dentrock

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.

I have the same problem with Sony macro lenses; i.e. actual point of focus is often not where you put it when you took the photo (check by reviewing in camera to compare). Even worse, sometimes the result is simply out of focus when again, the camera indicated 'in focus' when you took the photo. This can happen at all distances, not just macro. It is worse in dim light. It happens on land too, with insect macro. My solution is to 'slow down', allowing the AF time to settle, before taking the photo. This helps, but not great if you are in a hurry! You can also take multiple shots, and hope that the camera got it right at least once - it usually does. I shoot AFC / tracking / medium spot exclusively UW, and for land macro. I have experimented with "AF sensitivity" setting, but without any obvious improvement, so I leave this on 3 (default). It occurs to me I should try turning OIS off. Non-macro lenses sometimes show the same problem, but the result is usually OK due to the (usually) greater DOF. I concluded some time ago that Sony AF still has heaps of room for improvement. They seem to have prioritised development of AF with subject recognition, at the expense of AF accuracy when subject recognition is switched off.

Sold on Gumtree

I think there is still a fair weight advantage to a dome with the 16-25 lens. Some weights (kitchen scales): Nauticam 180 dome 1183g. N 140 dome 668g. N100-120 35 adap 313g. N100-120 25 adap 183g. N120 35 ext II 267g. I have tested the lens with both domes: 140 + 25 adap + 35 ext = 1118g. 180 + 35 adap + 35 ext = 1763g. Surprisingly, there is no discernible difference in central IQ between both domes, with f11 giving good sharpness into the corners (sharp across a 30mm circle, viewed at 100%).

Thanks heaps for the reference! I'm digesting it... while I enjoy reading about other systems, it's how to get the best from domes that interests me most, since I already own them and mine are smaller and lighter than the fascinating Seacam optics.

The 90 or 100 may be better for pure macro, but they certainly are not better as general purpose lenses. As a fish nerd I confirm the 50 is better for that, plus it is macro capable. That is the point! It is also the only macro option with AF in this focal length for Sony. I am happy to trade some AF issues for the incredible sharpness and detail I get right across the frame, in my particular application with the dome. It is also light weight and good for the survey work I do, which requires you to use a clip board and quickly take photos of any mobile invert or fish you can't immediately identify, for ID later on. Another advantage of this setup is I can exchange the 50 for any of: Tamron 35, Sigma 24 and 17, with no need to change the port or extension. I don't use it with a flat port, and the dome rules out water contact optics. It is of no interest to me whether anyone else takes the same approach, but I suggest if anyone is interested, there are plenty of used examples out there (although new is cheap when on special), so it's easy to try out, and move on if you don't like the results. And many members will have enough ports and accessories to do this without further expense. Anyway, enough of this. To be blunt, if you can't get some good results with this lens, it is not the lens' fault!

Very interesting clip. But at approx 4.40 he says 'we increase the depth of field enormously'... 'so you can focus on the glass'. I would love to see some hard data on this DoF increase.