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Winter Solstice with a glimpse of hope for the future

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My country has been the proverbial deep-freezer for months now and days get shorter and shorter. At Winter Solstice, the sun barely gets over the horizon and daylight lasts for a few hours only.

This picture is to remind that after Winter Solstice, there are hopes for a warmer season. The submerged plants already anticipate the march of the seasons so hibernate green to rapidly exploit the sunlight when it again is in abundance.

Even with a drysuit, running water and -20C make for a cold experience. ;D

post-24-129983585414_thumb.jpg

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Hot and cold, it works very nicely indeed!  ;)

Greetings from the frozen city of Copenhagen, hope  weather clears within the next days, so Jan Ann can join me 8)

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No tricks other than putting my 20/3.5 AIS into an Aquatica domed housing.

The huge dome remedies the changes in angles brought about by the refractive index of water (n=1.33). However, you cannot do this without shifts in the focal planes over-under the surface. So in-water focus is located differently from focus in air. This is what you observe here.

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Great standpoint. Very inspiring.

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Why the scepticism, Tom?

You observe the water interface air/water, details above the surface and details below. Ergo, the camera must be positioned at the interface itself.

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OK, now you have the explanation, so any problems should be sorted, yes?

A general remark: this is like shooting landscapes with a format-filling fisheye lens. If the horizon (or the water/air interface) goes through the centre of the frame,  it is rendered a straight line. If the intersection is in the upper part of the frame, it curves upwards; if below the centre line, it curves downwards. This is of course a result of the dome port being - well, a dome.

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Great camera operating at that temperature.

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Guest gerhard2006

So if this would have been shot with a half submerged Nikonos with a 20mm lens this distortion from the dome port would not be there? Love the shot Bj

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The main difference would be that the in-air image was *completely* out of focus. In fact, the 20/2.8 UW-Nikkor (a lovely lens, I have kept one of them in hope of there someday comes a digital Nikonos ...) cannot form a focused image in air, as the design depends on the refractive power exerted by water (n=1.33). The same goes for most of the other underwater Nikkors, both for the classic Nikonos and the Nikonos RS. Some people claim the 28/3.5 UW could be used in-air, but must never have looked closely at the result since the in-air image only had  superficial resemblance of sharpness. The 50 mm RS-Micro-Nikkor is in the same category as the 28; the image appears to be sharp but is not and besides, has horrible colour aberrations. There is also the 28/2.8 LW of course, but this lens while suitable for really rough and wet situations (rafting, etc.) cannot be used under water.

For over-under images, you need a dome port housing, and a wide-angle lens that is suitable. Most lenses won't sit in the correct position inside the dome, so they displace verticals going through the water surface, or they don't focus properly. The 20 mm Nikkors are quite good for this purpose and so is the 16/2.8 Fisheye which is the lens I'm using most in the Aquatica (it has been rebuilt from housing an F3+MD-4 to the DX Nikons). The 18 mm f/3.5 does nicely for the in-water shots, but doesn't work well for the over-under kind since the focus shift is very substantial. I guess for static subjcts, one could solve the problem by stacking shots at different focus, but the water surface rarely is placid enough for this technique to work efficiently.

I've seen excellent underwater captures made with the 14-24 in domed housings so perhaps that's the next avenue to approach.

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Guest gerhard2006

Wow, that's a lot of information. I had no idea the 20mm 2.8 UW would not focus an image out of water. So obviously a UW camera housing is the best way to go for underwater photography. Would a 35mm 2.5 not work either for under over shots? I guess it was more of general purpose lens not a really good UW lens like the 28 3.5, right? I was thinking of building a plexiglass box for such shots with a radio remote on the side to trigger the shutter. I can see though that shooting through a dome port would have its' advantages, but never thought of placement in the port as being a problem. Thanks for all the great info, I had no idea that plants stay green under water in the winter months. Regards, Gerry

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Even with a drysuit, running water and -20C make for a cold experience. ;D

Yes, especially if you only stay only half submerged ;D ;D ;D

Under water it stays close to freezing anyway unless you dive in supercooled water, and you better not! :o

Very nice shot Bjørn, and I can appreciate the effort in getting it!!

Curious about your rebuild, how did it work out for you with the viewfinder?

Also do you get to peek at the screen for preview?

I have a Subal housing for my F4, even with a rebuild it would be a bit sad to loose the nice action finder of the F4.

But at the price of new housings now, and with the resale value of old film housing dropping it seems well worth it!

Edited by otoien

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I ended up without access to the viewfinder. This is because the housing was designed for the action finder on top of the F3/MD-4, and my DX Nikons are not so tall. However, I'm very accustomed to shooting "blind-folded" with my IR cameras (before the last one, which has for the first time a built-in IR filter), and also with the various wide-angle UW Nikkors for which I hadn't the separate finder. Thus, not a real stumbling block, just a small challenge to spur you on. With a DSLR, you get rapid feedback anyway, so mistakes are easily corrected on the next round into the water.

The water in fact was supercooled and later that very day, the river froze. It had stayed clear of ice because of the swift currents despite the ambient -15 to -25C, but would not manage this for the whole of the winter season. When frosts penetrates the upper soil layers, run-off is reduced and the local rivers then are prone to be iced over.

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Wow, that is a lot of algae !!!

I also live at ~60 degrees north latitude and am looking forward to the next 6 months of day lengthening!  :angel: IMHO, the day length starts to get reasonable about St. Valentine's day.

The background of my Xmas card is also an over-under shot (see Merry Christmas thread). More of an accident or test shot (I do not recall which) between locations in the stream I was shooting in.

Tom

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Would a 35mm 2.5 not work either for under over shots?

No, You want to use a lens with a lot of depth of field like a fisheye since you need to focus on a virtual (the under water part) as well as real image (the above water part) at the same time. The apparent distance to the virtual image is on the order of one foot, or even less - depends on subject distance, dome port diameter * - while the above water part may be towards infinity.

Tom

* - actually dome port radius of curvature would be more accurate since not all ports are hemispheres, but we are getting too technical too fast!  :angel:

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Not algae, but a flowering plant (Juncus bulbosus; Bulbous Rush).

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No. This is the perennial submersed variety of J. bulbosus, which is almost always sterile and can have trailing shoots up to 6-7 m in length. A species widespread in Norwegian rivers and a troublesome aquatic weed in some rivers used for hydroelectricity production.

The submersed form is much more common than the small, tufted variety of muddy shores and bogs.

This species was one of my main targets for scientific studies over three decades, so am quite familiar with it  ;D

Below is an example of the mass development one can see in hydroelectric rivers. Same species, "only" more of it.

post-24-129983585449_thumb.jpg

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That is quite some growth. We have some sedges such as in salt marshes but nothing like that in terms of density.

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The prolific growth in these rivers secured substantial funding for my scientific projects for many years ....

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