Originally Posted by
Bernice Loui
Artar, non red dot lenses are often under rated. Some are coated, some are not. In the pile is an Artar, non red dot serial number 77xx... that is coated and excellent performer. They often have much lower resale value due to the perception Artar is not coated and lesser than Red Dot Artars.. which is simply not true. It is individual lens dependent.
If the lens barrel is constructed in the typical Goerz style, the aperture ring stays in place using very fine threads.
*The cure for the stuck aperture ring is to look for the screw-pin that operates the iris.
*Once it has been located on the aperture ring, carefully mark it's position relative to the lens barrel and using a high quality, proper fitting screwdriver remove it from the aperture ring.
*Dampen a Q-tip with just enough low viscosity oil to apply oil around the circumference of the aperture ring.
*Then carefully work the aperture ring free using CW & CCW motion.
*Once the aperture ring has eased enough to move some what freely, remove it completely off the lens barrel by rotating it CCW.
*Note the number of turns required to remove the aperture ring.
*Upon removal of the aperture ring from the lens barrel, clean the internal threads with 99% or greater Isopropyl alcohol, do the same to the threads on the lens barrel. Do not use too much Isopropyl alcohol as it will enter the iris inside the lens barrel.
*When the threads are clean down the base of the threads, apply a small amount of synthetic grease (Dupont Krytox) not heavier than NLGI-2 to the treads.
*Install the threaded aperture ring back on to the lens barrel body with the same number of turns as used for removal.
*line up the screw-pin location that operate the iris to the lens body.
*Install the screw-pin back into the aperture ring and seat the skew. If the screw does not engage the starting threads inside the aperture ring, very slightly rotate the aperture ring to line-up the screw-pin location to the iris operating slot inside the lens barrel.
It is dirt, grease turned to clay and other grit inside the aperture ring threads that cause this problem. The difference cleaning out and proper lubrication on the threads makes a "black -vs- white" difference in how the aperture operation of these Goerz lens barrels.
Bernice
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