Contax RF mount vs Nikon S-mount
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wlewisiii
Just another hotel clerk
Brian adjusted a 1937 collapsible Zeiss 50/2 Sonnar for my Nikon S2. It is also usable on my Leica M 240 with my Amedeo adapter.
I love shooting with it on either camera 😀
I love shooting with it on either camera 😀
wes loder
Photographer/Historian
Scherer's article fails to explain the different rotation of the helicoid to go from infinity to three feet.
@splitimageview
As Wes stated, the rotation is different between S-Mount and Contax RF. The thread pitch is the same. Contax has a longer throw. It is the same difference as between a Jupiter-3 in LTM and Leica Mount lens. SO- what I do is to adjust the Shim of a Sonnar for correct focus on the Nikon at about 5ft. DOF covers the residual error, and stopping down shifts focus towards infinity. I also changed out the Shims on a Nikon S2 to use with Contax lenses. Good enough to use the 13.5cm F4.
As Wes stated, the rotation is different between S-Mount and Contax RF. The thread pitch is the same. Contax has a longer throw. It is the same difference as between a Jupiter-3 in LTM and Leica Mount lens. SO- what I do is to adjust the Shim of a Sonnar for correct focus on the Nikon at about 5ft. DOF covers the residual error, and stopping down shifts focus towards infinity. I also changed out the Shims on a Nikon S2 to use with Contax lenses. Good enough to use the 13.5cm F4.
enasniearth
Well-known
I read an article years back
The take was the Japanese camera industry thought the Leica & Contax helicoid were metric pitch & thread
German threads were based on an early English microscope thread so slightly different that’s what it said - as zeiss & leica were microscope manufactures before cameras
& that’s the differance
Don’t remember where I read it many years back
They were mainly referring to the early canon rf serenars not screwing onto a leica
Screwmount body
I’ll look for it
The take was the Japanese camera industry thought the Leica & Contax helicoid were metric pitch & thread
German threads were based on an early English microscope thread so slightly different that’s what it said - as zeiss & leica were microscope manufactures before cameras
& that’s the differance
Don’t remember where I read it many years back
They were mainly referring to the early canon rf serenars not screwing onto a leica
Screwmount body
I’ll look for it
enasniearth
Well-known
My memory is the English standard was 25 threads per inch
While the metric was 25.4
My foggy memory was perhaps decharts canon rangefinder cameras book was the source — but I’ve misplaced it so I can’t say for sure
I do remember the author saying that much of Japan was destroyed during the war
& industry was rebuilding with limited precision measuring instruments
While the metric was 25.4
My foggy memory was perhaps decharts canon rangefinder cameras book was the source — but I’ve misplaced it so I can’t say for sure
I do remember the author saying that much of Japan was destroyed during the war
& industry was rebuilding with limited precision measuring instruments
enasniearth
Well-known
Shearers observations are from disassembling both & mateing the parts
The variables I would humbly think
Would perhaps cause a slight margin of error
In all honesty he’s great & has resurrected many Contax cameras & lenses - he’s an increadable assert to classic cameras & photography in general
The variables I would humbly think
Would perhaps cause a slight margin of error
In all honesty he’s great & has resurrected many Contax cameras & lenses - he’s an increadable assert to classic cameras & photography in general
Henry should have noticed that the Distance Marks are systematically different between the two mount, as shown in his webpage. The thread pitch is the same. The difference is caused by the difference on focal lengths on the internal mount lenses of the Nikon and Contax. The Nikon nominal focal length is 51.6mm and the Contax nominal focal length is 52.4mm.
This topic or variations of it has been discussed many times at RFF.
Check those other threads.
According to Amedeo, not only do the mounts have different rotations,
Contax and Nikon Rangefinder bodies also have different back focus.
Yes I’m well aware of the other threads, I just was curious about @Sonnar Brian ’s take on the article
Some 15 years ago I dedicated an Amedeo Contax to LTM adapter to my through-the-lens viewer that I use to test lenses and adjust the shim. I have a test target set at 5m, focus a lens on it, and shim it until a mark "C" comes up for Contax, or "N" comes up for Nikon. It works. Placing the original marks took some time. After that- easy. I have to mark the Sonnars and Jupiters with an "N" or "C" to remind me which they are for.
