Chris Ross

Isotta have a 4.5"glass dome, you can also use a Nauticam 140mm dome by changing the lug ring to an Isottta/Sea and Sea lug ring.

Check the o-ring is clean and seating properly, lubing it wouldn't hurt either. A couple of minutes seems faster than what I would expect for just a bit of grit or hair on an o-ring. If that doesn't help, pack the housing with tissue paper, add a weight and submerge it empty (no camera) for a couple of minutes to see where water gets in based on where the tissue gets wet.

It's not a native Sony lens but the Laowa 10mm dome was tested and discussed extensively including using it in a 140mm dome some time back, here's a thread mainly testing Canon lenses and some of them including the 10mm laowa in the 140mm dome. This was tested as Canon mount MF lens but they make it in a Sony mount in AF. In the absence of any experience on Sony native rectilinear in the 140mm dome this may give some idea on what you might expect, in general terms 140mm is regarded as too small a dome for most rectilinear lenses and I don't recall seeing much discussion on the topic here. Some more detail on the 10mm laowa here, quite an extensive thread: Scrolling down is some information on Sony lenses that work well in the 180mm dome. The Laowa seems to be a special case working as well as it dies in the 140mm dome, it is generally thought that the very short minimum focus distance helps the lens perform better than other rectilinear lenses. Without doubt the best performer in a 140mm dome is going to be the Canon 8-15. Fisheyes play better with dome ports and can work very well in quite small ports.

Might have been condensation on the rear element of the fisheye lens of the front element of the 2x. Particularly the last frame looks foggy like condensation. This could happen if the camera/lens was cold and had come out of an air conditioned area. The housing would warm up in the air as would the dome, but the 8-15 is a heavy lump of glass and could have stayed cold (high thermal mass). As it slowly warmed up the condensation re-evaporated. Opening up on the boat could have let very humid air in, more humid than back on land. Sealing in an air conditioned space is good, but if you open the housing you let humid air in and it will find the coldest thing to condense on. Ideally have your camera outside at ambient temperature and bring it inside to seal it up.

The RC protocol sends optical signals to the strobe to tell it how long to fire for so the camera can actually communicate to the strobe during the exposure. The exposure is set purely on the pre-flash image in both protocols. In theory the sTTL should do the same job as it is trying to mimic the durations of the pre-flash and the calculated main flash length, but in practice it seems it doesn't necessarily work that way. Another point is that RC mode tells the strobe to emit a pre-flash, which the camera reads. The pre-flash power is known by the strobe and all the camera needs to do is to send a multiplier for the pre-flash duration to get the exposure right, so if for example if the pre-flash power is 1/32 and you needs 4 stops more power in the main exposure the strobe needs to fire at 1/32 x 2 x2 x2 x2 = 1/2 power . In standard TTL there are assumptions about how powerful the pre-flash is as a percentage of the strobes full power as the camera has no idea about how much power the UW strobe actually has.. There are also issues with measuring the power of the pre-flash in the UW strobe as the duration may not be in the optimum range for triggering the UW strobe and it may not match the duration of the trigger signal from the camera. An RC UW strobe though knows exactly what power the pre-flash was it can then can do the calculations based on the communication signals from the camera to work out how long (how much power) the strobe needs to fire for in the main exposure.

I don't see how the standard lens correction tools in photoshop can do what you are saying, maybe lightroom has a different tool to capture one which I use. Before you write it off I would suggest you use the lens correction tool and see what it actually does and you can see how it changes the image shape when it is used. Have a look at about 6:20 mark of this video: You can see the top of the image bows in to correct the barrel distortion and you have to crop the image. If what you say is correct then when zoomed at 24mm and auto-corrected the field of view won't be as wide as a standard well corrected 24mm prime, because the correction tools need to crop to remove the barrel distortion. You would indeed likely get better corners at 28mm when you zoom in and then use the WWL I believe, the digital picture notes that corners improve at 28mm. In theory if you crop an image out of the vignetted image and don't apply distortion corrections, then the image won't be degraded further by those distortion corrections. I'm assuming you don't see those non-illuminated parts of the raw image in the viewfinder. This being the case the camera is cropping the image from the sensor so you can properly frame your image to match what happens after the corrections have been done.

How quickly does it lose vacuum? if it's quite slow it will be an o-ring leaking most likely. If it's really quick, it's potentially either the valve was not installed properly - check it o-ring is in position or the new valve is faulty or perhaps you've pinched an o-ring. Is it the push button style vacuum valve?

In fact fisheyes play better with domes, the Canon 8-15 is an amazingly sharp lens and the Tokina 10-17 works better UW than it does on land. This is because of dome port optics where the lens is focusing on a virtual image located around 3 dome radii from the dome surface. The Rectilinear wides are designed to focus on a flat plane. so struggle more and more towards the corners. The focal plane of a fisheye lens is curved around the lens so it matches the shape of the virtual image. I dive temperate waters around Sydney and shoot mostly macro with some use of the 12-40 lens (24-80 equivalent) on offshore dives and also using my 8-15 fisheye there on occasions. I have a 7-14 lens (14-28 equivalent) and it uses the same dome as the 12-40, but I rarely use it. I'm not sure the 10-18 would be a great lens for CFWA. To be really effective this requires the lens to focus on the glass of a small dome. Fisheyes do this, but rectilnears have poor corner performance in small domes. Fisheyes have barrel distortion which enlarges the centre of the field relative to the edges and this has the effect of bring the subject forward with the background seemingly receding and this gives the images more impact. The Tokina 10-17 zooms from 180° diagonal fisheye all the way through to about 23-24mm focal length range, so effectively combines the fisheye with the range of of a lens like the 10-18, it just doesn't quite have the reach, but it's close. The 22-24mm focal length range refers to the width of the frame of a wide angle (rectilinear) lens zoomed to about 24mm or so.

