Oil On the Aperture Blades

I thought it might be useful to do a blog about a lens that I just sold on eBay this week. It was a Nikkor 135mm 2.8 AIS that I’d owned and used fairly sparingly for probably around 15 years. It was a useful lens but nothing I was ever in love with, hence the infrequent use. Recently, I picked up a 180mm 2.8 AIS ED (which I am in love with and will be posting about soon) and because I am a fan of selling excess camera gear, I decided to clear some space for the 180 by selling either my Nikkor 135mm 2.8 Q Pre-AI or the newer, smaller, more expensive AIS version.

I removed both 135’s from my camera cabinet to examine them and decide which one should make its grand exit. The pre-AI lens is very large and heavy. My copy has not been AI’d so I can only use it on my Nikkormats and F2sb, not my FM2n‘s. I thought this lack of versatility would be the reason to say goodbye to my old friend. But as I examined the AIS copy, my thoughts took a turn.

When I removed the lens caps and looked at the aperture blades on the 135/2.8 AIS, I saw that several exhibited dabs of oil, I didn’t recall seeing this previously but then it had probably been about two years since I used this lens.

The dark blemish down center of the aperture is oil. Several blades had similarly sized spots on them but their size was reduced following my initial rotations of the aperture ring

I take very good care of my camera gear from a maintenance standpoint. I have everything that I use regularly, professionally serviced when necessary. And sometimes even when not necessary. I also only buy from retailers service their equipment and offer a warranty. Nothing enters my camera cabinet that hasn’t been serviced in recent history.

But, let’s face it, old is old and even well-kept gear will flake out on us sometimes. Despite having been purchased from KEH with a warranty long ago and having seen maybe only a hundred rolls of film behind it under my care, this lens was no longer in working condition.

As I rotated the aperture ring, the blades did not open and close in synchronization with the settings changes. The oil, which had migrated from the aperture diaphragm blade pivots, was now causing the blades to stick. So if the lens was set to f5.6 and I opened it to f2.8, the blades would open but stop at, say 3.5 and then a moment later, fling themselves open to 2.8. Then from 2.8, I’d set the ring to f22 and they’d stop at about 11 and not even get to 22.

Oil on the aperture blades is a common age-related issue with pretty much all camera lenses. Often with rangefinder lenses, it’s less of a problem because it doesn’t usually cause the blades to stick. But particularly with SLR lenses that feature open aperture metering capability, oil on the blades is a real problem.

Because a camera such as the Nikon FM2n holds the aperture blades at their widest position until the moment of exposure, the blades must fling back and forth from full aperture to the set aperture very rapidly. They can’t do this when they’re sticky.

Sticky, oily aperture blades on open aperture metering SLR lenses can cause incorrect exposures a well as darkened viewfinder images.

The solution is pretty easy and I’ve done it with several of my Olympus lenses which seem to be more prone to the issue than my Nikkor or Pentax’s for some reason. I’m going to tell you how I’ve resolved sticky aperture blades, however, I am a photographer by trade, not a repair tech. So there are probably other, maybe even better ways to do it. I’m only pointing out what I personally have done as an illustration of the nature of the problem. My intention is not to replace comprehensive repair advice from a well-researched book or service from a professional. The later of which is what I recommend if your goal is to concentrate on your photography instead of covering your dining room table with disassembled lenses that your cat inevitably knocks off, flinging tiny, nearly irreplaceably screws into oblivion.

One needs to disassemble then lens down to the aperture blades. The blades do not need to be removed and no further disassembly is required, however, you will also want to clean the surfaces of the glass on both sides of the blades – they likely have some haze on them from the migrated oil too.

Next. wipe the excess oil from the blades using something like an alcohol soaked lens wipe. I like lens wipes because they don’t leave any fibers behind and the alcohol helps dry the blades. The idea is to remove as much of this excess lubrication as possible because it has lost viscosity (resistance to flow) with age. Oil with less viscosity will leak onto things that it was not intended to lubricate. So you want to get as much of that old oil out of there as possible.

You know that you have thoroughly cleaned the blades when they are difficult to open and close because they’re so dry.

Next, I add the smallest, most conservative drop of lighter fluid to each aperture blade pivot point. This sort of reactivates the lubricants that are still there. You’ll need to exercise the blades in order to get that lubricant working again but before you do so, the aperture blades will need some attention because they are so dry now.

With the blades fully closed to their smallest aperture, I rub the tiniest bit of graphite on their surfaces. There should be no visible excess of graphite specks. You only need a very small amount and it should be rubbed evenly across the entire aperture assembly. It doesn’t have to be done on both sides, just the side that is exposed.

Now you can exercise the blades using the aperture ring. Be sure not to lose that little silver ball bearing for the click stops! Work the blades back and forth from one extreme to the other at first and then stopping at settings in between. They should now work as expected. If they do not, you can repeat the above steps as necessary.

Wrap up by cleaning the glass surfaces as mentioned, before reassembling.

So like I said, I am mentioning a basic repair procedure for oil the aperture blades not necessarily so you go fix all your sticky lenses but so that you know roughly what is going on here if you see oil. I imagine that a professional repair tech would fully clean out the old lubricant from the blade pivots by disassembling the diaphragm and re-lubing them entirely. If you want to repair your sticky blades yourself, I highly recommend reading some good repair manuals and joining some camera repair communities online. Doing so will fill in the details on specific projects and help you acquire the requisite tools and appropriate work space.

But for me, I decided to sell this lens since I already have the pre-AI version of this lens and a hard drive full of wedding and family photos to edit right now. I prefer to own a relatively small clutch of well-serviced, well-working gear than pile up projects for another day when I cold be shooting, editing or writing about shooting and editing!

That big, fat lens mounted on the chrome FTn is the 135/2.8 Q that I’ll be holding onto.

I described the lens very accurately, including the oily blades issue, and priced the 135/2.8 accordingly. The lens sold quickly because I wasn’t trying to make a huge return on it; just passing it on for the next guy to enjoy.

As a side note, I believe that I paid about $60 for this lens around 15 or so years ago when everyone was chanting “death to film!” It came with a 6 month warranty and worked perfectly. I was able to sell it for $50 with the aperture issue and saw that working examples sell for a little more than double this. One of the great things about old film gear of any reasonable quality is that it has increased in value since I got into photography so I seldom have to sell at a loss, even with inflation considered. We’ll see how long things continue this trajectory.

Understanding some of these basic, age-related problems that can occur with old camera lenses is useful for buying and selling gear as well as understanding how things work so as to make informed decisions. During a shoot, I could have, for example, continued shooting with this lens, provided that I only shot at full aperture. And of course, when buying a lens that is new to us, inspecting the blades for oil is an important factor in determining if we should purchase or pass. It’s nice to see that good deals can still be had, and there is a strong market for, serviceable vintage camera gear.

Thanks for reading and happy shooting!

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