Last spring I picked up a mint/new old stock lens from Japan. When I got it, it worked fine but recently I noticed that the aperture is really slow and doesn't connect to the camera. When I dismount the lens I can't get it to open easily and I think I can see some lubricant on the blades. Anyone know the best way to deal with this situation?
Nikon 35mm f:2 AF-D Sticky Aperture Fix?
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- Thread starter Robert Ley
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The oil needs to be removed from the blades. I put them all in a little jar of denatured alcohol then wipe them with paper towel before re-assembly. Other solvents will work fine too. You can have someone do this for you, it is an easy fix for any camera tech.
Checked out Youtube and there are numerous videos on this lens and oil on aperture blades. Evidently this is a common problem with this lens. Just ordered the basic tools that I will need for this repair and I'm going to give it a try to see if I can't fix this very nice lens.
If you will be keeping this lens, make sure to check it regularly for oil contamination on the blades. Even after removing and cleaning the blades they will get oily again, especially in high heat. Many years ago I had a repair client (gov agency) that had about 100 Nikon FM2 cameras each one equipped with the 35mm/f2 AF Nikkor and every Monday morning a box would be delivered with several of these lenses with sticking diaphragms. The issue seems to be that the inner helix and diaphragm housing is made of plastic and seems to allow the lubrication on the helical threads to pass through to the diaphragm blades.
This will be my first lens repair and I will be keeping this lens as 35mm is my favorite focal length. Is there a way to mitigate this transfer of lubricant?
It would be possible to remove the focus helix lubricant and install a new lubricant that would not "creep" but I never did experimentation on other greases other than Nikon's so can't give you any tips on that.
I see cleaning oily aperture blades as a service task that needs to be repeated regularly, provided you can reach the blades.
Regardless of whether you clean them when they are installed or removed, you can only rest when the lens has been cleaned of the grease that has turned to oil on the helicoids.
The most thorough method is dismantling, cleaning and re-greasing.
If the design allows it, the helicoids can also be cleaned when they are assembled, e.g. by rinsing them several times with solvent and applying grease. This saves you any problems when adjusting the lens after reassembling the helicoids. For this purpose, the lens must also be partially disassembled and the remaining optics must be protected from contamination.
Dismantling, cleaning and reassembling a lens is a lot of (dirty) work, so I prefer to regularly clean just the aperture blades, as far as possible.
Regardless of whether you clean them when they are installed or removed, you can only rest when the lens has been cleaned of the grease that has turned to oil on the helicoids.
The most thorough method is dismantling, cleaning and re-greasing.
If the design allows it, the helicoids can also be cleaned when they are assembled, e.g. by rinsing them several times with solvent and applying grease. This saves you any problems when adjusting the lens after reassembling the helicoids. For this purpose, the lens must also be partially disassembled and the remaining optics must be protected from contamination.
Dismantling, cleaning and reassembling a lens is a lot of (dirty) work, so I prefer to regularly clean just the aperture blades, as far as possible.
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At some point, the lens was subjected to sufficiently high temperature long enough for the oil component of the helicoid grease to separate from the thickener (referred to as “soap” in the grease-making industry). Once separated, the oil can slowly seep out and foul the aperture blades.
The drag (stiction) imposed by the oil between the overlapping aperture blades is too great for the closing spring to overcome on a spring-closing aperture, so the aperture first becomes sluggish. As the fouling increases, the oil will start to oxidize, making the oil become increasingly tar-like. Eventually, the diaphragm becomes immobilized.
This most often happens when the lens is left for hours in the interior or trunk of a hot, closed vehicle on a sunny day, stored in a shed, or if it is left on a heating radiator during the winter.
From Google using the search string “heat effect on grease:”
“When exposed to heat, grease will tend to separate, with the oil component thinning and separating from the thickener, leading to a loss of lubricating ability, increased friction, and potential damage to the components it's meant to protect; essentially, excessive heat causes grease to “bleed” and become less effective as a lubricant.”
