Sinar Copal shutter, usable WITHOUT cables?

**Steven Tribe** · 5-Mar-2012, 03:39

As it is cold outside to-day for final garden pruning, I have done a little experimenting with the copal/sinar shutter. I have come to the conclusion that the internal spring is so solid that there is no need for a coil spring to be built into the release cable mechanism. Even if the actuating rod does stick out of the threaded sleeve a little, the friction on a short and straight release will not be enough to accidentally trip the shutter. So we are talking about a very simple design.
The attachment thread appears to be an ordinary M4 with 0.75mm pitch. Unless Sinar/Copal had their own variant? Bob S would be useful here? But perhaps these cables are still available as new items?

**domaz** · 5-Mar-2012, 13:37

Originally Posted by rdenney

A bicycle brake cable is too flexible. It is designed to apply force in tension only.

I would suggest a different sort of Bowden cable that uses a solid inner wire designed to push as well as pull. Some control cables for automotive air-conditioners for really old cars (before digital AC controls), or the throttle cable on a lawn mower, might be something to explore. These are stiffer, of course, but if it's long enough you can still bend it around 90 degrees and eliminate transmitting movement to the camera from your hand.

McMaster-Carr sells a few models that might provide raw materials for making something. Search on "push-pull control cables".

The solid wire might be brazed or crimped in a tube to make a pushrod, but the tricky bit will be the threaded connection into the camera.

Actually the threaded connection was easy with brake cable housing. Like I said I just took the end of a standard cable release and press fitted onto the end of the housing. You can screw in a standard cable release onto the Sinar Shutter (at least on mine you can) and it stays there just fine. Agreed that bike brake cable is not the right material- I like your ideas of using other control cables. I really think this is possible- there is no magic to this cable really and it should be something that is possible to DIY.