Just returned from Bonaire where a fellow on the boat had the Backscatter system. According to him the vacuum caused a problem with his camera in that not all the buttons worked. His theory is that the vacuum caused the buttons in the camera to get sucked in a little bit which meant they did not meet up properly with the housing controls. Any comments on this?

I was actually on the boat the same day he was experiencing the sticky button on his housing. I won't get into which housing it was but I will tell you that in my assessment, the button that toggles between video and photo mode was getting stuck in the down position, causing the camera to be locked up. I experienced the same issue before with the same brand of housing last summer where I had pressed the "video/photo" button a little too hard and it would stay stuck in the down position. (In my situation last summer, we repaired this issue in the field by opening the hole in the delrin bracket of the button for the metal part of the button to have more breathing room. I didn't have any issues with the button for the rest of the trip.)

Regarding the guy at the Shootout who had a stuck button and thought it was related to the airlock, I told him to talk with the housing rep (who was on-site) at the Shootout to get the button swapped/repaired.

In my opinion the issue was not with the airlock but with the button on the housing itself.

John - That posting is a classic! I would love to use it as my Signature!

Please help yourself!

I buy my own photographic kit. Diving equipment manufacturers and diving services suppliers get even-handed treatment from me whether they choose to advertise in the publications I write for or not. All the equipment I get on loan is returned as soon as it is finished with.Did you know you can now get Diver Mag as an iPad/Android app?

Im about to buy a leak check. Either the backscatter or sentinel. The sentinel looks more streamline is almost half the cost! Any reason to shell out double the money for the backscatter?

Just returned from another successful week of diving in Key Largo, using the Leak Sentinel on my Aquatica AD90. It adds a tremendous level of confidence and eliminates much of my anxiety when the camera hits the salt water.

I always assemble my rig in my hotel or condo before leaving for the boat, and don't have to open the enclosure to replace data cards or batteries between dives. I pump the enclosure down about 1/2 hour before leaving, and make sure the blinking green light is on before I leave for the boat.

Diving the Spiegel Grove, I did find that the light went from blinking green to alternating blinking red-green, the caution condition. I noticed this at about 90 feet. I didn't see any water in the port or the back window, and thought it very likely that the enclosure was being squeezed to a slightly smaller volume at 90 feet than at the surface, thus raising the internal pressure very slightly. This turned out to be the case, and upon ascending the line at the end of the dive, the light went to straight blinking green at about 60 feet. There was not a hint of water in the enclosure when I opened it up at the condo that afternoon. I have taken to pumping the enclosure a bit further down than before: 8-10 strokes on the pump instead of 4-6, and that seems to have taken care of the false alarms.

Ergonomically, the Leak Sentinel LED is positioned right at the top of the housing for me, in the second strobe bulkhead port, placing it at eye level every time I swing the enclosure up to shoot. I can't help but see the light and check that it is blinking green (it looks yellow underwater) throughout the dive. Battery life appears to be very long, certainly more than the 24 hours I spent underwater and leak checking my enclosure in the condo (I pump the enclosure down and leave it blinking overnight if I make any changes such as removing the port or replacing a bulkhead).

I think any vacuum leak detection system makes a huge difference in reducing anxiety about your equipment. The Leak Sentinel does the job for me with no fuss, no muss, no sticky mess. I think the other systems would do a fine job as well.

Gates housing vacuum check system uses the same valve. Gates uses a battery powered pump. This system has been around for a long time for high end video housings. I have my own version for DSLR for over 8 years on request from customers. Not one had serious problems. No electronic is a plus. The pump with the gauge is all you need. It is only partial vacuum like -0.5 bars which simulates about 5m depth. User could either leave vacuum in or purge it. Very unusual to have a sudden o-ring seal failure when the housing is under equal hydrostatic pressure from the water column. Unless user decide to whack the port on a rock. I had over 8 years and more than 60 people with these vacuum valves for both DLSR or video housings. I know they work. Keep it simple. Electronic only adds more stress. The seal is checked on land and if seal is not working then the gauge will drop. Sort out the o-rings and then check again. O-ring either fail or working. They don't just decide to fail halfway. Anyway Backscatter version looks simple enough. Its the way to go for peace of mind.

Cheers

David

I put a hair across my main o-ring, and pumped down my system to 10" Hg. It took almost 10 minutes for the vacuum to fall below 5" Hg. So unless you make sure you pump down your system and check the pressure with the gauge at least 10 minutes later, AND before subsequent dives to make sure nothing got bumped out of place in the camera table, I still see a benefit for the electronic system.

