Advice on Port for SeaFrogs case for Sony 6300

Started Jul 5, 2021 | Questions thread
Barmaglot_07 Contributing Member • Posts: 629
Re: Advice on Port for SeaFrogs case for Sony 6300

GilbertH wrote:

Maybe the A6600 is a bit different here compared to the (quite similar) A6000..A6500?
My Lens chart here https://www.saltedlineeurope.com/products/seafrogs-40m-130ft-waterproof-housing-for-sony-a6600
Also shows the DSLR lenses and Ports - and the 16-55 Kit is not even listed.
Could it be that the A6600 has a bigger housing and a wider Port diameter?!?

Yes, their A6600 housing uses 90mm diameter ports, same as the A1/A7 series housings.

To an extent. You still need to stop down to get reasonably sharp corners.

Yes - I expected that (especially using the cheaper lenses)

Lens cost does not impact this the way you'd think. The issue with domes is that they present the lens behind them with a virtual image which is curved, with the curve radius being proportional to the dome's radius. In effect, the corners are closer to your image plane than the center, and if you shoot wide-open, with shallow depth of field, they fall out of the in-focus range. As you stop down and increase your depth of field, they gradually come into focus. Larger domes help as the difference between center and corners gets smaller, but they get more difficult to handle, to pack when traveling, and to get close to subjects when shooting close-focus wide-angle.

Well ... it gets sharper earlier - and most importantly it´s generally sharper.
But when zooming the lens gets quite a bit longer - that might be a reason... but not using the full range would also be OK up to a certain extent.
But i have no experience if the distance between Dome and Lens may lead to other issues too like focussing impossible due to the glass / acrylic dome in between, or distortions..

Again, you can't directly apply land logic to underwater lenses. One of the most popular underwater wide-angle underwater lenses out there is Tokina 10-17mm fisheye - it performs magnificently underwater, but is regarded as terrible lens for land use.

Just found this PDF
https://cdn.shopify.com/s/files/1/2244/3975/files/A6600.pdf?v=1608188336
Seems like A6600 is indeed an exception as the WA005 Dome is clearly shown in the image - anyhow i ordered the port at Amazon and will be able to send it back.
If i test my setup over water to check for vignetting with the Kit lens that should be the same over/under water, right??
(or do i have to expect any further surprises under water?)

You have to test underwater. Doesn't have to be a full dive, but the rig needs to be submerged. The refractive properties of water effectively add another lens element to your setup. More than a few people hadn't read the manual and put together an underwater setup that works on land but fails to focus after splashing down.

Regards,
Gilbert

[Edit]
One more thought regarding the G Lens
The focus Ring (front side) is 3mm wider in diameter compared to the zoom ring.
That might make it complicated to get the lens through the zoom gear into the housing...

That is not a problem at all, you just attach the zoom gear to the lens before attaching it to the camera. You want to see a complicated zoom gear, look at Nauticam gear for Olympus 12-50mm; that one pretty much needs a degree in mechanical engineering to assemble.

The thing about 16-55mm is just that it's not a very good zoom range for underwater use. It's not particularly wide and it can't do macro. The 16-50mm kit lens has internal zooming, so it can be used behind a flat port with wet lenses, but 16-55mm zooms externally, so it isn't suitable for that either. Its bright maximum aperture is largely wasted underwater, the only scenario in which it'd come into play is shooting large pelagics in limited ambient light when you can't use strobes, such as the thresher shark dives at Malapascua, Philippines - it's six in the morning, you're at 30m, the sharks don't come particularly close, and you can't use any form of artificial lighting, but on the other hand your corners are just water, so you don't care about them - but this is a very corner case. Thus you have a $1400 lens that doesn't do anything that an $800 16-70mm f/4 won't do better in the 'generalist fish portrait lens' application, and the $300 kit 16-50mm with $1200 Nauticam WWL-C  or $700 AOI/Fantasea UWL-09F will beat it handily for wide-angle. If you want a quality lens to house behind a dome, look at 10-18mm or the new 10-20mm.

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Sony a6300 Canon EF-S 60mm f/2.8 Macro USM Sony E 30mm F3.5 Macro Sony E 18-200mm F3.5-6.3 OSS LE Sony E 10-18mm F4 OSS +5 more
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