Does Nikon make a digital Nikonos?

[davelew]

The only problem is that with the cropped sensor it will not look like the 15 shot on film but more like a 24 mm lens. Still impressive, but not near as wide.
Bill

To expand a little more on my comment above:

The Nikonos 15mm lens has a field of view of 94 degrees. That corresponds, roughly, to a rectilinear lens with a 20mm focal length (note that the 20mm Nikonos is really about a 27mm lens, and the 28mm is really a 38mm lens). I don't know why Nikon did that with this lens, but not knowing this screwed up some optics calculations of mine when I first tried to make my adapters.

On the Sony NEX, a 15mm Nikonos lens would have a field of view equivalent to a "real" 30mm lens, and have a 72 degree field of view.

Here is where it gets complicated: A lens designed for use in the air, but used behind a flat port in the water, will have a narrower field of view. So, a 17mm lens used in air will have a 103 degree field of view, but that lens would only have a 72 degree FOV when put behind a flat port in water (from Snell's law, 1.33*sin(1/2 FOV in water) = 1.00 * sin( 1/2 FOV in air).

So, basically, a 15mm Nikonos lens used on a 1.5X crop sensor camera will have the field of view of a "true" 17mm lens used behind a flat port, or of a 30mm lens used behind a dome port. There will be lower chromatic aberrations and distortions with the Nikonos lens as well, since it's designed for underwater use and doesn't have to deal with an optically imperfect port.

 

[Chuck Tribolet]

The 15, 20, and 28 mm Nikonos lenses are behind a dome port,
and so have a narrower field of view.


Chuck

 

[davelew]

The 15, 20, and 28 mm Nikonos lenses are behind a dome port,
and so have a narrower field of view.


Chuck

A dome port shouldn't affect the FOV; isn't that kind of the point of a dome port?

And if you mean a flat port, you can't have a 15mm lens behind a flat port, because you will get the flat port turning into a mirror in the corners. The critical angle for an air-water interface is about 49 degrees, anything more than that gets 100% reflected. 49 degrees on each side makes for 98 degrees, which is the FOV of a 19mm lens, so any lens less than 19mm on a full-frame camera doesn't make sense behind a flat port. Nikon can't claim that they meant 15mm behind a flat port or behind a dome port.

The Nikonos 15mm lens is still a fantastic piece of optics, I'm just confused about calling it a 15mm lens.

 

[Ryan]

Some of the best images I've seen from the NEX system thus far are here:
Review: Sony NEX-5 in Nauticam with Nikonos Lens - DigiTalay

Too bad I don't read Thai.

I've used both Sea & Sea 12mm and Nikonos 15mm. Sea & Sea 12 is still a usable wide angle lens, where 15mm is now a razor sharp lens that works well for fish portraits to almost wide angle shooting.

 

[Chuck Tribolet]

A dome port shouldn't affect the FOV; isn't that kind of the point of a dome port?

Oh, DUH, you are correct.


Chuck

 

[bvanant]

A dome port shouldn't affect the FOV; isn't that kind of the point of a dome port?
.

I was under the impression (from a long time ago) that the FOV of a dome port is with a given lens is the same as that lens in air but only if the focal plane of the camera/lens is at the center of curvature of the dome. But that was for a homework problem in grad school (35 years ago) and maybe I remember it incorrectly.

Bill

 

[Ryan]

I have seen a reference before that Nikonos 15mm is a 20mm lens behind a dome, called 15mm by marketing peeps assuming customers would expect refractive mag. I can't find it now, it may be incorrect, and just because it is on the internet doesn't mean it is true.

I was under the impression (from a long time ago) that the FOV of a dome port is with a given lens is the same as that lens in air but only if the focal plane of the camera/lens is at the center of curvature of the dome. But that was for a homework problem in grad school (35 years ago) and maybe I remember it incorrectly.

Not focal plane, but entrance pupil. And as you move forward of that point the dome behaves less like a dome and more like a flat port, so fov is narrowed.

 

[Md Spear]

Ryan....thanks for the link to pics of the rig.

I am actually thinking of pulling the trigger on this .........anyone know any negatives w/ this idea? I have always done really well w/ my nikonos stuff and the 15mm does help to really impart the "wow, this is what it really looks like " feel to wide angle wreck dives , and u/w vistas of ledges and such. I'm thinking no stobe for less backscatter as this sony nex5 seems to do well in low light . I have had very good results w/15mm on film using 800 speed film and no strobe. So....What if I could apply this w/ digital and hdvideo? Like I said .....now i'm worked up.

 

[bvanant]

I have seen a reference before that Nikonos 15mm is a 20mm lens behind a dome, called 15mm by marketing peeps assuming customers would expect refractive mag. I can't find it now, it may be incorrect, and just because it is on the internet doesn't mean it is true.



Not focal plane, but entrance pupil. And as you move forward of that point the dome behaves less like a dome and more like a flat port, so fov is narrowed.

Ryan:
Thanks for the clarification. Now I have to go find my old optics book and refresh my tired brain.
Bill

 

[davelew]

Ryan....thanks for the link to pics of the rig.

I am actually thinking of pulling the trigger on this .........anyone know any negatives w/ this idea? I have always done really well w/ my nikonos stuff and the 15mm does help to really impart the "wow, this is what it really looks like " feel to wide angle wreck dives , and u/w vistas of ledges and such. I'm thinking no stobe for less backscatter as this sony nex5 seems to do well in low light . I have had very good results w/15mm on film using 800 speed film and no strobe. So....What if I could apply this w/ digital and hdvideo? Like I said .....now i'm worked up.

Advantages: With the 15mm, 28mm and closeup kit, you can get GREAT lenses that are relatively inexpensive for fish portraits and macro work.

Disadvantages: Many of the best underwater images these days are taken with fisheye lenses, and there's no equivalent fisheye lens for the Sony/Nikonos system.

Also, a strobe doesn't have to cause backscatter. A properly positioned strobe will add to a photograph, not make it worse. Many of the best underwater photographers use dual-strobe systems. It's possible, with a lot of work, to get decent images without a strobe, but much easier with a strobe or two.