I appears from some of the above posts that you have a few misunderstandings about the port systems for the 9-18mm Olympus M43 zoom lens.
Nauticam only has one port recommended for this lens, the four inch Nautican port.
Regarding ZEN Underwater ports, NO adapter is made for mounting the ZEN PEN ports to the Nauticam Mini housings. A ZEN adapter is made for Subal type III ports like the 100mm for use with the Panasonic 8mm fisheye on the OMD and other Nauticam housings. These are coated optical glass ports and that it the reason someone might want to pay more. ZEN also makes a 170mm glass port for the Nauticam Mini mount for use with lenses like the Panasonic 7-14,12-35 and Olympus 12 F/2.
ZEN also makes an adapter for mounting the ZEN PEN PORTS to the Olympus housing for the EM5 and a 100mm port that mounts direct to the housing for the 8mm fisheye and all are glass.
Regarding the ZEN ports on the Olympus housings the 9-18zoom port works quite well and does not vignette even at 9mm. The port charts above are wrong, first the lens is 100 degrees on the wide end not 62 degrees and lens placement is not correct and acts like a flat port not a dome.
For more info. Regarding the ZEN PORTS I suggest you go to ZENunderwater.com and do some research. Also checkout my photos in the gallery all of which were taken with the 9-18 zoom and the zen-100 port most at the 9mm end of the lens.
I don't quite agree with your last post. Here is what I can see from the olympus lens site.
Focal Length 9-18mm (35mm equivalent focal length 18-36mm) Lens construction 12 Elements in 8 Groups, including 2 DSA lenses, Aspherical lens, ED lens & HR lens Angle of View 62 Degree Closest Focusing Distance 0.25m Maximum Image Magnification 0.1x (35mm equivalent Maximum Image Magnification 0.2x) Minimum Field Size 173 x 130mm Number of Blades 7 (Circular Aperture Diaphragm) Maximum Aperture F4 (9mm) - F5.6 (18mm) Minimum Aperture F22 Filter Size Diameter 52mm Dimension Diameter 56.5 x 49.5mm Weight 155g Box Contents Lens Cap(LC-52C), Lens Rear Cap(LR-2) , Instruction Manual, Olympus Worldwide Warranty Card
Are you saying that there is a mistake on the manufactures web site regarding the lens. Where is this documented ?
I have viewed the zen site and see there statement that the dome increases the view to 100 degrees but that is not what my drawings reference. What the drawings reference is the placement of the dome in-relation to the nodal point (entrance pupil) of the lens.
How do you make a dome "acts like a flat port not a dome." ??? The only way I can figure that out is to heat up the dome and flatten it out. A dome underwater will give you a wider angle of view, hence the 100 degree view. Even tho the dome is not the correct correct dome for the lens ( it is either too small in diameter, too flat or incorrectly placed) there is no way it can function the same as a flat port.
In regards to what zen port works with what housing, that is not my area of expertise. I was simply addressing the incorrect dome for the lens mentioned.
I look forward to your reply with a detailed explanation and documentation of how and why my drawings are incorrect.
Edited by nikonscubadiver, 18 June 2013 - 12:03 PM.