17. januar 2016

How to clean and re-grease two Jupiter-8's

Last entry was about how you can fix and adjust the focus (collimation) of your Jupiter-lenses, to work with M-mount cameras (like Leica and Bessa rxm and rxa). http://helino-photo.blogspot.no/2015/12/jupiter-8-vs-jupiter-8-vs-carl-zeiss.html

Here's an attempt to make a tutorial on how to disassemble, clean and re-grease two versions of the Jupiter-8 50mm F2.

Jupiter-8 1963 to the left, 1955 to the right.
Both lenses are adapted to M-mount via attached adapter-rings.


Most often when you buy the old Soviet lenses, you can experience that the focus-ring is stiff or irregular when turning. The reason for this, is old, dried up grease inside the focus-helicoid.
To fix this, you need to disassemble the lens, clean out the focus mechanism and re-grease, before assembling the lens again.

**

I have two lenses, one from 1963 and one from 1955.
- Well, I actually have yet another one, a black one from the seventies or so, but it's not a part of this tutorial.

There are several variations of the silver Jupiter-8's, and I seem to have one simple and one complex type, regarding the helicoid. You can perhaps locate your variant here: http://www.pentax-manuals.com/repairs/j8service.pdf

This tutorial is basically similar to the above link, in my own words, maybe it can be used as a substitute or addition to the above excellent article.


Prerequisites

  • Jewelers screwdriver set since the screws are tiny.
  • A good, silicone or lithium-based grease.
    • Should not be too thick, or your focus will be smooth, but very stiff and probably not usable in the cold, as viscosity tend to change when you get below -7 to -8 degrees in the winter. 
    • You cannot use oil, WD-40 or similar, use grease.
  •  Electronic cleaner spray. 
    • I've found that this is the best to use to loosen old grease, it evaporates and leaves no residue. You can also use purified gasoline or maybe even some kind of spirit-based cleaner.
  • A stationary loupe/magnifying-glass which will enable you to work with both hands.
    • Some of the screws on the lens are so small you'll need a magnifier to get stuff together properly without breaking the screws.
  • A cloth to work on, use a t-shirt with some kind of bright color. It prevents parts and screws to roll and bounce away. It's also easy to spot any screws that fall off when you work and you can wipe your screwdrivers on it, if it (when it) gets all dirty from the old yak-fat :)
  • An old tooth-brush that you can use to clean out the fine threads on the rings.
  • Mobile phone to take photos of the process-steps

Tips 

  • When making a mark, try to use a screwdriver and not a pen/cd-marker.
    • When you clean and re-grease later and then fiddle to get it back together again, you will rub off the marks. 
    • Make the marks at places, so that they are not visible when the lens is assembled.

Jupiter-8 1963 edition, simple focus helicoid


This version is actually pretty straight forward.
The reason for this, is that my lens at least, have the three screws on each ring placed, so that they do not form a triangle with equal sides.

This makes sure that there is only one correct way to put the lens back together again.

Start by splitting the lens (twist the top part, lens part, counter-clockwise and the helicoid clockwise):

Split the lens, the top part should be screwed counter clockwise, and the bottom part clockwise.
If it's really stuck, use gloves or a cloth for better grip, they should come apart eventually.

When taking the focus-unit apart, I usually start by setting the lens at infinity. On my lenses, there is a real "stop" at infinity, while the close focus are usually not a dead stop, but a sort of a jam.

I usually set the lens to infinity before disassembling.
The reason for this, is that my lenses tend to have the correct marker for infinity
while close-focus is more variable (somewhere below 1 meter).

Not always obvious, but sometimes the screws are not aligned to form an equal sided triangle.

You'll normally find 3 screws for every ring, often they are placed, so that they
make up a triangle with one shorter side and two longer sides.
This helps when assembling the lens, but be aware that this is not always the case.
(take pictures and mark the lens with your screwdriver at certain points if you are unsure)
Work your way down the layers, starting with the focus-ring.
Take photos as you go and make sure those screws don't get lost!
The rear ring is removed, notice the screw, stopping the movements for close focus.
This screw needs to be removed as a last step of disassembly.

Focus ring is already removed, the ring indicated here, holds the aperture/distance relationship markers.
Note that all screws should be able to go all the way in without a hitch, if you experience issues when re-assembling, you have misaligned something.

