Once shutter cocked, do not move speed.

[Guest]

So in answer to a post I made last week, Ken Ruth has answered my question in an email. He said do not move the shutter speed after it had been cocked. ( he has just serviced the camera a Super Ikonta ) I wanted to know why, here is his answer.............

RE: changing speeds cocked.
On your version shutter the pin that follows the speed setting cam can
be bent going from step to another when the shutter is cocked, when the
shutter is tripped the pin is retracted out of harms way. The top speed
engages an additional drive spring. the shutter tension on that spring
is minimal when tripped but great force is required to shift into top
speed after the shutter is cocked which can damage both the spring end
and the speed setting cam.

 

[Vics]

My Rollei MX is like that. Can't change to or from 1/500 when cocked.

 

[Mackinaw]

I've heard this before about leaf shutters. The guy who worked on my old Mamiya 6 folder recommended the same thing, do not change speeds after the shutter is cocked.

Jim B.

 

[jnoir]

Thanks for sharing, it is a best practice indeed, even mandatory for some cases.

 

[sevo]

With some shutters it is impossible to move the shutter speed selector past the points where some escapement engages or disengages - the steps usually are at from/to the highest speed and at 1/10 or 1/15. Later shutters usually allow switching escapements, but as shutters age, they clog up and the force needed to do it may grow to critical proportions - if it feels as if you'd need to force it, don't do it...

 

[kuzano]

Not always true.....

Not always true.....

I understand that in the domain of the types of shutters discussed here, it's likely true. However, I have a Kiev (Kneb) FSU built from Contax parts (early Arsenal factory model).

The shutter in the Contax/Kiev is a vertical blind type shutterbox.

Those cameras are very specific about the potential for damaging the shutter if you adjust shutter speed Before cocking the camera.

Cock first, set shutter speed.

It's important not to apply any "given rules" across the range of shutter mechanisms. Find out what works best for your shutter-your camera.

Just a caution here.

 

[sevo]

I understand that in the domain of the types of shutters discussed here, it's likely true. However, I have a Kiev (Kneb) FSU built from Contax parts (early Arsenal factory model).

The shutter in the Contax/Kiev is a vertical blind type shutterbox.

Those cameras are very specific about the potential for damaging the shutter if you adjust shutter speed Before cocking the camera.

At least in theory you can not damage a Contax or Kiev shutter by adjusting it prior to cocking. According to the manual, shutter times can be set with the shutter either run down or tensioned (but not half tensioned) - and that holds true on every clean Contax and better assembled Kievs. On cameras in a less than perfect state, there however is a considerable chance that the tab will slip when setting the time on a shutter that is not tensioned, in particular if you go down past 1/50 - but unless the camera has additional issues that can't cause any damage worse than one random (slow) exposure on the next firing.

Damage can however happen on FSU cameras (and pre war German cameras) with cloth focal plane shutters - these lack the rigid, self stabilizing curtains of the Contax, so that losing sync between the curtains can result in the loose ribbon or curtain tearing or getting entangled.

As far as old cameras go, it is better to be more cautious than the maker thought necessary. Setting after cocking is generally advisable on FP shutters, as the extra tension reduces the risk of slippages - just like setting before cocking is advisable on leaf shutters, as that reduces the load on the cam. But slipping out of sync or breaking off a pin is not a matter of shutter design, but of condition on the (now antique) cameras.