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yhmah

Which zoom underwater

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Hi

Using a D200 with a Fisheye doom port

 

Which lens is sharper and better to use overall?

Nikon 12-24mm Dx or 17-35mm

 

12-24mm has a Canon500D +2 diopter on it

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The 17-35mm is a much sharper lens in air than the 12-24mm, but it is not as wide.

 

I use a dioptre on both lenses - although I would not use the Canon 500D - which is designed for telephoto lenses. I would also use a port extension ring too, with both lenses.

 

Alex

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The 17-35mm is a much sharper lens in air than the 12-24mm, but it is not as wide.

 

I use a dioptre on both lenses - although I would not use the Canon 500D - which is designed for telephoto lenses. I would also use a port extension ring too, with both lenses.

 

Alex

 

I was under the impression that a +2 diopter was just a closeup filter whether it was used on a telephoto or wide angle.

 

What would be the difference in a fisheye port if I was to use a +3 diopter vs a +2 diopter?

I have a +3 in heliopan

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Alex, am I right in thinking you use a +2 diopter on the 12-24 with a Subal 8" dome? Does it make a significant difference?

 

Thanks

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Alex, am I right in thinking you use a +2 diopter on the 12-24 with a Subal 8" dome? Does it make a significant difference?

 

I use a +3 and a +4. Usually +4 for reefy stuff, and +3 for big animals. I use quite a short extension ring, which is why a use a stronger than theoretical dioptre for the Subal FE2 dome (I think the correct theoretical dioptre is 2.2 for that dome). I have tried the 12-24mm without the dioptre - it works, of course, but the corner sharpness is poor.

 

Alex

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I use a dioptre on both lenses - although I would not use the Canon 500D - which is designed for telephoto lenses. I would also use a port extension ring too, with both lenses.

 

Alex

 

I think the Canon 500D should work fine, when Canon says it's designed for telephoto lenses, I believe they simply mean +2 diopters on land should be used (for best results) on 70-300mm lenses, and +4 diopters should be used in the 50mm-135mm range...

 

Of course underwater none of this applies, +2 diopters give good results with the nikon 12-24mm lens, the Canon 500d should give even better results since its a dual element lens, that will maintain a higher image quality than a regular (single-element) diopter.

 

btw, here's a link to some testing someone did with different extensions and diopters. they did find some minor vignetting with the canon 500d diopter.

 

http://www.gotosnapshot.com/digital-slr/di...graphy-17.shtml

 

Scott

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Thanks, Alex. What extension ring do you use then? Presumably not a 50mm?

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