dentrock

OK, thanks. Look forward to your AF update on the Tamron in due course. Regarding sharpness right across the frame with the Sony 100, I can't give you a clear answer, even though I went back to the original uncropped raws just now. My priority was the AF, and I assumed the sharpness question would fall into place. But because the AF target jumped away from what I intended, my sharpness reference point (always an eye, if there is one) is no longer accurate. So I have to look for what appears to be the sharpest point in the image and compare that with the far corners. And even then, perhaps the AF had not been properly acquired, so there may be no useful comparison. Best I can say at the moment is 'OK' into the corners (i.e. better than a flat port), but overall sharpness doesn't jump out like it does with the Sony 50 and 140 dome. I hope that changes if I get the AF sorted! At least I got some keepers, which is more than I can say I got with the 90 macro and MFO-1. I have just acquired a Nauticam 37122 4" WA port (as per Alex Mustard 'curved port' video quoted on another thread). I struggled a bit developing specs for it (Nauticam didn't bother to answer my query about the radius), but have firmed up on an estimate of 110mm outside dome radius, which makes sense as it would be the same as the 180 dome and possibly the 8.5" dome. But applying this radius to the port length suggests that Alex using a 16mm extension with that port and 50 macro means it is still quite a long way mis-aligned (my estimates suggest 45mm extension for the 50 macro with this port). Although he also said a longer extension was better for optimal sharpness, without saying how long! Anyway I have ordered 30 and 40 extensions which I think should cover the 50, 100 and also part of the 20-70 range (from about 40-70), using the 37122. OK, the 20-70 isn't macro, but it does a remarkable job with AF and close-up, so is good for moving fish. I will test everything AF with the 100 before giving up, as the combo would suit me perfectly if I can get it to perform.

Isaac, Just to confirm your thoughts on the Tamron 90 macro with your dome: have you noticed any negative results with AF, in particular AFC? And is it the latest version with VXD focus motor? I'm determined to keep testing the Sony 100 with a dome and AFC, but if I can't get it to perform as well (or better) than the Sony 50 macro with dome, passing the Sony 100 to my wife for spiders and getting a Tamron for underwater might be an option. Thanks

Small point which probably no-one will agree with: The PZ 10-20 is a great lens. If you move from Sony APS-C to FF as I did, there's nothing as compact as the 10-20 available in FF. I'm regretting selling my 10-20 instead of keeping it for use in crop mode with my A7CR (or even disable crop and get a bit more FOV out of it; e.g. square format). I found the button zooming a bit clunky though, and would probably go for the zoom gear instead.

Well, best to try it and see what you think. My estimates suggest using the 35.5mm adapter with 140 dome and 50 macro would put the dome approx 11mm too far forward. You will likely lose a little close-up range. I have both adapters. I never tested this combo with the 35.5mm. The 25mm one was hideously expensive when i bought it, but seems to have come down significantly in price (unique for Nauticam!)

I'm not intimately familiar with this dome, but how can you say that? If this dome is a portion of a larger dome, its optical centre will be well behind the port's mounting flange, and therefore (depending on the lens and its position in the housing) should be capable of aligning with the EP of at least some lenses, subject to adjustment with an extension ring if applicable. Regarding mis-alignment of WA rectilinear lenses' EPs with dome optical centres: the greater the mis-alignment, the smaller the central area of sharpness in the frame (some portion of the centre will always be sharp, regardless of alignment).

Just on the question of sRGB vs Adobe RGB, if you were ordering a photobook (eg. from Mixbook), would you (re)process the selected photos as sRGB, given that Mixbook recommends sRGB? Or would you leave them as Adobe RGB? And I'd appreciate any recommendations on photobooks anyone cares to make... Thanks

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...