Fathom SWP 35 Port Cleaning/Repair

Hi All:

I've encountered an issue that I could use some advice with concerning a Fathom SWP on a Gates Housing.

I have a "blemished" area on the port exterior element glass that - as best as I can describe it - looks like oil remnant on glass, except it won't clean off and it's certainly "there." I tried the standard Optimax cleaner, etc., - no joy. Even a mild detergent with lens cloth, again no luck.

I contacted Gates the other day and spoke to Pam. She said that Fathom will treat the port with Acetone and may be able to remove the blemish for $50. If not, they will replace the exterior element for about $500. I can't really see the blemish on underwater shots (as far as I can tell) but it is evident in daylight when shooting into the sun on the boat. For some reason, I also think it's getting worse, but that just may be my impression. (Click HERE and look at 00:25-29 and 00:41-43 into the time line on the bottom left of the video to see what I mean)

I have a Gates WP that I can use while the Fathom's away, and $50 is no big deal, but what about $500? Or, should I live with it? I paid about $1,000 for the port, meaning it's potentially 50% of purchase price to fix. I am VERY happy with the results it produces.

I'm planning to stick with SD and my VX2000 for at least another 2 years, until I start mastering video and HD standards get sorted out. Obviously, transferable memory cards are the future of video (and probably music!), so I know tape is gone and ultimately the value of this repair.

Suggestions and advice appreciated and respected...

Andy

Hi Drewski,

I have a SWP myself and have seen the marks that you describe.

After a dive I see an accumilation of what almost looks like limescale on the front of the lens. From the front it looks oily but when water has dried on there it looks salty.

Firstly I'd say live with it, $500 is a lot to pay, then I'd recommend that after every dive you wash the lens in fresh water then dry it with a non abrasive, absorbant, clean cloth, getting rid of any excess water, then polishing the glass, gently obviously until you can't see any smears or residue, it takes a while as the whole of the glass needs to have this done, the swp's are big and have a huge field of view and every imperfection shows up, sometimes annoyingly only in post.

I know it's annoying to have visual imperfections, especially with such an expensive peice of glass and all that care and polishing in an environment filled with spray may mean that you have to do it many times but it is is all part of the strive for a perfect image.

Keeping a lens cap on for everything but the shot on topside is almost now like a mantra to me.

I think that a slighty damp, clean, chamois leather would be the best bet together with a squeezy bottle filled with softened drinking water.

Hope this works

Richard

If you live or go to an area where the water has lots of calcium in it them you must make sure you wipe and dry the lens or else you may end up with a stain like you describe.

The water here in Exmouth is so bad that i often don't even bother to wash the housing if I am using it the next day as the calcium is so bad. I never use to wash out my outboard as well as the calcium would do more damage than salt crystals.

We have tried many things to clean a calcium stained port here even petrol to no luck. It's like it is etched into the glass itself.

If you wash a port make sure you wipe it dry.

If you really think it's calcium carbonate then why not try a little dilute hydrochloric acid? In the UK this can be bought as "brick cleaning acid" from hardware stores. It should react to remove the calcium carbonate. I've used it to clean everything from ancient toilets to salvaged brass from wrecks. I would just get a couple of drops on there and seal it somehow so it doesn't get on the metal parts that hold the glass. Maybe you could mix some with talc(?) or something inert to make it viscous so it stays put. It shouldn't harm the glass. You normally have to buy quite a lot of that stuff but it's cheap. There's another dilute hydrochloric acid available at hardware shops that's twice as strong but I can't remember what it's supposed to be for.

You could also try Coca Cola or tomato ketchup which are both acidic and used to clean stuff like drains and old coins. Ketchup might be just the thing to stay in place on the glass. But I'm no chemist so I don't know if these have the right type of acid to react with calcium carbonate. Worth a try maybe. Or perhaps get hold of acetone and try that yourself if it's what Fathom would use.

Then again perhaps the blemish is where a little of the glass coating has been removed and is gradually spreading. It can only take the slightest bit of fine sand etc. in a bag to damage a lens. I'd have a good look at it with a strong magnifying glass before doing the acid thing.