dentrock

Yes I was unable to get a decent estimate of EP position for the Sony 90. I had 48mm from flange mount at infinity, and less than 20mm at 0.5m, where it became difficult to see and appeared to recede into the camera at closest focus. I used EP estimate of 28mm for my dive test rig, which gave no keepers with lots of mis-focusing and soft images. I recommend a flat port with this one.

No, hugely better with the Sony 50 macro. With a flat port you can barely get a 12mm D circle in the middle of the frame sharp. With a dome (in my case the 140 fisheye) everything that's in focus is sharp, across the entire frame, as Mustard and co say.. That big better appeals to me, but I understand many wouldn't care / feel the need to add attachments. Just wish I could get it happening (with decent AF) for the 100 macro. At the moment, the 'dog' of a 50 focuses more reliably than the 100 behind a dome, in my tests! Something to remember when calculating EP position for dome alignment: do it at (say) 30-40cm focused distance, since that is a reasonable compromise for where the virtual image will be. No point using infinity...

Sorry, I meant radius!!! 140 D has 69-70 R and 180 D has 110 R. I am estimating EP by looking from the front and marking off the apparent position on the outside of the lens, then measuring this distance back to the flange. I think Subal make some large radius / small diameter domes. Nauticam makes or used to make the same kind of dome for a particular 35mm lens, in N100 size. But it costs c. AUD $800 plus would need an extension which I don't have, at another $800 or so. So unless I can get the 100 macro working with the 180 dome, I can't justify buying the more compact large radius dome, since I don't need it for the 50 macro.

So the Zen WA-100 port is only for Olympus housings (different from the fisheye port which has a smaller diameter)?

Thanks. Another problem with the Sony 90 is the EP moves a lot; in fact much closer to the camera when focusing close, so it ends up very far back. This is not the case with the Sony 100 - the EP only moves a little as you focus close in. I estimated it at 84mm from the lens flange mount. But with a small diameter port (Nauticam 140 / 70mm diameter) the best I can get is 17mm mis-alignment (OC forward of EP). For my one dive test so far, I used a total of 75mm extension with Nauticam 180 port (110 D). Theoretically I needed another 6mm. But as I mentioned, still some mis-focus problems using AFC and tracking. If I can't use tracking, I'll stick to a flat port for this lens, but I may test some more / hoping some one else has got it humming. My goal was to emulate the sharpness right across the frame I can get with the 50 macro and 140 dome.

This is a great question, but difficult to answer except by saying 'do the best you can' based on what extensions you have available. In practical terms I aim for <10mm misalignment for a typical WA rectlinear lens, and preferably c. 5mm. Something new to me in his clip was his method of checking alignment (of OC and CC) by viewing the reflection of your eye in the dome at an angle (on land) and seeing how close it is to the apparent position of the aperture diaphragm. Anyone tried this? I will when I get around to it. One point he made in his flat ports clip which at this stage I can't endorse is his assertion that domes work well with longer macro lenses. I asked him about this but he hasn't replied. I have tried to get the Sony 90 and 100 macros working with a correctly aligned dome, but I run into mis-focusing issues (with AFC). There is also the problem that due to the size of these lenses and position of their EPs (CC) you need a large radius dome (c. 100mm or better) to get within a bull's roar of alignment. But large radius domes are typically only available with large diameters (eg. Nauticam 180), so their bulk gets in the way for macro. I would love to be proved wrong on this, and hear from someone who is successfully using a dome with either of these lenses! (And details of their rig).

Can you see if it's coated (anti-reflective)? May show as a tint on the glass.

Thanks for pointing this out. Excellent clip, as is his Part 2 on domes.

The awful Nikonos connector system (and cords generally) vs modern (wet) fibre optic systems...

