Dome port vs Flat port

I currently use a 18-70 mm nikkor with a compact wide port (flat) for wide angle but am planning to get the nikkor 12-24mm.

I can still use my flat port with this lens however I would like to get some advice on dome ports.

What is the the real difference between the two (apart from the obvious physical ones) and would the images be noticably better with a dome port?

Also has anyone heard anything about the new Sea&Sea optical Dome Port?

Thanks

Andy

Hi Andy,

There are several reasons why you want/must use a dome port for wide angle primes or zooms

- Due to the different refractive index of water and air, a flat port behaves like a magnifying glass making everything ~30% larger. Obviously this reduces the field of view and makes your wide angle lens appear less wide.

- When light hits the flat port at a very glancing angle, light bounces off instead of passing through. I don't know what angle that is but this is obviously a situation where a dome is a must (the dome curvature makes the angle of incidence sharper).

- Zoom lenses extend and can be substantially shorter when zoomed to maximum WA than when zoomed to max tele. If you get a port that still accommodates the lens at its max tele setting, then in the max WA setting you may start to see the shade cast by the port edge.

- Although I prefer flat ports (don't do much WA) dome ports look much more impressive

Hope that helps!

Bart

Thanks Bart thats great info.

Andy