Any feedback on Seafrogs for A7IV + 90mm Macro?

[Pyndle]

The AOI housing also has considerably better ergonomics, with knobs and a thumb AF trigger positioned to be used while holding the tray handles.

What do you think of that one?

Sea Frogs Aluminum Alloy UW Underwater Camera Housing For Sony A7M4-Seafrogs

Sea Frogs Aluminum Alloy UW Underwater Camera Housing For Sony A7M4 Aluminum Alloy Depth ：100M/328FT

www.seafrogs.com

 

[Barmaglot]

Seafrogs system. I don' think it's meant to go underwater though, prehaps that's why it leaked?
What degraded exactly? The o-ring?

Correct. It has several o-rings sealing its battery/electronics compartment, and another o-ring sealing its cap, and at least one of those doesn't stand up well to saltwater immersion. The on/off button also doubles as the pressure release valve, so there is no way to keep it under vacuum overnight without draining the battery. Leak Sentinel is a much better solution.

What do you think of that one?

Sea Frogs Aluminum Alloy UW Underwater Camera Housing For Sony A7M4-Seafrogs

Sea Frogs Aluminum Alloy UW Underwater Camera Housing For Sony A7M4 Aluminum Alloy Depth ：100M/328FT

www.seafrogs.com

It's better than the SeaFrogs plastic housings, but commensurately more expensive. Factoring in accessories, at this price point you might as well get a 2nd hand housing from a proper manufacturer.

 

[Pyndle]

Correct. It has several o-rings sealing its battery/electronics compartment, and another o-ring sealing its cap, and at least one of those doesn't stand up well to saltwater immersion. The on/off button also doubles as the pressure release valve, so there is no way to keep it under vacuum overnight without draining the battery. Leak Sentinel is a much better solution.

I see. But why would you want to keep it under vacuum overnight?
I also don't understand why keeping under vacuum underwater is a thing? I know that vacuum will make the various parts hold very tight together, but pressure underwater will do the same thing. However with vacuum, the housing will "want" to suck in air or water from outside, which means if anything happens (you hit your camera and it breaks the seal a tiny bit), a lot of water is gonna go in very quickly no?

 

[Barmaglot]

I see. But why would you want to keep it under vacuum overnight?

Set up your rig in the evening to have it ready to dive in the morning, and make sure there aren't any small leaks.

I also don't understand why keeping under vacuum underwater is a thing? I know that vacuum will make the various parts hold very tight together, but pressure underwater will do the same thing.

The issue is not at depth, but rather on the surface. Prior to widespread availability of vacuum systems, many floods happened when the housing got bumped while getting passed from/to a boat, especially in rough seas, or in a rinse tank full of cameras bumping into one another. Creating a partial vacuum inside the housing makes the atmospheric pressure work for you, squeezing the parts very tightly and ensuring that no reasonable amount of force can separate them. If you pump out 40% of air from the housing, you get 400 grams of pressure on every square centimeter of surface - that's easily several hundred kilograms, far more force than the clamps can exert.

 

[Pyndle]

Oh I see, thanks.

Yeah rinse tank are a nightmare. I always tell the crew to NOT put my camera in the rinse tank, ever. I do it, my own way, and never let my camera sit in that tank without me watching.

 

[Pyndle]

As for triggers, it's a low-volume electronic item that requires reverse-engineering camera flash communication protocols and integrating with various underwater flashes; there is no way to do that on the cheap.

By the way, a bit off topic but I was thinking about what you said here. How is that complex?

There are cobra strobes that costs literally 30/40 usd. Dozens of brands make those. I get the low volume thing, but if a cobra strobe is also a bit specialized, it's not like they have iphone kind of volumes. And for a trigger you don't need an actual strobe, any basic LED can do the job, which I assume is cheaper than an actual strobe light.

And why do you need to integrate with various flashes? Flashes can read whatever light signal comes in from the camera with an integrated flash, why would it be different with a trigger?

Am I missing something?

 

[Barmaglot]

And why do you need to integrate with various flashes? Flashes can read whatever light signal comes in from the camera with an integrated flash, why would it be different with a trigger?

Am I missing something?

Different strobes have different output profiles, i.e. how long they take to reach peak brightness, how long they can stay there, and how steep the fall-off curve is. When used in TTL mode, they also react differently to triggering signals. This requires the TTL converter to behave differently according to the attached strobe(s) - UWTechnics boards have a rotary switch to select the appropriate profile; I believe the various TURTLE are programmed via an app. Also, different camera manufacturers have different hot shoe connectors and TTL protocols for communicating with attached devices; this also requires reverse engineering (as these protocols are proprietary) and different connectors for specific cameras.