The Laowa 10 is a poor performer behind the 140 dome, assuming we are talking sharpness across the frame, and uncropped images. I use a simple 3 point system to estimate sharpness across the frame. The centre is always sharp (assuming the lens can be properly focused) regardless of dome alignment or diameter. The question to be asked is: 'how big is that central sharp section?' not 'how sharp are the corners?' So I examine the centre at 100% and estimate the maximum diameter of the central sharp section. Score: 1= 12mm diameter, 2=24mm and 3=36mm. The figures are obviously approximate, but the fall-off in sharpness is actually quite easy to judge, assuming there are parts of the subject that should be in focus across the frame. I had high hopes for my Laowa 10, but its best score was 1 at f/11, using the 140 and total of 45mm extension, which gives a theoretical misalignment of -5mm (a minus indicates too much extension by that amount). The dome shade also vignetted moderately and would need to be removed. Now 12mm sharpness could be OK in some circumstances, but it's marginal. The 180 dome can't be used (vignettes too much), so I repeated the tests with my 8.5" dome. Best score was between 2 and 3 at f/11 with a total of 55mm extension and a theoretical misalignment of 4mm (meaning I needed another 4mm). But that's after removing the shade, and the port itself still vignetted a little. So I sold the lens. It is unusable for my purposes, but may suit others. I think the reason for its poor performance is its flat image plane (it is marketed as 'zero distortion' like some other Laowa WA lenses). Frankly I will avoid these for underwater use from now on. I second the comments on the Canon 8-15 with the 140. It works fine. But I long for the day when there is a useable E mount fisheye option! With AF of course... The 50 works very well behind the 140. Corners go from 1 at f/18 with a flat port, to 3+ (basically the entire frame) at f/8 with the 140. If you try to use the 90 or 100 with the 140, misalignment will be bad, due to the physical size of the lens and the location of the EP being far behind the front of the lens. Anyway I couldn't get the 90 to work, even with a larger radius 6" WA dome. Results were awful due to misfocusing. I think the problem here is that the EP is way back, and moves considerably as you focus closer. The 100 works a bit better (and the EP hardly moves), but best alignment with the 140 is theoretical -17, with total 80mm extension. It focused in water in a tub, but I didn't dive test it; opting instead to dive it with the 180 dome. There was quite a lot of misfocusing using AFC with tracking (my preference); plus a 180 dome is a bit clumsy for macro, so I won't pursue this option. Out of curiosity, I may still test it with the 140, despite the misalignment; and perhaps AFS is worth a shot. Other WA lenses (FF) I have tested with the 140 and work well (sharpness 2-3 at f/11) are the Sigma 17 and Sony 16-25. There are a variety of APS-C lenses which also work very well with the 140.

Couple of points: if you still decide to go FF A7C route, despite the other options suggested above: 1. Try to go for the A7CII (or A7CR). These have a much more useable EVF magnification than the original A7C (although the EVF is the same physical size). Plus the latest AF. You can use compact and relatively cheap APS-C lenses in crop mode, such as the Zeiss 50 macro or Sony 10-20, which would tick a lot of boxes. Or the kit lens with water contact options. Later, if you wish, you can go down the rabbit hole of FF lenses... or not!

With fond memories of Nikonos 15mm (94 degrees), which after extensively reviewing my favourite WA images, and checking what cropping I did (or didn't) do, suits my (Sony A7CR / A7RV) WA needs: 20-70 but needs 180 dome so not as portable as I would prefer, but can be (nearly) a do-anything lens, especially for coral reefs 16-25 - works fine with 140 dome at f11 or smaller. And (controversially) not wide but can shoot quite large stuff: 50 macro with 140 dome. I don't do adapted other-brand lenses or water contact stuff.

Regardless of housing choice, if you decide to go Sony, don't choose the 6500. Get at least the 6400, which still has built-in flash and has vastly improved AF over the 6500.

Sold on eBay. I have some other items I may sell, but won't do the full photo thing unless there is interest: Nauticam N120 8.5" acrylic dome AUD $450 plus post. Nauticam N120 10mm extension with screws AUD $175 plus post Nauticam N100 to N120 35mm adapter with knob (current model)... offers. I want one without the knob... and, maybe (can't decide): my A7RV body. Perfect condition, low shutter count. Offers considered. Sorry, can't ship to buyers in the US. It's just too hard.

I forgot to mention: for land insect macro, switching on 'Insect (eye)' improved things considerably. But for UW, I have found 'Animal (eye)' not very effective - works sometimes for (some) fish, but main problem is false positives, which you may not notice until after you download (you think you got the shot - but turns out you didn't, and nowhere near it!). So I don't use it UW.