The lens correction is removing barrel distortion and you can demonstrate this on a fisheye image with the lens correction tools in your IP program. Here is an example image taken with a Panasonic 8mm fisheye: If you use the lens correction tool it removes the barrel distortion at the cost of a reduced field of view: You can see that the image has lost the edges and it hasn't even been fully de-fished yet, so it doesn't actually stretch the image into the corners, but crops them out. I expect the lens correction on the 24-50 does something similar and I expect what Canon has done is that the 24-50 is actually wider than the a standard 24mm lens, knowing full well it will lose the corners when the barrel distortion correction is done. Unless you are doing raw conversions in Canons software the correction will be done using Lightroom's standard lens correction tool. It would be an interesting exercise to compare an image cropped out of the raw file with one that is automatically corrected and also to determine if the 24-50 has the same maximum field as a regular 24mm lens.

Also it seems the optics reduce the depth of field, noticeable in CFWA work, there was a thread on it a while back in the initial flurry after it was introduced.

Well, I would suggest that you base your selection on the availability of lenses and ability to easily add more lenses as time goes by without requiring a camera system change and the consequent new housing. UW is quite different to land based photography. using wide angle lenses up close to reduce water between you and the subject. I tried for the first year or two to apply some land based techniques and found they didn't work so well. Placing a lens in a dome port doesn't make it just like on land , it's necessary to stop down to deal with the aberrations caused by dome port optics, most people shoot around f11-13 for wide angle behind a dome port, even fisheyes are generally stopped down. Some of the wetoptics can be opened up a bit more. Typically a flexible solution involves a zoom lens, you can swim right up to a coral reef, but if you try doing the same thing to a shark or a tuna it will swim away. SO being able to zoom from a static subject to something with some more reach is very handy. By more reach it's something in the range of a 30mm equivalent lens on full frame. It's still significantly more reach than a fisheye. Wide apertures are used in macro work, where you can actually create some good bokeh, in wide angle work it can create some rather ugly out of focus things in the corners. Here is an example of photo taken 17mm and f8 in a small dome, note the lower left corner: https://uwaterphoto.com/?p=839 For fish portraits a longer zoom or a short macro lens tend to be good options. Again I'd suggest rather than gravitating to a camera body go ahead and see what you would need for macro, mid range and wide in a couple of different systems, then see how much it will cost you and the weight and size. I don't know if you plan to travel for diving but a compact system makes traveling a lot easier.

I believe what is happening is the lens has a lot of uncorrected barrel distortion and relies on software correction. Barrel distortion stretches the corners out and the corrected image needs to be cropped after correction. So Canon designed it a bit wider than 24mm to accomodate the cropping and the end result is black corners in the uncorrected image. There may be some benefit in in shooting uncorrected and zooming in till the vignetting stops as you really mostly don't need the corrections UW, it's no different to shooting a fisheye. If you don't do the software correction to remove the barrel distortion the overall image quality can improve. Whether it's worth the trouble I don't know, you would have to manually pick the widest zoom setting you can live with on the uncorrected lens and it would be fiddly. I agree the lens is a compromise, it seems like there might be sample variation as well, some land reviews give it a poor rating and others say it is quite good including sites that do performance testing.

Don't get me wrong, people will happily use the Sea frogs housings and they'll keep your camera dry and take decent photos, but they are somewhat limiting. Regarding strobes there are a great many on the market at the moment. The INON strobe, the S220 is a solid little strobe, but a little lacking in power, it will certainly work well getting a compact underwater and is I think fine for a m43 rig. There are a great many strobes available on the market today to pick from. On the Sony A6400, again I would encourage you to to look at the whole picture before jumping onto a camera body. With Sony APS-c and to a lesser extent other APS-C systems, the big manufacturers only make 90 or 100mm macro lenses. Canon and Nikon used to have 60 mm lenses, but are discontinued (at least the Canon is) . The long lenses on APS_C due to the crop factor are IMO too long for UW and force you to back up too far if shooting medium sized macro subjects. This means too much water between you and subject, strobes will struggle as strobe range UW is very limited and much greater chance of backscatter from the strobes. Sony has Zeiss 50mm macro, but the AF is quite slow except on certain bodies and can hunt a bit. On Sony you would be adapting a full frame fisheye for wide angle work if that's the way you wanted to go, though the 16-50 kit lens and WWL seems a good option if that is the way you wanted to go. I would suggest pricing out some options and working out which lenses you would use with which body before jumping on a camera body. Go into the exercise with your eyes wide open rather than discovering issues once you have invested into a system. On macro lenses again here is a pic of an Olympus 60mm macro side by side with a Canon EF100mm macro - massive difference in size and the ports have to cover this so also a difference in weight and size an $$. Canon vs olympus macro I would also suggest considering second hand rigs. Housings really don't hold their value and some bargains can be picked up if you consider using an older model.

First thing I would try is a multimeter to see if voltage is applied to the buzzer when it activates. It could either be the buzzer itself or the relay/transistor inside the electronics box that is not switching voltage to the buzzer. I assume the vacuum system is working, I expect the buzzer could be replaced if you had enough electronics experience to work out what type it is a select an appropriate replacment. Something like this would likely work, but you would need to check the voltage applied, I expect it would likely apply direct battery voltage. https://www.jaycar.com.au/mini-pcb-mount-buzzer-9-14vdc/p/AB3459 as you can see it's a $5 retail part.

Welcome Alastair, good to have another Sydney-sider on the forum. You'll have to break out your passport and come south one day and dive the Steps.