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Schacht Ulm Travegon 3.5 35mm Lens Dissassebly - Re Assembly
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PostPosted: Fri Mar 15, 2019 3:30 pm    Post subject: Schacht Ulm Travegon 3.5 35mm Lens Dissassebly - Re Assembly Reply with quote

Hello All!

I've been an avid reader of this site - great information!

I am in need of information on the Schacht Ulm Travegon 3.5 35mm (Exakta Mount) and if someone has ever take this lens apart and may have a diagram of how it is re assembeled. I received this lens nonfunctional with several auto aperture (spring , bearing and clutch?) parts loose inside. I did a selective disassembly but didn't want to go any further without a guide, a diagram or some notes of someones experience with this issue.

Any help is greatly appreciated!

Best Regards!

eldiii


PostPosted: Fri Mar 15, 2019 8:27 pm    Post subject: Reply with quote



Here are the lens parts.

Thanks again!

Regards,

eldiii


PostPosted: Sat Mar 16, 2019 6:11 am    Post subject: Reply with quote

eldiii wrote:


Here are the lens parts.

Thanks again!

Regards,

eldiii


I've not worked on one nor had one in hand... better close up pictures would help.

First thing I would do is figure out the helicoid arrangement, I would find a point on the main body to use as a reference point, the red dot for the aperture, an internal mark, groove, screw hole, etc... Then wrap the helicoid in tape that you can mark.
Find a start for the helicoid and mark it next to the reference point. You'll have to most likely try all the starts to find the correct one, you may luck out and find that all starts will achieve infinity focus. Are there any features to the helicoid ring? screw holes, flats or??? It looks like a hole on the left side... this will tell you if it needs to be in a specific location/orientation at infinity. the focus ring is probably adjustable to align it to the infinity stop, the infinity stop might be apart of the brass guide rail ring and the hole in the helicoid, a screw pin may move in the thin section of the guide rail ring, if this is it's purpose, you'll have to find a start the results in the hole ending up in the correct location at infinity. The reference point will help you figure out what direction and by what amount the correct start will be.

The guide rails that keep the front end from rotating when you turn the focus ring are part of the brass ring they are the little ears that point in. this attaches to the mount, it looks like the screw holes are not equally spaced so you won't have to guess that part.


From what I see, the rod goes into the button assembly, it should extend when the button is pressed, the ball bearing may go into the hole first, or it may be apart of the aperture detent, the aperture ring is at the front and I would assume that's where the detent is, you should be able to test the aperture ring, I believe the ball bearing rides a ramp on the bottom of the button and pushes the rod, the rod should push on the half moon fulcrum, which I think acts directly on the aperture or a post connected to it. The spring is likely for the aperture return.

The assembly would likely be the helicoid, then the aperture fulcrum & spring, followed by the guide rail ring, the mount, the focus ring, then the button assembly, and lastly, the black dust shield.

Hope that helps.

If the aperture works manually, and you don't have all the parts or you don't intend to use it on an Exakta or Topcon camera, you most likely can skip all the aperture bits and make it fully manual, you could even omit the button assembly and make a cover for the hole it leaves behind.


PostPosted: Mon Mar 18, 2019 6:03 pm    Post subject: Reply with quote

Thank you for the note Lightshow,

I think that there maybe other problems with this lens as the aperture ring at the front of the lens is not opening up the Iris nor will the aperture ring move beyond F8 (3.5 to Cool. I didn't open up the front of the lens, just the Auto Aperture at the rear. I look at it again this coming weekend.

eldiii


PostPosted: Mon Mar 18, 2019 9:28 pm    Post subject: Reply with quote

Is there any linkage from the aperture ring coming towards the rear? If there is, follow it and watch how it moves, then take a small stick or paint brush and gently push on the lever part that is attached to the iris, if it stops in the same place, it's the aperture, if it stops down further, it's the aperture linkage or ring, or something in that area.
Don't force anything, the blades are easily mangled, later auto lenses typically use springs as a safety device to absorb excessive pressure if something is stuck so the damage or rather the repair work is limited to the original cause and they don't have to fix bent parts.