

>> dNorm

 

 

Perhaps you got a lemon there, but the 50 mm-NOKTON I used for this shot (at f 1.1)

on the M8 a few days ago works VERY fine indeed.

 

There is a bit of backfocus from f 4 on, but since I only planned to use it at

f 1.1 to 1.7 I don´t care about this much.

 

 

 

Best

 

GEORG

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[Guest mc_k]

Actually, it is not THAT extreme a lens. With a DOF of 17 cm at 3 m, it is considerably easier to focus than a Summilux 75 or Summicron 90, that both have a DOF of 10 cm at 3 m....

 

if you equate for what is in the frame and compare at 3, 4.5, and 5.4m respectively the 50/1.1 has significantly less depth of field, no?

[Bo_Lorentzen]

Ehh. if you equates for what is in the frame, then you basically crop the 50mm to be 75mm ish. at that point the two lenses should have roughly the same dof at the same f.stop the difference would probably be the nokton being a bit dirtier than the 75 1.4 or a 50 1.4 with more scatter, but the actual dof is going to be about the same.

 

I think Jaap were refering to me claiming 1/4 inch dof at 1m

 

.

[Guest mc_k]

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Norm,

 

Ouch, that changes things a little I suppose, from what other posters are saying it seems the cam can no be adjusted. basically the issue you are describing could be fixed by a slight polishing of the cam, however I would not dare think about how to do that in a calibrated manner. :-) Stephen would be the closest guy to have a real answer to this.

 

.

 

well I am amused by the guys / gals buying the Russian lenses and making washers out of shim stock.

 

As someone said you really should have your rangefinder checked if convenient...even if your other lenses seem o.k.

 

If all else fails you might have a backup camera set slightly forward, as an alternative to adjusting a lens. You may find your other lenses still work as expected.

[Guest mc_k]

Ehh. if you equates for what is in the frame, then you basically crop the 50mm to be 75mm ish. at that point the two lenses should have roughly the same dof at the same f.stop...

 

...I was comparing the three lenses wide open: f/1.1, f/1.4, and f/2, respectively. It comes up a lot, that the 75/1.4 wide open has less depth of field than the noctilux wide open, but I think the proper comparison is to fill the same frame, like you would in a close-up portrait?

Edited December 29, 2009 by mckeough_k

[Bo_Lorentzen]

IF you shoot from different distances to make the subject fill the same amount in the frame. hmm . Ha. I don't have a DOF calculator book-marked.. But having both lenses, I would say the "practical" dof would be rather close to each other.

[Guest mc_k]

the usual online calculator gives 17cm for the 50 at 3m; 23cm for the 75 at 4.5m; and 33cm for the 90 at 5.4m (all wide open).

 

Anyway I was not disagreeing with your math or Jaap's...the point was that the 50/1.1 will be a handful even if correctly adjusted.

Edited December 29, 2009 by mckeough_k

[brill64]

I looked at a second hand mint nocti f1 which when all my lenses are spot on, it back focused quite a lot. I bought it anyway and adjusted my rangefinder myself until it was spot-on and perfect focus at f1. but then my 90 macro-elmar was completely off the ball park that i couldn't use it at all. it was so out of focus that i sent it to leica for checking. they sent it back saying "focus was more accurate than most 90's". all my other lenses were still focusing without a problem so i sent my m8.2 in for adjustment and now the nocti only ever-so-slightly back-focuses and the 90/4 works a treat. perhaps your rangefinder needs adjustment?

[wlaidlaw]

the usual online calculator gives 17cm for the 50 at 3m; 23cm for the 75 at 4.5m; and 33cm for the 90 at 5.4m (all wide open).

 

Anyway I was not disagreeing with your math or Jaap's...the point was that the 50/1.1 will be a handful even if correctly adjusted.

 

It is never going to be an easy lens but if it starts off "wrong" it will be impossible. This is like the furore over the 35/1.4 ASPH three years ago, where many of the lenses were coming out of Solms with back focus wide open. The aperture shift that the majority (but strangely not all) of these lenses suffer, took the focus point right out of the DOF and the lenses were to all intents and purposes, unusable.

 

Even at the "cheap" price of $1100, the Nokton should be fit for purpose and that means perfectly in focus wide open at all distances and with aperture shift that does not take it out of the DOF, again at all distances. It should be set up to work properly on the more critical digital M bodies. If it is not capable of all of these things, then it is a paperweight not a lens. The majority of my Leica lenses date from the film era and they all work or have been adjusted to work perfectly both on my film M's and digital M's.

 

Wilson

[jaapv]

You pin-pointed the problem exactly here with self-adjusting There are three adjustment points, of which only the roller wheel is easily accesible. The points are interdependent. So when the infinity adjustment, being the roller, is tweaked to get good focus at shorter distances, the whole system is thrown out of adjustment.

[lct]

...The majority of my Leica lenses date from the film era and they all work or have been adjusted to work perfectly both on my film M's and digital M's...

Same on R-D1 and R-D1s. Within a stable of 30+ M lenses, my only focusing poblems came from Minolta (Rokkor-M 40/2) and CV (35/1.4, 28/2). Anyway, any CV, Minolta or whatever lens has to be be accurate at full aperture. Focus shift is another story.

