cerich

on the mohs hardness scale.. salt is 2.5, glass 5.5-6. Salt won't scratch glass other than really long term erosions with some energy behind it. It can however scratch coatings that aren't designed or choosen for a high mohs rating. You can get coatings between 6-8 fairly easily and I would hope most glass domes the manufs are doing that... but YMMV. That said, keeping a done wet until after rinsed and then dry it properly is important but I worry more about staining than scratches with glass ports. From a technique POV you gave good advice

indeed, my post was to inform that the common thinking that any scratch on a glass dome is a done deal is not true always. For water marks, much easier to fix.

same, even used it a full day once and fine git sandpaper to rectify a pretty bad scratch in a glass dome one. That said, It's major work, requires power tools (drill with sandpaper on discs, 1500, 2000 then 3000 and a bench buffer for the cerium oxide polish stage first with 2.3 microns then with 1.2 microns). It is "doable" but had I been anywhere close to where could send it for new glass, I would have. Is it as optically as good or strong? Nope, but you can't see the scratch in images, no distortion I can discern and it didn't implode at 180 ft so.. there is that. You aren't going to get much results without power tools, just saying, or be there a week for scratch, for the stains, yeah but use elbow grease (or at least a dremel with appropriate bits It also occurred to me, after I was done, that there are actual businesses in almost everywhere that polish glass for glasses on face and other stuff like construction on the daily and it was likely could find someone willing to give it a go with better tools and are used to polishing glass and I should have tried finding one to give it a go first

ignore my earlier post, see you went different direction

Saw this on ebay, looks like a pawn shop is selling off a bunch of albums full of UW images in E6. I clicked on one and took a look, just curious..and it caught my eye. Seals caught in nets. Then I started clicking thru and I realized whoever it was that took these pictures was very, very good. There are 13 lots of 300, I saved them in my watch list and got an offer of $50 a set, and darn if I am not slightly temped. This stuff could make a book, and I still have no clue who it is. Whoever it is Here is a link to the guy selling, you can click in and enjoy. It's really quite something, for those that have never shot 35mm, these images are truly the work of someone very good. Store on Ebay with the slide collections

It truly looks like a pretty special lens. https://phillipreeve.net/blog/review-laowa-10mm-2-8-af-the-beginning-of-a-new-era/?fbclid=IwAR2pYdcHaDj1zGb97Xz-GoBuAgD82qrv2AWHxaEn9WYQi9kXCpWKghJkZy8

Chris Richardson, I have been shooting UW on and off since the late 80's and full time in dive industry since 95. Currently on sabbatical having decided to take on some side projects and my partner at Deep 6 (Deep 6 About us) running the show daily now after me doing for the first 7 years. Well done to those that have started this up and wish all success