rtrski

That's what I did (same as Eunjae's post above).  Just cut it out, hole-punch it to fit over the diffuser mount holes, screw diffuser back on.  Cheap and simple.  Doesn't even matter if it gets crinkled over time - it's not going to be taking too much away from a z240 or other high power strobe.

And of course original credit goes to Alex Mustard's article, at least for my inspiration.  Couple these with the new ability in LR (new to me - I haven't used LR very long) to do selective color shifts for the background water tint and I'm much happier about finding a pleasing foreground and background color balance (to my eye at least...I am not nor will I ever be a paid/pro photographer).

I use one on a Sony A55 crop sensor.  Check my username on Flickr (rtrski, same as here) for example shots.  I leave the EXIF in all my shots so you can verify settings that way as well as whether the particular shot has been cropped by the pixel count.

A couple of my personal favorite examples - not necessarily the sharpest focus on the main subject, just the overall field of view etc. (always would like to make the shot perfect, but of course never do).  Note also that I'm shooting with a custom minidome by Underwater Camera Stuff (uwcamerastuff.com), so take that into account when judging corner sharpness.  I could get better with a big 8" dome, certainly...but I just don't like travelling with those.

Selected faves are more or less in reverse chrono order (latest first).  At least one is a 'CFWA' type shot - the dome was almost touching the scorpionfish, maybe 3-4cm clearance maximum (I eased in slowly so it didn't bolt).

http://www.flickr.co...ski/8712548154/

http://www.flickr.co...ski/8711456025/

http://www.flickr.co...ski/8711535871/

http://www.flickr.co...ski/6858491341/

http://www.flickr.co...ski/6858500869/

Remember that the 8-16 has a domed front element, so you cannot use diopters or filters on it - you need to make sure your dome alone gives you the corner sharpness you're after.  The front element moves a little bit across the zoom and focus range, but not much, maybe 1cm travel total.  I'm also very pleased with this lens above water.

Bought a strobe from Kelpfish on this thread: http://wetpixel.com/...169#entry330081

Good communication, was flexible (held shipping for me for a few days to coincide with my being on a trip), item was as promised and padded well for shipping.  Recommended as a seller, and see no reason not to trust him as a buyer either.

Thanks again, Joe.

Joe: if the diffuser is a dealbreaker for the DS50 sale, I'll ship it to your DS50 buyer free of charge (US at least, international I might need postal reimbursement); just email me the contact info, or if you are the DS50 buyer and have already gotten it from Joe and need it, please let me know here via response or PM.  I can do without it for my planned usage, and/or print my own as a DIY project.

Joe, thanks for the shipment and good padding on the DS51.

My preferred method is a little dish soap (or other liquid soap, even baby shampoo) and running water, nothing physically touching the dome interior but the water spray.  Fill partway, and agitate and invert and rinse out until sure that both salt crystals and any sand or grit are gone.  Then follow with a hot clean water rinse (hot is important) and add a good sized splash of isopropyl alcohol to cut the surface tension, same theory as using it to help dry out your ears between dives, invert and shake it all out and you should have almost no droplets inside.  Let dry on a thick folded towel so air can kind of get in and it doesn't 'fog up' much (inside, low humidity, e.g. air conditioned room).

I don't think the alcohol should be able to harm any of the adhesives used in the dome to port attachment, but to be safe I never let that 'sit' inside very long, more just a swish around of about 1 part isopropyl (70% or so from the typical drug store bottle) to 3 parts hot water, then drain.

Any minor residual droplet marks can be gently polished off with a (CLEAN and dry) microfiber cloth, preferably one recently laundered (no fabric softener) if it was ever used during the trip to pick up grit, minor smears of o-ring lube, etc.  Goes without saying you wash and thoroughly dry your hands too before sticking one inside the port ring with the microfiber.