Not a huge fan of my GoPro

[tursiops]

Pretty much everything about a 4/3 system is smaller/lighter than a full-frame. I went 4/3 (original OMD-M10) because I wanted to carry my gear in a single, rolling, carry-on-sized bag. With the exception of my WWL-1 and spare batteries (and charger) for my two SEA & SEA DS-1 strobes, I can do that. In retrospect, it was a good decision, partly because I don't need to stop down quite as much to get the needed DOF. I have two camera bodies so one is a spare, and also used for my land pictures; using the same lenses is very nice. My system is now 7 years old and still is more capable than I am, although I am improving. My macros are fine, my reef scapes are fine, my close-focus/wide-angles are a work in progress.

I've been a land photographer (semi-pro for a while) since about the time of Tri-X in 35mm, and started underwater with a Nikonos I and flashbulbs. Post-Nikonos (various models), and went through some Sea & Sea models, then moved to digital with a Canon G2 in an Ikelite housing, then a G9 for a long while. When I sold my CCR, I treated myself to the 4/3 system.

I have found very little of my land experience to be useful underwater, except for basic technical understand. UW is a different world in terms of exposure, DOF issues, color balance, and composition.

 

[Barmaglot]

From a practical standpoint, what would that mean connecting a synchro cable to a Z-330 and having a 2nd Z-330 without a cable as a slave?

No, you'd be using a dual sync cable such as this: Sea Frogs Dual 5-Pin Sync Cord to Nikonos type bulkhead for underwater housings, 100M/330FT

I don't think there is any Seafrogs housing for a weatherproof camera with a popup flash except the Sony a6 line.

The camera series currently produced by Sony are:

1. RX0 - action camera format
2. RX1 - fixed-lens full-frame compact, not updated in over five years now
3. RX10 - ultrazoom bridge cameras with 1" sensor
   
4. RX100 - premium compact cameras with 1" sensor, can be housed for underwater use, have a pop-up flash except the very first model and offshoot ZV1 which a vlogger focused version of RX100V; both of those have a hot shoe
   
5. A6xxx series - all models except the old A5000 and A5100 have a hot shoe, all models except the top-end A6600 have a pop-up flash
6. Alpha full-frame - A1, A7 series, A9 - none have a built-in flash, all have a hot shoe.

For using a hot shoe with underwater strobes, your choices are:

1. Single or dual electric sync cord with the appropriate bulkhead on your housing and compatible strobes. Most midrange and high-end strobes have both optical and electrical connections, most entry-level strobes are optical-only. Notable exceptions are Retra Flash Prime/Pro which are optical-only, and Ikelite DS125/DS160/DS161 which are electrical only. In almost all cases this will only allow manual operation of the strobes, not TTL - one notable exception is the extremely expensive Seacam Seaflash strobes, which can operate in TTL mode with Canon and Nikon cameras.
   
2. Simple LED flash trigger with the appropriate bulkhead, fiber optic cables, and compatible strobes. This is easier to use than sync cords (no extra o-rings that have a chance of leaking), but is still manual-only.
3. TTL-capable trigger such as TRT-Electronics Turtle series and the wide range of triggering boards produced by UW-Technics. Turtle triggers are optical-only, using LEDs, but are largely housing-agnostic, being housed in a small box that mounts directly on the hot shoe. UWT triggers are shaped to mount in specific housing models, but can be used with both optical and electrical sync, given the appropriate bulkheads. They also sell a replacement bulkhead for SeaFrogs A7/A9 series housings which converts them from sync cord to fiber optic operation. These triggers are the only way to access advanced features such as high-speed sync.

Note that while the SeaFrogs housing for A6600 has an optical bulkhead, the A6600 camera lacks a pop-up flash. SeaFrogs has recently (a few days ago) released a simple and cheap ($20) optical trigger for that camera, but I don't know how well it actually operates.

 

[bvbellomo]

I hate ruling out the entire a7x line, but Seafrogs does not have dual cables in stock. Why can't I just use a single cable and optical slave?

How much of an improvement is the a6600 over the a6400 or a6500? I can also get those much cheaper. I like the idea of a big battery so I don't have to open the camera to charge it, but I have no idea how big a deal this is in practice.

 

[Barmaglot]

I hate ruling out the entire a7x line, but Seafrogs does not have dual cables in stock. Why can't I just use a single cable and optical slave?

