Fungus smell but no fungus visible in lens

<p>I just received a 180mm/f2.8 AF lens from KEH.com. The lens is in really good shape (it was rated EX+), but it has a fungus smell. Careful examination from both ends, using a very powerful flashlight, shows no sign of fungus on the glass or anywhere else on the inside of the lens. I have previously seen a lens with bad fungus (from B&H, BTW) so I know what it looks like when there's a lot of it.</p>

<p>Should I be concerned? Is it possible that someone took the lens apart and cleaned off the fungus, then put it back together and sold it to KEH? Should I return the lens?</p>

<p>Thanks,<br>

Bill D.</p>

<p>That smell is mildew - lens fungus has no smell. If you saw the house that the lens came from you may be a bit shocked (it takes a REALLY damp house to impart that mildew smell to a lens). I had a Kodak camera that came with that smell, and after leaving it in the open for a week or two, the smell soon faded. You can help the process by cleaning your lens with some foaming 'computer cleaner' which lifts of the smell and any dirt very well. Do not spray it directly onto the lens, but onto a cotton cloth first. I know the smell you speak of and it is not very nice, but rest assured it will fade in the end.</p>

<p>Ian</p>

<p>Mildew is a <a href="http://www.mypentax.com/Fungus.html">fungus</a>. The lens was obviously at least stored for some time in an environment in close proximity to a fungal growth. Before I was able to figure out how to control mildew and fungal growth in my home and optical equipment here in Hawaii, I was puzzled as to why one lens or two lenses of many stored together seemed impervious to infection while others exhibited the problem to the extreme. I still don't know the answer.</p>

<p>Get some 99% isopropyl alcohol from a pharmacy and swab the outside of the lens with a <b>slightly</b> dampened cotton bud. Leave the lens in sunlight by a window, rotating it occasionally to expose all surfaces UV rays, however don't bake the lens. That should help to kill the thousands of spores that are undoubtedly lying dormant on the surface of your lens.</p>

<p>Your theory that the lens may have been cleaned of a mild fungal infection is also a distinct possibility. Clean the outside of the lens as I described and see if that helps with the odor. If not, than the outside lens surface probably had some growth on it too at one point and the odor you still smell is resulting from the byproducts left behind by the fungus growth (see article). </p>

<p>The auther of the above article does not mention alcohol but, but I received that suggestion directly from a technician at Zeiss, years ago. </p>

<p>mildew is one type of fungus. but you won't see it right away. half of people who will clean the inside of the lens will also clean the outside to take away the smell. maybe it wasn't cleaned inside. or cleaned inside and it's your turn to do the outside :-) might help.<br>

the bad thing is if there is the smell, it's already there. cleaning the outside might prevent it to creep inside. what if it's already half-way there? this is just me but i would return the lens due to smell. i'm sure others will have better inputs. it's your call.</p>

<p>Thanks to all or your answers, and particularly for the link.</p>

<p>I left out one thing. The rear element is near the middle of the lens and is in front of the diaphram. The fungus smell is primarily from the rear of the lens. Obviously the lens was exposed to either moist conditions and/or an environment with lots of fungus, but there is no visible sign of fungus in the exposed rear inside portion of the lens. I believe that the smell is coming from inside that exposed portion of the lens.</p>

<p>Bill D.</p>