Yashica Yashinon DS 50mm f1.9 disassembly of front elements?

WNG555 · Joined: 18 Dec 2014 Posts: 784 Location: Arrid-Zone-A, USA

Hi folks!

Does anyone have experience or know of a source of info on how to disassemble a Yashica Yashinon DS 50mm f1.9 prime lens?
The body is shared between the f1.7 and f2 as well.

It's updated from the DX and differs slightly internally. And it's not like other Tomioka sourced lenses. The construction is different.

I have fungus and stains at the inner front elements. I've taken the lens apart and gotten to the (Yashinon) lens/aperture 'module' .
The 'module' is the rear elements, the middle aperture mechanism, and the front element assembly.

The rear element unscrewed easily, and the front elements are housed together. And that's the point I'm stuck at.
It appears the front ribbed 'cone' is screwed on and holds the first element in place. But there are no slots on the cone. It will not budge under hand friction alone, even after soaking in acetone in case there is thread locker.

Of course, this is assuming it's threaded onto the main front element assembly.
The front must come off some way, as I can see a slotted ring under the first element that secures the 2nd element.

Any advice is greatly appreciated.

EDIT:

Looks like as soon as I finished posting, I managed to make progress.

The acetone alone wasn't enough on my sample. I resorted to heating the outer body with a hair dryer. The expansion seemed to have done the trick. The thread locker yielded.

Once separated, it revealed the threads are deeper near the element, not at the rim. So, it will take a lot of patience to allow the acetone to work its way down.

I'll leave the post up for anyone who may search for tips on this model.

Gardener · Joined: 22 Sep 2013 Posts: 950 Location: USA

I have a piece like that sitting somewhere in the back of the cupboard - I never managed to open it. Perhaps it's time to try again.