You can, if you go with YS-D1/D2/D3 strobes. Those have an extra socket for daisy chaining another strobe via fiber optics. My Retras don't feature that, and I don't believe Inons have this capability either. SeaFrogs is not an exclusive vendor of sync cords, I just linked that one because it was convenient.

How much of an improvement is the a6600 over the a6400 or a6500? I can also get those much cheaper. I like the idea of a big battery so I don't have to open the camera to charge it, but I have no idea how big a deal this is in practice.

I'd say it's a matter of personal preference as well as individual circumstances. On my A6300, when it was new, I could do 3 dives with wide-angle (16-50 or 10-18) or two dives with macro (90) on a single battery charge. A few years down the line, with my two batteries somewhat worn out, I can do two wide-angle dives and just about manage two macro dives if I make an effort to conserve battery life. On my recent liveaboard, I was changing batteries between dives just to be safe. A6400 should be similar. The extra battery life of A6600 can be useful if you, say, do a lot of 3-tank day trips on relatively small boats where opening the housing to change batteries can be difficult and/or dangerous. The deeper buffer and in-body stabilization of A6600 are of limited use underwater, but can be beneficial on land.

 

[bvbellomo]

I assumed Seafrogs housing had proprietary connectors. If I can get another cable that works, I don't see a reason to chose an A6600 over something like a A7R II other than battery. Without the camera in hand, I have no idea how long it takes to change batteries.

 

[Barmaglot]

I assumed Seafrogs housing had proprietary connectors. If I can get another cable that works, I don't see a reason to chose an A6600 over something like a A7R II other than battery. Without the camera in hand, I have no idea how long it takes to change batteries.

No, it's a standard Nikonos connector at the housing end, and whatever it is that the strobes use on the strobe end (there are a few different options).

A6600 advantages over an older full-frame like A7R II include, but are not limited to:

• Two generations' worth of autofocus tech improvements - A7R II really is quite old at this point, and the jump between that model and A7(R) III was quite significant.
• Larger battery - A7R II uses the same NP-FW50 battery as the APS-C cameras, whereas A6600 uses the NP-FZ100 battery used by Gen III and newer full-frames. There were lots of complaints about battery life on those first two generations of A7 bodies before Sony introduced the larger battery in the third generation.
  
• If you want to use a dome and a SeaFrogs housing, SeaFrogs domes top out at 8 inches, which is quite limiting for a full-frame camera but is okay for APS-C.
• When shooting macro, you don't need as much magnification on the same subject, giving you more depth of field.
  
• Not so important for underwater work, but A6600 has much better burst capabilities (faster and deeper buffers) than A7R II.

 

[bvbellomo]

I'd still rather have a A7RIII than an A6600, but used a6500's go for under $1000 and the seafrogs housing is much cheaper. I am not sure I agree the dome is less limiting for APS-C, I won't use the dome on land and am not taking a telephoto under water. The standard housing does a E 18-55mm and the 6 inch dome (I don't see an 8 for any Sony) goes to 70mm. If I understand correctly, 70mm is 22 degrees on APS-C and 35 degrees on full frame.

 

[arew+4]

Dude, the breadth and be depth of this thread have established you are or will be a photographer who dives. Accept this and mortgage your future to purchase bleeding edge gear, knowing full well you will have to get second and third mortgages to keep up with photographer Jones. Please still help prior to resorting to prostitution. Turn back now, salvation is still attainable. But it really is a slippery slope, and the purchase prices are quite justifiable in small increments. And that awesome shot of XXX you took at YYY is really poop coarse if you had strobe z it would have been so much better.

Also, photographers who dive, dive alone always.

 

[Blackcrusader]

Also, photographers who dive, dive alone always.

Or we dive with other photographers who know how to give each other enough space
Better when you can also get your dive buddy in the shot at times. I've always found the best photo or video is the one you can get with the gear you have with you.

 

[Barmaglot]

I am not sure I agree the dome is less limiting for APS-C, I won't use the dome on land and am not taking a telephoto under water.

Domes are not for telephoto; they are for wide angles. Shooting a wide-angle lens underwater through a flat pane of glass introduces very significant distortion; compare and contrast:

Same camera (A6300), same lens (Sony 10-18mm) same settings (10mm, f/11), shot from as close to the same spot as I could make it, but the first shot is through the basic flat port bundled with SeaFrogs housings, while the second shot is through this.

