Barmaglot

I'm also shooting an a6300 (in a SeaFrogs housing, so not far removed from your Fantasea), and I've just moved to an a6700 for better AF. Between these three, unless you're really hurting for resolution, a6700 is an easy choice, as it has Sony's latest AF (shared with A7RV/A7CII/A7CR). A7IV and A7RIV have the previous generation AF - since you're mostly shooting macro, AF is important. A7RIV has a significant resolution advantage, so there's that, but A7IV doesn't have that many more pixels over a6700 (33MP vs 26MP), although it will give you some extra detail in your shots by the virtue of being FF. An FF camera would also give you a wider field of view over an APS-C one, but lose DoF at the same framing, so that's something to keep in mind. Speaking of DoF, among these three cameras only a6700 has focus bracketing, so given a static subject and a tripod, you could do focus stacking. Now an A7RV or an A7CR have the a6700 beat in just about every respect, but given what they cost - 6400₪ for an a6700 vs over 15,000₪ for an A7RV - I would expect them to. Note that a6700 has only three housing options at present - Nauticam, Ikelite and SeaFrogs. Nauticam costs $2513, Ikelite is $1195 but doesn't have a fiber optic bulkhead - electric sync only! - and doesn't let you access the front dial, while SeaFrogs costs about $450 and lets you access all the dials, but not the photo/movie/S&Q switch and doesn't have an 'AF-ON' thumb lever, only a regular button. Someone here on the forum mentioned that Isotta support replied to them that they don't plan to release an a6700 housing - I guess their a6600 housing didn't sell all that well. I wouldn't expect one from Marelux either; the only non-FF housing in their portfolio is an OM-1 one, and that one doesn't seem to be actually available. I'm going on a liveaboard in a week, and hopefully the a6700 housing will arrive before then - if it does, I will share my experience with it when I come back. Note that if your primary interest is macro, you might want to consider an OM-1 setup. Used OM-1 bodies seem to be available on ebay remarkably cheap - $1200-1300, down from their $2500 list price. The AOI housing is $999 including a vacuum system and flash trigger. What really sets it apart though, is the wealth of lens options - you have 30mm, 45mm, 60mm and 90mm, the latter of which can do 2:1 supermacro without add-on lenses, and given the smaller sensor size, a full-frame camera would have to do 4:1 magnification to match the same framing. The AOI port for the 90mm even lets you access the focus limiter switch. The 90mm lens is expensive, to be sure, but you can offset some of its cost by selling the Sony 90mm, which should not be difficult.

To be fair, the opening has double o-rings (one on the plug, the other on the housing), so it should be fairly reliable (unless you get a hair or something similar bridging both o-rings, in which case, OUCH), but I concur with you that it's a stupid system, and I wholeheartedly recommend the Leak Sentinel to every SeaFrogs housing owner. It's a shame that this option is not advertised anywhere except by word of mouth.

I see, thank you. If a previous version had the keying slots not removable, then I can see how that would be a problem. Thread depth should not be an issue; even if it gets in the way, it's easy enough to grind off some plastic on the front of the port. I use a UWL-09F (not pro) with SeaFrogs and Sony 16-50mm, and I've been considering getting the bayonet system for a while now, but the exorbitant cost (over $300 for mount base + lug ring + caddy, and then I would need an M67 adapter and another $122 caddy for a close-up lens) has been putting me off.

Yeowwwch!!! Good to know I wasn't simply paranoid about this, always padding the top of my housing around the Leak Sentinel with soft things when packing my bag for travel...

Huh, that Leak Sentinel V5 XB looks very different from mine. For one thing, it has a quick disconnect plug on the wires, which I thought was a feature of V6 - is it stock, or did you modify it? This is what my sample looks like: If you don't mind me asking, when is yours from? I got mine in January 2021.

Could you please elaborate on this? Looking at the QRS-01-MB1 installation manual, I don't see anything that would interfere with mounting it on a SeaFrogs port. What am I missing?

Funnily enough, size what what I don't like about the Leak Sentinel. The tall thin post sticking out the top of the housing always has me worried about some stray knock wrenching it out of the socket, or snapping it in half. Perhaps an irrational fear, but it's there nonetheless. At least the V6 can be easily removed when packing the housing; V5 - not so much.

Yeah, that's probably the best way to do it. I do have a set of calipers, so I can measure both width and depth of the existing o-ring groove and replicate it. Fingers crossed that the housing gets here before I leave for a Myanmar liveaboard trip on March 4th - I ordered it on February 7th, but due to Chinese New Year it didn't ship until the 20th, and right now tracking shows it as 'Leaving from departure country/region' yesterday.

Overhead. If they want me to check it - explain that it's full of very expensive camera gear; if they insist - well, into the hold it goes, it's not like there is any other choice.

Sure you can, if you're prepared to put a hurting on your credit card 🙂 https://www.backscatter.com/Isotta-Adaptor-Ring-B120-for-Nauticam-N120-Ports

While the SeaFrogs VPS-100 can be taken underwater, in my experience its seals eventually degrade and it starts leaking water - for me, it happened, quite reliably, after about 70-80 dives. I went through three VPS-100s that way. Vivid Housings make a version of the Leak Sentinel that can be mounted on SeaFrogs housings; I have not seen it advertised anywhere, but if you email Miso directly at info@vividhousings.com he will hook you up. I paid €230 for mine two years ago, plus another €25 for a manual pump, and it's been trouble-free since then.

Another satisfied Cinebags Square Grouper customer here. Does triple duty as airplane carry-on, boat camera bag, and rinse tank.

