Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
02-19-2009, 06:26 AM   #1
Forum Member




Join Date: Dec 2008
Location: Bronx
Posts: 70
oil on the blades

Hey all,

I am still learning my way around DSLR lenses and having a good time. QUestion for you, I can understand how dust and fungus get inside lenses (time and uses explain those), but what's up with this oil I keep reading about? What oil in the lenses moves and gets where it isn't supposed to? Is it really a big problem if it does? Its more a curiosity thing then anything else, but how does oil in the blades effect the shot?

THanks

02-19-2009, 06:38 AM   #2
Veteran Member




Join Date: Apr 2008
Location: Indiana
Photos: Gallery
Posts: 818
The oil comes from the mechanisms around the aperture blades. I believe the main problem with oil on the blades is that it causes them to stick in some cases. I currently have a Sears 135mm lens with the aperture stuck wide open. I imagine it could very well be the fault of gummed up oil on the blades.
02-19-2009, 06:47 AM   #3
Pentaxian
Asahiflex's Avatar

Join Date: Jan 2008
Location: Netherlands
Photos: Gallery
Posts: 2,753
The oil always originates from the focusing thread of the lens. Lenses get older and the oil slowly creeps to places where it does its dirty job... I've cleaned a few lenses myself (mostly Zeiss M42 ones) and it's pretty straightforward with a cotton swab soaked in naphta. You clean the blades with the cotton swab; the naphta evaporates and you'll end up with a clean diaphragm.

By the way: I never clean the blades of true manual lenses (pre-set and manual) because these do not have a spring mechanism to open and close the diaphragm.
02-19-2009, 11:45 AM   #4
Pentaxian
Just1MoreDave's Avatar

Join Date: Feb 2007
Location: Aurora, CO
Photos: Gallery | Albums
Posts: 4,814
When a K-mount lens is on the camera, the aperture is held fully open to allow you to focus. When you take the shot, the camera allows the aperture to close down to the setting you have chosen. This has to happen pretty fast, before the shutter opens. Otherwise the shot is overexposed. After the shutter closes, the aperture returns to its wide open state.

To move quickly, aperture blades are very thin and the whole mechanism has very low friction. You would think the oil would help, but sadly, no. Even a very light oil will stick the blades together more than it will lubricate them. As others have said, the oil is vaporized focusing grease, so it's not light.

Lens design helps a lot here. Screw-mount Takumars use a grease that doesn't vaporize easily, and the aperture mechanism is shielded from the focusing helix. So a lot of these 40-year-old lenses work just fine, even though on a DSLR you don't need them to. Cheaper designs have less shielding. AF lenses have an advantage here, because they need low friction in the focus mechanism, so they don't use lots of heavy grease.

02-19-2009, 12:09 PM   #5
Pentaxian




Join Date: Feb 2009
Location: Alameda, CA
Posts: 3,194
That's a reason not to leave equipment, in particular lenses, in a hot environment such as the trunk of a car during a warm day.

Some lens models are particularly prone to the problem of oil on blades. Kiron 28mm and 24mm f/2.0 (sold under Vivitar name) are known for this problem.

Here's a photo of aperture blades contaminated with oil (Vivitar 28mm f/2.0):




After cleaning with naptha (better than mineral spirits., which can leave an oily residue):

02-19-2009, 12:57 PM   #6
Site Supporter




Join Date: Aug 2008
Location: Massachusetts
Posts: 239
Very useful information in this thread, thanks everyone.

QuoteOriginally posted by SOldBear Quote
Here's a photo of aperture blades contaminated with oil (Vivitar 28mm f/2.0) ...
SOldBear -- which end of the lens did you have to dismantle to get to the aperture blades?

And does it depend on lens construction?

-- Duncan
02-19-2009, 01:23 PM   #7
Forum Member




Join Date: Dec 2008
Location: Bronx
Posts: 70
Original Poster
Thanks all, very helpful. NOw a followup: I don't actually have a lens I'm looking to buy yet, but if I did, should I let oil on the blades preclude me from buying said lens, or is it something I can overlook and just clean?

