TNEngineer
Contributor
Huh? The zoom factor is within the iPhone. How can a simple external case impose a limit on that?
Sealife 3.0?
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jonhall
Contributor
That was my first thought but......
I'm guessing to use the housing, you have to download the SportDiver app, which in turn changes the look of the camera screen so that the buttons on the housing will match up with that new screen look. So the zoom feature is embedded in the app and you don't use the phones actual zoom (or you use a limited version of it.). Any of this sound right?
While you are using the iphone while in the external case, it uses the "Sealife App". So the phone camera is being accessed through the Sealife app, using bluetooth, and thusly Sealife app software. Its a little bit more than just an external case. Once you are in the Sealife App and the phone is in the case, you cannot switch apps. So no way to use zoom settings except what Sealife has in its software.
TNEngineer
Contributor
How do you change settings while underwater? Does the housing have hardware and firmware integrated into it?
Four external buttons access the app through the Bluetooth. Mode, +,-, OK buttons.
TNEngineer
Contributor
I took the time to investigate the SportDiver case. It's a clever approach, I'll give them that. Having integrated electronics allows them to incorporate leak detectors, etc. One thing I'd have considered is to also add a pressure sensor... if the case developed a leak you'd know about it even if the water hadn't reached the physical location of the moisture sensor. Early warning and all that.
However, as noted by others this also tempts them to interfere with your control flexibility. "We know what's best for you" has a nasty way of creeping into people, in both politics and technology. Occasionally there's a valid technical reason for it (such as "enable this setting when the phone is inside our case and the battery explodes") but something like a zoom setting doesn't rise to that level.
I wonder if they did it to suppress customer service phone calls. Customers calling to complain "My images look all grainy, it must be your case" would get old fast.
However, as noted by others this also tempts them to interfere with your control flexibility. "We know what's best for you" has a nasty way of creeping into people, in both politics and technology. Occasionally there's a valid technical reason for it (such as "enable this setting when the phone is inside our case and the battery explodes") but something like a zoom setting doesn't rise to that level.
I wonder if they did it to suppress customer service phone calls. Customers calling to complain "My images look all grainy, it must be your case" would get old fast.
It is a clever approach. And it does have a pressure sensor, you pull a vacuum on the case through a small port with a small hand held vacuum pump. The unit checks to make sure it holds for three minutes before giving a green indication light. If that vacuum seal is broken the light will flash red. For the price of $300 I thought it was a great value until they changed the zoom settings,
Kraken makes a similar housing of aluminum that is rated to 260 feet. Its price is $325, I have not checked the specs to see what it does with the zoom function yet. However the Kraken does have attachments for an external diopter to boost macro images.
TNEngineer
Contributor
They should have you pressurize the case, not draw a vacuum. The idea is to keep water OUT. The seal and sensor can work with a delta in either direction... why not use the one that actually promotes the desired behavior?
I always wondered about pulling a vacuum instead of pressurizing the case for exactly what you point out, failed seal for a vacuum system will pull water in. However Sealife is not the only manufacturer of housings to use a vacuum system. Ikelite, Subal, and Nauticam to name a few also use a vacuum system instead of a pressure system.
Think about a housing without a vacuum system or pressure system. The housing door when closes compresses the o ring to conform to the groove in the housing. When the housing is brought underwater the housing door is being pushed further (albeit minutely) against the housing because, the housing was sealed at ambient atmospheric pressure. For this reason it is not advisable to leave camera housing in a rinse bucket because the o ring is less compressed, and thusly more vulnerable to leaking than at depth. But also if the housing with out a pressure system leaks at depth, water is going to rush in anyway because relative to the depth pressure the housing is under a vacuum.
Now consider putting a vacuum on the housing. When doing so the door is pulled (you could argue pushed by ambient outside pressure) further against the housing which compresses the o ring similar to having the camera already at depth. When entering the water the door is no longer relying on the differential between the pressure inside the housing and the water pressure to make the o ring conform better to groove.
Consider now pressurizing the housing. Camera goes in the housing the door is closed, and o ring is compressed somewhat into its groove. Now add pressure to the inside of the camera housing. The housing door is being pushed away from the housing. This does not make for a good seal between o ring, housing door and housing, thusly making it more vulnerable to leaks. I think a pressurized system could be used, however then the whole housing has to be redesigned to account for effect pressure has on every button and switch penetrating the housing, along with the ports and housing door. I imagine the redesign would be "beefer" (such a great engineering term), and thusly a more heavier, possibly bigger, and less ergonomic housing.
My guess is that when designing the housings prior to the vacuum systems (which are relatively new) the engineers took into account how the housing being at depth would effect all the o rings that are used on the housing. Effectively a camera housing that starts out at ambient air pressure at the surface is under a vacuum at depth, or it might be better to say relative vacuum at depth. So it was easier to engineer the add on of a vacuum system as opposed to a pressure system.
TNEngineer
Contributor
Good point about pressurization reducing the o-ring seal.
However, I wouldn't say the enclosure is at a relative vacuum at depth. Whatever internal pressure it has at the surface will increase as depth increases. The external pressure will act upon the enclosure, seeking to compress its walls and especially squeezing the door tighter into its seal. The resulting reduction of volume must yield an increase of internal pressure. It may still be negative relative to the surrounding pressure, but the increase will definitely occur.
This leads us to the question of whether it's better to have positive, negative, or ambient pressure at the surface. I'm going to revise my earlier position and say I'd prefer ambient. Positive pressure is bad because it reduces the reliability of the seal. Negative is bad because it "encourages" water intrusion. That leaves us with neutral pressure, which at the surface has no effect (good). At depth the internal pressure will always be lower than the external - theoretically a bad thing - but having the differential in that direction encourages better sealing which works in our favor. And a pressure sensor could still provide early warning of a leak, at least a sudden one, by watching the slope of the curve.
In practice a normal housing always has a slight positive pressure because the seal first makes contact, and then gets compressed a bit by whatever latching system is used. Unless you provide a bleed port - itself a potential point of failure - there's no way to avoid this. So if I were designing it, I'd just do "the usual thing" and provide a seal and a latch, with no vacuum or pressure pump at all.
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