wide angle dome vs wide angle camera

hello

I had alway used a wide angle port

but i like to know what is the diference in you use a flat port and the wide angle on the camera

I know that you can have vigneting is the lens if the camera is not enought close, or you have to zoom to remouve the vigneting

But is there something else good or bad ?

thank you

philippe

I am not an expert but from what I understand, a dome port will correct for the magnification you get from the light refracting from water into glass and into air, which makes objects appear 25% bigger underwater. A flat port will make your "wide angle" be 25% less wide or narrower.