I know, and I actually have this port for the A6xxx Salted Line housing, but I am interested in the Tokina 10-17mm for its CFWA capabilities, and this requires a small port. Unlike the 6-inch and 8-inch domes, the 4-inch dome does not have a removable extension barrel that can be swapped; one would need to replace the entire port base as it is molded as a single piece with the bayonet mount. It is also out of production - I recall reading mentions that it was produced for SeaFrogs by another manufacturer who went out of business.

The SeaFrogs o-ring for 90mm ports is specified as 90x3mm, so I'm guessing a 2mm deep x 3mm wide groove should do it. Thank you; this is very helpful. The fact that 6mm thick walls easily stood up to 10 bars of pressure is quite reassuring. If and when I go forward with this, I think I will use a local service for draft prints until I get the fit perfect, then get in touch for a final print.

I've seen mentions - no personal experience, mind you - that Sony blocks the use of their teleconverters with third party lenses. This was in the context of Sigma/Tamron E-mount telephotos, but if that is true, I can see an EF-mount lens on Metabones/MC-11 getting blocked as well. Considering that a Sony 2x TC costs $550 while a Kenko one costs $300, the choice seems pretty clear.

That's reasonably easy to work out from the existing charts - the 2x converter is 40mm long, so just add 40mm of extension, i.e. Nauticam recommends 35.5mm N100 to N120 adapter + 30mm extension ring + 140mm dome for the bare lens, so by adding a 40mm extension ring (#22140) or using a single #22170 for a total of 70mm of extension you should have the lens and dome in the same alignment.

There's a pinned thread in the DIY forum -

Photos of the rings on their website seem to show an internal ledge that would limit how far it could slide in: Although if I end up needing something like 30mm of extension, might as well make it wider on the outside so that it gets supported by the rim of the extension ring.

Actually, giving it some further thought, I could reduce my risks by using a stock extension ring for the barrel part and just making a very short ring plug to reduce its port-side opening diameter to 80mm. If either the 23mm or the 37mm ring is within a few mm of the needed extension length, it can even sit flush with the top of the extension ring, with very little surface exposed to water. This ring itself would have to take very little load, as it would be supported radially by the dome port bayonet, and axially by an internal ledge on the extension ring. Hmm... just gotta wait for the housing to get here so that I can take a proper measurement of how deep in the housing the camera is going to sit. Edit: Basically something like this:

Yeah, I don't have ready access to machining equipment, and I have no idea how to even design a part for manufacture with it - I'm sure there are significant differences between designing for 3D printing in plastic and designing for milling on a lathe or whatever. Isaac, if you don't mind sharing, how thick did you make your RS 13mm adapter for SeaFrogs A9, and what did you print it from? I figure, with the 90mm port opening diameter, and 70mm lens outer diameter, I can do 5-6mm wall thickness on the bayonet itself and leave enough clearance for a zoom gear, then flare out to ~1cm walls on the outside portion of the cylinder - would that be enough? Although, thinking about it, I need to have an o-ring groove right at the thinnest part, thinning it further, but it will be supported by thicker material around it.

Metal extension rings are typically used with metal housings. The extension rings for Ikelite, AOI and SeaFrogs are plastic. Of course this is, I'm guessing, injection-molded plastic rather than 3D printed, but still - how thick should the 3d printed ring be in order to resist the pressure? The symmetrical cylinder shape should give it additional strength, as opposed to a flat-sided box.

I've got a SeaFrogs 4-inch (100mm) dome that I haven't used in years. It doesn't have any extension, and is meant to be used with the old Sony 16mm f/2.8 pancake lens and VCL-ECF fisheye adapter. That combination is widely panned for its image quality, so I never spent any money on it. I tried it with a cheap manual fisheye, but the manual focus and fixed aperture was too much of a pain to manage, so it's been on a shelf since then. I've considered getting a Tokina 10-17mm, as I already have a Metabones IV, but that would require an extension, which SeaFrogs only sell for their newer 90mm port mount, as opposed to the 80mm that my housing and port use. Well, now I've got an almost-new a6700, and a new SeaFrogs housing on the way, so I'm revisiting this idea. The new housing uses the 90mm port mount, so I figure it should be possible to 3d print a straight-walled cylinder that has the larger-diameter bayonet on the outside of one side, and the smaller-diameter one on the inside of the other. Question is, can a 3d printed part of reasonable thickness hold up to the pressure of 30-odd meter depth with some safety margin? I don't own a 3d printer myself, so I would have to use a service for it - what kind of settings should I request they use? I'm guessing that 100% infill is a given, but I have little experience with 3d printing, so I don't know what I don't know. Also, the bayonet lugs and o-ring grooves present surfaces that are perpendicular to the direction of printing - is this even possible to print? Do I need to include support structures in my design that are removed after printing? Or is it something that should be machined? Or maybe omit the lugs altogether? Just have o-ring friction hold the parts together on the camera table, and then vacuum (and water pressure) should apply much more force than the little plastic tabs would've been able to withstand anyway. Finally, what's the best way to estimate the required extension length? I understand that the entrance pupil of the lens should be aligned with the geometric center of the dome, and the dome appears to be a 180 degree hemisphere so its center should be at the base of the transparent element, but where is the entrance pupil? By how much should the lens extend into the dome?

Never heard of one. I have seen an adapter from SeaFrogs to Inon ports offered at unterwasserkamera.at (link) but it's quite expensive for what it gives you. It also won't fit an A7C housing, as it uses a larger port opening (90mm, rather than the older 80mm). I suppose Saga could do a custom job, but it would also be expensive, and if one is using a SeaFrogs housing to begin with, they're going to be cost-conscious (I know I am).

I think the front element is too big for that.

Yeah, but at $2k, it's not in the territory of an 'impulse purchase - I might use it sometimes for a specific shot' for most people.