Following the failed test on the Nauticam Electrical Sync Cord bulkhead I was out in the market to check what else could be done with the M16 port on the RX100 Mark II housing.
I bumped into the leak sentinel while at the London Dive Show. As you may know Nauticam provides now a vacuum system with temperature compensation on all new micro 4:3 and DSLR housings. Also older models can be retrofitted but not the RX100 because essentially the moisture sensor is much simpler.
So if the Nauticam housing has already a moisture sensor why bother adding a vacuum test. The advantages are numerous:
- A moisture sensor still requires the housing to be put into water to be tested
- A moisture sensor starts beeping when water has already made its way into the housing, if you are in a situation where you have a mandatory safety stop or a deco stop you don’t want really to have the additional stress of a camera flood.
- With a leak sensor you can check the integrity of the housing before the dive and without putting it in water
- You can rapidly change battery and the likes and not worry if you have compromised the seal of your housing
With all of this in mind I went off and contacted Vivid housings
After an email exchange about the design of the product I was convinced that it was worth getting it so I ordered one and after just 3 days it turned up in my post directly from Slovenia.
The system comes with an M16 adapter to screw on the housing bulkhead. The best way to remove the cap on the Mark II housing is using a CR2032 battery like the one of the moisture sensor.
I set up the system on the housing as in the featured image and started my preparation. It takes 3 pump strokes to get a green light and the instructions say to add between half and a full stroke to make sure it is not on the edge. I had 4 full strokes.
I prepared the housing and camera in a room at 21C and waited 20 minutes before putting it in water at 15C.
I then put the camera in video recording mode for one hour, the Rx100 has a limit at 30′ so I had to record two files. After one hour the system was still showing a green light I took it out of the water and follow the depressurization procedure and extracted the camera. Measuring the temperature inside the battery compartment the sensor indicated 28C.
Now this made me think to the fact that this solution, although equipped with a temperature sensor, does not actually manage temperature compensation. If you know anything about physics you know that the following is true for an gas also known as Gay Lussac law
the pressure of a gas of fixed mass and fixed volume is directly proportional to the gas’s absolute temperature
As our housing is rigid and not compressible this means that the ratio between temperature and pressure is constant.
This also means that if the temperature increases because the camera warms up with use the vacuum will drop (pressure increases), this could create a false positive.
I therefore performed the following steps
- I immersed in water at 32C and started shooting a video clip.
- After around 50 minutes the led started to alternate red and green. The camera has the temperature warning indicating a possible temperature close to 40 degrees
- I kept the camera in water pretty sure there was no leak and then at 60 minutes took it out of the water
- After few minutes outside water in a room at 21C the light went back to green
- The camera temperature in the battery compartment was 36C
The ambient pressure was 1016 mpa so I estimate I created around 750mpa inside the housing with 4 full strokes, however as the camera sustained an increase of 19 degrees from 21 to 40 the pressure sustained an increase of 6.5% bringing it in the warning area of the leak sentinel and generated a false positive.
Now there are a few considerations to be done:
1. If you shoot pictures even firing the flash is unlikely to get the camera as hot as when you shoot video
2. The water in the dive will seldom be 30C anyway
3. It is preferable to prepare the camera in a temperature as close as possible to the diving temperature and in the driest environment available
4. It is possible to estimate the amount of vacuum each pump strokes gives and compensate for the temperature changes
The worst possible scenario is a video camera housing prepared in an air conditioned environment this is the only scenario where temperature compensation is useful.
Generally the suggestion of the user manual to give one or half pump strokes should be changed. Say that I have a large housing and it takes 10 strokes to create the vacuum, I would suggest another 3 strokes is diving in warm water otherwise the possibility of false positives is increased.
For what concerns the RX100 and only for very warm water shooting a lot of video there is a theoretical possibility that the camera overheats, and if the housing had been assembled in a much colder room, this gives a false positive.
To minimize this possibility prepare your housing at the normal ambient temperature of your dive site is generally the best practice for tropical diving. I also do not recommend practices like preparing your housing in a cold air conditioned cabin, some people think they avoid condensation not thinking that a 20+ degrees thermal shock does do any good to the camera.
Ultimately at €200 including worldwide shipping I can definitely recommend the leak sentinel to all RX100 users. Considering the cost of your investment even at the price of the RX100 Mark II of $750/£649/€699 this is a good tool and more than anything give you the extra reassurance of having a watertight housing, and also helps you in all your situations where you have a battery change or you have to open the housing before the end of your day.