Chris Ross

Exactly, it's a good solution for a great many people. I don't use it, but I've adapted a Canon 8-15 which is an excellent solution as well, even if it's a little expensive and heavy.

I leave the o-rings in place, but I dive locally and do single dives every few weeks as well as trips away. I think if I was only diving on trips once or twice a year I could see pulling to o-rings and storing them in zip-locks inside the housings, but If I'm diving regularly, they just stay in the housing and get checked as required. I don't see much point in putting old o-rings in place - you may get contaminants in the groove, but you need to check the groove before installing the o-ring regardless and you have to keep track of which o-ring is the old one. For travel they also stay in place, the port is detached so the housing is not sealed and a cap goes over the port/o-ring for travel and this protects it well enough.

Voltages are not that different, nominal 3.6V per cell, so 7.2V total with two cells, four 1.2V cells gives 4.8V, if using a Retra with 8 cells it's 9.6V nominal. What counts is the voltage of all of the batteries in series. The voltage in isolation doesn't give the whole story as it is the current produced which is related to circuit resistance and voltage that sets the energy being transmitted. I don't know exactly what is going on here, 20A is a high current load for a battery , but for example a normal 220-240V power point can handle 15 amps of AC current without any problem. I know DC is different, but for contacts the main issue is arcing when disconnecting. You don't get power plugs being destroyed and they are handling a lot more power and video lights with bigger contacts don't seem to have the issue.

Note that S&S strobes used to be notorious for having low sensitivity on their optical trigger and were quite sensitive to fibre optic cable quality. You can bypass this by using an infra-red remote control. Just point the remote's LED directly into the fibre optic port on the strobe and press any of the buttons. the infra red signals will trigger strobes quite easily. A remote for a TV, DVD player, aircon unit etc is fine as long as it has an LED you point at the device.

I'd get the EM-5 III over the EM-10V model, the feature list on the 10 series is a lot more limited, things like custom settings on te top dial is missing - you can save all your UW settings and call it up on the top dial, AF is better with the Em-5 III as well. Downsides to the AOI housing include no rear eyepiece, so you can only use the rear screen and if I recall correctly limitations on flash sync speed with the built in trigger. There was a thread on that recently, believe in RC mode the sync limit is 1/160 for EM10IV and manual limited to 1/200. An EM-1 MKII is also a great option if you can pickup a second hand Nauticam housing. The EM-1 II has 3 custom settings on the dial you can recall. Regarding lenses used, the question is what he wants to shoot. Macro - the 60mm macro is the go-to lens. Wide angle there are a few options to look at, the 14-42 by all accounts is sharp at the widest, but a bit soft when zoomed right in. Can't comment on the AOI wet lens, but a review on almost any camera would have some relevance. A lot of people seem happy with a 14-42 with a WWL or a Panasonic 12-35 with WWL-C. There was a Nauticam EM1-II on the classifieds for a great price recently. Other wide options include a 12-45 in the Zen 170mm dome, the 8mm fisheye in the Zen 100mm dome or something like the 8-18 or 8-15 or 7-14 lenses but they require an N120 adapter and N120 Zen dome. The rectilinears are easier to deal with in Isotta as they have a 102mm port system rather than the 85mm port system and you don't need to get into the expensive N85-N120 adapters. Be easier to suggest something knowing what the preferred subjects are.

Yes these are the people without mechanical sympathy, they'll probably find some other way to flood their strobes even if they stop servicing them, it's a skill UW photographers need to learn and avoiding ultimately won't solve the issue. It's very dependent on the situation whether you need to pull them, but if you see water droplets that needs to be dealt with.

I think the lights have lower current, a 100 W-hr battery if it lasts 1 hour at full power it's running at 100W and I believe they are 14.4V, so running 7 amps. Some newer ones have higher power of course, but typically aren't run at full power for long periods. The backscatter flashes talk about 20Amp current drain. The contact area on the RG Blue battery is also a lot bigger. As the video light is constant draw, it probably needs the bigger contact area to minimise resistance and heat build up.

It depends on the exact situation, whether or not you get grit and also the type of enclosure. Clam shell housings are different than housings with a separate back for example. You can get away with lube on flat housing backs, ikelite specifically say not to on theirs, but clamshell housings need to be lubed. It also depends on the o-ring itself, the tiny 1mm dia o-rings on dive computers are much more fragile than the 4mm dia port o-rings on N120 Nauticam ports. My Z240 o-rings get serviced every battery change as they have drops of water clinging to them and usually some grit, My nauticam OM-1 main o-ring is also pulled every time it is opened after a dive - it's a clamshell housing and usually has water drops clinging to it which you risk pushing into the housings when you close it again. My INON torch never gets these droplets, it has a sand seal ring which is basically an external o-ring that the cap edge contacts as you screw it down, so the o-rings on that torch never get droplets or grit. The o-rings are pulled every couple of years for a clean and service. My Retra strobes, I've been using a blower bulb to blow away any water drops, they mostly seem quite small and only on the outer o-ring and I have been following the advice to lube/service them less frequently. They are not too hard to deal with though and they seem to resist getting grit with the tight fit of the cap. I think the risk of damage to an o-ring is quite small for most people - some people naturally have what I call mechanical sympathy , they know how to handle things and not break them, others not so much. But apart from very fine o-rings like you might find on dive computers they are reasonably robust and don't damage that easily if handled well.

