calibrating / tuning nikonos UW 15mm f2.8

[paulraymaekers]

hello, I use a nikonos UW 15mm on a nauticam housing, AS7 body, for under water filming
problem is that I cannot focus beyond 1m from the lens: when set at infinity, my focus point is at 1m.

question: can the nikonos lens be adjusted, so the focal point goes further?  I notice an internal lens shift of 0.4mm  when focussing from 1m to infinity

paul

[Bjørn Rørslett]

Probably if there are internal stops that can be moved or adjusted. With such a short focal length it won't take much to  shift focus off infinity.

The register distance of your underwater housing is slightly too long for the UW 15. What kind of mount is in use?

[Øivind Tøien]

I would love to see some images of this setup.

[Bjørn Rørslett]

and to make sure, the front dome of the  UW 15 lens is in direct contact with water? You cannot put this lens behind an ordinary dome port as it needs to be 'wet'. The optical design requires the refractive power of water to be present.

[paulraymaekers]

yes, it's a wet lens, directly in the water, no dome
its on a nauticam housing, directly mounted on the house, no port
inside only the a7S body, no lens of course
nauticam makes it for this setup

anyone has ever opened a UW 15mm nikonos?

[Bjørn Rørslett]

Yes I have (I got a flooded one [freshwater] for free, so nothing to lose ...), but it's been a while and except for there being a smaller internal cell holding the optics, really cannot contribute much vital information.

Take the lens to a camera repair shop and let a competent tech have a look at it. Some internal adjustments might be possible to carry out. There is also a question of whether your camera sits correctly inside the housing. The Nikonos uses a double bayonet mount, in which the inner claws actually couple to the camera inner core and the outer to the camera's outer casing.

[paulraymaekers]

Yes I have (I got a flooded one [freshwater] for free, so nothing to lose ...),

I'll gladly pay for the shipping if you want to give it away, so I can experiment a bit on it

going to a camerashop with it will not work: nobody still services nikonos UW15mm here,  my housing is brand new, the camera body is positioned inside the housing on hard positioning taps, so it cannot be moved into another position

the lens only clips into the mounting plate of the housing, it's not connected to the camera body

[Bjørn Rørslett]

Not giving the lens away - it works ...

I'll have a look inside it when I return to Oslo in a few days' time to se what might be done to the 15.

By the way, no need for a specialised repair shop, we're talking pretty basic gear adjustments here. A pity you aren't located in Europe - Erik would likely love to fix the lens.

[pluton]

Have you ruled out that the Nauticam product might need adjusting?

[paulraymaekers]

Have you ruled out that the Nauticam product might need adjusting?

there is no adjustment possible on the housing side,the camera body is 'pushed' against 3 fixed metal 'studs' inside the housing, to keep it in exact position
only a different lens mount plate would could change

I contacted nauticam, they suggested to check the lens... :-)

[paulraymaekers]

By the way, no need for a specialised repair shop, we're talking pretty basic gear adjustments here.

is there any document available that shows how to open the lens?   so that it can be closed again and still being waterproof :-)

[Bjørn Rørslett]

Which variant of the UW15 do you have? The early one with long rear end is very simple to take apart, the 'N' version less so.

[paulraymaekers]

Which variant of the UW15 do you have? The early one with long rear end is very simple to take apart, the 'N' version less so.

the newer version, no long rear end

[Bjørn Rørslett]

OK (I have both). Will check and report back.

[Bjørn Rørslett]

Just returned to my office digs and had a look at the 15/2.8 UW-N. Apparently there are two main O-rings in operation, one for the glass dome in front (front section held in position by 6 screws) and a smaller one for the Nikonos bayonet. The inner section of the lens is held (at the rear) by 4 screws.

I am reluctant to take the lens apart as there are several mechanical linkages for the control of focusing and aperture settings ,and these apparently are much more complex than on my 15/2.8 UW (first edition). Not liking the idea of having the lens flooded anew.

My advice of presenting the lens to a competent repair shop still stands. This is not an electronic device so only the basics of repair technology are required.