I put a hair across my main o-ring, and pumped down my system to 10" Hg. It took almost 10 minutes for the vacuum to fall below 5" Hg. So unless you make sure you pump down your system and check the pressure with the gauge at least 10 minutes later, AND before subsequent dives to make sure nothing got bumped out of place in the camera table, I still see a benefit for the electronic system.

Doug,

Good point, indeed.

I have the non electronic version... seems like a solid piece of gear. Very reassuring, but: With that model, a STABLE vacuum reading is critical.

If the vacuum is changing, the housing is leaking.

If you start out at -10in/Hg and it "drops" to -5in/Hg the absolute value doesn't matter. It doesn't start to leak when it gets to 0in/Hg.

The ∆ indicates a leak, and if its leaking air, it is leaking water.

The point is, with a non monitored system, stability of the initial reading is key. Don't fool yourself into thinking a small change doesn't matter. It does.

Why do divers hate ideas that are obviously good? You will ALL be using vacuum leak tests (complete with flashing green lights) within a decade, apart from the dinosaurs among you!

A leak check system is a good thing, but people are paying a lot for flashing lights to indicate either enough, or not enough vacuum. Such basic two point monitoring could fail to detect a slow leak, so we should hope to improve on that over the next decade.

An altimeter within the housing gives constant assurance that the housing is tight. Some Swiss Army knives come equipped with tiny altimeters, so maybe housing manufacturers will design better and cheaper vacuum monitoring.

I plan on pumping my system down to -7''Hg, then if it goes from green to yellow in the time it takes me to get ready to dive, I will be alerted to a leak. I will keep in mind that a significant increase in internal housing temperature may give me a "false positive" leak test.

I used to be more tempted by electronic vacuum checks, I mean the ones with a LED like Hugycheck, Leak Sentinel, Airlock electronic.

However I got troubling situations with my Leak Sentinel several times: the LED was green on land, and after a dive was no more (and it didn't return to green later). In another occasion I left the housing ready at home for a few hours, it was still green, and when arriving on the dive site, no more green. This did not sound logical to me so both times I did dive (closely watching the moisture alarm), and the housing didn't flood.

From above discussions it seems those "fake warnings" could be due to temperature changes. Maybe, but I am missing the purpose of feeling calmer when taking my gear underwater...

If I understood well the above talks, if I get a stable pressure after 30 minutes of vacuum, then it won't move no more, a leak would have been detected. Then I don't need any LED, right?

Actually there's one situation where I'm in doubt: what if your vaccuumed housing gets a shock, e.g. in the dive boat, let's say on your macro port. Any risk the vacuum between port and housing gets jeopardized? Then I'd see a clear interest for continuous feedback LED.

Sounds like you've got reliability issues with the electronics. The only time I got a false red on the Hugycheck (two different housings owned and a great many dive trips) was when I took it from a cold environment where I closed up the housing into a very warm pool. I wouldn't countenance a housing without it now. (Nauticam's will be available any day now)

I've had two red lights, both with the D800.

1/ I arrived in Cyprus and put my housing/camera together for an early morning start, in my hotel room. I went for dinner with green flashing. When I came back I had a red. Reassembled the camera and woke up in the night to see a comforting green light.

2/ Went to Malpelo. I assembled the housing/camera during a rough crossing. Went for dinner. Came back to find a red light.

That's twice I might have lost a D800 and lens. It's very comforting to see the green light reflected on a cabin ceiling and helps you get a good night's rest!

Edited by John Bantin, 20 September 2013 - 04:58 AM.

I buy my own photographic kit. Diving equipment manufacturers and diving services suppliers get even-handed treatment from me whether they choose to advertise in the publications I write for or not. All the equipment I get on loan is returned as soon as it is finished with.Did you know you can now get Diver Mag as an iPad/Android app?

Going from a 71 degree airconditioned room to 85 degree water caused my vacuum reading to go from -10"Hg to -7"Hg. If it had caused a slightly greater decrease in vacuum, my indicator light would have flashed yellow.

I have just come back from the Red Sea with my bulkhead Housing Sentry equipped housing. I strongly support the reassurance that the flashing green light provides although of course this is no substitute for careful assembly procedures. After one rather rushed equipment change in my hot and dark resort room, the housing was de-pressurised but it seemed to take longer than usual to reach the green light pressure. As I put the housing into it's carry bag a few minutes later, the flashing changed to red. Reassembly of all the o rings traced the probable leak to salt crystals on the main housing o ring/seating, with no subsequent problems on re-cleaning and reassembly. I believe that in all probability, Housing Sentry saved an expensive flood and a disappointing photography trip. No matter what we all believe about our own careful and methodological procedures, we are all susceptible to human error, especially when under pressure or in suboptimal conditions.

