Oil on aperture blades, lens is toasted?

I just located an old Vivitar 28mm F/2.0 (made by Kiron I believe). The problem is that there is some oil on the blades, and they don't snap as quickly as other lenses.

But the result of the tests I ran show no problem, at least not yet. Photos taken with a K10D are right on, no over-exposure, even at F/16.

I will take the lens if it stays at the current condition. My concern is that the problem will get worse over time. Is that likely? Or is there a way to contain the problem?

I guess cleaning the blades is not a DIY project, and having it fix professionally is not worth the cost. What do you think?

Thanks in advance for your inputs.

-- SOldBear

There's no way to contain this problem AFAIK. Clean it, or forget it IMO.

If there is already perceptible slowing of the aperture action, that doesn't sound great. As oil works its way further between the blades, the suction will get worse.

Diaphragm blades are only designed to work clean. I assume there is no visible corrosion.

I had an old favourite (A28) cleaned and serviced recently, for about 80% of the buy cost of a replacement. I came out with a beautifully working lens that I have full confidence in - the replacement would still have been a 2nd hand gamble. So please don't regard it as necessarily "toast" - if you are sure the lens will be useful to you in the long run.

If you have the patience aptitude and some related experience, this is doable as a home project. But only "if" - disassembling a lens can be nervewracking, springs and tiny parts can fly out without warning. There's a little less complexity in a prime than a zoom, but it seems that the aperture end is the tricky bit anyway.

RP

soldbear said:

I just located an old Vivitar 28mm F/2.0 (made by Kiron I believe).
The problem is that there is some oil on the blades, and they don't
snap as quickly as other lenses.

But the result of the tests I ran show no problem, at least not yet.
Photos taken with a K10D are right on, no over-exposure, even at F/16.

I will take the lens if it stays at the current condition. My
concern is that the problem will get worse over time. Is that
likely? Or is there a way to contain the problem?

Click to expand...

Yes, the problem will get worse. Sometimes to the point where the aperture blades are stuck at wide open position.

soldbear said:

I guess cleaning the blades is not a DIY project, and having it fix
professionally is not worth the cost. What do you think?

Click to expand...

It is easy to clean if you know what you are doing. For this lens, you need to remove the lens mount, but be careful not to damage the screw heads. Some screws may require a lot of force to remove as they are really tight and/or if there is some corrosion between screw and mount. After the mount comes off, the rear lens group need to be removed and solvent (such as mineral spirits or kerosene) applied to the blades. Then you dry the blades with cotton swabs and also let the lens sit for a while for the solvent to evaporate. Sometimes you need to repeat this procedure several times to get the oil out.

soldbear said:

Thanks in advance for your inputs.

-- SOldBear

Click to expand...

You can also try dumping it on eBay. People are so desperate for quality Pentax mount glass that they will pay a good price for your lens and then have it fixed by a repair shop just so they can get their hands on this lens.

If you do decide to clean it yourself, the best colvent to use is lighter fluid (e.g. for a Zippo lighter). It has less residue, and has a lower flash point, thus evaporates quicker.

As long as you can get either the front or rear elements off, you can clean the blades easily. You don't have to take both front and rear off if you're careful about not getting the solvent on the remaining glass.

Hi,

I've been searching for one of those for quite some time now and would be willing to make you a good offer for the lens if it is otherwise in good condition. Optics all ok? Cosmetically?

Does your lens have an "A" setting so the camera can control aperture, or do you need to use the aperture ring for that?

--
Take it easy,

-Matt

http://www.pentaxphotogallery.com/mattbulow

Typically, getting to the aperture blades is not an extremely difficult task but of course it varies by lens. Once you get to them, you can gently wet them with lighter fluid to remove the oil (this is the basics -- I've yet to try this as I've been too busy to handle my lone oily aperture blades lens). I'd recommend doing some googling and visiting some of the forums dedicated to such lenses. I know there are more then one but the place I like is the Manual Focus Forum that is located here:

http://forum.manualfocus.org/

Your lens has been discussed there along with the typical approaches to solving this problem.