Thanks
02-19-2009, 01:43 PM   #8
Pentaxian
Asahiflex's Avatar

Join Date: Jan 2008
Location: Netherlands
Photos: Gallery
Posts: 2,753
QuoteOriginally posted by oatman911 Quote
Thanks all, very helpful. NOw a followup: I don't actually have a lens I'm looking to buy yet, but if I did, should I let oil on the blades preclude me from buying said lens, or is it something I can overlook and just clean?
If you are looking for a M42 lens, and are going to use it on digital. then there's no need for the diaphragm to be snappy. Unless you need much force to open and close the diaphragm, you can use it as is. The good thing is that such lenses can be had for cheap sometimes...

02-19-2009, 01:49 PM   #9
Pentaxian




Join Date: Feb 2009
Location: Alameda, CA
Posts: 3,194
QuoteQuote:
which end of the lens did you have to dismantle to get to the aperture blades?

And does it depend on lens construction?

I don't actually have a lens I'm looking to buy yet, but if I did, should I let oil on the blades preclude me from buying said lens, or is it something I can overlook and just clean?
To get to the aperture blades, one needs to dissemble both ends of the lens. This of course depends a great deal on the lens construction. So if you are not familiar with a particular lens, stay away from lenses with oil-contaminated aperture blades.

The Kiron-made Vivitar lenses I quoted are well-known for the problem. Fortunately, they are among the easiest to dissemble. The front can be removed from the rear part of the lens by unscrewing it, similar to opening a lid of a jar. The rear optics can be removed by undoing 3 (or is it 6?) screws.

I've just clean the blade of an 85-205 Vivitar zoom lens without much problem. I successfully did that to a few other lenses (Super-Takumar 50mm f/1.4, SMC Pentax-F 50mm f/1.7, ...).

But I also managed to destroy a few lenses in the process: a Takumar Bayonet 135mm f/2.5, an SMC Pentax-M 100mm f/2.8, a Yashinon 35mm f/2.8.

I stay away from autofocus zoom lenses. Fortunately, they are relative new with better grease, and the grease is used sparingly in those lenses, so the problem is less frequent.
02-19-2009, 01:58 PM   #10
Forum Member




Join Date: Oct 2008
Location: Utah
Posts: 51
I had oil on one of the glass elements in a lens of mine. The lens took fantastic pictures, but around Christmas, when I tried to get nice Christmas light bokeh, I noticed the lights were rendered badly when I shot wide open. What should've been perfect circles had smeared and broken edges. The problem went away when I stopped down a bit. I inspected the lens closely and discovered the oil on the element inside. It had creeped onto it by a couple of millimeters or so around the edge. I had to pay forty bucks to have it cleaned. The camera repair guy said over time it would've creeped further until it would affect all shots. That's not oil on the aperture blades, but I've heard that oil on the aperture blades indicates oil maybe creeping around elsewhere in the lens.
02-19-2009, 02:30 PM   #11
Pentaxian




Join Date: Feb 2009
Location: Alameda, CA
Posts: 3,194
QuoteOriginally posted by Asahiflex Quote
If you are looking for a M42 lens, and are going to use it on digital. then there's no need for the diaphragm to be snappy. Unless you need much force to open and close the diaphragm, you can use it as is. The good thing is that such lenses can be had for cheap sometimes...
Be careful though. The problem needs to be corrected sooner rather than later. Over time, there is so much oil on the blades that they can be dislodged from the alignment rails/pins. The blades are so thin and the mechanism is so delicate it does not take much force to ruin them.

