Quote Originally Posted by pgk View Post
Except with dome ports which produce a virtual image at 4r from the centre of the dome's sphere.

Actually its a wonder that we ever get 'sharp' images with all these complications. I would suggest that photography is, in practice, an essentially empirical activity and (although in my case my original background was in photoscience) we gain experience and as we doo we start to understand many of these and other interactions intuitively because we assess the images produced and learn from them. Digital has speeded this process up.

In generalist photography I am unsure just how much of the science behind image creation is relevant, although it is often interesting and can at times provide an insight into observed phenomena.

Still, what would photforums be without something to discuss and argue about?
Yes dome ports do correct but my Nikonos didn't have one. I shot through the Nikonos lens directly. The other thing is that refraction works through an underwater mask as well. So everything appears 1/3 (25%?) closer to your eyes as well as to the film. The issue is that when you're shooting let's say a 35mm lens, refraction causes the lens to "see" as if it is a 50mm lens due to the refractive magnification.