If it isn't affecting your exposures then I see no need to clean it yet.

Thanks for the offer to buy, Matt. I need to think about it some more.

Except for the oil, the lens looks and feels good. I'd give it a 7/10 cosmetically. There are several very minor scratches on the front element but I don't think they affect the image quality. Glass is clean, no haze, no fungus.

It is a P/K mount, not P/K-A. I think the lens was made before P/K-A time.

Regards,

-- SOldBear

Hi SOldBear,

ok, no problem, take your time. If you later feel like sending me a price you'd be willing to part with the lens for, please e-mail it to

uebersetzer [at sign] gmail [dot] com

--
Take it easy,

-Matt

http://www.pentaxphotogallery.com/mattbulow

In industry one would use something like 1-1-1 trichloroethane for this. (Notice ethane on the end. Not trichloroethylene, even worse for the environment and theoretically not available.) This is not completely banned. I still have a tiny bit from years past reserved for just exactly diaphragm blades in SLR lenses. I would worry about what else is in lighter fluid, to change the scent for example, but maybe it is OK. When I was a college student we were supposed to use lighter fluid as part of getting the best shine on our shoes for ROTC, but I would avoid it on precision equipment if possible.

Although 1-1-1 trichloroethane is not banned outright for sale, one vendor I found using google says: "This is now an EPA-regulated chemical due to its ozone-depleting properties. U.S. production was stopped in 1996 and, though not prohibited, it is taxed heavily and is now available only in small quantities." But there are substitutes used professionally, you can find some of them googling 1-1-1 trichloroethane, but they are hard to find in small quantities.

While the goo might be oil, the most common source of gummy lubricant on the blades is the heavy grease used to lubricate the focusing helix. When a lens gets hot, e.g. in the sun, that evaporates, then it gets distilled over onto EVERYTHING including the blades, but also a film on the glass, and cools there. So with digital I worry more about leaving a lens in the sun than the camera body. (In the past I might worry about the film getting hot.)
--
Bob Wilson

I just noticed online, in case you want to try this, a book with details on cleaning blades: http://books.google.com/books?id=FG4Kas5kO5wC&pg=PA45&lpg=PA45&dq=cleaning+diaphragm+blades&source=web&ots=l5cIP6DSI5&sig=Aw5hSRQDm1cS6Y_gVl2PGC8y86Y#PPA45,M1 is the actual book, not just something to buy. If the link does not work, try google book search with the search terms cleaning diaphragm blades
And despite my rant a few minutes ago, the book does recommend lighter fluid!
--
Bob Wilson

Thanks to your encouragement, I got brave and dissembled the lens yesterday. It was much simpler than I had thought (I realize I may not be that lucky with other lenses). I removed the front and the rear elements of the lens to get access to either side of the aperture blades. Here's a "before" photo (notice the glossy parts at the blades' tips):



I then used a small fine brush to saturate the blades with naptha, then mopped up the naptha with small pieces of paper towel. I did this to either side of the blades several times. Here is the "after" photo:



I left the lens dissembled overnight for the naptha to evaporate. I may do another treatment tonight to get rid of as much oil as possible.

Thank you all.

-- SOldBear

Well done on that little job -

I have done a similar job to a Tokina 28mm f2.8 screw mount and it s not so difficult is it - have had to repeat the treatment a few times but the interval between treatments is getting longer. Makes me feel that the images I get from that lens are even more special as I have invested more effort into the optics somehow.

Here is one example from that lens



Perhaps you feel the same about your resurrected lens.

Cheers, Arjay

I had this problem on a second hand A70-200

Pulled it apart and rinsed the diaphragm blades off in a ethanol. Also spent a long time mopping up the nasty lubricant someone had used inside to reduce the chance of a repeat!