Steven Tribe
9-May-2014, 06:34
If you read the thread in lenses entitled "advice on Cooke with stuck Soft focus" you will get a background for this.
The problem is that, looking in from the rear, it is difficult to tell where the soft focus thread is. Photo 1 shows the position of this thread. There are two rings which may look like one thick ring if the thread is screwed right in. On my example the inner ring (moveable front barrel) is painted black, whilst the outer ring has a plain brass finish.
I applied the standard WD "XY" fluid around this thread and did the usual heating and repeated the application a few times. I used a small piston ring clamp to obtain a purchase on the barrel. It is very important that compression is all around the barrel as even small distortions of the barrel will lead to problems mounting the front lens cell afterwards.
In my case the direction of unscrewing was anti-clockwise - but just follow the direction shown for the soft lens option.
There are no channels in the inside of the fixed receiving sleeve. This means all the various visable screws/screw holes are for locking the barrel in fixed position. You can see from photo 4 that there is a short routed section which corresponds to the position of the screw hole in the "SHARP" position. My guess is that a screw thread was inserted along this groove when Cooke found out where the "best" sharp position was. In my example there were a total of 3 holes around this position and some remnants of sheared screws. This may be an attempt to find the right soft position for a previous photgraphers preferred style.
It is therefore not a problem to remove any screws - or even bore out sheared screws. The soft mechanism will not be effected.
Later: I have done a post-Mortem on the 3 "locking screws! The one on the "track" is not a screw, but an identation which contained the remains of the sheared off original screw. The two others were threaded screws which were mounted in threads. The hole for these threads had been drilled right through the barrel.
The problem is that, looking in from the rear, it is difficult to tell where the soft focus thread is. Photo 1 shows the position of this thread. There are two rings which may look like one thick ring if the thread is screwed right in. On my example the inner ring (moveable front barrel) is painted black, whilst the outer ring has a plain brass finish.
I applied the standard WD "XY" fluid around this thread and did the usual heating and repeated the application a few times. I used a small piston ring clamp to obtain a purchase on the barrel. It is very important that compression is all around the barrel as even small distortions of the barrel will lead to problems mounting the front lens cell afterwards.
In my case the direction of unscrewing was anti-clockwise - but just follow the direction shown for the soft lens option.
There are no channels in the inside of the fixed receiving sleeve. This means all the various visable screws/screw holes are for locking the barrel in fixed position. You can see from photo 4 that there is a short routed section which corresponds to the position of the screw hole in the "SHARP" position. My guess is that a screw thread was inserted along this groove when Cooke found out where the "best" sharp position was. In my example there were a total of 3 holes around this position and some remnants of sheared screws. This may be an attempt to find the right soft position for a previous photgraphers preferred style.
It is therefore not a problem to remove any screws - or even bore out sheared screws. The soft mechanism will not be effected.
Later: I have done a post-Mortem on the 3 "locking screws! The one on the "track" is not a screw, but an identation which contained the remains of the sheared off original screw. The two others were threaded screws which were mounted in threads. The hole for these threads had been drilled right through the barrel.