A quick plug for Housing Sentry - I discovered that the electronic module was not functioning properly during preparations shortly before this trip. An exchange of emails between myself, Bill and Mary at Underwater Camera Stuff led to the electronics speeding back across the Atlantic, being repaired (threshold components replaced), exhaustively tested and express couriered back to the UK FOC, all in 8 days door to door. Remarkable service and back-up for their kit.

I buy my own photographic kit. Diving equipment manufacturers and diving services suppliers get even-handed treatment from me whether they choose to advertise in the publications I write for or not. All the equipment I get on loan is returned as soon as it is finished with.Did you know you can now get Diver Mag as an iPad/Android app?

I don't want to be a shill for Backscatter, but I bought one of their systems and am very happy with it. It was a bit pricey but the peace of mind is worth it. Besides no one is suggesting that a vacuum system is a substitute for regular maintenance and careful inspection during assembly. Being able to measure the housing integrity sure beats looking for bubbles in the rinse tank.

It also solves one of the things that has bugged me about my housing for years. That is that the main housing o-ring is intentionally under compressed by design. If you go to any o-ring catalog or consult the Machinist's handbook, there are very clear design guidelines that date back nearly a century. Face seal o-rings are supposed to be clamped tightly enough that the two metal surfaces come into contact, with the o-ring trapped in the groove. Every housing I have seen violates this design rule. I believe that it is because the clamping force required for such a large o-ring would require bolts, and housing vendors perceive that this would be too annoying. Instead, for convenience, they use suitcase style cam-latches, which cannot provide enough force to complete the face seal. That is one of the reasons there are so many floods in the rinse tank. An under-compressed o-ring seal can flood when bumped. Most housing vendors explain away this design decision by saying that the water pressure causes the housing to "seal better" when you take it diving. This is certainly true, but it is really an acknowledgment that the seal is marginal at the surface! Perhaps someone can correct me, but I think that only Hugyfot uses bolts instead of suitcase clamps.

Another benefit from a real face seal, is that if you shore dive with your housing (which I rarely do), the gap between the two surfaces can allow sand to enter. It doesn't necessarily compromise the seal, because it is outside the o-ring, but as you descend, it gets ground into the surface as they are pressed together under pressure.

The vacuum check system solves this problem. The partial vacuum provides the additional pressure to complete the face seal. It also locks the ports. I love it!

I buy my own photographic kit. Diving equipment manufacturers and diving services suppliers get even-handed treatment from me whether they choose to advertise in the publications I write for or not. All the equipment I get on loan is returned as soon as it is finished with.Did you know you can now get Diver Mag as an iPad/Android app?

I have been following this thread and have decided that purchasing a vacuum system is a good thing. I have researched what is available and when it gets down to the details I decided to go with the Housing Sentry Basic from Underwater Camera Stuff http://uwcamerastuff...entry_basic.pdf. There product does not use any plastic parts that could possibly break in the vacuum connector and there price was the best total price for the non-electronics setup.

I was surprised to find out that the "Airlock" Vacuum from Backscatter does not include the bulkhead adapter to fit your housing and that they charge a extra $75 for this bulkhead adapter. "Total cost was $424 plus $75 for the bulkhead....so $499 total http://wetpixel.com/...342#entry337095" They also do not offer a bulkhead adapter for Ikelite and various other systems such ad Olympus and compact camera systems.

As I understand it, if an O ring seal is to be tightened until metal to metal contact is ensured, a soft O ring of 50 or 60 shore is required. Unfortunately, this softness of O ring would deform and need replacing after almost every use. The reason this features in machinists handbooks and the like is that most engineering applications for O rings are for permanent installations, rather than situations in which the seals are regularly disturbed.

Even with a bolt type closure, the only way to guarantee metal to metal contact would be to specify a torque to do so.

Firmer, harder O rings, located in a suitably deep groove, have sufficient material hardness to form a seal that will not extrude despite the metal not meeting. There are quite literally millions of examples of this in action-not least of which would be the O ring sealing your regulator onto your tank!

Just to emphasise again, I would imagine that few underwater photographers rely on "gingerly dipping" their housings in a rinse tank. Cleaning, inspection and careful preventative maintenance are the key. Vacuum detectors simply prove that you have followed these procedures correctly.