Printable View
Hello
I have a question about the Schneider Symmar 5.6 / 240mm on Sinar DB board
Has anyone had any experience of dismantling/revising the spring mechanism for the aperture ring? It's stiff.
On the back, the fastenings are supposedly sealed: how do you remove this seal and how do you reseal it?
Thank you for your help!
NormaN
Attachment 207963
Attachment 207964
The "mickey mouse ears" (DB) mounted lenses that I have experienced have been a bit stiff to move in general, which may be because of its construction, or that the aperture on the lens itself is stiff from age. I think the fastenings (screwed into the board) possibly could be lacquered (nail polish, sort of) on the rear to prevent them from getting loose. It could be something more permanent like Loctite, too.
Thanks JimiQuote:
Originally Posted by Jimi
Have you seen photos or even a film somewhere where you can see the inside of this mechanism? I hoped that the functionality could be restored. I imagine that a spiral spring or something similar is built in ...
What do you think? Is it worth getting the lens going again?
I already have the Norma Copal Shutter (including all cable releases) and it works.
"Mikeno62" had already put various repair films on the network, for example about the Sinar Coplal Shutter
https://youtu.be/p1_1Cmfwi28
I'll see if something can be found in his film collection
Regards NormaN
I am just guessing, but I think the mechanism is very simple, relying on the coil being strong enough to move the black metal piece connected to the aperture ring. Since you release it by pressing the "mouse ears" together and then pushing/pulling, I believe that is all there is to it. On the coil you have the apertures marked with the plastic rings.
If one could temporarily disconnect the black metal piece from the lens barrel (or remove the lens from the lensboard) you could test if the aperture seems smooth on the lens itself.
I think it might be worth fixing, since one can use this with the Copal shutter and work the lens/shutter combo from the rear of the camera, checking aperture and firing the shutter. Great for portraiture if you are going to do that, for example.
That is the deluxe Norma version, with spring loaded aperture control, which fully integrates with the Sinar Norma Shutter. The automation is outstanding. I have a few of these lenses that need a bit of help, like yours does. Sometimes when the cables are sticky, I will just provide a bit of "persuasion" to move things properly into position. Slow but it will work as intended. I had my clockmaker friend clean one of these and he did so, but was not happy about how it went! An expert repairperson I believe is required. Somebody familiar with the mechanism.
There are plenty of these automatic boards stripped of all parts on Ebay, so obviously it is doable. But why if you have the Norma shutter? If you go that route fill the holes with aluminum epoxy (I use JB WELD).