Nokton 1.1 First Results

Dez

Dez

Bodger Extraordinaire
Local time
8:25 AM
Joined
May 12, 2009
Messages
1,537
I recently acquired one of these lovely lenses from another RFF'er, and here are a couple of shots taken at f1.1.



I had heard all sorts of conflicting stories about the out-of-focus performance of this lens. Here can be seen very smooth bokeh for relatively low-contrast background details, and rather sharp-edged representations of very bright highlights. The Leica version is permanently out of my financial league, so I am very happy with this result, especially given the price of this lens.



This shot, focused on the central rosebud, pops fairly well, but as I found in a subsequent test, this lens front focuses by about an inch with my M5 at closest range. I'll need to remember that in the future. Is that typical of this lens?

I was originally looking for a Nokton 1.5 in M-mount, but I suspect its performance would be indistinguishable from that of my V2 Summilux, so there would be little point in getting one. I can see myself falling in love with this big lens though.

Cheers,
Dez
 
The lens should focus accurately (wide open). Then it will shift the focus as you stop down. I have found this lens little usable, because wide open it wasn't terribly sharp with fast film, and stopped down it was shifting focus so much, that for me it was unusable. This lens performs well wide open on slow, sharp film or on digital. At f 1.4 your Summilux is much prettier.
 
I would like to try it one day, I do like the 50 f1.5 (I prefer the LTM focus ring style).
Thank you for posting samples.
Marek I'm happy you posted about focus shift. I did not know this before.... thank you.

Cheers!
 
Hi Dez
Lovely shots !
I'm a fan of this lens ...Lots of character and charm
I use it and my 50 C Sonnar

Will add some photos to your thread ,... have had No real issues in focusing / focus shift / wide open with my lens
 
Nice shots Dez.

After noticing some photographs made with my Nokton 50/1.1 I proceeded to do some testing of my own. I also found that my copy was front focusing about 2 inches when wide open.

I sent mine to DAG and had it adjusted and it now focuses perfectly wide open (when I do my part of course.)

Most of my use is wide open but it also works beautifully from 5.6 through 11 giving very, very sharp results.

I use it most frequently on film, usually with my Zeiss Ikon, as it seems a little more forgiving on film when shot wide open. I also use it on my M9 but if I intend to shoot at f1.1 I always use a tripod because the depth of field is very unforgiving on the M9s sensor.

A bit chunky but a wonderful, wonderful lens.
 
Does it focus shift toward the back as it is stopped down? Maybe my copy is optimized for focus at a smaller aperture, although that really does not make sense, does it? No point in having a superfast lens that is out of focus wide open.

Cheers,
Dez
 
Dez said:
Does it focus shift toward the back as it is stopped down? .....
Click to expand...

Yes, the subject distance of best focus moves back as the aperture is closed. This is common with big aperture lenses.

In my opinion, it should focus perfectly at full aperture. Given the tiny depth of field it wouldn't be a surprise if it's a bit out. Mine does focus optimally at full aperture on my M6.

I had an f/1 Noctilux which also focused perfectly at full aperture. In fact it was so sharp in the center that it astounded me (tripod, TechPan etc). The focus shift on stopping down a couple of stops was astronomical. Well documented by Erwin Puts, whose article I saved. It's no longer on his web site.

Dez, I doubt that your f/1.1 would have been optimized for a smaller aperture. My guess is that it's just a bit of inaccuracy in either you camera (which you would not have noticed until now) or the lens maybe.
 
Yes. Point of focus on mine shifted back as the aperture closed. By 3.5 +/- it was dead on. As the aperture continued to close any focus inaccuracies were probably covered by DOF.

DAG optimized my lens with my M9 but it also works wonderfully with my other film M mount cameras.
 
Mine focuses perfectly on my M3 and is pretty sharp on fast film. I like the lens wide open very much. When I need more dept-of-field I prefer slower lenses like the Color-Skopar 50mm f/2.5 or the Nokton-M 50mm f/1.5 however.
Above all it is a portrait lens.

