Why cocking Pronto SVS shutter is so easy compared to Synchro-Compur in Rolleicord Va

[baachitraka]

My Rolleicord Va needs some effort to cock the shutter, but compare it to Isolette III they are so easy and smooth to do the same.

 

[BrianShaw]

Your Rolleicord should be VERY smooth and easy to cock.

 

[baachitraka]

Strange, that Rolleicord came back from Paepke fototechnik and they did a job on shutter and film transport. :-|

 

[BrianShaw]

I've had Rolleicords overhauled and the cocking lever was not properly lubed. Don't know if that is the situaiton on yours or not; I woul dhope not if it was just serviced.

But not knowing what shutter the Isolette has I can't say I can imagine what difference you are feeling. Doesn't Isolette have several different shutters: prontor, Compur-Rapid and synchroCompur.

Perhaps there is better mechanical advantage on the Isolette. The Rollei is almost a straight connection so feeling the full power of the mainspring is to be anticipated. I know I have experienced difference between cameras based on mechanical advantage... and both have Synchro Compur shutters of the same size.

 

[baachitraka]

Thats Prontor-SVS with speeds till 1/300.

 

[BrianShaw]

The synchro compurs also seem to be a tiny bit smoother to cock if set to X rather than M synch.

 

[R.Gould]

It should be very smooth to cock the shutter on your rolleicord, I have the same model, a Va, and it is very easy and smooth to cock, only on the 500th does it get harder, I also have several cameras with the Prontor shutter, The svs and they are very easy indeed to cock,but they are very different beasts

 

[baachitraka]

Nothing is obstructing when cocking the Rolleicord but it needs a little more effort compare to SVS. But, I do not know how I will feel if I CLA the SVS.

 

[E. von Hoegh]

Nothing is obstructing when cocking the Rolleicord but it needs a little more effort compare to SVS. But, I do not know how I will feel if I CLA the SVS.

What speed is the shutter set to? I ask because there is an auxiliary spring which comes into action at the highest shutter speed, the cocking effort will be noticeably higher when set to 1/500.

 

[baachitraka]

I felt that it require same effort for all the speeds. I will check again this evening and see whether there is any subtle difference between speeds.

 

[E. von Hoegh]

I felt that it require same effort for all the speeds. I will check again this evening and see whether there is any subtle difference between speeds.

It isn't subtle, it's very apparent.

 

[BrianShaw]

I don't believe that 00 size synchro compur shutter in a Rolleicord V uses a helper pring.

 

[Aron]

I could be wrong, but I think this is normal operation for Rolleicords using the EV system. I used to have a plain Rolleicord V (EV) and I don't remember that the action of the shutter cocking lever got stiffer when the shutter speed was set on 1/500, pretty much like a newer Compur 0 for LF cameras.

My Rolleicord IV (non-EV) on the other hand is very easy to cock for speeds between B and 1/250 and similarly hard as the Rolleicord V when set on 1/500.

So, could it be that in order for the EV system to function smooth at all settings, the auxiliary spring is also tightened at each winding or maybe the normal spring has increased rate, rendering an auxiliary spring unnecessary?

 

[E. von Hoegh]

I could be wrong, but I think this is normal operation for Rolleicords using the EV system. I used to have a plain Rolleicord V (EV) and I don't remember that the action of the shutter cocking lever got stiffer when the shutter speed was set on 1/500, pretty much like a newer Compur 0 for LF cameras.

My Rolleicord IV (non-EV) on the other hand is very easy to @#!*% for speeds between B and 1/250 and similarly hard as the Rolleicord V when set on 1/500.

So, could it be that in order for the EV system to function smooth at all settings, the auxiliary spring is also tightened at each winding or maybe the normal spring has increased rate, rendering an auxiliary spring unnecessary?

The auxiliary spring was used for the 1/400 and 1/500 sec.(depending on the vintage and size) top shutter speeds, it had to do with the design of the shutter, not it's application or the EV interlock on the Rolleis. Brian may be correct, the OP's shutter may not have the auxiliary spring - later and smaller Compurs didn't use it IIRC.

 

[Aron]

By "rendering an auxiliary spring unnecessary" I meant that is it possible for the shutter designs to be sufficiently different, that there would be no need for it for the top speed in the later version?

Could you give an explanation for the behaviour I described in my earlier post? The EV-system equiped Rolleicord V's shutter speed lever was as easy to move from 1/250 to 1/500 sec as it was from 1/125 to 1/250, if I remember correctly. The same is not the case with the previous generation 'Cord. I didn't imply the shutter speed setting levers had anything to do with the design of the shutters (whether there is an auxiliary spring present), but it is via these levers naturally, that one has to apply a little extra force when going from 1/250 to 1/500 on the older model.

If there was no increase in tension with the possibly newer shutters, than it's not a coincidence Rollei introduced the EV-system to the Rolleicord line together with these shutters.

 

[baachitraka]

I just found that it require the same effort to cock at any speeds. I will write to Paepke on tomorrow and find whether this is the case for later cords.

 

[elekm]

The mechanisms of the two shutters are different. With a Pronto(r), you are simply moving a lever that resets the tension on the shutter blades. With a Compur, the shutter tensioning lever is a flat ring that surrounds the opening for the lens. When you tension a shutter, you are applying tension to several springs. Tripping the shutter then allows the springs to pull back on the shutter tenioning ring and trip the shutter.

It would be easier to show in a video, but I'm feeling lazy right now.

The short version is that a Pronto(r) will almost always be easier to cock than a Compur.

 

[baachitraka]

At the same time I can't imagine giving the same effort to SVS on Isolette, which may seriously bend the mount.

 

[JPD]

The reason is that the Prontor and Compur are different shutters with different cocking mechanisms. The Prontor has a cocking lever, while the Compur has a cocking ring, and they work a bit differently.

The cocking ring from a Compur on the left (borrowed the pics from a flickr member):

http://farm5.staticflickr.com/4026/4346178057_33596fa368_b.jpg

Here's a Prontor-S (not too different from the SVS):

http://farm6.staticflickr.com/5061/5672380312_9edf942f13_b.jpg

 

[baachitraka]

Thank you very much indeed.

 

[18%gray]

Hmmm, So Many Bugs . . .

Literally.

A Rolleicord Va with Synchro Compur that I have here would not cock the shutter. I sent it in for service, and the tech discovered a dead bug caught between two gears in the shutter!

But now "the bugs are out" so to speak, and everything works fine!