Chris Ross

Of course if it looks the right size and won't screw in you are dealing with imperial threads.

the AF for fisheye lenses is not particularly challenging, the Metabones with my olympus and 8-15 is fine for AF. I think the Metabones is a viable solution if you want to use a fisheye.

Quite possibly an M6 or M8?, you could try in any hardware store then knowing the right thread order the correct screws. If you have a Nauticam housing it will likely have a screw about that size you could try out, mine seems to have M6, M8 and M10 screws. If you find one that fits you can measure the OD with calipers and consult a thread chart to work out what is what.

The wet lenses use a bayonet mount (apart from the original WWL-1 which has an M67 thread) and the while bayonet mount screw onto an M67 threaded port the issue is that the bayonet attachment for the port has a U-shaped groove and is the port lip is too wide it won't screw on. It might work on some ports but not others. One work around is to adapt a Nauticam port to your housing and this will work if you can get the right adapter length/port length combination. If you have a Isotta or Sea and Sea housing that uses N120 ports you can adapt the Nauticam port directly by changing the lug plate over to a S&S/Isotta lug plate.

It really depends on your subjects, expectations and to some extent what type of waters. Strobes really can make a big difference to the type of photos you can take. Certainly you should be able to white balance photos from clear tropical waters, very green temperate waters might be more of a challenge. The 12mm lens I've not heard much about but it is not particularly wide in UW terms. The use of wide angle lenses is less to get a wide angle of view and more to allow you to get closer to your subject. The less water between you and your subject the better. You may be thinking of no strobes initially but I would think you might be better served with a zoom lens like the 10-18 or similar which I would think would be more adaptable in the long run. On the vacuum pump don't get the Seafrogs vacuum valve as it is not water proof, many people use the Vivid leak sentinel you can contact them to get a valve with the right thread to use on Seafrogs.

Basically go to a fastener store with the housing and find a stainless steel cap screw with the right thread. Canada is metric but being next door to the US, threads could be imperial. Presumably they screw into a tapped hole on the housing?

Basically while you can still Raw process the TG-6 gives you much less latitude to boost shadows and and boost contrast before noise and processing artifacts intrude.

the only reason to seal the outside might be aesthetics and to try to strengthen it against scratching and also sun protection. It is made to be inside a composite structure so UV stability may not be great. In round numbers the buoyancy should be about 950 grams/litre (1000 cm3)

I would be trying to add some buoyancy below the housing, your original query was around the effort required to twist the housing as all of the buoyancy is above the housing. I have a similar issue with 1200 gr of buoyancy arms above the housing. I would think you should be able to find some type of board to bolt to your housing base using the tripod holes and securely attach something like half of your stix floats to that. You could shape a piece of marine ply to suit or some other type of waterproof board to attach to housing and securely attach your floats.

this is relative to the same strobe, so if any given strobe is pulsed for less time it will not reach the same peak/average temperature so it will be warmer than its maximum power temperature. It doesn't apply comparing big round tubes to short linear tubes.

As I understand things strobes emit a full spectrum centred around their colour temperature and they do this by generating a plasma which glows giving a black-body type continuous spectrum centred on a particular wavelength. Technically it produces grey body radiation which is transparent to its own radiation. This wavelength is what defines the colour temperature produced. The temperature achieved inside the tube corresponds to plasma temperature achieved so 4500-6000 degrees kelvin (Kelvin = degrees C plus 273) The peak wavelength moves to shorter wavelengths as the current density increases due to the plasma getting hotter. If the strobe is using small linear tubes the current density needs to be higher to match the output produced from a larger tube so light is bluer. The light produced is proportional to the volume of gas that is excited into a plasma. So physically large tubes can use lower current densities and their light tends to be warmer. Similarly a shorter pulse will shift warmer as the shorter duration means less energy is added to tube so peak temperature reached is lower, color temperature lower and peak wavelength longer.

It's good that they do standard comparison tests of strobes, but when I last looked the only way to find them was buried in individual videos be nice if they had a central site where you could find their data to directly compare strobes you are interested in. I find I am really not a fan of video reviews they are nice enough to watch but I'd much rather have a written review where I can skim to the interesting bits.

