Japan---Exposures
Member
Has anyone had a third party optimize focussing of a CV Nokton Classic 1.4/35? I read that some people have considered sending it to DAG, but never heard of anyone with results. Can it be done?
I just thought I'd give CV one more try, but it seems impossible to get a useful picture out of it where focus is on target. It is about OK at 1.4, but of course soft. I can live with that, but the shift is so bad at f2 and above even at distances more than 2 meters, the lens seems practically unusable. Very disappointed so far.
I cannot exchange for another as I bought it used, but a full return is an option. If the adjustment is possible I'd be willing to put some money towards that.
Any advice appreciated… thanks
Here is a test image, view the large or full size
CV35 by Dirk | JapanExposures.com, on Flickr
I just thought I'd give CV one more try, but it seems impossible to get a useful picture out of it where focus is on target. It is about OK at 1.4, but of course soft. I can live with that, but the shift is so bad at f2 and above even at distances more than 2 meters, the lens seems practically unusable. Very disappointed so far.
I cannot exchange for another as I bought it used, but a full return is an option. If the adjustment is possible I'd be willing to put some money towards that.
Any advice appreciated… thanks
Here is a test image, view the large or full size
CV35 by Dirk | JapanExposures.com, on Flickr
ampguy
Veteran
Dirk, one thing to keep in mind is if you ever end up using this on a live view camera, the shift gets dialed out. I don't recommend using this lens with an RF based legacy camera.
Does the cam of the lens rotate as you focus, or does it stay stationary?
The easiest way to "hack" a fix for back-focus on a lens is to build up the RF cam. One strip of copper tape on the RF Cam of a Nikkor 10.5cm F2.5 solved the back-focus issue on the Leica M8 for me. 5 minute fix, going on a year now.
The easiest way to "hack" a fix for back-focus on a lens is to build up the RF cam. One strip of copper tape on the RF Cam of a Nikkor 10.5cm F2.5 solved the back-focus issue on the Leica M8 for me. 5 minute fix, going on a year now.
Dominum
Member
My Nokton doesn't focus shift that much. I'm using the SC version. Is it a QC issue?
Japan---Exposures
Member
Yes, the cam rotates and the RF patch moves too (M8). I don't want to muck around with it before talking to the seller again. Perhaps it is really the best to just return it and forget about it. I also don't like that the focus action is quite stiff in cold weather, makes it hard to operate and focus quickly. It's too bad because - in theory - this is a lens with good properties and the price I paid was fair.
Chriscrawfordphoto
Real Men Shoot Film.
You guys testing this on film or with an M8 or M9? I ask because some people have said it focus shifts far more on digital than film.
Dominum
Member
My copy's always on my M8.2
Mister E
Well-known
Everything focus shifts on digital more than film On film you wouldn't notice as much because the thickness of the film compensates. These lenses were designed for film.
Dirk, if you send the lens to Cosina they can adjust the focus so it is smoother, and you could talk to them about the focus shift. No idea if they do anything about that though. I do know from personal experience that a trip back to them will help to make the lens smoother in cold weather. Oil of course looses viscosity when it's cold.
Dirk, if you send the lens to Cosina they can adjust the focus so it is smoother, and you could talk to them about the focus shift. No idea if they do anything about that though. I do know from personal experience that a trip back to them will help to make the lens smoother in cold weather. Oil of course looses viscosity when it's cold.
ferider
Veteran
Dirk, if you take the rear element off ((1) by hand - grabbing the two baffles) you get access to a span ring (2). You take this off, and the lens comes into pieces:
The screws (5) can be used for fine RF coupling adjustment. You can also shim it differently, of course (4).
From your pic, it seems to me your lens is off also at f1.4. So I would try a wide open, infinity adjustment first. That's most likely what's wrong.
Roland.
The screws (5) can be used for fine RF coupling adjustment. You can also shim it differently, of course (4).
From your pic, it seems to me your lens is off also at f1.4. So I would try a wide open, infinity adjustment first. That's most likely what's wrong.
Roland.
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Lss
Well-known
It's my main lens on the M8, so I don't quite agree. It's a good lens, although the distortion is fairly noticeable. The focus shift in OP's image looks very strong and not very consistent. In my experience it should be gone by 5.6 (mostly due to depth of field) and certainly by 8. The sample is not representative in my opinion.
Japan---Exposures
Member
Thank you, thank you, thank you!
I had a feeling that something was wrong with this lens from the first picture I took with it. It just had a very strange quality to it that I have not seen in a modern lens before.
I appreciate the instructions on how to take it apart, but I think this is a return job before anything.
The film vs digital thing I think is not really valid, because there are people using it on digital without issues and sample variations are a known issue with this lens. I wonder even whether it suffered an impact of any sort by the previous owner. We can only hope it did not leave the factory in this state.
