monopix
Cam repairer
Thought I would pass on this info for anyone interested.
I have one of the above lenses which has always had a slightly loose front section. That is, you could rotate the front section a little. This could also be felt when focussing as backlash in the focussing.
Here's the fix.
Remove the front cap and hood. Unscrew the front optical assembly by using a wrench in the slots shown in the picture.
Make sure you use these outer slots, not the inner ones.
Now remove the front trim. This is just stuck on and is best removed by inserting a blade underneath and lifting it up.
Now unscrew the three screws which are visible and remove the front section of the lens. Then remove the aperture ring which wil now be loose. DON'T LOOSE THE BALL BEARING AND SPRING WHICH ARE UNDER THE APERTURE RING (if you're afraid of the spring shooting off or of dropping the ball bearing, put the whole lens into a plastic bag while removing the aperture ring).
You should now have this.
Note the two brass coloured pieces marked in the above picture. One of these is slotted - you should just about be able to see which without removing them. Remove the slotted one.
The problem is these two brass pieces are loose in their slots and that causes (or allows) the movement. To fix the problem, spread the two arms of the piece shown above such that it is a tight fit in it's slot.
Now reassemble everything. You may find it easier to reassemble the aperture ring if you remove the aperture actuating arm from it first.
Notes: Most of the screws seem to be locked with locktite or similar and so are difficult to remove. Make sure you're using the correct screwdriver or you'll damage the screw.
After fixing the above, you may still get a slight backlash in the focussing ring. This is caused by another part which sits in a slot in a similar way but isn't adjustable. It's also very difficult to get at as it requires further dismantling (from the back of the lens) and splitting the helicals. I would leave alone.
Hope this is useful.
I have one of the above lenses which has always had a slightly loose front section. That is, you could rotate the front section a little. This could also be felt when focussing as backlash in the focussing.
Here's the fix.
Remove the front cap and hood. Unscrew the front optical assembly by using a wrench in the slots shown in the picture.
Make sure you use these outer slots, not the inner ones.
Now remove the front trim. This is just stuck on and is best removed by inserting a blade underneath and lifting it up.
Now unscrew the three screws which are visible and remove the front section of the lens. Then remove the aperture ring which wil now be loose. DON'T LOOSE THE BALL BEARING AND SPRING WHICH ARE UNDER THE APERTURE RING (if you're afraid of the spring shooting off or of dropping the ball bearing, put the whole lens into a plastic bag while removing the aperture ring).
You should now have this.
Note the two brass coloured pieces marked in the above picture. One of these is slotted - you should just about be able to see which without removing them. Remove the slotted one.
The problem is these two brass pieces are loose in their slots and that causes (or allows) the movement. To fix the problem, spread the two arms of the piece shown above such that it is a tight fit in it's slot.
Now reassemble everything. You may find it easier to reassemble the aperture ring if you remove the aperture actuating arm from it first.
Notes: Most of the screws seem to be locked with locktite or similar and so are difficult to remove. Make sure you're using the correct screwdriver or you'll damage the screw.
After fixing the above, you may still get a slight backlash in the focussing ring. This is caused by another part which sits in a slot in a similar way but isn't adjustable. It's also very difficult to get at as it requires further dismantling (from the back of the lens) and splitting the helicals. I would leave alone.
Hope this is useful.
