W-20 Fog

jim2386 · Jun 14, 2009

Hey guys,

I just used my W-20 wide angle lens this weekend in some "extreme conditions". The surface temp was 78F and when we the thermocline at 20' the temp dropped to about 60F (Got down to 33F but didn't take my camera that far)

Anyway, the inside of my A570IS port fogged. This is normal and my fault and I'm totally cool with this. Just have to let the housing acclimate and the fog goes away. The problem I have is that the actual INSIDE of the W-20 lens fogged up too from the cold. This was EXTREMELY annoying as I couldn't take any pictures.

I thought it might be a manufacturing error but my instructor shoots underwater video with the W-20 and when he hit the thermocline the inside of his lens fogged up too!

Wouldn't a simple solution to this be that the lenses should be assembled in a minimal humidity room? Is there a solution for this problem? I do a lot of colder water diving with thermoclines and it's just really frustrating.

Thanks for your help!
Jim

Ikelite Staff · Jun 17, 2009

The lenses are assembled in as low of humidity as possible. However, they are not vacuum purged so there is the possibility a very slight amount of moisture will be present inside.

The best way to avoid fogging in the future is to cool the lens down gradually in fresh tap water before you begin diving with it. Before and between dives, store the lens in a cold bucket of water to keep it acclimated to the lower temperature and prevent fogging from occurring.

Hope this suggestion helps.

Regards,
Jean / Ikelite
IKELITE Underwater Systems

jim2386 · Jun 18, 2009

Ikelite Staff:
The lenses are assembled in as low of humidity as possible. However, they are not vacuum purged so there is the possibility a very slight amount of moisture will be present inside.

The best way to avoid fogging in the future is to cool the lens down gradually in fresh tap water before you begin diving with it. Before and between dives, store the lens in a cold bucket of water to keep it acclimated to the lower temperature and prevent fogging from occurring.

Hope this suggestion helps.

Regards,
Jean / Ikelite
IKELITE Underwater Systems

Thank you Jean, it's good to know that while it is an "issue" that it is normal. I'd be really really frustrated if I just got a 'dud'

The lens does beautifully in places with less dramatic thermoclines. I'll just have to bring a bucket o' ice water with me next time!

ethan_brodsky · Jul 8, 2013

I know this thread is quite old, but it seems to be the only discussion on the internet of this problem, so I thought I would add my input. I bought a W-20 wide-angle lens and was having severe problems with internal fogging. I'd get a quarter-sized spot of fog right in the center of the lens (on the front inner surface) that would last for the first 5-15 minutes of each dive, leading to a hazy spot in the middle of all my photos. Even prechilling the camera in a bucket wasn't always effective, as the lens would apparently warm up enough on my descent that the spot would still sometimes appear when I went thorough the 41°F thermocline. One other trick that works somewhat is to submerge just the bottom 1/2" or so of the lens in cold water for a few minutes before your dive - that causes the condensation spot to appear at the edge of the lens instead of in the center.

The solution I finally found was to to carefully take the lens apart (the front element comes off by removing the tiny allen-head setscrew on the perimeter of the front ring) and then immediately reassemble it in a -40° walk-in freezer. The air in the freezer is extremely dry and so very little moisture gets sealed into the lens. If you do this, be super careful not to get any fingerprints on the inner lens surfaces or to trap any fibers inside (a bit of lint floated in the first time I did it), but otherwise the process is fairly straight-forward, assuming you live somewhere with a proper winter. I'm sure this voids the warranty, but it works!

I did this about two years ago and there was an immediate and marked improvement in the fogging. For dives down to ~50°F I never had any problems, and it was much better, though not quite perfect, for colder dives. I'd still sometimes get a spot on really cold dives, but it would usually only last a minute or two and was often gone by the time I finished my descent.

However, on my last dive I started running into issues with fogging again (the reason I googled "W-20 fogging" and found this thread again). My guess is that either the internal plastic elements of the lens have off-gassed some absorbed moisture over the years or that there was still moist air trapped in between other (rear) elements of the lens and it has now migrated to the cavity behind the front element. I'm hoping that another treatment in the freezer will solve this problem for a few more years!

I don't know how huge Ikelite's production runs are, but it would be really nice if final assembly for these lenses happened in a dry nitrogen environment, a freezer, or if they were vacuum purged. I'd certainly pay more for a lens that would never fog internally!

Ethan Brodsky

W-20 Fog

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