Pictures and instructions lost from years of forum changes- I have reposted towards the end of this thread.
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Jupiter-3 Close Focus Mod
- Thread starter Sonnar Brian
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Pictures and instructions lost from years of forum changes- I have reposted towards the end of this thread.
tenderobject
paper negative
close focus at 2.5 ft? awesome!
dee
Well-known
Stunning - I love it . Miss close focus lenses for my M8 .
just found this thread .
just found this thread .
Thankyou, I had this lens out yesterday on my Bessa R2.This is an easy modification, remove the focus ring, take out the stop screw, and file down the threads as shown.
The pictures shown are with the Canon P. Taking the threads off the mount allowed the RF wheel to get in closer than 3ft with this lens.
The pictures shown are with the Canon P. Taking the threads off the mount allowed the RF wheel to get in closer than 3ft with this lens.
I picked up another J-3 that had issues, and did a rebuild on it.
The J-3 uses a double helical focus mechanism, and in my opinion, is a simplification and improvement of the LTM Sonnar. Like the Sonnar, it uses two guide slots with guide pins to prevent the second helical from rotating, and to make it move forward and back as you focus. The LTM Sonnar and J-3 use a set screw in a groove for the near stop at 1M and infinity.
I took that screw out, and am using just the guide rail for close-up and infinity stops.
That was the easy part: taking something off the lens. Getting to it: not bad, remove the optics module from the mount, take off the focus ring, the groove with the stop screw is visible: then remove it.
That allows the lens to be focussed ~6" closer.
But, the threads of the mount will block the RF follower of the camera from keeping up with it.
SO: take out the set screws that hold the helical into the mount, take the helical out. You now have the lens mount without any moving parts in it that you can mess up because of the filing that you have to do. Find out exactly how the lens aligns on your camera, mark it, and file down about 1mm or so: about to the first thread.
The J-3 uses a double helical focus mechanism, and in my opinion, is a simplification and improvement of the LTM Sonnar. Like the Sonnar, it uses two guide slots with guide pins to prevent the second helical from rotating, and to make it move forward and back as you focus. The LTM Sonnar and J-3 use a set screw in a groove for the near stop at 1M and infinity.
I took that screw out, and am using just the guide rail for close-up and infinity stops.
That was the easy part: taking something off the lens. Getting to it: not bad, remove the optics module from the mount, take off the focus ring, the groove with the stop screw is visible: then remove it.
That allows the lens to be focussed ~6" closer.
But, the threads of the mount will block the RF follower of the camera from keeping up with it.
SO: take out the set screws that hold the helical into the mount, take the helical out. You now have the lens mount without any moving parts in it that you can mess up because of the filing that you have to do. Find out exactly how the lens aligns on your camera, mark it, and file down about 1mm or so: about to the first thread.
Keith
The best camera is one that still works!
Wow ... a lens mod from a mod! 😎
One day I must get myself a J-3 in LTM ... every time I want to use the one I have I have to attach it to that damned Kiev with the viewfinder from hell!
😀
One day I must get myself a J-3 in LTM ... every time I want to use the one I have I have to attach it to that damned Kiev with the viewfinder from hell!
😀
The close-focus mod J-3 is perfect on the M8. It gets in closer than the new Zeiss Sonnar lens.
Roland has modified his Nikkor to close-focus, and the mod is easier than the J-3. But- the Nikkors tend to cost much more.
Roland has modified his Nikkor to close-focus, and the mod is easier than the J-3. But- the Nikkors tend to cost much more.
Phil_F_NM
Camera hacker
Awesome!
Now i have to get one of these too!
Of course a case of GAS isn't nearly as painful when it comes to FSU gear, so I've got that going for me.
Now i have to get one of these too!
Of course a case of GAS isn't nearly as painful when it comes to FSU gear, so I've got that going for me.
The close-focus is about 0.8m,
On the Canon P, which can follow it down almost to the closest focus:
Very useful for portraits.
On the M8, with the 1.3x crop factor, no problem following the Cam:
On the Canon P, which can follow it down almost to the closest focus:
Very useful for portraits.
On the M8, with the 1.3x crop factor, no problem following the Cam:
john neal
fallor ergo sum
Brian,
Yet another great idea that I just have to try - I have a 1955 J3 with a 1970's front element that could be the candidate for this.
Congrats on the new forum & your mod status too!
Yet another great idea that I just have to try - I have a 1955 J3 with a 1970's front element that could be the candidate for this.
Congrats on the new forum & your mod status too!
ampguy
Veteran
Wow, I need this mod!!
Next time I have one apart, I'm going to look at rounding off the end of the slots for the guide pin, so that the rounded head fits into it. That should allow it to get in just a bit closer.
john neal
fallor ergo sum
As ever, I'm talking through my hat - it's a J8 that I have, and it would be interesting to try this with that too. Unfortunately, the one I have has the body thread held on with a clamp that has 3 screws, and I can't get enough purchase to fully screw the lens onto the body without the guide screw providing some torque. (is that type 2 or 3?)
