Chris Ross

I don't believe that's what's happening here. Yes you likely need more strobe light to balance against the brighter ambient light. There's various things you can do in processing to assist First pull highlights down to deal with the bright water, then boost shadows to get your subject right. You can do a lot with this, otherwise you need to boost strobe power some more. On the question of WB, I believe that technically your photo is close to white balanced, just needed some tint adjustment. If you look at the Red/Green/Blue histograms they are all even and run all the way from 0 to 256. This is a sign the image is properly white balanced. The Hue adjustment is restricted to the cyans and made them bluer this is outside of a global WB. One thing you could try is to process for the water and boost shadows in post but don't draw on images to make a mask though! too easy to detect. If you have full PS the luminosity masks from Tony Kupyer are great, the free one works fine. Otherwise copy the image and invert it and use that as your mask. Increase the contrast of the mask so that the brightest highlights go white and it's a perfect mask. Here is the shadow mask from your image, D3 from the Tony Kupyer action panel, D4 would basically exclude water all together from the adjustment: With this method you don't have to deal with feathering and trying to hide the transition. Use it on curves layer with an "S" curve pin the bottom of the curve very low down before pulling up shadows:

The Leak detectors are reliable but they do need some liquid water to reach them to activate them, a drop or two may not set them off. I agree it's very likely water from opening the housing. You can get your self a hand held blower bulb (I use the Giotto rocket blower) and use that to blow away excess water drops along the seam and in the latch mechanism. It gets water that a towel won't reach. A microfibre cloth (lint free) is useful to wipe down the o-ring to remove any remaining droplets. I keep one in a clean ziplock to stop it picking up grit and hair for this purpose. On a side note water droplets like this are likely the source of the myth that leaving the housing in the sun causes condensation. The root cause is actually the water that vapourises and then re-condenses on the glass port.

you don't actually need a cotton bud, a damp finger does just fine. One less piece of plastic waste in the waste stream each month.

I agree never leave a camera alone in a rinse tank, bad things can happen. However the vacuum doesn't hurt you in this situation it helps. Typically you have a 200 mbar vacuum in a housing like Nauticam and this is exactly equivalent to being 2m under water. What is important is the pressure difference. 200 mBar is 0.2 kgf/cm2. On a small compact housing measuring say 14 x 10 cm this means the closing force is 0.2 x 14 x 10 = 28 kg. This means the housing back will be very difficult to open, particularly the clamshell style where you can't push the back sideways at all. All that matters is the air pressure outside is greater than the air pressure inside. One of the big benefits of the vacuum systems is that it pre-loads the o-rings and that means it's much less likely to leak in shallow water.

I commonly see various aquas/greens in bright shallow water in my shots. It seems to me the cause is the reds, yellows have not scattered away and there is always some algae in the water which shows up under these conditions. Easier to fix on the Raw file perhaps. Basically you need to add some magenta, the browns in the corals to my eye contain some green so move tint towards magenta some more. I had a look at the image in PS (I don't use lightroom) and added some magenta in levels, however any global adjustments don't really do the full job as they will send off the subject colours. SO I then used a Hue/saturation layer and went to the cyan channel and pushed the Hue towards Blue: Here is what I got you can adjust the hue to your taste if you work on your original image I left a little of the aqua/green in the brightest bits and also boosted shadows as adding magenta makes the blues darker:

Good to sea this, after all charging Li-ion is said to the cause of some liveaboard fires. If you really want a USB-C battery charger you could always upgrade to an OM-1 it has a twin USB-charger🤣. But seriously I really don't see the attraction to power everything off USB-C. I'm quite happy with my 8-cell MAHA charger and the little camera battery charger. Though last trip I installed a USB-C bulkhead on my OM-1 housing and could download images with the camera in the housing, then switch over and charge the battery in there as well. The Nauticam bulkhead is vacuum tight. The download speed is a touch slow compared to a card reader and battery charge is a little slow too. But it means I don't need to pull off the front port, remove the Canon 8-15 to pull the camera body to charge/download and then put it all back together again every night Not an option for the EM-1 II as it won't charge over USB-C though.

Resize the files to 1200-1600 pixels on the long side and then save them as jpeg and adjust quality, to get the file size down, you should achieve 300-400 kB easily this way. As to your question , in shallow water green light is still coming through and has not scattered out as yet, if you are shooting into the sun, then it will be bright and may even have some red in the mix. However post your examples, there are different ways to approach this depending on your starting point.

