Chris Ross

Thanks for the added info, I might get it eventually and get a trial first to see that it works or not. The 48 hr trial period though means I have to find a slot where I have time to play with it. Seems like it would be beneficial to provide at least some of the tutorial pages pre-trial download, it may convince some people to give a trial a go. I would think that seeing as how it can create a layer with the processed results it shouldn't matter when you do it as long as the layer is at the bottom of the stack - that way the layers above apply to the combined layers below. If you make mask adjustments you just need to be sure the mask is based upon the combined backscatter free image - you don't want the masks to include any of the backscatter. This would happen for example with luminosity masks that use the image to create the mask.

The issue is that the Nauticam wet optics don't necessarily work with any 28mm full frame equivalent lens, something about entrance pupil size, so they mostly work with slower kit lenses. The 16-50 lens you reference seems like it probably should work due to the small 58mm filter size and internal zoom, but it's a gamble. The fact that that Nauticam only list the 15-45 lens with MWL/WWL/WACP may be due to the fact that's all that works or that they haven't tested the 16-50 with the other ports yet. The WACP-C is basically the same as the WWL optics as I understand things from previous posts so if the 16-50 works with the WACP-C it should also work with a WWL, bt again until someone tests it...... I see a few options: Buy the 16-50 and take both it and the 15-45 with you and use with MWL. If you have issues with the 16-50 you could revert to the 15-45 lens. You might need a different flat port to house it though as it is about 6.5mm longer. You could message Nauticam and ask them, I recall others have done this and they have responded. You could consider other options, perhaps an adapted Tokina 10-17mm with a 100mm dome?

It seems it is a Photoshop plug-in - at least the Astro version of it is, though some here are calling it an action which it could well be if it feeds a seperate app which does the processing. If you can access plug-ins or actions within ACR then I guess you might be able to use it that way. I use Photoshop quite a bit but it's CS6, so likely BXT won't work for me. Though I see the Star exterminator on the RC astro site will work for CS4 or later as a plugin. IT might be worthwhile my trying it out. As for where it's best to use I expect it should also work on a completed image as long as your processing doesn't do anything strange to the backscatter. Probably be best to download the trial version to see if it works OK or not with your workflow.

The 180mm dome will use a different extension as it's not a full hemisphere so I would expect it to need a bit less extension as the centre of curvature is further behind the dome. Both the 140mm and 230mm dome are closer to a full hemisphere and it appears they have the centre of curvature the same distance behind the dome mounting flange. You would want to use the same extension on the 140mm dome/14-35 as you do with the 230mm dome. If you did the test shots with 30mm extension the entrance pupil was likely well forward of the optimum point. I would expect the 14-35 to perform better at 14mm with the right extension. I thought you had used the 60mm extension for the tests. I'd suggest trying it dry first to check it doesn't vignette, it shouldn't based on the port chart but you might just catch the corner of the shade which could be solved by zooming in a little. You can check for vignetting dry as it's purely down to geometry, test shots of course should be UW.

Reading all these replies, I can see how subjective this is. I've seen what Dave Hicks does and can see why he's less concerned with even light with the dramatic lighting used to create shadows. I can also see the point of view of those who shoot big reef scenes exploding with colour from soft corals, Alex Mustard comes to mind, talking of the benefits he sees from the even lighting coverage. It using a different means to create drama in the image. I see some people saying that once they went to premium strobe they stopped having problems with light "missing"in the centre of frame- I'm guessing that's because the Retras in that case have a wider beam with more light at the edge of the cone so are less demanding of positioning and as I recall testing showed that indeed the Retra has more light out in the edges of the light cone. You could argue you could do the same with the INONs - but they obviously haven’t managed to work that out previously. Some people are perhaps not so rigorous when positioning their strobes. If the strobe helps them overcome this it seems like it's well worth it. The Blue water colour is certainly a real advantage of warmer strobes - you can get it with coloured diffusers at a cost of loss of light. I'm wondering also if upgrading strobes to higher power or even just pushing that power to the edge to the light cone away from the centre hot spot just puts more strobe light on the scene? I often find I need to tweak subject colour a little shooting my Z-240s as they are not putting out enough power or conversely I'm not close enough. More power will certainly help a bit with this, if you don't need to warm up the subject you won't impact the water colour adversely with your adjustments.

Based on that test I'd say you have your solution and it doesn't involve buying anything new. Corners look fine at 35mm, any unsharpness could just be depth of field. 14mm is of course pretty soft in the corners, but it doesn't sound like you'll need it at your destination.