I had a feeling that something was wrong with this lens from the first picture I took with it. It just had a very strange quality to it that I have not seen in a modern lens before.
I appreciate the instructions on how to take it apart, but I think this is a return job before anything.
The film vs digital thing I think is not really valid, because there are people using it on digital without issues and sample variations are a known issue with this lens. I wonder even whether it suffered an impact of any sort by the previous owner. We can only hope it did not leave the factory in this state.
For what it's worth: Just did some "pixel-Peeping" with the just-arrived Nokton 50/1.1 and silver Nokton 35/1.2 on the M8. I ended up building up the Cam by 0.05mm on both of them. The M8 agrees with my other cameras, but I tend to adjust most of them myself.
I am going to venture a guess that assumptions are made about film bowing out from the film plane, and various manufacturers make different assumptions based on their camera bodies. Digital sensors lay flat, and have a series of microlenses and other planes such as the Mosaic filter that is part of the optical path. With modern, fast lenses- these assumptions are more critical and the effects are readily visible when pixel-peeping.
I am going to venture a guess that assumptions are made about film bowing out from the film plane, and various manufacturers make different assumptions based on their camera bodies. Digital sensors lay flat, and have a series of microlenses and other planes such as the Mosaic filter that is part of the optical path. With modern, fast lenses- these assumptions are more critical and the effects are readily visible when pixel-peeping.
ferider
Veteran
If you follow Bill Pierce's forum - there used to be a time when Leica Ms of professionals were adjusted to the lens kits they were used with. Nowadays this seems forgotten, and all is attributed to "focus shift".
The different kits that I have (M-Hex, Leica, CV lenses, among others), all need slightly different infinity alignment. Which is why I keep different cameras for different lens sets.
CV M lenses - when compared to Leica M lenses are in my experience always a little off at infinity, consistent with what Brian describes for his 50/1.1 and 35/1.2. On a Bessa, due to short EBL you will not notice the difference. On an M, in particular my M3s, it's another story. However, once you align the cameras and lenses at infinity (provided the cameras RF works as spec'ed), you get great performance.
With LTM lenses, similarly, I have to pick the right adapters. Leica and CV type II adapters have the same thickness. CV type I adapters are slightly thinner. Sometimes (for my L-Hex 50/2.4 for instance), an adapter needs to be ground.
M lenses across brands are not truly interchangeable out of the box. When you buy used, in particular for older lenses, there is a chance that a lens was fitted to another camera (again, read what Bill wrote about his interactions with Don's (DAG) father). This must particularly be noticeable on a sensor, in my opinion.
This is probably hard to swallow for most RFF members with extensive lens collections. But it's my story and I'm sticking to it.
Roland.
The different kits that I have (M-Hex, Leica, CV lenses, among others), all need slightly different infinity alignment. Which is why I keep different cameras for different lens sets.
CV M lenses - when compared to Leica M lenses are in my experience always a little off at infinity, consistent with what Brian describes for his 50/1.1 and 35/1.2. On a Bessa, due to short EBL you will not notice the difference. On an M, in particular my M3s, it's another story. However, once you align the cameras and lenses at infinity (provided the cameras RF works as spec'ed), you get great performance.
With LTM lenses, similarly, I have to pick the right adapters. Leica and CV type II adapters have the same thickness. CV type I adapters are slightly thinner. Sometimes (for my L-Hex 50/2.4 for instance), an adapter needs to be ground.
M lenses across brands are not truly interchangeable out of the box. When you buy used, in particular for older lenses, there is a chance that a lens was fitted to another camera (again, read what Bill wrote about his interactions with Don's (DAG) father). This must particularly be noticeable on a sensor, in my opinion.
This is probably hard to swallow for most RFF members with extensive lens collections. But it's my story and I'm sticking to it.
Roland.
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Dirk, it does look to me like that Nokton is back-focused even wide open and gets worse from there. Maybe ~30mm or so, hard to say as it's also soft at that aperture. So I'd say it's out of adjustment, even ignoring the focus shift issue.
Last year I sent five 35mm lenses to DAG, some for coding, one for CLA, all for adjustment as needed. He said ALL the lenses needed focus adjustment... but he could not adjust the 35/1.4 Nokton. Didn't say why; whether it was a mechanical matter or perhaps that the focus shift just made it futile.
The lens is ok on my M8, though, the back-focusing not rendering it unusable. Whether you return it or get it tweaked, good luck! I'd be interested to know how it works out...
Last year I sent five 35mm lenses to DAG, some for coding, one for CLA, all for adjustment as needed. He said ALL the lenses needed focus adjustment... but he could not adjust the 35/1.4 Nokton. Didn't say why; whether it was a mechanical matter or perhaps that the focus shift just made it futile.
