Nikon 18-70mm Lens

In a Subal I use a +2, 60 mm ext ring and the FE2 superdome.

Seems sharp throughout it's range.

Just don't try to shoot an Orca with one.

http://homepage.mac.com/daveburroughs/PhotoAlbum36.html

The Orca shots are with the 17-55. The whale shark with the 12-24.

OBTW, the 17-55 is a 2.8 lens and very sharp. Focuses very fast as well.

Reference 17-55mm lens on Nexus, 12-24 port, 60mm ext, +4D/+3D

These are #'s I used to calculate optimum setup to place dome center of curvature at lens nodal point:

Lens Nodal Point ~125mm from film plane

Housing Flange 88mm from film plane

Port Radius 95mm

Port Height 75mm (top center of dome to base)

Lens Nodal Point to Housing Flange 37mm (125mm-88mm)

Port Radius - Port Height 20mm (95mm-75mm)

Ext Ring Required 57mm (37mm+20mm)

Using 60mm ext ring

Hope this makes sense to someone besides me

Using +4D if I need to shoot close, +3D if its mostly medium/distance

+4D gives best results - sharpest edges & corners

+3D gives very good overall sharpness, but slightly soft in corners (not really that noticeable)

Been working on pics from last year (yes, I'm really behind) with this setup w/+3D. Very happy with results.

Thanks for posting your results.

 

Did you have an opportunity to evaluate sharpness between 40 - 55 mm when focused on infinity?

 

Jerry

In UK freshwater visibility?!

I couldn't see an obvious difference in pool shots, but I need to find some clear water to find out more. I have tried a 50mm extension,but can't see any difference to the 40mm extension, despite the theoretical benefit from moving the nodal point with respect to the dome.

Tim

Thanks Jim, very helpful.

Jerry