The following is a useful article about the properties of various types of grease.
https://reliability.com/resources/articles/understanding-the-basics-of-grease/
An important consideration with grease intended for lens helicoids is the significant amount of mating surface area. Both male and female helicoids are usually made of aluminum, soft and relatively delicate. So, they must be lubricated. But to keep the resistance low enough so that they will move freely requires a relatively thin grease. The most suitable grease I’ve found is the helicoid greases #10 and #30 sold by Japan Hobby tool.
#10 is the thinnest and is a good choice for cold weather use. #30 is medium and the best choice for manual focus lenses in average conditions. Since these greases are miscible, you can mix them to achieve intermediate densities. I stipple the male helicoid with small dabs of #10 applied with a toothpick and then use even more of the #30 for an intermediate result.
https://japanhobbytool.com/collections/camera-repair-material/products/hg
It’s pointless to apply a copious amount of grease because there is little clearance between the male and female parts. Any excess will simply be pushed out of the ends and make a mess.
There is a problem with simply dissolving the oil on the diaphragm with a solvent, and mopping out the oil-plus-solvent liquid. This will free the aperture and allow it to work normally. But eventually, the heat-damaged grease will continue to weep more oil. That will foul the diaphragm again. The damaged grease must be entirely removed and replenished with fresh, undamaged grease for a permanent repair. Then, so long as the lens isn’t re-exposed to prolonged excess heat, the problem will most likely not recur. My lenses that I’ve cleaned of oil-weeping grease and relubricated as described have not had a recurrence of the problem. I’ve only encountered this with second-hand lenses, never with any that I bought new.
The drag (stiction) imposed by the oil between the overlapping aperture blades is too great for the closing spring to overcome on a spring-closing aperture, so the aperture first becomes sluggish. As the fouling increases, the oil will start to oxidize, making the oil become increasingly tar-like. Eventually, the diaphragm becomes immobilized.
This most often happens when the lens is left for hours in the interior or trunk of a hot, closed vehicle on a sunny day, stored in a shed, or if it is left on a heating radiator during the winter.
From Google using the search string “heat effect on grease:”
“When exposed to heat, grease will tend to separate, with the oil component thinning and separating from the thickener, leading to a loss of lubricating ability, increased friction, and potential damage to the components it's meant to protect; essentially, excessive heat causes grease to “bleed” and become less effective as a lubricant.”
The following is a useful article about the properties of various types of grease.
https://reliability.com/resources/articles/understanding-the-basics-of-grease/
An important consideration with grease intended for lens helicoids is the significant amount of mating surface area. Both male and female helicoids are usually made of aluminum, soft and relatively delicate. So, they must be lubricated. But to keep the resistance low enough so that they will move freely requires a relatively thin grease. The most suitable grease I’ve found is the helicoid greases #10 and #30 sold by Japan Hobby tool.
#10 is the thinnest and is a good choice for cold weather use. #30 is medium and the best choice for manual focus lenses in average conditions. Since these greases are miscible, you can mix them to achieve intermediate densities. I stipple the male helicoid with small dabs of #10 applied with a toothpick and then use even more of the #30 for an intermediate result.
https://japanhobbytool.com/collections/camera-repair-material/products/hg
It’s pointless to apply a copious amount of grease because there is little clearance between the male and female parts. Any excess will simply be pushed out of the ends and make a mess.
There is a problem with simply dissolving the oil on the diaphragm with a solvent, and mopping out the oil-plus-solvent liquid. This will free the aperture and allow it to work normally. But eventually, the heat-damaged grease will continue to weep more oil. That will foul the diaphragm again. The damaged grease must be entirely removed and replenished with fresh, undamaged grease for a permanent repair. Then, so long as the lens isn’t re-exposed to prolonged excess heat, the problem will most likely not recur. My lenses that I’ve cleaned of oil-weeping grease and relubricated as described have not had a recurrence of the problem. I’ve only encountered this with second-hand lenses, never with any that I bought new.
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