The 14-35 might be a better option, the lens achieves 0.38x magnification and the with 200mm MFD you get 80mm working distance. I found a review by the digital picture and it said measured MFD was 184mm so that gets you to about 64mm working distance which is right on the dome for the 140mm. So if it is placed correctly it should work as well as any other 35mm lens. I suspect it might work OK behind the dome between maybe 30 and 35mm, especially considering you are likely to have blue water in the corners, so if you trust yourself not to zoom too far having a zoom gear might allow you to capture a shark that is bigger or approaches closer that you might otherwise not get. The review also mentions 14-35 AF is extremely fast, while reviews of the 35mm f1.8 mention slowish AF and one mentions a bit of hunting. Looking at the Marelux port chart the Canon 8-15 uses the same extension with the 140mm and 230mm domes - so the 14-35mm should also use the same extension for both the 140mm and 230mm domes. So presumably you would have nothing to buy if you use the 14-35 with the 140mm, if you are already using it with the 230mm.

I would suggest make sure you have good travel insurance, with enough missed connections cover. Never flown Lion, but have heard of lots of people being left in the lurch by them. Sounds like you have already booked but it is possibly wise to arrive with a spare day if you are connecting to a liveaboard.

The min focus distance for this lens is 170mm, given its dimensions and the size 0f the 140mm dome at 0.5x it will be focusing right on the dome, so I expect that the maximum practical magnification might be around 0.3x , so filling the frame with a 120mm long subject on the horizontal axis of the sensor. You could also consider a 1.4x to add to your 8-15 which would give you 21mm focal length, about the same field of view on the horizontal field as a 16mm rectilnear lens

You get vignetting at 8mm The 8-15 has a limit switch for APS_C so that it restricts you to 10-15mm. That way you don't end up with vignetting in the corners if you zoom past 10mm. It will have about the same angle of view as the Tokina 10-17 - something around 175° on the diagonal. For fields as you zoom, this table has calculated horizontal, vertical and diagonal fields of view along with the approximate equivalent rectilnear lens based upon the horizontal field. Horizontal APS-C horizontal vertical diagonal rectilinear Equiv Fisheye – 10mm 144 92 180 Fisheye – 11 mm 129 84 160 Fisheye – 12mm 117 76 144 11mm Fisheye 13mm 107 70 132 13.5mm Fisheye – 15mm 92 61 112 17.5mm Fisheye – 17mm 81 53 98 22mm

I found an online video where they explained about the bushing, sounds like it's hardened stainless steel, it can be replaced but needs to be drilled out., but it seems it only needs that is it's worn. I'd definitely try re-installing the knob and twisting and pulling if you haven't tried already. I would only tap it lightly trying to remove it, if you can rotate it it doesn't seem like it is seized. You might for example need to rotate it to a certain position before you can remove it.

I'm using the Nauticam N120 140mm port with the recommended 34.7mm N85-N120 and the 35mm extension ring.

I don't have direct experience, I don't recall many Seacam users among the forum members. It looks like they use an insert in the alloy of the housing for the shaft. It is possible that has a lip on it to prevent it pushing inwards? First thing I would try is replacing the outer knob and rotating while trying to pull it out. If that doesn't work I would try using a pin punch and gently tapping it to push it out from the inside. It may help to have the handle on the shaft on the outside so that you can rotate the handle a little in between taps or have someone rotate as you tap gently. If that doesn't work, try someone like Backscatter to see if they can assist.

The 10-17's main benefit is flexibility, sure you can get a bit better image quality, but the 8-15 is a much bigger lens. I suspect being a Canon mount lens it will work better on the EF-RF adapter compared to Sony-Canon metabones adapter. If you go with this setup you can always upgrade to Canon 8-15 with just an extension tube and zoom gear. It has a limit switch so that it zooms from 10-15 mm only for APS-C. As for the WWL, it is certainly versatile but it's not a fisheye, you would still want a fisheye of some sort if you are a wide angle person. You don't get the extreme central barrel distortion so much on the WWL compared to what you get with a fisheye. If you were using the Sigma 50mm previously. look at the Canon EF-S 60mm lens you would need to get one second hand, but it was extremely popular and should focus OK on an RF-EF adapter. When I upgraded recently I went with the OM-1 Very happy with that and I have the Canon 8-15 with Metabones adapter and it makes a very versatile wide angle solution it covers an 8mm fisheye plus the full range of a 7-14 lens so has more reach than the 10-17 does on APS-C. From what I have seen from test sites it's very close in image quality to the APS-C sensors.

Are you talking about more working distance or are you thinking a different shape to let light get on the subject more easily?