Chris Ross

The only reason I think that might give you trouble is if the lens is too wide through the N100 part of the extension. Obviously the bottom part will but this is a fairly fat lens that only gets narrower right at the bottom, but I expect it's probably OK. You can test to see if the lens fits through the N100-N120 you already have. The question you haven't asked is if you really want to use this lens UW? Wide rectilinears have their uses of course, but the 180mm dome geometry requires the lens to be positioned with the entrance pupil forward of the optimum point at the dome centre of curvature to avoid vignetting, meaning the lens won't perform as well as it would properly positioned. You will see that the port chart shows the 250mm dome with an " * " meaning that is the optimum dome to use. The 180mm dome will certainly work and the images produced will be usable but other lenses may well do better particularly in the corners, There are other Sony lenses which may work better with the 180mm dome. I would suggest asking for experience using the Sony 180mm dome with the 14mm f1.8G lens, to see if you would want to do that. Apparently some of the new 16-35 lenses work quite well with the 180mm and I think there have been some tests published on this site from memory. The other question is what sort of photos are you thinking you might like to take and is a 14mm rectilinear the best option for this?

Be interesting to test it out, the test case would probably be shooting into the light, like a sunball or something.

Nice, I'm yet to dive from up there, it's on the list though

There is good reason they are locked, so that people don't change their post in the event of a dispute. I do agree a mark as sold button would be worthwhile, but not sure if forum software allows this. We can check.

You can download the manual which will include how to setup the strobes - just go to the S&S website. They have a few procedures to customise the strobe to work with various cameras.

It's been a long time coming interesting to see if it was worth the wait, so far I can only find pre-order with some basic pics on the two sites mentioned.

expect you're right, I couldn't see the connector which is why I mentioned it.

You should also probably remove the trigger as well - is it an UWT trigger or some other type? What are the cables attached to?

They could be different types of glass, there are many different types of optical glass around. BK7 is one of the most common. The procedure is straight forward - on a dive boat either keep the lens wet or apply the wet neoprene lens cover and keep it cool. Soak the lens for a period in fresh water. Then remove it and dry it straight away. I have a battery duster that I use, you could also use a blower attachment on a scuba tank or a compressed ir hose, depending on what you have available. Then dry with a microfibre cloth.

Perhaps, but in general higher concentrations of salts are more corrosive, in any case you can't dissolve these markings, maybe they have etched the glass, maybe the compounds have chemically combined with components in the glass. Apparently BK7 glass (a common optical glass) only has moderate chemical resistance. This topic has been raised many times and reports are dissolving the spots doesn't work and they require polish to remove. Whatever the mechanism, the cause is still allowing water to evaporate on the glass and the prevention is blowing off or wiping dry so evaporation doesn't occur. Apparently cerium oxide is slightly softer than BK7 glass and can polish without causing micro scratches.

could be different glass compositions? in any case the cause doesn't change and allowing your rinse water to dry can do this. What is your fresh water like? Is it hard water? This makes things worse as hard water is caused by alkaline salts and they can etch (corrode) the glass if sufficiently concentrated. You can use a blower or a nozzle attached to a tank to blow water off.

Unfortunately this is a case of prevention being better than cure. This happens when salty water is allowed to dry on the surface. The salts concentrate and the pH increases and eventually it etches the glass. Some people have reported success using optical grade cerium oxide to polish. This risks damage to anti reflective coatings, so use at your own risk, but there are reports of it cleaning the surface up reasonable well. To prevent keep the glass wet till you can soak it in freshwater. When you remove it it blow it dry and wipe with a microfibre cloth to prevent the droplets evaporating on the surface. Even the rinse water drying repeatedly will eventually etch the glass surface.