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Lens and Optics
Jupiter-8 Lens Dismantle and Clean

Rev.1

The following describes the steps to dismantle and clean a Kiev mount Jupiter-8 lens.

If your lens has correct focus you may want to mark a scribe line for reference so that you can reassemble the mount base back to the same mark.

 

Loosen the set-screw on the mount base.

 

Unscrew the mount base from the lens block. Note the spacer that sets up the correct lens flange to film plane distance. When it is time to fine tune the lens working distance this spacer will be adjusted.

 

Loosen the three set-screws from the aperture ring. I find it best to remove these set-screws and put them in a safe place so that they don’t inadvertently drop out become lost. They’re really small!

 

Unscrew the aperture ring from the collar towards the lens rear.

 

Loosen the set-screw on the locking collar and unscrew the locking collar from the lens block.

 

Remove set-screw from aperture collar.

 

Slide the aperture collar off from the lens block. Notice all that gummed up grease, it will have to be cleaned up.

 

Use a spanner to loosen the rear lens group from the lens block.

 

Unscrew the rear lens group to remove completely. Since this lens group is a cemented group there is no particular reason to dismantle the lens group any further for cleaning. But, If you have a burning desire to find out what is inside, then follow along.

 

Instead of removing the whole lens group it is easier to work with it still installed on the lens block. Unscrew the inner retaining collar for the rear lens element with a spanner.

 

Remove the lens group from the block and set aside.

 

Remove the outer lens group holder.

 

Here is a close view of that remarkable cemented lens group.

 

On to the front lens group, remove the two set-screws on the bezel and put in a safe place as per previously mentioned.

 

Unscrew the front bezel to gain access to the front lens element.

 

Remove the front lens element from the front lens group.

 

Remove the rest of the front lens group from the main lens block.

 

Here’s the whole front lens group ready for cleaning or what ever you had in mind when you decided to take your lens apart.

Reassembly is pretty much the reverse operation with a few things to be mindful of. First, a little word on grease, you are probably taking your lens apart because of some oil residue on the lens elements or aperture. Use grease that will not “creep” or flow. I did this test several months ago where I placed a dollop of grease on a sheet of glass and left it. Here are the results. No slumping or running of the grease.

 

There is no need to go crazy when applying grease for the aperture collar. You spent some time cleaning the needless gunk that was in there from the factory. Only a thin coat on the above surfaces are required, as these are the only parts that slid together.

 

When screwing the retaining ring back on make note of the dimple that the set-screw seated in and turn the ring to align with this dimple.

 

Blow off any dust with a can of compressed air and clean optics with a good approved cleaning system prior to final assembly.

 

Make note of the dimple the set-screw seated in, as well note your previous small scribe mark when you screw on the lens mount base.

 

If you are at all lucky, the lens mount base will screw on, line up with the dimple for the set-screw and even as an added bonus, line up with the aperture marks.

 

June 24, 2007