gogums
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Looking for some clarity on using a wide angle lens to do splits. Specifically whether split diopters are needed to bring subjects both above water and below water in focus.
I'll be using a Canon 5D FF camera with a Canon 20 mm 2.8 lens behind a 8" dome.
I've read that so long as the lens has a minimum focus distance of less than 16 inches (4 x dome radius) then the lens can be stopped down enough to keep both underwater, near objects and above water (and further away) objects in focus. Within reason of course...
My Canon 20 mm 2.8 lens has a MFD of .8 feet...well under the 16 inch minimum focus distance a 8 inch dome requires. Cool. I think I'm OK...
However I also read how split diopters are needed for over/under shots, to compensate for the affect the spherical dome has on how objects appear to the camera underwater. This is where the wheels start to wobble for me...
Is the use of a +2 split diopter (+2 side rotated over the lens to affect only the UW object) to better balance out the affect you see when you have a person/object half in the water and half out of the water? To correct the bottom portion looking considerably larger than the top portion?
Maybe a better way to ask would be, given the equipment I will be using (WA lens w/ .8' MFD on full frame camera behind 8" dome):
1- Is a split diopter needed to shoot say a diver fully underwater with the dive boat in the background (on the surface of course
)?
2- Is a split diopter needed to shoot an single object where a portion of it is underwater and a portion is above water?
Since I haven't used a dome yet I clearly don't know what I'm doing
Thanks I appreciate any help here!
I'll be using a Canon 5D FF camera with a Canon 20 mm 2.8 lens behind a 8" dome.
I've read that so long as the lens has a minimum focus distance of less than 16 inches (4 x dome radius) then the lens can be stopped down enough to keep both underwater, near objects and above water (and further away) objects in focus. Within reason of course...
My Canon 20 mm 2.8 lens has a MFD of .8 feet...well under the 16 inch minimum focus distance a 8 inch dome requires. Cool. I think I'm OK...
However I also read how split diopters are needed for over/under shots, to compensate for the affect the spherical dome has on how objects appear to the camera underwater. This is where the wheels start to wobble for me...
Is the use of a +2 split diopter (+2 side rotated over the lens to affect only the UW object) to better balance out the affect you see when you have a person/object half in the water and half out of the water? To correct the bottom portion looking considerably larger than the top portion?
Maybe a better way to ask would be, given the equipment I will be using (WA lens w/ .8' MFD on full frame camera behind 8" dome):
1- Is a split diopter needed to shoot say a diver fully underwater with the dive boat in the background (on the surface of course
)?2- Is a split diopter needed to shoot an single object where a portion of it is underwater and a portion is above water?
Since I haven't used a dome yet I clearly don't know what I'm doing
Thanks I appreciate any help here!
