SeaFrogs A6xxx Salted Line ports comparison

[tarponchik]

I'm curious, what's the use of 55-210 underwater?

 

[Barmaglot]

I'm curious, what's the use of 55-210 underwater?

Not much, although I wonder how will it function as a macro lens with a diopter in front of it. However, this housing also targets surf photographers, where 55-210mm is quite useful.

Incidentally, I just found out that there is now a 3rd party port for this housing - a 6" shallow dome for fisheye lenses.

 

[Hector1959]

Thnks for your replies. Always very helpful.

Regards

 

[Hector1959]

If I ever use a fisheye lens like the Rokinon / Samyang 8mm F3.5 UMC (said to be compatible with 6" dome port ) would'nt the petals/shades interfere?
I have never used a fisheye lens underwater. I may assume that virtual image in front of dome where lens focuses would avoid this interference, but I am not sure.
I see Seafrogs / Meikon sells a "swap ring" to replace the shade but they propose it as for Surfing Photography to avoid drag.
Regards

 

[Barmaglot]

8mm fisheye on APS-C is a diagonal fisheye rather than circular - the diagonal FoV is roughly 180 degrees, but horizontal and vertical is considerably less. If you were to mount this lens on a full-frame camera, it would project its entire image circle onto the sensor, and then the hood petals would come into view, but on APS-C, their shadows land outside the sensor.
That said, a manual fisheye lens is a fairly specialized tool - fisheye lenses are specialized in general, but a manual one inside a housing is even more so. You'll have to DIY focus controls, and even then, you'll have to preset the aperture before sealing the housing. A Sony 16mm f/2.8 + VCL-ECF converter inside the 4" port is probably a better option, as it will autofocus and give you aperture control via the camera.

 

[Hector1959]

Good point, Barmaglot. I had never viewed that way: 180 degrees on the diagonal. The parts of the sensor not hit by the light circle are smaller on the sides (left-right) of the sensor's rectangle, where petals of the dome are shorter. And the oppossite up and down.
I was not really thinking to buy a manual fisheye. I used the reference as the Rokinon is the only fisheye in the compatible list for this dome. I was more concerned about the incidence of petals when using a fisheye lens.
4" dome has no petals.
I have a Raynox 0.66x CL. I ordered a step-up ring 40.5 - 52 mm (not big investment) to give it a try with the 16-50 mm inside the 6" dome. I tested it just presented in front of the lens and seems to work and focus fine (top side, without dome). No vignetting from 18 mm on, which would "convert" the lens into a usable 12 - 33 mm (18-50, 35 mm equivalent).

Regards

 

[Pascale Lagarde]

I used the hotel pool on my current trip to compare the results of 7Artisans 7.5mm fisheye, Sony 10-18mm and Sony 16-50mm PZ lenses behind SeaFrogs 4", 6" and 8" domes, as well as the bundled wide flat port, attached to the Salted Line A6xxx housing with an A6300 camera and dual SeaFrogs ST-100 strobes. I shot the 10-18mm at 10mm and 18mm focal lengths, and 16-50mm at 16mm, 30mm and 50mm focal lengths, using a range of apertures from wide-open (depending on the lens and focal length) to f/5.6, to f/8 to f/11; didn't stop down past that. All the shots were taken from more or less the same position in the pool - I was sitting down on a bench, elbows braced, camera held just below the surface and center of the frame aimed at floor/wall joint in front of me.

Full results (straight out of camera JPEGs) are here: https://1drv.ms/f/s!AupWSggdlFYKjtRFu-IIxyopM8fvAA

Thanks for this, it was helpful.
I have the Salted Line A6xxx housing with 6" dome and A6300 camera with 10-18mm. Corners are a little flat, look ok at 13mm F9/10. I found the housing very big and heavy, plenty of space inside for nothing and don't find a way to add a battery pack inside, even the small Nauticam battery pack don't fit. But for the price I will not complaint too much.
I also have the small Meikon housing for the A6300 with the 16-50mm and a 4" wet dome, corners are sharper than the 6" dry dome even at F8. Finally I found the 16-50mm more versatile than the 10-18mm, Meikon has a new 6" wet dome M67, I thinking to buy it with the flat port M67 for the salted line.
For macro I prefer to use a compact camera with 1" sensor.

 

[Ben-Terje]

Great comparison - thank you so much for sharing this!!
Barmaglot, may I ask which focus distance you used on the 7artisans? I've recently purchased the same lens and the SeaFrogs 4" dome for my Sony a6400.

Regards

 

[Barmaglot]

Great comparison - thank you so much for sharing this!!
Barmaglot, may I ask which focus distance you used on the 7artisans? I've recently purchased the same lens and the SeaFrogs 4" dome for my Sony a6400.

Regards

I used double-sided tape to pad out its focus ring to use with the gear for 16-50mm lens, so I was able to focus underwater (with peaking highlights for reference), while aperture was preset to f/8. Note that SeaFrogs now sells a focus gear for Samyang 8mm f/2.8 lens, so that one can be used without jury rigging.

 

[Ben-Terje]

I used double-sided tape to pad out its focus ring to use with the gear for 16-50mm lens, so I was able to focus underwater (with peaking highlights for reference), while aperture was preset to f/8. Note that SeaFrogs now sells a focus gear for Samyang 8mm f/2.8 lens, so that one can be used without jury rigging.

Thanks again, that was a good idea!