30" Artar very stiff aperture. How to fix? OIL?!!!

[Tin Can]

My very nice 30" Artar has a very stiff aperture. It is nearly impossible to adjust. These are not worth that much, not like Red Dot Artars. I do want to use it.

The aperture blades look fine and not binding. I think it is a problem with the aperture ring binding.

Would a tiny drop or 2 of penetrating oil to the suspect area be a good or bad thing to do?

[BrianShaw]

I've faced that situation twice. Here is my experience: (1) forcing it will break things. I broke the adjusting knob off of an old brass lens by trying to force it. Bad me. (2) a drop of two of lighter fluid is much better than oil. A solvent loosens up the gunk and hopefully redistributes that gunk thinner than before, leaving the aperture more functional than it was previously. The lgihter fluid will evaporate whereas a penetrating oil won't.

Summary: The oil idea is a bad one.

[Tin Can]

Good idea and I even have some. Trying it now. Reporting later. Thanks!

Any other hints?

I've faced that situation twice. Here is my experience: (1) forcing it will break things. I broke the adjusting knob off of an old brass lens by trying to force it. Bad me. (2) a drop of two of lighter fluid is much better than oil. A solvent loosens up the gunk and hopefully redistributes that gunk thinner than before, leaving the aperture more functional than it was previously. The lgihter fluid will evaporate whereas a penetrating oil won't.

Summary: The oil idea is a bad one.

[BrianShaw]

Only one additional hint. Small drop(s) of lighter fluid or equivelent solvent. Small drops can be repeated wheras flooding may be too much and spread gunk too far.

[BrianShaw]

Oh.. may be one more hint. Let remove the lens cells and let the solvent fully evaporate before reassembling.

[jcoldslabs]

A solvent loosens up the gunk and hopefully redistributes that gunk thinner than before, leaving the aperture more functional than it was previously. The lgihter fluid will evaporate whereas a penetrating oil won't.

Good advice. I was able to free up a very stuck aperture ring on an old Wollensak lens barrel using the lighter fluid trick.

Jonathan

[blueribbontea]

I tried lighter fluid on a 21 inch eastman and it loosened up while there was still some moisture but then stiff again. The grease had hardened with accumulated dirt and needed to be removed, not just softened. That required dissassembly. It's working fine now.

[Jim C.]

You need to flush the gunk out, decades of finger oils, oiling, moisture, and dirt makes a nasty "snot" in the aperture mechanism,
redistributing it isn't a very good solution as blueribbontea found out.
I've used DeoxIT D series contact cleaner to flush the crud out. I've ordered it from McMaster ( they don't mention brands, my pet peeve with them )
but it can be ordered from Caig directly - http://store.caig.com/s.nl/sc.2/category.292/.f
It does leave a ever so slight residue, but that can be flushed off with naptha or lighter fluid, I seem to recall Caig having a version that cleans only.

[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

My very nice 30" Artar has a very stiff aperture. It is nearly impossible to adjust. These are not worth that much, not like Red Dot Artars. I do want to use it.

The aperture blades look fine and not binding. I think it is a problem with the aperture ring binding.

Would a tiny drop or 2 of penetrating oil to the suspect area be a good or bad thing to do?

[Tin Can]

Great detailed advice. I have done nothing yet, as i went for a long walk on our first nice day in 5 months, came home and fell asleep.

I have the right screwdriver, I can count turns and i have that grease.

This will be great when it works.

I like Artars and have a few, both Red Dot and not and in studio shooting, I see no difference.

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