Case in point: I have an old M42 lens that has oil on the blades. I use the lens once in a while and did not bother to clean the lens (as you said, the aperture blades don't need to be snappy). The night before last, I decided to give the lens a naptha bath before putting it up for sale. When I turned the aperture ring, the blades were dislodged and now the aperture opening has a "funny" shape. Now I'm not sure if I can repair the lens.
02-19-2009, 03:35 PM   #12
Site Supporter




Join Date: Aug 2008
Location: Massachusetts
Posts: 239
QuoteOriginally posted by SOldBear Quote
The Kiron-made Vivitar lenses I quoted are well-known for the problem. Fortunately, they are among the easiest to dissemble. The front can be removed from the rear part of the lens by unscrewing it, similar to opening a lid of a jar. The rear optics can be removed by undoing 3 (or is it 6?) screws.
You make it sound so easy

On one of those Kiron's (for example - I've got a couple of #22... Vivitar zooms), where would I find the release mechanism that allows the front to unscrew from the back? (I'm thinking there must be something that stops it coming apart as I turn it every time I focus the lens)
02-19-2009, 04:06 PM   #13
Pentaxian




Join Date: Feb 2009
Location: Alameda, CA
Posts: 3,194
QuoteOriginally posted by duncsuss Quote
You make it sound so easy
It is easy, Duncan, for the lenses I quoted - the Kiron-made Vivitar 28mm f/2 and 24mm f/2. I happen to own both of them and had to give them both the naphta bath treatment. The front part is just twisted off from the rear part, there is no "release mechanism." I just have to make sure I tighten the parts together real good.

I just worked on a screwmount Vivitar 85-205mm. The front part is attached to the rear part with three screws, highly visible on the barrel of the lens.

I did not say all lenses were easy. In fact, I admitted that I totally damaged some during the process.

QuoteQuote:
On one of those Kiron's (for example - I've got a couple of #22... Vivitar zooms), where would I find the release mechanism that allows the front to unscrew from the back? (I'm thinking there must be something that stops it coming apart as I turn it every time I focus the lens)
I can't tell until I work on the particular lens. Even then, there is a good chance I'll screw it up. This is why I wrote "if you are not familiar with a particular lens, stay away from lenses with oil-contaminated aperture blades."

Last edited by SOldBear; 02-19-2009 at 06:43 PM.
02-19-2009, 06:17 PM   #14
Pentaxian
Just1MoreDave's Avatar

Join Date: Feb 2007
Location: Aurora, CO
Photos: Gallery | Albums
Posts: 4,814
QuoteOriginally posted by duncsuss Quote
You make it sound so easy

On one of those Kiron's (for example - I've got a couple of #22... Vivitar zooms), where would I find the release mechanism that allows the front to unscrew from the back? (I'm thinking there must be something that stops it coming apart as I turn it every time I focus the lens)
Some lenses are really easy, some lenses are a puzzle you might not be able to crack. Zooms have more moving parts and can be trickier. They went together somehow, it's just a matter of discovering how. I admit to completely failing with a Riconar 55mm f2.2, a Tokina AT-X 80-200 f.8 and a couple of others. I have a few where I can't unscrew parts that should unscrew.

If you're not lucky enough to find someone who's already taken apart your lens, you have to jump in on your own. Take pictures to make sure you document how it should be reassembled.
02-19-2009, 07:14 PM   #15
Veteran Member
Jodokast96's Avatar

Join Date: Oct 2007
Location: Erial, NJ USA
Photos: Gallery | Albums
Posts: 2,133
QuoteOriginally posted by SOldBear Quote

After cleaning with naptha...
And where do you get that?
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
blades, k-mount, lenses, oil, pentax lens, slr lens, time
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Oil on aperture blades dgaies Pentax SLR Lens Discussion 2 08-10-2010 07:41 AM
I'm Heartbroken Oil on the Blades A-50mm Macro F 2.8 Indecent Exposure Pentax SLR Lens Discussion 21 04-12-2010 09:18 AM
Used lens with oil blades w003txz Pentax SLR Lens Discussion 1 02-05-2010 07:02 AM
Oil on apeture blades Scott_the_Artist Troubleshooting and Beginner Help 14 01-31-2010 12:01 AM
For Sale - Sold: A flawed diamond: Pentax SMC-A 50/2.8 Macro..with oil on the blades :-( dumrox Sold Items 5 01-27-2009 03:46 PM



All times are GMT -7. The time now is 01:49 PM. | See also: NikonForums.com, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top