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05-09-2012, 03:30 PM   #1
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Muliti colored stain on lens

I had bought this pentax k 135mm 2.5 from a camera fair last year. There was a small spot a little away from the center, visible from the front which looked multicolored like oil film on water. It was not visible when viewed straight on. Its not on the outside but somewhere a little bit inside. Now the spot has increased in size and spread. Another multicolored oil-like spot has started to rise from one side. So .. experts can you please tell what is this? Is this bad for the lens?

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05-09-2012, 03:40 PM   #2
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Looks like some sort of fungus to me. It probably won't have too much of an effect on your photos until it gets bigger.

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05-09-2012, 06:02 PM   #3
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I second that.What you have shown in that image looks like fungus.
05-09-2012, 06:05 PM   #4
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QuoteOriginally posted by arunava82 Quote
I had bought this pentax k 135mm 2.5 from a camera fair last year. There was a small spot a little away from the center, visible from the front which looked multicolored like oil film on water. It was not visible when viewed straight on. Its not on the outside but somewhere a little bit inside. Now the spot has increased in size and spread. Another multicolored oil-like spot has started to rise from one side. So .. experts can you please tell what is this? Is this bad for the lens?
I agree with adam on this one. I think it is a bit of fungus.

If you are competent with pulling stuff to bits, I would have a go a cleaning it. If fungus is left too long on a lens it can etch into the glass leaving permanent marks. I have pulled a couple of lenses to bits for dust and smudge marks on internal elements as well as fixing jammed focus rings etc. I have found the older designed Prime lenses tend to be pretty straight forward to open up and then its just a matter of some iso-propyl alcohol and cleaning it up then putting it back together.

05-10-2012, 11:14 AM   #5
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Thanks guys for the replies. I will try to take it apart and clean it and let you know how it goes.
05-10-2012, 01:48 PM   #6
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The beauty ring on that model looks a bit tricky to get off, because of the steep angle and the curvature of the front element.

But the writing is etched into it, which means that if you use venier calipers as your lens spanner you could use the points of the ID measuring side to engage in the etched deeper parts and the ring should come off easily. You would then use the same tool to enagage the next screw out sections.

I have opened a Super Tak - very easy, and can only be reassembled correctly (good design).

I also tried on an Osawa 80-205/4.5 zoom and gave up after getting the front element out. It was not clear what was the next thing to come off.
05-10-2012, 02:16 PM   #7
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QuoteOriginally posted by arunava82 Quote
I had bought this pentax k 135mm 2.5 from a camera fair last year. There was a small spot a little away from the center, visible from the front which looked multicolored like oil film on water. It was not visible when viewed straight on. Its not on the outside but somewhere a little bit inside. Now the spot has increased in size and spread. Another multicolored oil-like spot has started to rise from one side. So .. experts can you please tell what is this? Is this bad for the lens?
Recently I opened a thread about a problem with my 50mm/1.7. Although it's not the same problem you have, people referred to 'Lens Separation'. I did an extensive research on the internet and you're description really matches the symptoms of lens separation. Lens Separation is when two cemented elements begin to separate:

''What does it look like? Like a patch of oil when the sunlight hits it. There will be an iridescent rainbow colored area, usually along the edges. The shape varies, but it's typically crescent or wave-like.''

Just my 2 cents
05-10-2012, 05:40 PM   #8
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QuoteOriginally posted by Tomm Quote
Recently I opened a thread about a problem with my 50mm/1.7. Although it's not the same problem you have, people referred to 'Lens Separation'. I did an extensive research on the internet and you're description really matches the symptoms of lens separation. Lens Separation is when two cemented elements begin to separate:

''What does it look like? Like a patch of oil when the sunlight hits it. There will be an iridescent rainbow colored area, usually along the edges. The shape varies, but it's typically crescent or wave-like.''

Just my 2 cents
I agree. This is lens separation and there is no point in taking the lens apart because there is nothing that can be done. Use the lens until the separation start affecting the image - shoot wide open to minimize the effect of lens separation.

05-10-2012, 06:09 PM   #9
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QuoteOriginally posted by excanonfd Quote
I agree. This is lens separation and there is no point in taking the lens apart because there is nothing that can be done. Use the lens until the separation start affecting the image - shoot wide open to minimize the effect of lens separation.
Now that you guys mention it, This could be the case.

But I have had a closer look and although I am not sure It looks like it could be a combination of separation and fungus or scratches?
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05-10-2012, 07:42 PM   #10
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QuoteOriginally posted by Chaos_Realm Quote
Now that you guys mention it, This could be the case.

But I have had a closer look and although I am not sure It looks like it could be a combination of separation and fungus or scratches?
Sorry, still can't see anything definitive in those pictures, you might try shining a small flashlight from the other end while taking the shot. I am going by your description, a typical fungus growth would look like fine tendrils spreading out, like pictures of snowflakes only not as well defined geometrically as snowflakes.
05-10-2012, 07:49 PM   #11
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QuoteOriginally posted by excanonfd Quote
Sorry, still can't see anything definitive in those pictures, you might try shining a small flashlight from the other end while taking the shot. I am going by your description, a typical fungus growth would look like fine tendrils spreading out, like pictures of snowflakes only not as well defined geometrically as snowflakes.
Not me, but the OP might wish to look into it. I attached the image to highlight the two different marks that I could see. The box I highlighted in yellow has a fungus (or scratch) look but the red circle looks like separation.
05-10-2012, 08:52 PM   #12
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QuoteOriginally posted by Tomm Quote
Recently I opened a thread about a problem with my 50mm/1.7. Although it's not the same problem you have, people referred to 'Lens Separation'. I did an extensive research on the internet and you're description really matches the symptoms of lens separation. Lens Separation is when two cemented elements begin to separate:

''What does it look like? Like a patch of oil when the sunlight hits it. There will be an iridescent rainbow colored area, usually along the edges. The shape varies, but it's typically crescent or wave-like.''

Just my 2 cents
The explanation for the appearance is that the very small distance inthe separation results in reflections on each of the surfaces witht eh colours indicating the exact dimensions of the separation in wavelengths, through wave interference effects. The same physical effect is what causes the rainbow effect in oil slicks, which is the effect with which this has been compared.
05-11-2012, 12:04 PM   #13
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Thanks guys for looking into this. So you guys think it is lens separation? I wished it was fungus! alteast i could try to clean it.
Sorry for the bad pics, I will post some better ones, now that I have removed the front part.
As for opening the lens, i was able to remove the front ring, quite easily. Tim60, I didn't have vernier calipers. But there were two small slots on the ring. I put the two ends of a scissor in those and turned and it unscrewed easily. I then unscrewed the front element. I couldn't open the screws under the rubber grip as my philips 00 screw driver tip broke!
Chaos_realm, i think it is not a scratch, as it is not on the front glass, and also that it spread out a little since the time i bought it. And the spots are quite colorful, but may be my angle was not good, so it didnt come out like that in the pic. I will post some pics in the evening.
05-16-2012, 12:57 PM   #14
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I was able to take apart the lens and the pic below is the glass which has the colorful stains in it. The stains are not on either surface. The second pic is how the part looks from the side. According to the diagram on this site (http://kmp.bdimitrov.de/lenses/primes/_optics/135f2.5-i.gif) , this looks like the third and the fourth lens (from the left) in the diagram are glued together. Can anything be done without doing damage to the lens?
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05-16-2012, 04:38 PM   #15
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Looks like separation (for the one that is coming out from the edge) as for the other bits I have no idea what they are. I can only assume they are somehow related to the separation.
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