In general round tube flashes are slower. The old YS-250 had a duration of 1/50 second or so at full power, quickly got faster of course as it was turned down. There was a post on Wetpixel some time back where someone quoted flash duration times. Mostly not a problem till you get into 1/400 plus flash sync speed. I think some flashes might be an issue with for example a manual flash trigger and an Olympus camera which can do 1/400 to 1/500 sync if I recall correctly. One post is here but there are more I'm sure: https://wetpixel.com/forums/index.php?/topic/60459-flash-duration/

Did you open the housing to change the battery prior to this? Water will cling to the o-ring and when you close a clamshell style housing it can push some of this water inside. If it was the first dive it could just be water drops dislodging as you open the housing. Do you have a vacuum system on the housing? I would suggest to pull the o-ring and dry underneath it in the groove, shake the o-ring dry, clean and grease it and re -install. For drying the housing, do you have access to a fan, a hair dryer or perhaps the dive operator can provide an air gun attached to a scuba tank to blow out the housing, use the airflow to dry out the inside of the housing. Take care when you open the housing and watch for water drops. Dry off the o-ring before you close the housing . Have a lint free cloth ready to wipe up any drops that are clinging to the o-ring when you open the housing. As to where the water came from, I checked current weather in Marsa alam and it said 37° and 26% humidity, so it's quite unlikely to be condensation.

The Canon 8-15 is adapted more often I believe is due to the fact that Canon lenses are easier to adapt compared to Nikon F mount. There are so many flavours of Nikon F mount as well which no doubt complicates things. this link has some explanations: https://briansmith.com/where-are-the-nikon-af-lens-adapters/ As far as fisheye goes it comes down to what you shoot and what effect you like, for me fisheye is unbeatable for reef scenics and CFWA. I now use the Canon 8-15 on OM-1 which gives amazing versatility and effectively combines a full frame fisheye with a 7-14 (14-28mm full frame equivalent) lens. Of course in full frame to get the same versatility you would be looking at adding a 1.4x to the 8-15 which doesn't have as much range or venturing into FCP which has it's own set of issues, cost possibly not the least of them?

When you say regular line voltage, do you mean a 220V cord plugs directly into the charger? Doesn't seem like it would be that much saving to not pack a short 220V cord? For me I look for a solution that allows me to charge flash batteries and camera batteries at the same time, as well as potentially having the laptop on charge. Normally they are done by the time I finish downloading and an initial cull is done and I don't need to leave them unattended. I hear also some liveaboards these days some don't allow Li-ion charging unattended in your room so it's crowded at the battery charging station.

While it would be interesting to know Backscatters test setup, if we assume that they have taken reasonable care to have a reproducible setup as far as distance from strobe and camera position is concerned and taken basic care to do minimal image processing and do the same for each test, I would argue we don't really need to know the details of their test setup. I would assume they just insert the still images into the video to display them rather than take video . The images snipped from the video should then be usable as a comparison tool. The plots I got out of the images just taking eyedropper readings look remarkably similar to the plots Retra produced. They should give reasonable basis for comparing flash performance. You really need both plots to make sense of things, the first plot shows how much brightness difference at full power is and the normalised plot shows distribution differences. While it's commendable that Backscatter does these tests, just putting them into a video review really doesn't help anyone as looking at a bunch of separate clips showing the beam pattern, the human brain really can't make much of a comparison. To be truly useful and helpful for prospective flash buyers providing a link to a standardised test image from the product page of each strobe they have tested would be a good start. @James Emery any chance of providing access to test images?

I don't think there is any danger of losing 1:1 just working distance. Flat ports don't have a virtual image in the same way dome ports do, the impact of the virtual image is basically to just magnify the subject so it looks closer but they also need to focus closer than the subject on that virtual image. With the nikon Z the working distance is 290-140-16 = 134mm. You can use this calculator to see how much closer the focal point is: https://oceanity.com.au/tools/flat-port-virtual-image-visualiser with this situation with the virtual image at 290mm, the subject distance from the focal plane is 400mm so you according to the calculator the working distance would 254mm at 1:1. I think I've interpreted that correctly.... And you lose 10mm of that working distance.

I think the simplest way to consider it is that you can frame up smaller subjects in your CFWA shots. For example a 70mm subject would be the same size in frame as 100mm subject without the TC.