The lens is ok on my M8, though, the back-focusing not rendering it unusable. Whether you return it or get it tweaked, good luck! I'd be interested to know how it works out...
ampguy
Veteran
sounds good Roland
sounds good Roland
I'd pretty much agree with this.
Would just add that there was a time when folks moved to SLR's because of focus shift, on a pro-level SLR, you can stop down and see the shift, and correct for it at the given aperture you want to use.
RF technology never accommodated for this, even though we now have the tools to quickly see it with very basic image editing software.
A lens has no way of knowing if it is attached to a body with a film or sensor. Use some flat film at the same distance as a digital sensor, and you will see the same focus shift when magnified.
Today we have live view cameras that show the focus shift in real-time.
If you're using a rangefinder, you're using obsolete focusing technology.
sounds good Roland
I'd pretty much agree with this.
Would just add that there was a time when folks moved to SLR's because of focus shift, on a pro-level SLR, you can stop down and see the shift, and correct for it at the given aperture you want to use.
RF technology never accommodated for this, even though we now have the tools to quickly see it with very basic image editing software.
A lens has no way of knowing if it is attached to a body with a film or sensor. Use some flat film at the same distance as a digital sensor, and you will see the same focus shift when magnified.
Today we have live view cameras that show the focus shift in real-time.
If you're using a rangefinder, you're using obsolete focusing technology.
If you follow Bill Pierce's forum - there used to be a time when Leica Ms of professionals were adjusted to the lens kits they were used with. Nowadays this seems forgotten, and all is attributed to "focus shift".
The different kits that I have (M-Hex, Leica, CV lenses, among others), all need slightly different infinity alignment. Which is why I keep different cameras for different lens sets.
CV M lenses - when compared to Leica M lenses are in my experience always a little off at infinity, consistent with what Brian describes for his 50/1.1 and 35/1.2. On a Bessa, due to short EBL you will not notice the difference. On an M, in particular my M3s, it's another story. However, once you align the cameras and lenses at infinity (provided the cameras RF works as spec'ed), you get great performance.
With LTM lenses, similarly, I have to pick the right adapters. Leica and CV type II adapters have the same thickness. CV type I adapters are slightly thinner. Sometimes (for my L-Hex 50/2.4 for instance), an adapter needs to be ground.
M lenses across brands are not truly interchangeable out of the box. When you buy used, in particular for older lenses, there is a chance that a lens was fitted to another camera (again, read what Bill wrote about his interactions with Don's (DAG) father). This must particularly be noticeable on a sensor, in my opinion.
This is probably hard to swallow for most RFF members with extensive lens collections. But it's my story and I'm sticking to it.
Roland.
Mister E
Well-known
What? I've never heard of a long time film shooter even mentioning focus shift? Sure it existed before, but the thickness of film, and a million other things made it complete irrelevant and largely unnoticeable. Back in the day no one was looking at 100% crops.
As for adjusting your camera for your lenses or vice versa, this is still done. I have all of my camera set for my longest, fastest lens. On my film M even a huge, noticeable focus disparity gives me sharp, spot on focus on my .72 bodies and on my M3 it is even less of a big deal. Funny thing is that all of my Leica lenses and my ZM 18/4 all agree exactly for infinity focus. It's easiest to see on my M3, but they are all spot on.
I don't buy that people moved to SLRs because of focus shift, ever. The number of shooters I know who use DoF are 0. There are only a very few SLR lenses I've heard of or dealt with that even have a reputation for focus shift, the Canon 50/1.2L is one. With autofocus few are stopping their own lenses down to refocus.
ampguy
Veteran
well...
well...
Well, we learn something new every day, don't we?
I've been shooting film since the '60s, and focus shift is always there in some lenses, and you can't shim or dial it out, you can only optimize for a given aperture if your lens has it.
Maybe not as many people did 100% crops back then, but they did use loupes, magnifiers, and microscopes.
Oh, and enlargers. remember those??
well...
Well, we learn something new every day, don't we?
I've been shooting film since the '60s, and focus shift is always there in some lenses, and you can't shim or dial it out, you can only optimize for a given aperture if your lens has it.
Maybe not as many people did 100% crops back then, but they did use loupes, magnifiers, and microscopes.
Oh, and enlargers. remember those??
Mister E
Well-known
Ha! You're funny.
One could certainly design an RF lens where the focus-shift is accommodated by linking the aperture ring to the RF Cam. Put a Cam on the Aperture ring that translates the change in focus to the RF cam. Zoom lenses have more complex cams. I am not aware of any RF lens ever made that incorporates such a mechanism, but certainly would not be too hard to do. Aperture ring would probably be near the rear of the lens, like on an SLR.
Krosya
Konicaze
I agree, but than again, there are some even simpler things, such as making lens focus down to 0.7m vs 1m. - something simple enogh. So, making an RF lens that compensates for a focus shift - I dont see them doing that any time soon, if ever.