[dNorm]

Just wanted to follow up. I ended up ordering a new 50mm f/1.1 Nokton from the second batch, which supposedly corrected the back-focus issue on the digital M's. All I can say is that the lens I received is spot-on at f/1.1 on my M8.2. Awesome lens! Cheers. -Norm

[Ronazle]

Norm, I see that you checked focus a variety of apertures. If this was close-up, all apertures of less than 1.1 are likely to exhibit easily measurable backfocus. My excellent Nokton 1.1 is dead on wide open but backfocuses in more or less proportion to stopping down (something like 50mm backfocus at f:/11.0). This is not a real problem except at close-up distances.

 

Having said that, I just compared my 1.1 with the 1.5 Nokton at all apertures from wide open to 4.0. Interestingly, contrast, sharpness, and color rendition was better on the 1.1 than the 1.5 except wide open on the 1.1. Pardon the lack of proper terminology, but at wide open apertures both lenses showed a haze like halo around a white license plate on a black car at about 100 feet. The halo disappeared on the 1.1 at 1.4! Exposures were made w/tripod and self-timer. I sort of conclude (recognizing the limits of the informal comparison testing) that for general use the 1.1 is the better lens if one overlooks the bulk and weight. Neither of these lenses are nearly equal to 50 and 90mm Summicrons at the same range, conditiions and magnification (100). Hope the above is of interest to you or others. ron .

[dNorm]

Ron - Thank you for your feedback. Like I mentioned above, my sample is suppose to be from the second batch, which I was told is a slightly redesigned version, whatever that is suppose to mean. So far, I am very pleased, although I've not done any scientific testing for back-focus. My previous sample was simply off at every aperture. I've only done some casual shooting from f/1.1 - f/4 and do not see any apparent problems, which is good enough for me to be very pleased with the lens. At f/2, the images are razor sharp. Perhaps, Sean Reid will get an opportunity to do the scientific test in the future. Cheers. -Norm

 

Norm, I see that you checked focus a variety of apertures. If this was close-up, all apertures of less than 1.1 are likely to exhibit easily measurable backfocus. My excellent Nokton 1.1 is dead on wide open but backfocuses in more or less proportion to stopping down (something like 50mm backfocus at f:/11.0). This is not a real problem except at close-up distances.

 

Having said that, I just compared my 1.1 with the 1.5 Nokton at all apertures from wide open to 4.0. Interestingly, contrast, sharpness, and color rendition was better on the 1.1 than the 1.5 except wide open on the 1.1. Pardon the lack of proper terminology, but at wide open apertures both lenses showed a haze like halo around a white license plate on a black car at about 100 feet. The halo disappeared on the 1.1 at 1.4! Exposures were made w/tripod and self-timer. I sort of conclude (recognizing the limits of the informal comparison testing) that for general use the 1.1 is the better lens if one overlooks the bulk and weight. Neither of these lenses are nearly equal to 50 and 90mm Summicrons at the same range, conditiions and magnification (100). Hope the above is of interest to you or others. ron .

[Lindolfi]

Bought an unused Nokton 50/1.1 for 600 Euro a few days ago and tested it beforehand. Found backfocus with a constant amount of turn of the focus ring to focus correctly, so I trusted I would be able to correct that.

 

As suggested earlier in this thread that the cam could be polished is wrong when the lens backfocusses! The cam is too short, not too long.

 

So, in very small steps I compressed the cam of the lens by tapping on it with a small hammer, using a flat headed pin (diameter 3 mm) exactly in the middle where it (when mounted) rests agains the rangefinder wheel of the camera. The other side of the cam was supported well with a steel flat object. This compression makes the cam a bit longer (just a few hundredth of a mm) and now the lens focusses exact throughout the range of focussing, from 1 meter to infinity. It took me about half an hour to correct it. It is not necessary to take the lens apart. There is enough room for the pin to reach the cam from the inside when the lens is set to infinity. The outside of the cam is supported by the steel flat object. the lens is supported with a bean bag for instance.

 

So perhaps worthwhile for those who feel they have an overpriced paperweight.

 

But beware: you need only light hammer taps to get the effect needed. If you did too much, you can file it off with a very fine diamond-powdered file, but when you take your time, that is not needed. Tap not quite at the edge of the cam, you want the edge to remain smooth, just about 2 or 3 mm away from the edge with the pin lightly resting on it.

 

Here an example of how well it focusses, taken at f/1.1, focussed on the lips (square crop at full height taken with the M9, no post-processing): click

 

(I dremel coded the lens as a Noctilux 1.0)

 

The lens certainly is worth being corrected, because it is very sharp indeed.

Edited January 10, 2011 by Lindolfi

[epand56]

Perhaps you got a lemon there, but the 50 mm-NOKTON I used for this shot (at f 1.1)

on the M8 a few days ago works VERY fine indeed.

 

There is a bit of backfocus from f 4 on, but since I only planned to use it at

f 1.1 to 1.7 I don´t care about this much.

 

Georg, great picture of one of the most beautiful object on earth. This is the first picture I've seen so far taken with the CV 50/1.1 that makes me wonder if I shouldn't have one.

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[crfcuibap]

You guys should try this http://www.l-camera-forum.com/leica-forum/leica-m8-forum/13933-new-backfocus-thread-solution.html

I found same back focus problem with it on my M8, but I did adjusted well with instructions of the link. Now, it just works, and it works very very well. I love it