Here's the plots with HF-1 added: and here it is normalised to the Retra centre value: The YS-D3 is with the diffuser. I can't see wanting to use it without the diffuser. You can see that the ikelite and Retra closely mimic each others distribution pattern and the diffused HF-1 and YS-D3 also closely mimic each other. The HF-1 is interesting the distribution is quite similar with and without the diffusers until close till the outer edge where the Illumination drops dramatically without the diffuser. This should not be surprising, the Retra and Ikelite both use circular flash tubes and the HF-1 and YS-D3 use a similar linear flash tube layout. The ikelite and Retra are very close with a slight edge to the Retra on even distribution of light. There is very little to pick between the YS-D3 and the HF-1 with diffusers apart from the additional power of the HF-1 and the batteries. Why would you want even distribution of light? with 2 strobes the edges of the beam intersect and overlap in the centre of your photo, so if the edge has more light then you can turn down the power compared to a strobe with dimmer edges. The 160° dome diffuser though throws light around everywhere and it would be hard to avoid illuminating the dome with it. just look at the pool wall behind the test chart to see how wide it throws the beam compared to the flat diffuser.

with diffuser, the without diffuser shot shows only that you should always have a diffuser on that strobe.

Server problems I believe. Seems like it's sorted out now.

I'm not sure exactly what you are saying with regards to a larger air gap between the port glass and lens, but basically the point in focus at 1:1 is a constant distance from the sensor and if the port is longer this eats into the distance so at 1:1 (for example) you have less space between the end of the port and the subject if the port is too long. Looking at the EMWL another way, if you've spent all that money why compromise to save the price of an extension ring?

I plotted up the brightness from the centre and the square just inside each ring plus the outermost square at the level of the "X"axis horizontally out from the centre. The X axis of the plot is arbitrary values with ) being centre and 1, 2 and 3 being the 3 rings on the target. Imported each jpeg in PS, convert to greyscale then LAB colour to get luminance values. Here is the plot: You can see the YS-D3 has more dramatic fall off and the Retra has the same brightness at points 3 and 4 even though it started off with lower luminance in the centre. The ikelite has roughly the same curve shape as the YS-D3 just brighter through out the range. Basically this means the Retra spreads its light out more evenly with less fall off. You need the plot to judge the difference because the human eye is terrible at such comparisons. Basically what this means that at constant centre brightness, the Retra has the brightest edge to the light cones.

To my eye the Retra looks most even but it is difficult to judge with different centre brightnesses I think the photos really need to be converted to plots to judge properly. I think also for example the retra has the target a bit folded so the bits angled away from the camera seem darkened. You can see in the plot provided, I think its from Retra the RF pro mirrors the seacam and the curve is flatter than the DS-161 ikelite flash

Diopters don't work as well if there is too much gap between lens and port. You could probably just use what you have now and get the right port to go with the EMWL when you go that way - The wide angle of the EMWL will probably impact that more so and getting the right port more critical. The other impact of course if the port is too long is that you lose that much working distance.

The Tokina 10-17 would be a fine option for wide angle work and with the zoom will adapt for pelagics quite well. Going for the widest option will also encourage you to get closer and this is probably the No.1 thing you can do improve your photos. at 17mm the field of view is equivalent to about a 21mm lens (FF equiv) or 14mm or so lens on an APS-C. SO it covers a full frame fisheye, the WWL max view which is about a 14mm full frame equivalent and about half of the range available with the 10-18 zoom. All in the one lens. Fisheye zooms cover more range of field of view than their zoom ratio suggests as the barrel distortion means the centre of field is magnified so when zooming the area covered on the horizontal axis decreases more as you zoom in. This table shows it: APS-C coverage horizontal vertical diagonal 10mm fisheye 144 92 180 17mm fisheye 81 53 98 WWL max 122 100 130 10mm rectilinear 99 76 109 18mm rectilinear 66 47 76 The advantage of the fisheye over the other options is it will work in a 4"dome, making CFWA easier and can Replace about 2 1/2 lenses. You can add a 1.4x to it and you have a complete coverage for everything bar macro work in one very small package and it very light for travel and manoeuvrable in the water.

A fisheye zoom like the Tokina is quite a good option, though on a Sony camera you want to adapt a Canon lens not Nikon. The Nikon mount lens is screw drive AF and won't work on anything but a Nikon F mount camera. There is an adapter that supports screw drive now I believe but I wouldn't go this way if you can use electronic AF with the Canon. you may well be on your own if want a zoom gear with the Seafrogs housing though. Whichever lens you choose - a zoom is going to be a better option for flexibility. Also with regards to natural light photography, even then you benefit from being closer to your subject, you can see in the example file that the colours start to fade out further from the lens, this being due to having to travel through more water to reach you than that from closer objects. Not as dramatic as strobe light , but still there and you also have less water between you and the subject so less particles and distortion from the water. Plus it's a good habit to get into.

The 100mm macro would work nicely for your smaller subjects but you would be a bit distant for the larger subjects. a 150mm subject you might be about 300mm away from and a 300mm subject you would be close to 900mm away.

Yes, but even then you can back button focus as the depth of field is enough, video and fisheyes don't mix well it seems.