Now, with regard to dome size, the boundary of water/glass/air acts as an additional lens element in front of the camera, presenting a virtual image to the camera's actual objective lens. This image is curved, and the distance to this image as well as the degree of curvature scale directly with the dome's radius. However, non-fisheye lenses are built to present a flat focal plane to the camera's sensor, i.e. if you're shooting a flat wall, the corners of your image are further away from the camera than the center is, and the lens uses aspherical elements to correct for this. The wider your perspective is, the more correction has to be applied to get that flat wall into focus across the frame. This is, of course, great when shooting architecture and stuff, but very ill-suited to underwater photography where the image that we shoot is curved in towards the corners - these corners fall outside the available depth of field and become smeared.

In order to counteract that, we do one or more of the following things:

1. Use larger domes. If the dome radius is increased, then the virtual image has less curvature and is presented further away from the camera, where the available depth of field is greater.
2. Close down the aperture, creating a greater depth of field (but losing light).
3. Use special add-on lenses called field flatteners, which reduce (but not eliminate completely) the virtual image curvature. The only one that I know of that is made for underwater photography is the Sea & Sea Internal Correction Lens, and it only works with certain lenses for full-frame cameras.
   
4. Use a smaller sensor camera. For the same image, a smaller sensor camera will be proportionally further away from the subject - i.e. if you're using a 36mm-wide sensor, and your subject is 1 meter away, then you have 28 sensor-widths between sensor and subject, but if you're using a 24mm-wide sensor, it's 42 sensor-widths - and this produces a proportionally greater depth of field, as DoF scales with the ratio of sensor size to subject distance.

The common solution to shooting full-frame cameras wide-angle underwater is to use a 230mm dome and an internal correction lens, with apertures of f/9-f/11 or smaller. Without an internal correction lens, most people don't shoot wider than f/16, unless the image corners are just water (e.g. large pelagics rather than reefs). APS-C and M4/3 cameras, with their greater depth of field, generally suffice with 170-180mm domes.

Now, circling back to SeaFrogs, they only produce 6-inch and 8-inch domes (plus a 4-inch for small fisheyes). These are adequate sizes for APS-C, but quite small for full-frame. This is compounded by the fact that they don't produce extension rings - a dome port's performance is contingent on the lenses entrance pupil being as close as possible to the center of the dome's curvature. Basically, the distortion that I illustrated above happens because when light rays pass through the water/glass/air boundary at an angle, they refract, and the greater the initial angle is, the stronger the resulting refraction gets. Domes correct for this by (ideally) having all the light that goes towards the lens pass through the water/glass/air boundary at a perfect 90 degree angle, eliminating refraction. However, for this to work perfectly, the optical center of the dome and optical center of the lens must be in the same spot, or as close to one another as possible. With different lenses having their entrance pupils in different locations, this means that the length of the dome extension (the cylindrical barrel that connects it to the housing) must vary between lenses, and most manufacturers produce extension rings in a variety of lengths to customize that, making the extension longer or shorter to suit the lens. SeaFrogs does not have those - their dome ports have a fixed extension, sized to more or less fit the lenses they consider to be most likely used with this particular camera model, which limits your options. Additional complications are introduced by the fact that they have a number of different port diameters that they use - the Salted Line housings for A6xxx cameras and RX100 cameras use an 80mm diameter port, but the A7/A9 series housings and the A6600 housing use a 90mm diameter port.

For what it's worth, I own both 6-inch and 8-inch dome ports, have compared them in a pool, and the corner sharpness with 10-18mm lens and 8-inch dome is somewhat better, albeit still imperfect. I only travel with the 8-inch dome these days; the 6-inch one has been gathering dust on a shelf for a while now. However, this creates a certain gap in their lineup with regards to the A6600 housing - it has a 6-inch dome with an extension sized to fit the 10-18mm lens (I presume), but the 8-inch dome that they produce in this port diameter is sized to fit the full-frame 16-35mm lenses, which are considerably longer. Now, I don't really know whether or not the 6-inch port they bundle with the A6600 housing is actually sized to fit the 10-18mm - they may have just dropped the same 6-inch port that they sell with the A7 housings into the box and called it a day, and I don't know how well or whether at all will the 8-inch/90mm port fit the 10-18mm lens, but this is a potential problem to watch for.

If you're chasing image quality, want a full-frame setup, and can't afford Nauticam et al, then SeaFrogs, at present, is not a very desirable route. It could potentially work very well with Sony 28-60mm and WWL-1, but alas, they do not, at present, offer a port option with which it would be feasible. If they bring out a short flat port with a threaded front to fit the 28-60mm plus a zoom gear for it, then it will become a much more interesting option. I wonder if they have an A7C housing in the pipeline.