[arpaagent]

Hey guys, I recently purchased a K200D (after thoroughly reviewing all the other similar SLR choices, pentax came out on top by a significant margin ), and I've been ebaying in order to get my hands on some older lenses so I can get some good shots without spending an arm and a leg on modern lenses.

So found some decent deals on ebay for Pentax(-K) and Pentax-M SMC 50mm f/1.4 lenses, both of which take fantastic photos. But unfortunately I noticed something on one of the elements of the K lens, and I am wondering if it might be fungus. I have read what I could find regarding lens fungus, but not sure that I want to come to the unfortunate conclusion.

If i am just looking at the lens towards a bright wall or with a little bit of light shining through it, i see nothing. But when I use a flashlight to illuminate one of the elements near the back of the lens, I see some stuff that might be fungus. So far it doesn't seem to be affecting IQ, but I'd like to know for sure if I'm being attacked by fungus. Attached are a few shots of the lens with a flashlight shining on it from an angle. Disregard the bright glares on the glass, but pay attention to the somewhat hazy stuff that is near the glare.

Let me know your opinions and if you have any ideas or solutions for this.

Thanks!

- Jim

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Last edited by arpaagent; 01-04-2009 at 08:44 AM.

[creampuff]

It looks pretty bad. The fungus has etched the surface of the lens.
Buying a lens in such a condition (close to junk imo) is a crap shoot. Keep it with you other lenses and you risk the fungal spores spreading to other lenses. You can try getting a lens repair shop to dismantle and clean the elements (more money spent) but there is no guarantee the fungus can be removed without leaving a blemish.

Stick with newer lenses. Full functionality plus peace of mind.

[pentaxman]

If the fungus is on the outside of the lens, you can try cleaning it with some MEK (Methyl Ethyl Ketone). It is available at paint supply stores and is used as paint remover. Put a little on a lens cloth and softly rub the part of the lens that has the fungus. It should clean the fungus off of the lens. I bought a Pentax-M 135 F3.5 that had this problem and it cleaned it off beautifully. Be careful not to get the MEK on any paint or plastic surfaces - it will dissolve them.

If the fungus is inside the lens, you will have to disassemble the lens. If you have no experience with this, I suggest that you have a professional do this - the charge will be $50 to $100. It is up to you to decide if it is worth it to have a professional do the job. Otherwise you can sell the lens cheap and mention the fungus in the ad.

[Photomaximum]

Its hard to say with those pics.

Take it to a repair shop and get some hand inspected opinions. I have several lenses that work fine, but I am sure that if i shone a light through the back end I could create "bad" looking images.

Not saying your lens is OK, you just need better, hand inspected information...

[stevebrot]

I agree with creampuff...It looks like fungus and it looks pretty bad. Sorry

I disagree with him in regards to older lenses. The same thing may be found on newer glass as well. It mostly depends on the history of the lens, what it has been exposed to and how it has been stored.

The best thing as far as buying from the Bay place or through any channel where you cannot examine the goods before buying is to get the seller's assurance that the lens is free of fungus and other internal crud, that the diaphragm blades are clean, snappy, and free from oil and that all controls work properly.

If the seller is not willing to commit to those conditions with the offer of refund, look elsewhere.

When you take delivery or if you are able to inspect before purchase:

1. Visually inspect the outside of the lens for obvious damage caused by dropping/crushing
2. Check that the filter threads are clean and undamaged
3. Check that the mount is clean with no burrs or scars that would hinder a clean mount to the body
4. turn focus, aperture, and zoom rings to confirm that they are smooth and free through their full range of travel
5. For push/pull zooms, confirm that the mechanism is free through its full range and that the lens barrel is without significant play. Roughness or play in the barrel is an indication of poor quality or that the lens has been dropped.
6. Look through the lens at a white background. The view should be clear with no obvious distortion. There should be only incidental dust, if any.
7. While looking through the lens, work the aperture through its full range of stops. The blades should move smoothly and symmetrically into place and should be free of oil*.
8. Look at the front surface of the lens. The surface and coating should be free of scratches or blemish.
9. Look at the surface of the rear element. It too should be free of scratches or blemish. The rear element is much more critical then the front as far as scratchs are concerned.
10. Check that the aperture actuator works and that the blades snap into place without binding.
11. Shine a flashlight obliquely into both the front and back of the lens to look for fungus, oils, or hazing.

If you see anything that was not disclosed by the seller, you should arrange for a refund or reduction in price.

Steve

*There are exceptions to the oil on the blades rule. Some lenses with pre-set or manual aperture normally have some oil on the blades as required lubrication. A good example is the Jupiter-9 85/2.

[Just1MoreDave]

This is how I ended up taking apart lenses. Something is on the lens surfaces, and it doesn't really matter what it is. The current value of this lens is pretty low, unless you can return it. It might be repairable. The SMC coating is pretty tough, and a lot of awful looking surfaces have cleaned up well for me.

It looks to me like this is the rear lens group, which I think is easier to access than the front. If you can find something to act as a lens spanner, you can remove the small slotted rings that hold the elements together. I can't find my only photo of the rear of the 50/1.4 K, so I'm going on memory, but it's not too difficult.

[arpaagent]

Ok, well i'm going to let it sit in the sun for a couple days (per recommendation of other peoples experiences with fungus), then attempt a partial disassembly to see if I can clean that sucker out. I really like the feel of the K version of the lens over the M version, even if it is 20g heavier and a little chunkier, so hopefully my operation will be a success. I'll post some pics of the disassembly once I have done that.

Does anyone else have a recommendation on what type of cleaner I could use? Would a commercial lens cleaning agent that I could pick up at the local photo shop work ok, or would I need something more powerful?

Thanks, and wish me luck!

[marlon]

For a moment I thought this might be a medical thread...
Yes, I have to agree with everyone else, it's hard to say by looking at those photos.
Sometimes you should be able to save em and sometimes not.
Leaving it in the sun will kill mildew, but leave black residue, not sure if that will work?

[pentaxman]

Ok, well i'm going to let it sit in the sun for a couple days (per recommendation of other peoples experiences with fungus), then attempt a partial disassembly to see if I can clean that sucker out. I really like the feel of the K version of the lens over the M version, even if it is 20g heavier and a little chunkier, so hopefully my operation will be a success. I'll post some pics of the disassembly once I have done that.

Does anyone else have a recommendation on what type of cleaner I could use? Would a commercial lens cleaning agent that I could pick up at the local photo shop work ok, or would I need something more powerful?

Thanks, and wish me luck!

MEK - It works well on fungus and will not damage the coating. It is also cheap.

[Just1MoreDave]

Ok, well i'm going to let it sit in the sun for a couple days (per recommendation of other peoples experiences with fungus), then attempt a partial disassembly to see if I can clean that sucker out. I really like the feel of the K version of the lens over the M version, even if it is 20g heavier and a little chunkier, so hopefully my operation will be a success. I'll post some pics of the disassembly once I have done that.

Does anyone else have a recommendation on what type of cleaner I could use? Would a commercial lens cleaning agent that I could pick up at the local photo shop work ok, or would I need something more powerful?

Thanks, and wish me luck!

I have always used Windex. I have read internet experts who say it doesn't work, leaves residue and can remove lens coatings. Well, it's what I use, so maybe one of us is wrong. The rear lens group has some lens elements glued together, as you can see here:

http://kmp.bdimitrov.de/lenses/primes/_optics/50f1.4-i.jpg

You don't want to use a strong solvent such as lacquer thinner, which may dissolve the glue.

I liked the feel of the K version too. It is a different optical formula than the M, and uses 52mm filters instead of 49mm. It's not as common either.