Chris Ross

I think this can potentially be a cause for some otherwise good wide angle lenses not working so well underwater. One issue is field curvature - all wide angle lenses have it to some extent and the plane of sharpest focus can be concave or convex or even wavy with respect the sensor which is perfectly flat. Wide zooms tend to be more complicated and the curvature may change from concave to convex or vice versa as you zoom in. This link discusses in some detail: https://www.dpreview.com/opinion/7031211310/roger-cicala-field-curvature-pt-2 Why is this important UW? For lenses behind a dome port they are imaging a curved virtual image which mean the image plane of sharpest focus is also curved. If the lens's field curvature works with the curvature of the virtual image it can tend to help bring the edges into focus, but if it works against it it can push the edges even more out of focus. Field curvature doesn't change shape as you stop down, the depth of field just increases so that the edges progressively improve as the edges come into focus as you stop down. UW we tend to shoot well stopped down in dome ports which may mask some of this but a lens with strong field curvature in the wrong direction could potentially be impacted. It is most important on full frame, and gets to be less on an issue with smaller formats. On the topic of sea water, that and the air/water interfaces reduce image quality, ultimately limiting resolution that can be achieved. So it seems to me there are limiting returns when chasing sharper lenses. This can even happen in air, I was shooting across a fairly wide turbulent river in Ecuador in the mountains, the river was snow melt so very cold - I had noticeable image degradation shooting across a 20m wide river. bad enough I could see it in camera, I ended up raising ISO , opening the aperture to get the shutter speed a lot higher which helped a little. I'm not sure I agree with the premise that because lens manufacturers make lenses with lots of elements that adding optics does not always degrade performance. First we are talking about external elements such as domes and wet optics not being able to improve performance, not internal elements. Any internal elements are custom designed to work with other all the other elements while external wet optics are all so far designed to be universal. Even looking at the premise of adding elements will produce some degradation with each air/glass interface losing some light transmission and not being perfectly manufactured, however it is a compromise to correct aberrations in the optics, you might for example add an element to correct field curvature accepting that it reduces light transmission by 0.5% and centre sharpness by 0.1%.

I basically agree with the premise, any additional elements tend to degrade performance to varying degrees, it may degrade a lot or a little to the point it is hard to see, but it entirely reasonable to expect that it won't improve. As for the statement : start with the best land candidate, then optimize the underwater setup as intelligently as possible yes but it still seems that some lenses play better underwater than others, so there is a need to be selective in what you try to take underwater. Just because it is an amazing lens above water doesn't automatically translate into good UW performance. Though it seems that with the latest crop of close focusing mirrorless zoom lenses many of them work quite well UW. For the specific case of the Tokina 10-17 potentially what we are seeing is that this lens works exceptionally well with small domes and the degradation in performance when taken UW is minimal. But if you compare the UW results with some of the older rectilinear zooms that don't seem to work well UW or perhaps people are using them in too small a dome, the Tokina seems to really shine if you just compare UW shots taken with these older lenses with shots taken with the 10-17. It is also a very flexible wide angle option the ability to zoom in and take reef scenics and CFWA on the same dive can trump ultimate sharpness for many people.

A couple of points on this, equidistant and equisolid angle projections are quite close to each other and while lenses are described as such, they probably do not strictly conform to the ideal model. So telling the difference between them from a random photo may be difficult. Ideally you would want a photo of a brick wall or similar taken with the each of the lenses with a tripod in the same position so you can see how the stretching varies. This link for example shows some measurements taken from optical formulas, look at the second and thirs plots where various lenses have been plotted on the curve, they mostly cluster around equisolid but there is quite a variation. https://www.photonstophotos.net/GeneralTopics/Lenses/Optics_Primer/Optics_Primer_25.htm Other references state the equisolid has more barrel distortion so more fisheye effect - the forward placement of the subject in the frame. This link has some projections plotted - it takes some time to look at the plots to see the differences in equisolid and equidistant if you look at orthographic and sterographic plots they are more exaggerated versions of the changes between the first two: https://paulbourke.net/dome/fisheyetypes/

I didn't say special, I said right - and scissors are the wrong tool, I recall someone saying they used scissors and had problems with their cables.

