Lenses for Sony A7III user

Hello Everyone!  Really happy to be here and learn from you all. 

So I am looking to get a wide angle or fisheye lens for my Sony A7iii.  I have been told many things like the Sony 16-35 f4, Canon 8-15, Sigma 15 f2.8 fisheye. 

The Sigma would be the least expensive and I was wondering if any of you Sony users have used it under water?  If so, which adapter did you use?

My next choice would be the Sony 16-35 f4 since it is the most versatile and it seems like everyone says that would be a good choice. 

If you have any input, I would love to hear it. I would greatly appreciate any feedback.  I currently use the Isotta Housing and thinking of getting either a 6inch or 8inch dome for it.  Thank you so much!

Hey Wesley

Just to make sure, the three lenses you suggest are a bit Apples n'Oranges. 

The Sigma 15mm and the Canon (and Nikon) 8-15 are fisheye lenses. The 16-35 is rectilinear.

For full frame sensors, the Sigma has been a go-to lens for many years. Brilliant for reef scenes or divers-on-the-reef.  Because of the fisheye bending effect, images where straightlines are a factor (say, wrecks) fisheyes need careful handling. But as underwater wide-angle lenses, they are brilliant.

The 8-15 offers the fisheye plus the 360 circle of a 180 degree field of view. Dramatic!

The 16-35 is rectilinear, ie flat field not fisheye. Great lens but housing them can be quite an issue. To get sharp edges you should reckon on a 230mm domeport and possibly a S&S correction lens - and all stopped well down. This is a costly package.

Fisheyes, on the other hand, manage very well with much smaller ports - even down to 100mm - so costs are less as is ease of travel.

Forgive me if this is teaching you to suck eggs but I thought it worth pointing out.

Thank you Tim!  Do you use the Sigma 15mm on the Sony?  How is it on the Sony?  I think I would like to go with the Sigma but not many people seem to use it on the Sony.  Which adapter do you use?  

Some recommendations not listed are the new Sony FE 28-60mm zoom which can be used on the A7III with an N-100 port, zoom gear and WWL-1/1B, WACP and CMC-1&2 closeup lenses.

The Rokinon 18mm F/2.8(retail $399.00 sale $350/299)  with with Nauticam 180mm port and no extension. This is assuming you already own an N100-N120 35.5 extension. 

The excellent Tamron 17-28mm F/2.8 with the S&S 77mm correction lens and 67mm to 77mm step-up ring which also works with the Sony 16-35 F/4. With the Tamron a Nauticam 180mm port and 40mm extension, again assuming the 35.5 extension. TheTamron has noticeably better image quality over the Sony 16-35 F/4 and you can buy the Tamron and the S&S correction lens for less than the 16-35 alone. Cost wise everything else is about equal port, zoom gear and extension wise. 40 v 60mm for 16-35.

The Rokinon and Tamron/Sony choices work well for splits while the 28-60 package does not. 

The Sony FE 28-60 with WWL-1 or WACP seem a much more versatile choice than a fisheye. But to each his own.

Turtle image with the Rokinon 18mm at F/11.

Diver with the Tamron 17-28 and S&S at 17mm and F/10, both images with the Nauticam 180mm optical glass dome port. The vertical is full frame and the rather large crop is from the same photo for detail.

I will be reviewing both of these lenses for the next issue of UWPMAG due March 1st.

3 hours ago, WesleyD said:

Thank you Tim!  Do you use the Sigma 15mm on the Sony?  How is it on the Sony?  I think I would like to go with the Sigma but not many people seem to use it on the Sony.  Which adapter do you use?  

Sorry, Wesley - I'm a Nikon user have no experience of the Sigma on Sony. I'm sure someone here will give you a view; and Phil Rudin (above) has given lots of info on other options.

Just wanted to make sue you were clear about the difference between the lenses you were thinking of.

Probably be good to start with your main uses for the lenses - wide angle is a very wide field .  It's been covered briefly in that a fisheye may not great for wrecks.   Some other considerations include do you need good corners - you'll probably want that for reef scenics with important detail in the corners, possibly less important if you are shooting big animals in the blue.

If big animals is your thing, the fisheye may be a little short for something like reef sharks that don't come that close.  If you are interested in CFWA, corner detail and the ability to get really close is important and a fisheye in a small dome will be the choice item.  For split shots a big dome helps. 

You mention a 6 or 8"dome, this will be fine for fisheye, but at the wide end end with a 16mm lens on full frame your corners will be mushy - this is a function of dome port optics, there is some small variation with the characteristics of individual lens designs, but generally this applies to any rectilinear lens with that field of view.

I would also suggest checking the port charts to see what is supported in the way of gears if you are looking at zoom lenses.  There are ways around this if the manufacturer does not have a zoom gear, but not everyone wants to get into 3D printing.  Port chart is here: https://www.isotecnic.it/images/pdf/port_systems/isotta_port_chart_Sony_for_Sony_Alpha.pdf

I would also suggest that performance of a particular lens will be similar optically whatever camera system you use so full frame experience on Canon or Nikon is relevant to Sony in that regard.   The high MP cameras are more demanding of the optical quality of lenses, but actually getting that resolution advantage underwater is not always possible.  What will make a difference is how adapted lenses perform and this can be tested on land.  Autofocus on wide lenses does tend to be less of a problem.