When adjusting a Nikon camera to use the Sonnar- I used "MWS2" washers, stacked to 0.5mm. The Nikon S2 was missing a set of original shims under one of the three fastening points. SO- I had to do something, and had 4 other S2 bodies. I adjusted the Rangefinder to agree with the Sonnar used close-up and wide-open, focus set using a Loupe with the camera on "T". I happened to have an 8ft optics bench handy at the time, almost 25 years ago.
Focus is perfect, wide-open and close-up. Stop down a little for infinity.
Nikon S2 (0.5mm shims) with Carl Zeiss 50mm F1.5, wide-open.
With the Contax mount 135, wide-open.
Using Zeiss lenses on the Nikon is easier as focus shift for most lenses is towards infinity, over-corrected for spherical aberration.
Using Nikkor lenses on a Contax: except for the 10.5cm F2.5, which is under-corrected for spherical aberration, the error increases as you stop down.
When adjusting a Nikon camera to use the Sonnar- I used "MWS2" washers, stacked to 0.5mm. The Nikon S2 was missing a set of original shims under one of the three fastening points. SO- I had to do something, and had 4 other S2 bodies. I adjusted the Rangefinder to agree with the Sonnar used close-up and wide-open, focus set using a Loupe with the camera on "T". I happened to have an 8ft optics bench handy at the time, almost 25 years ago.
Focus is perfect, wide-open and close-up. Stop down a little for infinity.
Nikon S2 (0.5mm shims) with Carl Zeiss 50mm F1.5, wide-open.
With the Contax mount 135, wide-open.
Using Zeiss lenses on the Nikon is easier as focus shift for most lenses is towards infinity, over-corrected for spherical aberration.
Using Nikkor lenses on a Contax: except for the 10.5cm F2.5, which is under-corrected for spherical aberration, the error increases as you stop down.
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enasniearth
Well-known
Perhaps the article I read was not accurate & I can’t find it now
It referenced early canon thread mount lenses not fitting Leica screwmount bodies
I know Amedeo makes 2 different adapters for the Contax or Nikon lenses
To account for the difference in focal length
I’ve not seen a comparison between the contax & Nikon body’s measured distance flange to film plane at different distances & rotation with a measuring device
The same thread pitch would have equal extension for degrees of rotation
I guess I don’t trust just threading parts together & stating they are the same pitch
What you have written makes the most sense though
It referenced early canon thread mount lenses not fitting Leica screwmount bodies
I know Amedeo makes 2 different adapters for the Contax or Nikon lenses
To account for the difference in focal length
I’ve not seen a comparison between the contax & Nikon body’s measured distance flange to film plane at different distances & rotation with a measuring device
The same thread pitch would have equal extension for degrees of rotation
I guess I don’t trust just threading parts together & stating they are the same pitch
What you have written makes the most sense though
zeitz
Established
"It referenced early canon thread mount lenses not fitting Leica screwmount bodies." This is true. Canon was M39, which means 39mm diameter and 1.0mm thread pitch. Leica was L39, which means 39mm diameter and 26 threads per inch. It's only a slight difference, but it prevents the lens from seating correctly. Both cameras are 28.8mm lens flange to film plane.
"I’ve not seen a comparison between the contax & Nikon body’s measured distance flange to film plane." They are exactly the same, 34.85mm.
"The same thread pitch would have equal extension for degrees of rotation." And that would only work correctly for the same focal length of lenses. Wide angle lenses have small extensions to focus closer; tele lenses have large extensions to focus closer. Each specific focal length has an extension requirement that is set by physical optics. So if the focal length is different, the extension required is different. The pitch of whatever is extending is irrelevant as long as the rangefinder levers and optics are correctly coupled.
"I’ve not seen a comparison between the contax & Nikon body’s measured distance flange to film plane." They are exactly the same, 34.85mm.
"The same thread pitch would have equal extension for degrees of rotation." And that would only work correctly for the same focal length of lenses. Wide angle lenses have small extensions to focus closer; tele lenses have large extensions to focus closer. Each specific focal length has an extension requirement that is set by physical optics. So if the focal length is different, the extension required is different. The pitch of whatever is extending is irrelevant as long as the rangefinder levers and optics are correctly coupled.
wes loder
Photographer/Historian
If the bodies have different back focus. why are the various reflex housings and microflex units interchangeable? All the various units I have worked with over the years, including the 500mm Fernobjekiv for the Panflex on a Nikon RF and a Zeiss Microflex on Nikon have yielded sharp results. The problem does appear to be the mount rotations.