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Diopter for WA?


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#1 JWNZ

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Posted 14 May 2019 - 09:15 AM

Hi there. Would you recommend I use a diopter with my Canon 16-35 f4 lens? I use it with either the Aquatica 9.5" glass dome or the 8" acrylic dome.
Any advice appreciated.
James.

#2 Chris Kippax

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Posted 14 May 2019 - 01:23 PM

Check out the sea & sea internal correction lens



#3 ChrisRoss

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Posted 15 May 2019 - 01:27 AM

You don't need a diopter for this lens,  as it focuses close enough by itself.  A diopter is used for WA if the lens can't focus close enough to focus on the virtual image formed by the dome which is about 3 dome radii away from the dome surface.  If the lens can already focus on this a diopter does not help.

 

The S&S lens helps by bringing the corners into focus, the virtual image is curved and the corners are closer and you need to stop down to bring them into focus.  The S&S lens helps by partly correcting this curved image so you dont need to stop down as much to bring the corners into focus.



#4 JWNZ

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Posted 15 May 2019 - 12:01 PM

Many thanks for the info guys, much appreciated.