Focusing The Nokton 50/1.5 Down To 0.7m

I never knew that the Nokton 50/1.5 was so freakin' sharp! The negatives are scorching at f1.5 and 0.7m! Wow! I can only hope that my mediocre flatbed scanner will be able to the lens some justice.

Just picked up a set of alloy shims... 0.8mm, 0.9mm, 1.0mm, 1.1mm.

Scans and photos to come soon...
 
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Here as some 'test' scans as promised.

Here are the technical details -

Leica M5
Nokton 50mm f1.5
Efke KB100
Rodinal 1:25
Epson V500 scanner

All images were shot hand-held at 1/60th of sec at f1.5 at minimum focus distance, that is just before the lens decoupled from the rangefinder, which is about 0.65m.

The Efke 100 was rated at box speed and developed in Rodinal 1:25 at 19°C for 6:30 minutes with vigorous agitation.

The negatives were scanned on my Epson V500 at 3200dpi as transparencies in .tif format. The .tif files were imported into Photoshop CS4, inverted with CF Systems ColorNeg filter. The files were converted to Black & White with Photoshop B&W command with no filters. All files were adjusted with the same contrast curve. The files were resized to 900 x 600 images with Bicubic Sharper and saved as Highest Quality .jpeg files.

Here are the scans...

2010_08_003_005_900.jpg


2010_08_003_006_900.jpg


2010_08_003_007_900.jpg


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2010_08_003_012_900.jpg


The scanner simply does not come close to capturing the resolution that is on the negative. With a loupe I can easily read the newspapers. And unexpected bonus was the M5 rangefinder is spot-on.

I am already hearing grumblings about not having full-resolution scans and the small web images. Well, I am happy with the negatives and this is as technical as I am going to get. I am stunned at the resolution the Nokton 50/1.5 is putting on the negative, not unlike my Collapsible Heliar 50/3.5 negatives.

There is no reason that the Nokton 50/1.5 cannot be used with confidence down to 0.7m and that was the only reason for these test shots. I am more than happy with the performance wide-open and close-up.

Now I am waiting for someone to complain about the bokeh!
 
For a collapsible lens: you would have two detente's in the tube, one for use close-up and the second to undo the shim. The tube would not hold flat enough without being locked into place.

This should work on the Canon 50/1.2 as well, in fact just about any 50mm thread mount lens.

As for the trouble of using a dual-range lens, Leica and Nikon made dual-range lenses. People use extension tubes. This is essentially an RF coupled extension tube.

Is it worth it? 0.7m gives an edge. That is why Leica moved to it.

If you have spare shims... sending PM.
 
First things first... let's give credit where credit is due... while I was banging on about getting a Nokton to focus down to 0.7m... it was Brian's idea to make a simple shim to allow an LTM lens to close focus... not mine. I am just the mechanic, while Brian is the engineer.

This has to be the simplest lens hack ever, only using a filter is simpler only if you do not have to remove the lens hood to install the filter.

Absolutely no modification is needed to the lens, M-adapter or camera.

Here is the set-up... camera, the Nokton 50/1.5, LTM to M-mount adapter, and a shim. Here are the 4 shims that I had made to different thicknesses to determine how much extension was needed to allow the lens to focus to 0.7m. The shims are 0.8mm, 0.9mm, 1.0mm, and 1.1mm thick.
nokton5015_07shim_101.jpg


50-75 M-mount adapter, 0.9mm shim, and Nokton 50/1.5
nokton5015_07shim_102.jpg


Showing shim on lens...
nokton5015_07shim_103.jpg


So here is how simple this modification is... here is the lens mounted without the shim...
nokton5015_07shim_104.jpg


Here is the 0.9mm alloy shim... lightweight, virtually indestructible, easily carried in a shirt-pocket...
nokton5015_07shim_105.jpg


To deploy the shim and convert the Nokton 50/1.5 to a close-focus lens... unscrew the lens from the M-mount adapter... leaving the adapter mounted on the camera... put the shim on the lens mount...
nokton5015_07shim_106.jpg


And screw the lens back onto the camera... the shim is almost undetectable...
nokton5015_07shim_107.jpg


I have settled on using the 0.9mm shim, this will let the Nokton focus to just under 0.7m without letting the lens uncouple from the rangefinder. I do not like having a decoupled lens, especially when shooting quickly at close-focus, you can forget the lens decouples and end up with lots of out-of-focus negatives.

Since there must be a standard helical twist for all 50mm LTM lenses, I am thinking that any 50mm LTM lens that focuses to 0.9m will focus to 0.7m. The same will go with a lens the will only focus to 1m, 1.1m and etc, once the shim thickness has been established for that MFD(minimum focus distance), it should apply to all lens of the MFD regardless of brand or aperture. Am I right about this Brian?

Thanks!
 
patrickjames said:
...if you cut the shim so it makes a elongated C shape, you will be able to take it on and off without screwing the lens all the way off. As long as the shim extends past the midway point there should be no problems with the lens remaining parallel to the mount.
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Patrick,

Sorry I did not address your idea yet, got busy with scans, photos and etc.

An elongated C-shaped shim should work, although that thread interface between an LTM lens and adapter is pretty loose and provides no support for the lens.

Good idea... I will see if I can get one made. I am running on the good-will of my machinist friend at the moment, so this may start to cost me!

I guess the question is... how much is one willing to pay for a this adapter. Cost to manufacture in quantities of 20 should be very reasonable. You would need to have a few thicknesses on hand to cater for different lenses.

