Barmaglot

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 [email protected] 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.

Yeah, after I posted that I had a thought that maybe the A7CR had its aperture drive in AF set to 'silent' - this would certainly affect AF speed, especially in low light conditions.

They have ports designed specifically for 28-60mm on FF and 16-50mm on crop, so this shouldn't be an issue. I don't own the FF version, but the short macro port fits the 16-50mm lens very well, and I'm pretty sure I've seen 28-60mm users reporting the same. I've taken to splashing down with the UWL-09F in a thigh pocket and attaching it as I descend - saves the stress on the mount threads and is actually more convenient than detaching the lens to burp it.

@jjmochi shared an interesting experience with A7CR here - it's not specifically A7CII, but it's supposed to be the same camera except for the sensor. Something weird might be going on there. You may want to test before you buy.

Aren't the tripod attachments on those big telephotos specifically there so that you don't load the mount bayonet? You mount (or handhold) the whole thing by the lens, so that the lens mount is loaded by <1kg of camera on a very short lever, instead of 3-5kg of lens on a long lever. Does anyone mount any such rig by the camera tripod socket instead of the one on the lens, when the latter is available?

I dimly recall some guy who was tossing octopuses into mid-water to take shots of them swimming that caused some commotion? Don't recall any details.

https://www.bhphotovideo.com/c/product/1812335-REG/sony_fe_24_50mm_f_2_8_g.html/specs 440g, 67mm filter size, 18cm minimum focus distance (0.33x magnification), US$1098 list price - possible higher quality alternative to 28-60/28-70mm behind WACP-C/WACP-1/FCP? Doubt it will work behind WWL-C/WWL-1 with this large front element.

It's not the tripod collar in and of itself that is the problem; it's the 1.36kg of lens cantilevered off the camera mount, in turn cantilevered off the tripod socket, not supported by anything else, and potentially bouncing around on dinghies, in rinse tanks, etc. This is no small amount of stress getting put on fairly fragile hardware.

I'm guessing it more of the former than the latter. I just went from a6300 to a6700, and although I haven't taken it underwater yet, on land the new autofocus feels like magic. Kinda kicking myself for not upgrading to an a6400 earlier; even though I could've used it in the same housing, I figured the improvement in AF can't be that great to be worth an upgrade in and of itself.

Looks like an astrophotography lens; not meant for us amphibians. For underwater purposes, Sigma's own 15mm/2.8 fisheye works much better for 1/5th the cost including an adapter. Native-schmative, autofocus with adapted lenses works fine on reasonably modern bodies; even my fairly old now Sony a6300 works quite well with a Metabones IV and a Canon 60mm macro.