There is a guy here in London that has made floats for years now and has tried quite a few materials. The stuff you guys are trying to use is not marine grade so when you lay a thick coat to fill the cells and then go into water I the long term there is a chance that the paint itself designed for ambient water pressure cracks. This is why I got his recommendation of using epoxy as it is the strongest material around though it takes time to harden is so viscous that you need a thin coat to completely seal and harden a block of divinylcell. You do need two separate steps one to paint the raw material if green or yellow bothers you and the next to lay the epoxy. The colouring can be done easily with anything even water based it will penetrate the fibres easily. For small adjustment blocks you can even use a permanent marker and a single pack of gorilla you get quite a few floats done for less than $5. Epoxy is used in marine application at it has extreme thermal and mechanical resistance
The paints you guys are discussing are not waterproof and not designed for marine application. Once they start solving in water they may create problems to the environment. You need to find something that is waterproof and not soluble like epoxy. Look in the boat or aircraft use not on the home use
Divinylcell used on boats is under a hull not exposed to water for this reason as it is too much work to harden on extensive surfaces
If you want to draw a hole in it so that they wrap around the ark segment you do need a tool. For cutting blocks you don't of course but not looks rough. Also it's not that easy to find at the end. You need the right grade to make sure it doesn't squeeze at depth
You can make floats using divinycell as suggested however as the material gets brittle you will need to finish it with epoxy glue all over to seal it. One of the other challenges is to make a shape that goes around the arms. Unless you have good cutting tools and a lathe it won't be possible so you will need cable tyre to fix it. It works fine until 40 meters with minimal buoyancy loss. I wrote a comprehensive comparison of commercially available float systems here
I would be very interested to see the results. Can you give me an idea why you think they work for one lens and not another?
I did some tests that are on my blog with the 14-42mm
Panasonic Lumix G X Vario 14-42mm / F3.5 – 5.6 / Power OIS and Nauticam Macro Port 35 | Interceptor121 Underwater Photo & Video Blog http://interceptor12...-macro-port-35/
Those lenses (without a macro mode) have working distance around 20-22 cm from the port in water when you add the wet lens the distance gets much shorter with a +10 around 5-6cm from the port this gives a large improvement as it is 1/4 of what the lens could do all be
With the 60mm in water you can focus at 9cm which is closer than the +10 diopter at infinity, when you add the diopter although the front of the wet lens is now just a few cm to the subject the port is still at around 6cm which is 2/3 the distance of the lens alone. So the gain is not that much and you have wasted now 5-6 cm of working distance
The lens focal length determines the field of view and the distance to subject then determines magnification (if the lens can focus)
Close up lens allow the camera lens to focus closer but the gain depends on the relative improvement in focus distance
The Olympus 60mm with around 9cm from the port in water is already a +11 diopter alone so to improve you need something really much stronger say the CMC is 15 the total power is now 26 diopters and although you are nearly touching you do see a benefit. In practice I can see that the Olympus lens doesn't take full benefit from the close up lens and a bit of the lower gets lost
Another consideration is that the field of view is really limited and the Olympus lens is best around f/5.6 - f/8 at f/11 is ok at f/16 has lost most sharpness and at f/22 is just garbled so you may have better results staying further away and using f/11 and crop than getting close and using f/22 with loss is resolution obviously this is a theory that needs to be tested
For me having a lens that can do 2:1 in 35 mm terms in its own is sufficient
The 4.33" dome is designed for the fisheye lens that focuses at 10cm. The olympus 9-18mm has a 25cm minimum focus distance. So I think the lens will not focus at all unless you use a diopter. For what concerns image quality the increased curve of the dome will deteriorate corners further. I am not even sure your concern is genuine. Measure the zen port on the housing from the camera focus point it is possible that you are already at the minimum distance and can't get closer anyway. I have a Panasonic 7-14 with the wide angle port and I measured against the zen with extension and the port length was the same. The port is anyway shorter than the minimum focus distance so a smaller port wouldn't make any difference except it wouldn't focus
From what I have seen there is no difference in perceived quality on a screen with the canon 7D when you compare with a new micro four third. There is however a big gap in colours and sharpness when you look at the best Nikon and Sony cameras. The low ISO is not the major point there is colour depth and sharpness and the best cropped sensor do look better on both camps the issue is are you prepared to bear the cost and extra volume and weight. A nauticam mirror less housing is 35% cheaper than a cropped sensor that seems to be the same reduction in weight. I used to pack all my camera two strobes and arms in a lowepro camera bag when I had a compact now it doesn't fit all ports with a four third. The real drop in space and weight is when you go to a fixed lens. If you really want to look at a good macro rig and want to cut on weight you may need to look at a canon g7x Alex tattersall has posted some good sample images
Having seen the performance you can get out on comparable subject the best quality right now is a Nikon D810 with a 105mm macro lens and if stuff is really small you can use a wet diopter.
The sharpness of this combination even at f/32 is such that it compensates to the fact you need a few stops down.
You can get decent results on a cropped D7100/D7200 with the same lens you get more magnification but the sharpness is just less and it drops more quickly
Finally you can get good shots on a MFT with an olympus 60mm however all MFT lenses perform best around f/4 and diffraction kicks in quite quickly so after f/11 the lens is not as sharp and you still need around f/13-f/16 for really small stuff.
Obviously a MFT rig is much smaller but if budget and weight are not an issue nothing beats the best larger sensor cameras.
By the way I shoot compact and MFT my shots come out OK but I can see myself the quality is not the same on the same shot. And I do have a cropped sensor D7100 that I do not take in water as I can't be bother with the large housing (so far)
Of course you can put a large dome for a fisheye but the Panasonic 8mm works fine with both 4.33" and 3.5" port (only 3:2 no vignette). The main use of a fisheye without Zoom is cfwa and wam and you don't want a large dome for those. I have the Panasonic 7-14 and corner sharpness is decent at f/8 with the nauticam 6" port. The 6" port is a cut of a 230mm dome
It depends on the distance to the subject. In this case the corners are further behind in other cases they are in the same focal plane of the centre of the picture. For reef shots you really want to use the fisheye, this lens is more for wreck interiors and large fish where there is blue water background
You have a bit too much purple tint. I sit in the middle of the camp as I use filters with or without custom white balance. I don't want the clips to look as my eyes saw it as otherwise they would look green and blue unless I have lights but also not to exceed on the other side. I don't change saturation in post never. If you didn't have a filter and you are not happy with the colours after custom white balance you may need to change the picture settings to push blue further. If I do any editing is sometimes to remove the cast not to push the colours further