Thanks!
 
Maybe the Japanese gods will in their wisdom produce an M-Mount version of this lens. I've always found this lens to be sharp, even wide open. Really an amazing lens for the price. A great value.
 
patrickjames said:
The shim could also have a protrusion to facilitate it being removed, perhaps with either a thumbnail slot similar to a pocket knife, or a bent up edge that would be far away enough not to interfere with the lens being mounted.
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Patrick,

Been speaking the Brian and I am going to make a rudimentary C-shaped shim for him to test with his M8 for 'parallelness' and etc. If you want to test one as well, send me a PM with the thickness you want or the lens that you are going to be testing.

Making a circular shim is straight-forward and quite simple with a metal lathe. But when you start making shapes, you start looking at needing to use ground flat-stock or making over-size circulars and then machining or hand-cutting the shape into the shim.

It can certainly be done, but as you know, each step adds time and cost.

Give me an hour or two...
 
bwcolor said:
Maybe the Japanese gods will in their wisdom produce an M-Mount version of this lens. I've always found this lens to be sharp, even wide open. Really an amazing lens for the price. A great value.
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I hope that they choose to make it a real f1.4 lens as well. A close focusing M-mount version of the Nokton 50/1.5 would be very nice. The only off-shelf close-focusing 50/1.4 is the Summilux, which is simply unaffordable for me at this time. And I am sure I am not alone.
 
Here are a few candid portraits with the Nokton 50/1.5... focused to 0.7m and wide-open. Remember these negatives were taken while I was still using the CD plastic spacer.

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Leica M5 | Voigtländer Nokton 50mm f1.5 | Efke KB100 | Rodinal 1:25 | 6:30 minutes | 19ºC

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Leica M5 | Voigtländer Nokton 50mm f1.5 | Efke KB100 | Rodinal 1:25 | 6:30 minutes | 19ºC

2010_08_003_027_800.jpg

Leica M5 | Voigtländer Nokton 50mm f1.5 | Efke KB100 | Rodinal 1:25 | 6:30 minutes | 19ºC

There is no sharpening on these scans. Rodinal at 1:25 can make the grain pop on this emulsion.
 
Notice anything strange about this photo...

nokton5015_07_101.jpg


No shims... but racked out to 0.7m! The Nokton 50/1.5 has been modified internally to allow it focus all the way down to just under 0.7m. Mission accomplished!

The modification was relatively straight-forward without compromising the integrity of the lens in any way. While I did leave a few tracks internally, there is no evidence of the modification externally except for the small notch filed in the LTM mount as shown below.

nokton5015_07_102.jpg


With a fabrication of a few tools, I can modify these lens without any trace of the lens ever being tampered with except the notch on the mount. All I need now is to be able to engrave the '0.7' on the meter scale and '2.5' on the feet scale. If the ZM 50/1.5 is made in the same way, this modification could be done to that lens as well.

Having the Nokton 50/1.5 being able to focus as a full range lens from infinity to 0.7m has filled my need/want for a versatile 50/1.4 RF lens and my need/want for a Summilux 50. Instead I am looking for a silver Nokton 50/1.5 to modify as well to go with my new, yet to be bought silver M5.
 
Roland (ferider) knows the procedure for doing the same on the Canon f1.2 ... I must get around to it one day.


Notice anything strange about this photo...
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Seems to be extrermely underexposed! :angel:
 
If you took any pictures of the lens while apart, or do one again- please post it here!

A number of these lenses have internal stops, some even external stops, that can be removed or changed. That is the trick used for the close-focus J-3.

Filing the threads down allows the RF wheel of the camera to follow the cam inside the lens. ~3ft focus is where the Cam and edge of the threads lines up. When the threads are filed, many LTM cameras can also focus closer. My Canon P keeps up with the modified J-3.

Close focus lenses on a Leica- now everyone will want one.
 
Brian Sweeney said:
If you took any pictures of the lens while apart, or do one again- please post it here!

A number of these lenses have internal stops, some even external stops, that can be removed or changed. That is the trick used for the close-focus J-3.

Filing the threads down allows the RF wheel of the camera to follow the cam inside the lens. ~3ft focus is where the Cam and edge of the threads lines up. When the threads are filed, many LTM cameras can also focus closer. My Canon P keeps up with the modified J-3.

Close focus lenses on a Leica- now everyone will want one.
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Brian,

No photos... I got stuck into it and forgot. The construction of the Nokton is odd compared to any lens I worked on before.

The modification requires complete disassembly of the focus helical and some serious filing since the stops are machined into the lens mountings. And, of course, the actual lens mount had to filed to allow the RF arm to follow the cam, but that was a few light touches of the file as you can see.

Keith,

I am sure there are many lenses that can be modified to focus to 0.7m. I wanted a modern lens without 'character issues', so that is why I picked the Nokton 50/1.5. It has a reputation of good resolution, good contrast, well-controlled flare, and lack of focus-shift. I am pleased with the end result.
 
With a fabrication of a few tools, I can modify these lens without any trace of the lens ever being tampered with except the notch on the mount. All I need now is to be able to engrave the '0.7' on the meter scale and '2.5' on the feet scale. If the ZM 50/1.5 is made in the same way, this modification could be done to that lens as well.
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Oh my goodness. That would make my favorite lens (ZM Sonnar 50/f1.5) so much more incredible. I wonder what would happen to the focus shift.

With your modification to the Nokton, you can still focus to infinity, correct?

How about with the shims? My understanding is that you cannot, but that DOF would cover the error.
 
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