[ASK] new model of Fogging?

<p>hi, i'm dave from indonesia.<br /> i have 70-200 f2.8 is.this lens i always use when doing prewedding job and i occasionally bring this lens to beach.<br>

after using it, i always put it inside dry box with humidity 30~60%.<br /> after 3 month i just realize, something wrong, the element inside the lens got strange mark.<br /> http://i717.photobucket.com/albums/ww179/apajaklah/garam.jpg<br /> i thought it was salt! so i send my lens to canon service centre...when the invoice came out...strange mark mean fogging not salt so they said i have to replace the element with new one and it cost me Rp.4.500.000 or $450 that was alot of money.</p>

<p>does anyone ever got this new model of fogging?<br /> is there any way to reduce the cost? by cleaning it or doing something else.</p>

<p>sorry my english is bad.</p>

<p>david,</p>

<p>That is fungus, not fogging. You need airflow and light, as well as controlled humidity to prevent it. At all costs keep that lens away from your other gear.</p>

<p>A regular camera repair store should be able to get that under control for a lot less than $450, it just needs the element taken out and cleaned with hydrogen peroxide. There might be a mark or two left but the lens will still be very good, but get it fixed as soon as you can, it will only get worse.</p>

<p>I think they rationalize the lens replacement because the fungus eats/etches the layering on the lens element, and so would be impossible to return to 'spec'. Whether or not you'd ever notice the lack of layering at that spot (without the fungus there anymore) is not something you are allowed to consider (by Canon).</p>

<p>What <em>is</em> likely is that there are other spots of fungus in the lens. Unless they did an excellent job cleaning it (the whole thing), and if you ignore Scott's advice, you'll see more in the future. </p>

<p>Good luck!</p>

<p>What Scott and Marcus said! Your humidity range of 30-60% is too wide. It is at 60% that lens fungus starts to grow. Internal humidity might have been a tiny bit higher for any number of reasons, resulting in your problem. For instance, if you keep all your optics in a heated storage location the temperature might not be uniform throughout. You might measure 60% in a relatively warmer spot and feel comfortable that you've achieved a safe humidity, but if your lens is in a slightly cooler spot, its RH would be higher than 60%.</p>

<p>I, too, live in a very humid place, and I store my lenses in a big, insulated, hermetically sealed box with silica gel inside. Temperature is uniform throughout the container, and I maintain RH between 30 and 40%. (Lower than 30% is not safe for other reasons.) When using silica gel, it is important to equilibrate the gel to the correct humidity. Let it absorb moisture from the air if it stabilizes humidity below 30%. Dry it out in an oven if it stabilizes RH above 40%. If your RH setpoint wanders above 40%, you can actually just add some freshly dried silica to the existing silica. The fresh silica will absorb moisture from the existing silica, dragging down the RH setpoint. If you store your optics in this way, you won't need light or air movement to keep the fungus away.</p>

<p>You need to know that lens fungus is somewhat contagious, so it can spread from your lens to your camera to another lens. You can kill the fungus by heating your lenses very carefully to approx 44 deg C (115 deg F) for a few hours. (This is a safe temperature, as many photographers shoot in these conditions, but be careful not to exceed this temperature.) However, the (dead) fungus will continue to etch your glass until it is removed. </p>

<p>It looks as though the fungal infestation is relatively mild, so there might not be significant etching YET. You need to have the lens disassembled and cleaned as soon as possible, and if you're very lucky, maybe you won't really have to replace the lens element you mentioned.</p>

<p>@scott, @marcus thank you for the advice, there is no other option getting worst or fix it.<br>

@sarah thank you for the info, i just knew that 60% is not recommended humidity.<br>

because in indonesia especially borneo the rain forest region, humidity hit 82%.daytime 36c, night 28c.</p>

<p>thx for the responses, more carefull about the humidity.</p>

<blockquote>

<p>(Lower than 30% is not safe for other reasons.)</p>

</blockquote>

<p>What is the problem if humidity drops below 30%?</p>

<p>Matthias, I don't really know, but Zeiss cautions about humidity below 30%. I asked that question of Zeiss, but never got a return email. I've also asked the question of other PNet members, and most suggest it's because the grease can dry out. However, low humidity cannot cause grease to dry out. My own speculation is that lens coatings can be hygroscopic and that excessive drying can cause them to become brittle and shrunken, resulting in crazing and separation from the glass. I've seen this happen, although I can only suspect the cause. Both lenses were subjected to very low humidity. That said, I used to live in West Texas, and prolonged exposure of my lenses to extremely low humidity did not harm them. Anyway, I just play it safe and follow Zeiss' recommendations.</p>