Leica M3, Nokton 50mm f/1.1, Tmax400.

Erik.

14812276017_91f5e9f647_c.jpg
 
Most if not all large aperture lenses suffer from "focus shift" as you stop down and focus moves backwards to give what is commonly called back focus. Accuracy wide open at f1.1 should be spot on if your camera rangefinder is accurately calibrated.

But as you stop down further still , the depth of field increases and this can cause your subject to come back into focus again as yet smaller apertures are selected because the focus "error" from back focus is smaller than the increase in depth of field. The back focus issue mainly affects subjects at closer distances of course as at any given aperture depth of field in any lens is less when a lens is focused closer and more when the subject is further away. At longer ranges any focus shift should therefore be less noticeable.

Mine does the same of course. The only way of handling this is to experiment to work out how much the focus shift is at any aperture. (Unless you wish to shoot full open all the time). Once you know this you can compensate. Some people do this by focusing the lens according to the rangefinder then moving the focus ring on the lens back a little to compensate. Practice allows them to estimate how much is needed - its just a tiny amount typically. Other people prefer simply to focus their lens using the rangefinder then with the camera still held up to their eye, to move their head backwards by the required amount before taking the shot. Both methods seem hit and miss but can work with practice.

Focus shift is not an issue with modern digital cameras where manual focus is achieved on the LCD or through the EVF as you can directly see if it is in or out of focus before you shoot. For this reason I often enjoy using my Nokton on a Sony NEX 5 with adapter where it performs well and is fun to use.
 
Its been a little while since I last used mine - its more of a night time or winter lens for me. I expect I'll start using it again soon as I lose light.









I think all of these were taken wide open (or very close to it). Several were ~1/15th of a second with faster film.
 
I'm very rusty on my optical theory, but I'm sure there are some experts out there.
I need to check the focus error of this lens with a different body to ensure the error is in the lens rather than the rangefinder, but assuming that it is, the centre of focus of the lens will need to be brought a bit closer to the film. Going from the basic thin lens equation as a close-enough approximation:

1/(focal length) = 1/(object distance) + 1/(image distance), and assuming the lens front focuses by 30mm at a distance of 1m, I would need to machine 0.07mm (.003") off whatever shim locates the optical block in the mount to get the focus spot-on. Have I got this wrong somehow?

Has anyone out there had one of these lenses apart? Is there a shim setting the optical block position, or would I need to do something scary with the focus mount itself?

Cheers,
Dez
 
Dez said:
I'm very rusty on my optical theory, but I'm sure there are some experts out there.
I need to check the focus error of this lens with a different body to ensure the error is in the lens rather than the rangefinder, but assuming that it is, the centre of focus of the lens will need to be brought a bit closer to the film. Going from the basic thin lens equation as a close-enough approximation:

1/(focal length) = 1/(object distance) + 1/(image distance), and assuming the lens front focuses by 30mm at a distance of 1m, I would need to machine 0.07mm (.003") off whatever shim locates the optical block in the mount to get the focus spot-on. Have I got this wrong somehow?

Has anyone out there had one of these lenses apart? Is there a shim setting the optical block position, or would I need to do something scary with the focus mount itself?

Cheers,
Dez
Click to expand...

I am pretty sure I have read that this lens cannot be shimmed in the normal manner of older lenses.
 
Very nice.
To my Amateur untrained eye.... It looks infinitely better than the Mitakon 50 0.95
Raved about on another website this week.
 
Dez, before doing work on the Nokton you might like to critically check the focusing on your M5 to ensure that it's your lens not your body. Perhaps your body's rangefinder is a fraction out but you haven't noticed with your other lenses because their smaller apertures require less accuracy.

I'd also be inclined to check the focus at a couple of distances. I take more photos at 2m than 1m, especially since the DoF at 1m at f/1.1 is pretty small!
 