Interesting, however the sensor is only slightly larger than the current iphone pro it seems (11.4 x 8.6 vs ~10.2 x 77.5). The design of the lenses for these must be getting more challenging to keep them low profile as it gets more difficult as the sensor grows in size and also the depth of field steadily drops away as the sensor gets bigger. Have to wait for the reviews of the phone perhaps to see if it's an accounting feature (less sensors and lenses in the phone) or really does improve images ?

I would add that the MWL doesn't seem to have a lot of users, I recall various people asking about it but the fact they recommend using at f16 seems to be an issue, I only ever remember one review by Jack Connick and he confirmed that f16 was best and probably f14 the lower limit. the 150° field sounds closer to a fisheye but just looking at diagonal field of view is a little misleading, all these wet lenses have barrel distortion and this means the corners stretch out more than the horizontal axis. The WWL gets 130 diagonal which is about the field of a 13-14mm rectilinear lens and the MWL would have a 121° horizontal field which is the same as a 10mm rectilnear. A Fisheye lens is about 140° wide horizontally (175 diagonal like the 8-15). As you zoom in on a WWL the barrel distortion is progressively less noticeable and approaches the proportions of a rectilinear lens.

Just to compare my strobes here's my Z240 cap contacts and a swab that just wiped them over, this is the first time I've cleaned them: I can only see the slightest trace of residue being picked up. I agree though if you are getting corrosion on contacts regular cleaning will help. My routine with these strobes is that every time I pull the batteries the o-rings are removed shaken dry checked and greased and the water left in the o-ring groove dried out and cleaned, then replaced and sealed up. Because I'm diving regularly, the batteries normally go back in the strobe. The strobe is 10 years old. Even after soaking the strobes for 2 hours the water trapped in the cap between the edge of the cap and the o-ring in still salty (I've checked by taste). If I don't pull the batteries I end up with salt crystals in there as the water slowly evaporates. The O-ring on these strobes is not a super tight fit in the groove and it seems to me there is a risk of traces of salt water making its way inside the strobe unless I dry out the o-ring as described.

Sorry, you actually do need liquid water to setup an electrochemical reaction, a thin film of salt is enough to do it as salt is hygroscopic and will pull water out of the air. But unless the humidity reaches 100% you won't get any condensation and even pure water needs a little in the way of salts to become conductive enough to facilitate dis-similar metal corrosion. I'm quite familiar with corrosion mechanisms in my line of work. It won't happen if the contacts are dry. Leaking batteries of course can cause it as they leak electrolyte. Regarding copper, it is quite resistant to sea water corrosion, but tarnishes quite readily which can reduce conduction. Regarding Coca cola, it contains phosphoric acid which will clean away corrosion products. you just have to rinse it well or the residue will be hygroscopic and come back to haunt you at a later date. I just looked at my Z240 again, bottom contacts seem to be brass, maybe gold plated?? but totally tarnish free after 10 years, the spring contacts in the insert cap appear to be stainless steel. Stainless is much less prone to tarnish, it's electrical conductivity is not as good as copper/brass but I expect it's good enough.and you can compensate with thicker cross sections. I never opened them up under suspect conditions like on a boat with strong winds blowing, but always made sure no water was left clinging to the o-ring before re-assembly. I think the issue is the high currents required, they make a big deal about having properly rated batteries - unless the contacts are good the extra resistance will just reduce the current. I don't think they cause the corrosion as such but are more sensitive to the impact of it.

Hi Tim, welcome aboard, good to have you here. I dived Byron a couple of years back, must get back up there.

Must be made with poor quality material, I'd expect this for materials left outside for extended periods, but not metal that spends its whole life inside a battery compartment sealed off from the outside. My INON Z240 strobes i had for 10 years and the contacts in the little cap thing and inside look as new. Dissimilar metal corrosion requires some moisture to condense, now if you get a trace of saltwater inside that will draw in moisture and can start corrosion. I always pulled my o-rings every time I opened them as I could see water droplets clinging to them and dried them off and wiped out the water in the o-ring groove before replacing them, if any of that water gets inside it will cause problems. My new Retra strobes don't seem to gather droplets of water so readily so those o-rings stay on most of the time and they are serviced periodically. The best is my INON torch which has a sand seal which basically means water never gets on my o-rings.

The port charts list the two 30mm macros and the 12-50 so it seems it would work with the 45mm. I'd estimate the field would be be a bit wider than the 12-50 - about 24mm FF equivalent in terms of horizontal field. The MWL seems like a great idea but never really took off and there is probably a reason for that. For one thing it is said it needs to stop down to f16 to be at its best which is well into diffraction softness with m43. It seems not too dis-similar to my situation in Sydney, I mostly dive Macro and regularly see things that would benefit from the MFO3, but possibly might see a big subject - a grey nurse shark shows up occasionally as do other things like wobbegongs, large rays etc. I still dive with the macro setup and now the MFO3 as it covers 95% of what I shoot very well. There is FOMO of course but I'd rather have a system that does well on the most common subjects. I'll occasionally dive with something wider at this site.