"Dome ports - what for?"
When light passes from one medium to the next it is refracted at the boundary surface. With modern cameras this happens a couple of times before the light ray hits the sensor. This means that with a lens´ increasing camera angle (from 28mm) behind a flat glass pane an optical distortion of the image field is the result. Light rays however that hit the boundary surface at a right angle are not refracted. With a dome pane you take advantage of this and can thus make use of the lens´ full camera angle. SEACAM dome ports are precisely calculated and thus guarantee perfect image quality and the most precise corner sharpness.