Three solutions presnt themselves to my fevered brain -
1. make some sort of gasket that increases the clamping pressure of the securing ring (should work, but I have to make sure I subsequently collimate the lens, just in case I change the 28.8mm distance, and that the focus ring will still turn)
2. Grind off about half the head on the guide screw - this will give about 1.2mm additional throw towards close focus (might work, providing I can get the screw to end up with its slot axial with the lens axis)
3. the "extreme" solution - set up an end mill on my lathe and rebate a clearance groove for the guide screw, so that the focus collar can move about 1/6th of a turn past present close focus. (the worry I have about this one is that the screw will actually move out of its slot on the focus mount, and may not want to return!)
I think I will try #2 first, as a spare screw is not much to lose if it doesn't work 😉
Now, how would Brian do it?
Three solutions presnt themselves to my fevered brain -
1. make some sort of gasket that increases the clamping pressure of the securing ring (should work, but I have to make sure I subsequently collimate the lens, just in case I change the 28.8mm distance, and that the focus ring will still turn)
2. Grind off about half the head on the guide screw - this will give about 1.2mm additional throw towards close focus (might work, providing I can get the screw to end up with its slot axial with the lens axis)
3. the "extreme" solution - set up an end mill on my lathe and rebate a clearance groove for the guide screw, so that the focus collar can move about 1/6th of a turn past present close focus. (the worry I have about this one is that the screw will actually move out of its slot on the focus mount, and may not want to return!)
I think I will try #2 first, as a spare screw is not much to lose if it doesn't work 😉
Now, how would Brian do it?
Going from memory here: Take out the optics module, then take off the focus collar which is held in my three set screws. You should see two screws in the mechanism, one is the close-focus stop, the other is the infinity stop. Try taking them out, see how far that gets you.
john neal
fallor ergo sum
Brian,
This is the "other" build of J8 - it doesn't have those screws - it relies on one screw at the rear of the inner helix, just in front of the rf face at the back of the lens. This single screw runs in a groove in the inner helix and is stopped at close focus by hitting the back of the rotating focus coller. IYSWIM 🙂
This is the "other" build of J8 - it doesn't have those screws - it relies on one screw at the rear of the inner helix, just in front of the rf face at the back of the lens. This single screw runs in a groove in the inner helix and is stopped at close focus by hitting the back of the rotating focus coller. IYSWIM 🙂
Krosya
Konicaze
Nice results, Brian. Now if you can make Canon "Sonnar" 50/1.5 focus closer - THAT I would love to see. I too did a mod on a Nikkor LTM 5cm/1.4 a while back and it made it for a much more versatile lens. See here :
http://www.rangefinderforum.com/forums/showthread.php?t=73271
I wonder if there is a way to do the same for a Canon 50/1.5?
http://www.rangefinderforum.com/forums/showthread.php?t=73271
I wonder if there is a way to do the same for a Canon 50/1.5?
I have a spare Canon focus mount: i will give it a look-see. Off-hand, I do not think there is an easy way to do it. It is a very different mechanism.
myM8yogi
Well-known
From
http://www.rangefinderforum.com/forums/showthread.php?threadid=82765
Brian, this is the best news I have had in a long time.
I have a 1953 J-3 I bought on the classifieds here from Eugene. Absolutely fantastic lens. Just love its size considering the speed. I love it so much that I now embrace flare. Anyway, the only problem is the minimum close focus of 1m.
I did a search and found this thread, but the pictures have been removed and the link to the ZI thread does not seem to be functioning.
Brian, how exactly do I modify it for close focus?
I have a copy of your excellent J-3 disassembly and CLA as pdf ... can you give me any pointers as to what I need to do to focus any closer?
Does the mod' entail loss of infinity focus? If so, to what degree?
I could be in possession of the perfect lens after all!
http://www.rangefinderforum.com/forums/showthread.php?threadid=82765
Brian, this is the best news I have had in a long time.
I have a 1953 J-3 I bought on the classifieds here from Eugene. Absolutely fantastic lens. Just love its size considering the speed. I love it so much that I now embrace flare. Anyway, the only problem is the minimum close focus of 1m.
I did a search and found this thread, but the pictures have been removed and the link to the ZI thread does not seem to be functioning.
Brian, how exactly do I modify it for close focus?
I have a copy of your excellent J-3 disassembly and CLA as pdf ... can you give me any pointers as to what I need to do to focus any closer?
Does the mod' entail loss of infinity focus? If so, to what degree?
I could be in possession of the perfect lens after all!
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The pictures are showing up- before the host I use was down, so the pictures could not be accessed.
Try it again.
The close-focus mod also lets you focus past infinity, which for a J-3 modified for a Leica, is a good thing.
A J-3 typically has to be moved out (shimmed) 0.1mm for best close-up and wide-open focus on a Leica. You give up a bit at infinity. Removing the screw allows you to go slightly past the infinity stop, allows true infinity on a Leica.
I've also modified a late-version Black J-8 for 0.7m focus. Even gets that close on my Canon P.
Try it again.
The close-focus mod also lets you focus past infinity, which for a J-3 modified for a Leica, is a good thing.
A J-3 typically has to be moved out (shimmed) 0.1mm for best close-up and wide-open focus on a Leica. You give up a bit at infinity. Removing the screw allows you to go slightly past the infinity stop, allows true infinity on a Leica.
I've also modified a late-version Black J-8 for 0.7m focus. Even gets that close on my Canon P.
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ampguy
Veteran
Hi Brian, I've got a question - if you just remove the guide screw, but don't do the filing of the mount, at one point do you lose coupling, is it at 1m, or somewhere between .8 and 1m?