I found that the most important thing here, is to make sure to note now the silver ring sits when at infinity.
On my lens, it is flush to the lip of the black inner tube as it hits the infinity screw. The ring can be set at at least 2 different positions (possibly more), so make sure you put it in the right way.
The final part of the helicoid, make sure you know how it looks when it is screwed all the way in (infinity)
The silver-ting should be flush to the lip on the back-part of the black tube, as shown.
Remove the ring indicated by 4) and you are ready to start cleaning and re-grease everything.

Now you can start cleaning. Use paper and cleaner to get all the obvious grease off, then use the tooth-brush with cleaning agent to clean out the threads for the rings.
Make sure everything is clean, or you will experience that your lens is still irregular and not smooth as butter.
If you are sloppy here, you may have to do the whole procedure again.
All parts, screws are collected so that they are inside the ring they belong to.
(They can be different in length and size).





Jupiter-8, 1955 edition, complex helicoid.


The 1955 (early to mid 50's) is supposed to be the better Jupiters, or, atleast the ones with less faults and maybe better glass. So I bought this one from eBay before Christmas. I also wanted the notched focus ring, as I find it more practical than a naked ring you twist.

This one is a bit of a challenge to clean and grease though.

**

There are more rings to take off and you need to mark the parts more, to be able to get everything back together again correctly.

It's not extremely hard, but I think I used like 1,5 hours getting only the three rings back together correctly the first time I tried. (second time, I spent "only" 30 minutes on that part =D ).

It's tricky to get the three rings together correctly.
I refer to them as "the black tube" and the two silver rings, for convenience.

Again, take your time, take photos during the process and make sure to mark (especially the final rings) properly and you will be able to get it back together again.


As always, you start by twisting the lens apart.





I've found that the focus limit screw also act as a focus-break, so if you tighten it too much, your lens will be hard to focus with. You need to tinker with it to set it correctly.



The relationship between the rings can be hard to explain, but I can explain the purpose of the design:
This is a (complex) way to transfer the circular movements of focusing, to a straight (lateral) movement of the focus unit (the black tube).


This is whats preventing the front of your lens to rotate when you focus, but rather move in and out.

Basically it works like this:
The focus ring, with knob, is fastened to ring 2.
As this one turns, it screws itself in and out on the black tube, simple, it's a "screw" after all.
It is threaded inverted though, so you screw the opposite way you would a normal screw, to screw it on or off the black tube.

Now....

Ring 1 is the magic part here.
This is a normal ring and is screwed onto ring 2, but it also has a notch or groove on the inside. This notch needs to fit over the stop screw.

When you screw ring 1 onto ring 2, it jams when it gets as far as the stop-screw. So to get it further in, it will need to be in a position where the groove/notch is over the stop screw (mine goes just past the stop-screw before it stops, when correctly inserted and I need to rotate it back 1/6'th of a turn to place the notch directly in line with the stop-screw). Then ring 1 needs the help of ring number 2 to get all the way in. To do this, you switch your hands over, hold both the black tube and ring number 1 stationary, and then turn ring 2.

Ring 2 will then (as screws do) move towards the lip of the black tube, but at the same time it screws ring 1 onto itself, in other words, ring 1 is "pulled" onto the black tube by the turning of ring 2, while being otherwise stationary (not rotating), held in place by the stop-screw in the notch/groove.
- You'll need to jiggle a little to get the stop-screw into the groove. :)


When you get to this step, observe, mark generously (but try to avoid confusing yourself) and then twist ring 2 to see what happens. When you screw it out, it goes out, but "pushes" ring 1 away from itself.

The problem with re-assembly, is that ring 1 can be screwed on 8 different ways (I think), it's fiddly to align it properly with the stop screw and ring 2 can be tough to move (with added grease, even more so).

Ring 2 can be threaded at least 2 different ways as well, so it has a relationship both to ring 1 as well as the black tube and should be marked accordingly.

With ring 2 having minimum 2 different ways to be put on, and ring 1 having 8, you have a minimum of 15 wrong ways and only one right way the rings can go in with this lens. If you get ring 2 on correctly, you have 7 wrongs and one right way, where some of the wrong ways looks fine.
That's why you should mark the rings as you disassemble it, so you can confirm that you found the correct way. ^^

Also, on my lens. When the two silver rings are correct, they have a slight gap to the lip of the black tube, it is easy to believe that they should be all the way in (which is also possible), but in my case, they are not supposed to be all the way in when correctly assembled. (just to add to the confusion).








Hope it helped.

There are videos out there which show how to disassemble Jupiter-8 lenses, but there are, off-course not any videos explaining the complex type in detail. :)




Lens-elements, disassemble and cleaning:







Good luck and have fun ^_^