White balance and colour grading is similar just color grading can't go as far, DaVinci can do that for you in the free version. It should work if it's close to balanced. I don't do much video, but I managed to grade a clip from a TG6 shot just using the UW white balance setting. Turning a completely green clip blue would be a stretch, but if you make some attempt to do a custom white balance it should work OK for you.

With the right tool of course - no scissors!

In the meantime you could try logging out, closing your browser then reopen and log back in. Could get you going again, if not have to wait for Rich to look into it.

I think it kind of depends, for example say you are diving in Lembeh, well known for black sand getting all over everything, it's probably quicker to clean up the o-ring on the seal plug than pull the o-ring and service it particularly on a clamshell style housing. It's about the same as what you would do on a bulkhead which is also o-ring sealed. I agree though that a bulkhead is a better solution if you can source it.

You can download the manual for the strobe from the S&S site now, it has a bit of information about the batteries in it. The battery looks just like the battery from a Canon DSLR/mirrorless the LP-E6P - not saying it is but the locking tabs etc look the same, the S&S battery has a nearly 50% higher stated capacity than the Canon LP-E6Pbattery though. It seems the Li-ion battery comes with the Pro model. The features and details of the strobe look quite familiar to the prior S&S models. Download link here: https://www.seaandsea.jp/support/download/manual/manual_en_03133_ysd130r.pdf

Probably no real advantage unless you really need the speed, but shooting wide open even in a 230mm dome is going to produce pretty horrible corners. Then there's the question about whether it plays well behind a dome and also if it will work behind a WACP-2, probably more likely to work on this optic than the WACP-1, the large front element can be the issue for these optics. The WACP-2 might be a chance as it works with the Sony 14mm f1.8.

I think for something this old that you probably need to print gears. You say zoom can sometimes can be adjusted, does that mean you have a zoom gear and it is slipping sometimes? You might be able to pack it out or otherwise adjust it so that it doesn't slip - how to do this would vary with the design of the zoom gear. If you need a zoom gear made you could try messaging on of our members @gudge as he prints zoom gears. It seems that the N90 doesn't allow for viewfinder diopter adjustment, seems to me that is the most important thing to get sorted before attacking anything else. It uses screw in diopetr adjustment eyepieces, so you would need to source one of the correct strength, or something like this might work? https://www.aliexpress.com/item/1005007792504364.html Though if it is too thick it might not work. Is the viewfinder in focus outside of the housing? it is unclear from the attached document how the viewfinder is meant to work, does yours have an external eyepice On the aperture ring - not sure how this is setup in the housing - when you say it can't be adjusted - is there no control for it? Are you lacking a gear? what is on the inside of the aperture control knob? is it a gear or a wheel? If you can't solve the viewfinder it might simpler to look around for a different film camera model housing preferably one that takes "G" lenses where the aperture is adjusted electronically. Maybe an F100 or F80 ?

INON strobes have very sensitive fibre optic receivers, so triggering them tends to be very easy. to test you could try placing the fibre optic port directly over the trigger port on the housing. Also check the housing port by looking into it and triggering to see if seems bright or not, you could perhaps compare brightness to the TRT trigger. You say that it used to work with the TRT trigger, does it still work with that trigger? It's possible for example the LEDs are not well aligned on the housing ports.

I have a Panasonic 8mm and I used it in a Zen 100mmglass dome and didn't notice any reflections. There is no white lettering upfront which is the usual culprit with lenses causing reflections and the petals have cast in lines which are designed so that the lens sees the shaded underside of the lines. I can't see it being a problem.

Allowing water to evaporate on the glass is what causes this, the salts concentrate and it will eventually etch the glass, the same with anodizing on the housings. If you can't remove it with glass cleaner then it appears the glass has become etched. You can replace the port glass. The solution is prevention. I keep my housing covered after dives and it gets a long soak after each days diving before being dried off. I'm using a blower now from wolfbox, the high velocity blows the water off rather than letting it evaporate.

Welcome aboard Andrey, good to have you here.