Fungus (?) inside RF 70-200 F4 L

Started 3 months ago | Discussions thread
OP Sinawang Forum Member • Posts: 67
Re: Fungus (?) inside RF 70-200 F4 L

PicPocket wrote:

Sinawang wrote:

What I'm asking is not about if the seals are air tight or not, but the integrity of the seal from preventing dust particles which are relatively bigger than air particles, where fungus spores might sticks on that dust particles, hope that make sense for Canon to understand this issue.

How do you know the integrity of seals is compromised?

Dust particles. I see some dust particles, 2 on the front element which one of them has kind of radial halo like something grows from that single dust, and single bigger dust particle on the rear element. I don't know how they got inside the lens barrel.

What specifications are the seals? You might have seen the seal on the lens mount - that exists to save the lens from water seeping in when lens is mounted on a weather sealed body. That means, when it's not mounted to such a body, the back is not protected.

More importantly, fungus grows well in moist less ventilated spaces. So the same sealing that keeps water out, also helps fungus grow once it is in. A weather sealed lens isn't very well ventilated

Weather sealed is not waterproof. It's also not hermetically sealed. If it was, manufacturers will proudly claim so. So rather than focus on seals, focus on getting your lens in order if it's really fungus. Call Canon, and ask nicely. They might help

Since you are in Asia, you might be able to find eureka dry cabinets. It's a Taiwanese company I have used for about 15 years. Simple and effective

But even before all that, take care of your lens. If fungus stays in, it will eventually grow

https://www.dyxum.com/dforum/weather-sealed-fungus-free_topic90256.html

I suspect the fungus is already with the dust and the dust got inside the lens then ended up on the front element and the suspected fungus eventually moving from the dust particle and spreading to the glass.

Here's after 24 hr I buried the lens with all the silica gel sachets I have while waiting my dry cabinet & UV light shipped.

From different angle you can see that kind of halo around the dust. It doesn't spread further as I worried. That's still the same size when I first saw it 2 days ago. The centre dot is the dust and there are another dust there in the back of the front element.

This stresses me out. The only relief is that it's not seen in the frame as it's outside the coverage area of the sensor.

I'll call canon today and see what I can get.

 Sinawang's gear list:Sinawang's gear list
Canon EOS RP Canon EF 16-35mm F4L IS USM Canon 85mm F1.4L IS USM Canon RF 50mm F1.8 STM Canon RF 70-200 F4 L +1 more
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