Vignette when using Sony 14mm 1.8 GM

Hey,

So as the forum suggests I’m pretty new to underwater photography, and have just upgraded from a Sony a6300 to an A7r iii with a pair of ys-d2 strobes. I’m using a seafrogs housing with a 6 inch dome (will upgrade to 8inch when I stop travelling) and a Sony 14mm 1.8GM lens for wide angle. The seafrogs lens port chart said the lens was compatible but when I look through the viewfinder there is a slight vignette in each corner.

My questions are:

1. Will this be a significant issue, considering I’m aware I’ll lose corner sharpness anyway with a 6 inch dome so maybe the cropping won’t be the worst thing.

2. Is this fixable somehow and does anyone have similar experience possibly with a Seafrogs housing? I know most people on here use nauticam etc but that’s way outside my budget.

3. Is the 14mm 1.8gm lens worth using for underwater photography? There’s next to no info online regarding this and I haven’t had a chance to take it into the water yet, and when I do it’ll probably be too late to try sell it and get a new lens if not. Are there any recommendations for a wide angle lens for (hopefully) shooting big pelagics?

All help and related advice is appreciated!

Thank you

Sent from my iPhone using Tapatalk

Hi ej3233

Welcome to Wetpixel and enjoy your trip - sounds great!

Just a quick response as others will be better to comment on the combination you have.

But, essentially, slight vignetting in the corners should not be a problem unless there's something in the corners you desperately want in the picture! Just crop them out or Heal them using a suitable editing tool.

I reviewed this lens for UWPMAG.com issue #122, you can see images with the lens in that review and the Inon Z-330 review. Nauticam has the following ports listed as comparable with the 14mm F/1.8, 180mm, 8.5 inch acrylic, 230mm (marked as best) and the 250mm. For a lens this wide bigger ports are going to have better corners assuming proper port placement. This lens has become my go to wide lens for rectilinear in the 230mm port. 

Hi ej3233
Welcome to Wetpixel and enjoy your trip - sounds great!
Just a quick response as others will be better to comment on the combination you have.
But, essentially, slight vignetting in the corners should not be a problem unless there's something in the corners you desperately want in the picture! Just crop them out or Heal them using a suitable editing tool.

I reviewed this lens for UWPMAG.com issue #122, you can see images with the lens in that review and the Inon Z-330 review. Nauticam has the following ports listed as comparable with the 14mm F/1.8, 180mm, 8.5 inch acrylic, 230mm (marked as best) and the 250mm. For a lens this wide bigger ports are going to have better corners assuming proper port placement. This lens has become my go to wide lens for rectilinear in the 230mm port. 

The way to fix vignetting is to use less extension with the lens.  The Seafrogs housings will allow you to take your lens and camera UW and take pictures but the domes are often not optimised.   Properly optimised the dome will be place the centre of the radius of curvature of the dome at the lens entrance pupil and also be placed to avoid vignetting.   A lens will still work if the centre of curvature is not properly placed, however the setup will induce abberations and distortion.  Just how much it impacts the image varies among different lenses.

A 6" dome is as you know too small to give you good corners and an 8" dome is also on the small side for a 14mm lens particularly if you are interested in corner sharpness.  Typically a 14mm uses a 230mm dome and even then some people complain about less than ideal corners even stopped down.

You mention big pelagics as your subject - typically there is water in the corners when shooting them so corner sharpness is less important, but you might find that 14mm does not provide enough reach for shooting these big pelagics.  You might be better off with a 16-35 zoom , either the f4 model or the latest Sony 16-35 which was released recently.  The ability to zoom in for big pelagics will probably be quite useful and as you zoom the corner sharpness problems reduce.  Stopping down to the f11-16 range will also help improve corners.

Appreciate the response. Yeah you’ve addressed some of my thoughts there, mainly the reach. I’ve considered going with the Sony 16-35 f2.8 but it seems the seafrogs lens port chart won’t support it, so I’ve come back to looking at the tamron 17-28 once again, but looking back to the dreaded seafrogs chart it seems like only a 6 inch dome is compatible for whatever reason. Bit of a minefield here [emoji51] can’t wait to finally find a working solution.


Sent from my iPhone using Tapatalk

You don't need the f2.8, you'll never shoot it close to that aperture.  The 17-28 or the 16-35 f4 are both fine and the 16-35 can be used with the v.9 8"dome.  I've seen shots with the 16-35mm f4 in an 8"dome (ikelite ) and they were quite nice.

Just to add my +1 to the discussion and confirm what Chris said. I also shoot with the 14mm 1.8, with a Seacam compact port which is 170mm or 6.7 inches. I did not notice any visible vignetting but I use an extension that is optimized for this port+lens combo. Corner sharpness is generally fine, though at close focus it's certainly less sharp. The min aperture of the lens is f/16, so it's not possible to go to 22 for extra sharpness either.

The lens is great for wrecks and reefscapes, but to shoot wildlife you need to be extremely close to the subject. I have not tested the not-as-wide-angle options such as 16-35 but they could be better suited to your needs.