hyp 115 Posted June 8 Quick question for those more invested in the optical physics side of underwater photography. Do Flat ports just change the FoV of macro lenses (I think about 30% compared to on land?) or does magnification get changed too? Basically, will the same macro lens behind a dome port produce less magnification or have a different working distance, compared to on land. Asking because I'm interested in trying the 4" semidome for my 12-50mm lens. Share this post Link to post Share on other sites
Interceptor121 843 Posted June 8 Quick question for those more invested in the optical physics side of underwater photography. Do Flat ports just change the FoV of macro lenses (I think about 30% compared to on land?) or does magnification get changed too? Basically, will the same macro lens behind a dome port produce less magnification or have a different working distance, compared to on land. Asking because I'm interested in trying the 4" semidome for my 12-50mm lens.A flat port increases magnification and working distance resulting in exactly the same magnification that you have on landWith a dome port assuming all is correct you will get the same situation at the land working distanceHopefully this was clear enough Sent from my iPhone using Tapatalk 1 Share this post Link to post Share on other sites
hyp 115 Posted June 8 13 minutes ago, Interceptor121 said: A flat port increases magnification and working distance resulting in exactly the same magnification that you have on land This is not quite clear to me. You say it increases magnification resulting in the same as on land. Do you mean it increases working distance, but magnification stays the same? Share this post Link to post Share on other sites
Interceptor121 843 Posted June 8 This is not quite clear to me. You say it increases magnification resulting in the same as on land. Do you mean it increases working distance, but magnification stays the same?The apparent focal length increases but the working distance also increases so you get the same magnification from further awayWith a dome port you are closer but the field if view is the same as topsideMagnification doesn’t change but with the flat port you are further awayGenerally for true macro you don’t want to be closer but for a zoom lens that is not a macro lens where you could be at half a meter a dome may helpYour position changes not the maximum magnification you can getSent from my iPhone using Tapatalk 1 Share this post Link to post Share on other sites
Interceptor121 843 Posted June 8 Thank you, now it is clear.Magnification in photographic terms is the ratio of the frame size in the image and the sensor sizeIf you take your macro lens on land and go as close as you can to a ruler and take a shot then put that macro port underwater go as close as you can you will get the same frame size but from further behindThe photographic magnification didn’t change but the apparent magnification standing at the same distance didThis however is irrelevant to your objective as photographer in terms of frame size and photographic magnification Sent from my iPhone using Tapatalk 1 Share this post Link to post Share on other sites