Lens dust, INSIDE an element??

[flosseR]

Hi, has anyone ever had this happen? I have an old(ish) AF-s lens which died and I bought a new one (same lens). So I opened the old one just to check how it works etc. and there was dust in there, so I cleaned each element. Well it turns out the dust/dirt was INSIDE an element! WTF!.

The story is a little longer and you can read it here if you are interested in more details, but if you just want to look at a picture see below.

This is one of the back elements of a Nikon 24-85mm f3.5-4.5 AF-s lens. Believe me, I tried cleaning this like there is no tomorrow...

 

[HBOC]

Dust in the front element is not uncommon. The 17-55IS (Canon) is notorious for dust in the element. Same with dust getting in the 5D sensor/pentaprism.

Just the way things go. 99% of the time it doesn't affect IQ, as it is too close to focus on.

 

[Ruahrc]

Not 100% sure what you are referring to as "inside the element"... is it inside as in "dust on the surfaces of elements inside the lens" or "dust/debris actually embedded within the glass of an element". The first one, well that's pretty common especially for zooms as they suck in air and with it comes dust. For the second- it is possible that this is lens fungus?

Ruahrc

P.S. Unless you can verify it was like this when new (you say you bought this lens used), you cannot justifiably blame this on Nikon QA. Who knows what the previous owner(s) of this lens did to it. Especially when you say it had dirt inside it when you purchased it used.

 

[Westside guy]

Dust isn't just from the outside air - it builds up over time simply from the wear of the internal focusing gears and such. It's a very common phenomenon, and shouldn't cause problems unless there's lots of it (in which case you might experience a loss of contrast in images shot with that lens).

Now, lens dust is usually quite fine - those look like metal chunks in your photo rather than dust. But as you said the lens stopped working, I guess it's not surprising that pieces may have broken off inside.

 

[flosseR]

Hi everyone, sorry let me clarify:
these pieces are embedded inside the glass. there is no way that chips can find their way inside because it is not multipart, it is just one piece of glass.
It is not fungus either as it is embedded. it cannot be dislodged. The store I bought it from used said that it they sold it as used because it was one of their in store demo units and when they noticed the dirt, they sold it as used.

In regards to broken and pieces falling in, yes that is possible but in this case just the electronics and the AF-s motor failed, i can manually focus with no problem and no grinding noise can be heard or could be heard before it failed.

You all are correct that I cannot verify if this was there before BUT for pieces to be contained within a glass piece, it is weird and rare.

Dust in a lens itself I have no problem with really and I am well aware of the problem (my 105mm micro has some dust too) and it also never affected IQ of this lens either. The lens produced nice crisp and sharp images. Ju after i opened it I noticed the dirt being inside the glass.

//f

 

[chrono1081]

I've had that happen before. Only a speck or two though. It doesn't affect image quality because the dust is too close to focus on.

 

[gnd]

It kind of looks to me from your photos that the dust particles are between the glass elements of one group (if the glass is clean you will not see individual elements within a group). I find it incredibly improbably that one glass element with such huge particles embedded inside would make it through all those QC checks, it would get discarded at the first check, it wouldn't even make it to the assembly line.
Try bumping it against something and see if any particle inside will move.

 

[leighonigar]

I would agree with the others who have suggested that this is dirt between the lenses of a group. Of course, anything could be mixed into glass, it would just be dire QC/QA and I have never seen it before.

 

[flosseR]

It kind of looks to me from your photos that the dust particles are between the glass elements of one group (if the glass is clean you will not see individual elements within a group). I find it incredibly improbably that one glass element with such huge particles embedded inside would make it through all those QC checks, it would get discarded at the first check, it wouldn't even make it to the assembly line.
Try bumping it against something and see if any particle inside will move.

Tried that. Once I am back home, I will fully disassemble the whole lens and take better shots. That will be sunday night or so.
Have a nice weekend everyone.

 

[timbos]

If the lens is an achromat (designed for minimum chromatic aberration), it'll actually be made from two lenses bonded together. Without very close inspection of the edges, achromats look like one lens.
I could perhaps imagine that the glue has failed over time and allowed dust in.