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Steinheil 105mm 3.8 can't focus to infinity
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PostPosted: Tue Jul 03, 2018 3:24 am    Post subject: Steinheil 105mm 3.8 can't focus to infinity Reply with quote
It is the Cassar 105mm f/3.8 VL, M42 mount. It is a pretty beaten-up lens and can't seem to focus to infinity. I am not sure if I didn't the right thing. But there is no focus ring as in a regular lens. I can only rotate the top ring (which has one optical element) to focus. It is essentially a screwing/unscrewing process. Any information is appreciated!


PostPosted: Tue Jul 03, 2018 4:24 am    Post subject: Reply with quote
The lens use front focus by rotating the top ring.


PostPosted: Tue Jul 03, 2018 4:30 am    Post subject: Reply with quote
calvin83 wrote:
The lens use front focus by rotating the top ring.


Thanks. That's what I did. The top ring has a single piece of glass. It feels the ring wants to pass "infinity". I am not sure if the lens has been disassembled, as I see engraved marks. I suspect one of the glass could be reversed. My M42-NEX adapter should work fine, I've used it for other M42 lenses.


PostPosted: Tue Jul 03, 2018 9:38 am    Post subject: Reply with quote
Photos of lens, please?


PostPosted: Tue Jul 03, 2018 2:42 pm    Post subject: Reply with quote
visualopsins wrote:
Photos of lens, please?


I took a shot of the side view. Look at the engraved marks: One at f22 and one slight to the right of 8", minimum focus distance.
Now the lens can focus much less that but can't focus to infinity. I paid $30 total and am thinking whether I should return it or just find a way to fix it as it is a triplet (looks easy, but I never fixed a lens before).

Thanks.

#1


PostPosted: Tue Jul 03, 2018 8:12 pm    Post subject: Reply with quote
Its a front-cell focus lens like on many folders and other early cameras. The original Kodak 35 for instance.
I have adjusted infinity on many of these front cell focus lenses (not on yours though).
On folders you have to do it every time when cleaning the lens, in order to get rid of haze on the internal surfaces.

The front cell (with one element) is on a simple screw, not a helical.

There is normally a crown or shell or ring, whatever you want to call it, over the actual front cell, that has the focus stop.
To adjust infinity you remove this ring, usually held on by set screws (I think I see one in your picture).
This lets you adjust the front cell until you get infinity.
Then you replace the ring with the infinity indicator lined up correctly (and the infinity stops in the right place), and tighten down the set screws.


PostPosted: Wed Jul 04, 2018 3:12 am    Post subject: Reply with quote
luisalegria wrote:
Its a front-cell focus lens like on many folders and other early cameras. The original Kodak 35 for instance.
I have adjusted infinity on many of these front cell focus lenses (not on yours though).
On folders you have to do it every time when cleaning the lens, in order to get rid of haze on the internal surfaces.

The front cell (with one element) is on a simple screw, not a helical.

There is normally a crown or shell or ring, whatever you want to call it, over the actual front cell, that has the focus stop.
To adjust infinity you remove this ring, usually held on by set screws (I think I see one in your picture).
This lets you adjust the front cell until you get infinity.
Then you replace the ring with the infinity indicator lined up correctly (and the infinity stops in the right place), and tighten down the set screws.


Thanks. I understand what you described exactly. However, I didn't seem to see the set screws. I am attaching three photos.

The first one shows the unscrewed the front element or the crown. Do you know what the little stub is? The one that sticks out?

#1


The second one shows the lens looking inside from the top with the crown removed. There is also a stub sticking out. It is a little wry. What is it for, I am not sure.

#2


The third one shows the lens looking inside from the mount.

#3


One thing that I noticed is the curvature of the aperture blades. Usually when looking into a lens from the top, the aperture blades are concave; when looking into the lens from the mount, the aperture blades are convex. However, this lens shows the opposite. I am not sure if it is normal or not.

Do you have any other idea how I can make the adjustment? Appreciate!


PostPosted: Wed Jul 04, 2018 3:23 am    Post subject: Reply with quote
vivaldibow wrote:
visualopsins wrote:
Photos of lens, please?


I took a shot of the side view. Look at the engraved marks: One at f22 and one slight to the right of 8", minimum focus distance.
Now the lens can focus much less that but can't focus to infinity. I paid $30 total and am thinking whether I should return it or just find a way to fix it as it is a triplet (looks easy, but I never fixed a lens before).

Thanks.

#1


Set screw above 8 on distance scale?


PostPosted: Wed Jul 04, 2018 4:18 am    Post subject: Reply with quote
visualopsins wrote:
vivaldibow wrote:
visualopsins wrote:
Photos of lens, please?


I took a shot of the side view. Look at the engraved marks: One at f22 and one slight to the right of 8", minimum focus distance.
Now the lens can focus much less that but can't focus to infinity. I paid $30 total and am thinking whether I should return it or just find a way to fix it as it is a triplet (looks easy, but I never fixed a lens before).

Thanks.

#1


Set screw above 8 on distance scale?


Ok, now I see. I tried to unscrew those set screws but the screw slots are all gone. If there is a way to loosen those screws, did you mean by changing the relative position of the front element, I can adjust the focus, correct?


PostPosted: Wed Jul 04, 2018 6:10 am    Post subject: Reply with quote
Yes, basically that, the relative position of the front element vs the crown, which holds the infinity stop.
I am surprised you can remove the front element, the infinity stop must be bent or worn, or that bit on the base that is bent lets the infinity stop go past.

This looks like a triplet which is normal for front cell focus lenses, though there are four element Tessar types like that too.

The Steinheil Cassar one finds on old folders was a triplet.

This thing is a "Trioplan", just with smaller max aperture.


PostPosted: Wed Jul 04, 2018 9:48 pm    Post subject: Reply with quote
luisalegria wrote:
Yes, basically that, the relative position of the front element vs the crown, which holds the infinity stop.
I am surprised you can remove the front element, the infinity stop must be bent or worn, or that bit on the base that is bent lets the infinity stop go past.

This looks like a triplet which is normal for front cell focus lenses, though there are four element Tessar types like that too.

The Steinheil Cassar one finds on old folders was a triplet.

This thing is a "Trioplan", just with smaller max aperture.


I haven't tried to removed the front element. It is held by the black ring with two notches. I'll probably need to spanner wrench to remove the front element if I need. I'll start with the set screws. Worst thing is all the screws are stripped and I don't know how I am going to remove the them.

The infinity stop in the lens barrel is bent; the stop in the crown isn't.

I thought Trioplan only applies to the series of lenses made by Meyer Optik. What I read from the internet that this Cassar 105mm/3.8 is a Cooke-Triplet construction. Anyway, I did learn a lot from you. Appreciate the information!
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