I have found that the Nokton 50/1.1 exhibits the usual (back)focus shift which is described above, but also a focus shift (again, back focus) with distant subjects (>3m). My lens has been re-calibrated by Voigtlander in Japan and the focus is spot on at f/1.1 close distances, however for the rest of the photographic cases, there is a need to know exactly how the lens "works". It definitely takes some practice.
Has anyone had the same experience, of focus shifting when focusing for distant subjects ?
Thanks
 
john_s said:
Dez, before doing work on the Nokton you might like to critically check the focusing on your M5 to ensure that it's your lens not your body. Perhaps your body's rangefinder is a fraction out but you haven't noticed with your other lenses because their smaller apertures require less accuracy.

I'd also be inclined to check the focus at a couple of distances. I take more photos at 2m than 1m, especially since the DoF at 1m at f/1.1 is pretty small!
Click to expand...

Its a bit hard to do with a film camera, but how I check the focus of my M8 is to mark a two meter long piece of wood at one centimeter intervals around a central aiming point which is also clearly marked on the center of the wooden rod. i.e. they will be marked +1 / -1 centimeters, +2 /-2 centimeters etc out to say 30 centimeters in front and behind the focus point. So in effect, you have centimeters of back focus (+) and centimeters of front focus (-) marked clearly on the rod around the point of focus.

Lay the rod on the floor and measure a specific exact distance to the central aiming point from your camera. Incidentally your camera needs to be mounted on a tripod and aimed at the rod to facilitate measuring and get rid of shot to shot error. This means the camera will be pointed down at an angle of around say, 45 degrees or something like that. I used a measured distance (using a tape measure) from film plane to aiming point of exactly 3 meters distance from film plane to aiming point. Or you could use 4 meters if you wish. Then shoot some images at each aperture to be tested having focused on the aiming point using the rangefinder. Shoot some more images using scale focusing and the same apertures - i.e. set the lens distance to 3 meters or 4 meters depending on the test distance you used. Incidentally the distance you choose should ideally be guided by the distance markings on the lens barrel as you want to be able to match them when scale focusing. i.e. if your lens has a 3 meter marking use this as your test distance so you can scale focus precisely.

I also lay down a piece of paper marked with the details of each test (e.g. distance, which lens used - (I tested several lenses to see how they compared), what aperture was used for each test and whether that shot was rangefinder focused or distance / scale focused). I made sure the piece of paper was in frame when the photo was taken - that way there record of each shot made and there was no scope for later confusion about which image related to which lens / aperture combination etc. when I came to view the photos.

When you get your film images back it will be immediately obvious if any lens tested is either front or back focusing and by how much according to the marked scale on the rod.

If there is back focus and this only shows up when focusing by rangefinder then logically rangefinder calibration is a problem, particularly if this occurs when the f1.1 lens is shot wide open (where it should be sharp). You can then have your camera tech adjust ythe rangefinder for this amount. This is what I did as my M8 got out of whack for some obscure reason.

On the other hand if back focus shows up when the f1.1 lens is scale focused using the distances marked on the lens barrel (and when stopped down a bit) this suggests this back focusing is due to the normal focus shift we have discussed in this thread, due to the optical characteristics associated with stopping down such a lens. You will then know how much to compensate by when shooting this lens at that aperture and that distance (and it will change with distance but because its more apparent at closer distances this is another reason for using 3 or 4 meters as a test distance). As I indicated in another post compensation can be achieved in use by simply moving your head and camera after focusing using the rangefinder and "guestimating" the required amount of head movement forward (for a front focusing lens) or backward (for a back focusing lens) based on your test findings. Alternatively having first focused according to the rangefinder you can then adjust the focus ring by the required amount to compensate. Which ever method works best for you.

Its a bit of fooling around, I grant you but its about the only way to know for sure what you lens is doing focus wise
 
You must log in or register to reply here.
Back
Top Bottom