I'm as baffled as you about green water turning blue, you can do it in post processing but the diffuser has little to do with it.

I'm not sure how this relates to my comment (quoted by you) I made no mention of turning green water blue - perhaps it applies to another comment.

Indeed, It's really WB method independent and requires no more thought than doing the standard WB adjustment on your subject. The main point if that it really only is a big benefit in clean tropical waters. I've left the 4600K diffusers on in temperate Sydney water and the photos come out just fine, but I don't see a big benefit for it in that situation.

Advertised Guide numbers are somewhere between a general guide and works of fiction, most seem to report centre brightness in air and previous studies have shown some strobe models are quite bright in the centre with more than average fall off. It sounds like the S220 should be on my list to replce my Z-240s one day! If you have all of this data it would make a great write up to give people some objectivity when choosing strobes. Would you consider writing it up as an article for the site?

Which is exactly the application they are suited for, warm strobes really give you no advantage in cold dirtier waters.

I would think the problem lies within the camera/UWT trigger combination. When in manual the INON strobe just fires when it receives a light pulse. You might be best to message Pavel if he doesn't chime in.

Welcome on board Gerald, hope you find the forums useful. On your question about the Nikonos lens perhaps you could ask the question in this post where it might get more visiblity?

What I have seen if they are forward is the lens sees the particles very close to the strobe which then become very bright and intrusive. perhaps I didn't express it right. The main point of the post really is to point out that stating that you can't avoid backscatter by using edges because you can see unilluminated particles in the image is being pedantic. The whole point is not to illuminate them so you don't notice them.

There's the physics of course, but this ignores the aesthetics, using blue filters on your light source does indeed provide an even colour profile throughout and it does suit some subjects. But it mutes the reds through yellows and looks kind of flat - it suits some subjects but not others IMO. For skin tones, vibrant soft corals the images look kind of dull that I have seen. One of the big things underwater is to restore reds - all the warm colours but putting a blue filter on your light source kind of defeats the purpose. I would agree that you don't necessarily need a warm strobe, but you might want one.

I would argue you care about both, the sun does a fine job of illuminating the upper surfaces but the sides of fish, corals etc don't get much illumination, then of course there's the undersides, you only have to look at how dark it is under even a small overhang.

Technically yes you can see the particles but I would argue that un-illuminated particles are not backscatter. The meaning of backscatter is light reflected back towards the camera and these particles are very close to the strobe so are very bright and objectionable. Particles you avoid illuminating may or may not be noticeable depending upon what is behind them many times I can zoom into 100% and see stuff floating around but the final image you really don't see them. For all practical purposes they have no impact on the image. I've positioned my strobes badly often enough that I can say for certain that avoiding illuminating the particles is a real positive for the photo. the most important parameter seems to be to pull the strobes well back behind the plane of the dome port.

Back to the original question, regarding strobe selection, The small INONs are nice strobes, however my experience is with Z-240 I find that shooting at f8 on m43 lenses I am at 1/2 power or the next level which is 1/2 stop less than full. at ISO200 I find lighting big scenes a struggle at times. On full frame you will be stopping down to F11-13 most likely. You can bring your ISO up to 400 but might find you are running into your sync speed if shooting sunballs or even bright surface waters. 1/250 @ f8 ISO 200 is the same as 1/250 @ f11 ISO400. I've just finished diving at Walindi in PNG shooting Barracuda schools etc. I didn't really want to go full power as I was ready to shoot again quite quickly at the powers I used. I kind of felt I'd like a little more strobe power. You could probably get away with the S220 if shooting at less than 1 m distance and using full power, but might find them wanting when shooting big scenes.

This is correct, if you white balance with a warmer strobe to make your subject neutral you cool the image overall which means the water is colder/bluer, no masks required. This happens because the strobe illuminates the subject and not the water. Though I would say there is no harm in 4600K light, I've used in clean tropical waters and results are fine.