Diopter? Nexus D70s with 18-70 mm and ZP1224-10 port??

Hello,

I am hoping there is an expert out there that can help me.

I recently purchased a used Nexus D70s housing with a ZP 1224-10 dome port , and camera with 18-70 mm lens.

The port manual indicates that this port can be used for both the 12-24 mm and 18-70 mm lenses.

The package did not include a lens diopter, and unfortunately the port manual is in Japanese and I can not read it for further guidance as to whether or not a diopter is required and which one.

Searching the internet has not yield much results (the port no longer seems available). I contacted a Nexus dealer with my question, but after the person who responded indicated that the ZP 1224-10 port is a flat port rather than a dome port ... I became less confident in their answer.

QUESTION: Using this combination of port and lens - will I need to add a lens diopter and if so which one?

The reason I ask this question is that the setup currently takes very nice photos at medium and wide zoom but I am unable to focus on anything that is not further than 3 feet away (even though in air I can focus the camera at a few inches working distance). So I am not able to take any close up, near macro photos.

QUESTION: Will the addition of a diopter/closeup lens solve this problem? What would I lose by adding a diopter to this setup?

Thank you so much for anyone that can shed some light on this subject.

Hey Bloke,

If you do a search for an Aussie member by the name of Panda, I seem to remember him doing similar tests with this lens, but with a Nikon D80,

I'm pretty sure that he ended up using a diopter of some description, although I don't remember what brand or power?

HTH,

Bruce...

Thanks for the tip on Panda's great blog.

Unfortunately Panda was using a 18-55 mm Nikon lens and different types of ports. I'm not sure how that would translate to my system.

Hopefully someone will chime in with experience with the same port and lens ... or be knowledgable in the area.

Most of my readings are leaning me towards a +4 diopter for my system but it would be nice to hear first hand.

Cheers!

You likely will not appericate me telling you how to spend your money, but I would consider another lens option. The first thing I would do is ask a different Nexus dealer.

The current Nexus set up for the Nikkor 12-24 is a 170 mm diameter dome port with a 40 mm extension. A +4 diopter seems to work best. The close focus for the 12-24 IF is 33 cm. It is 82 mm long regardlees of focal length or focus point (the IF thing).

I don't have or know much about the 18-70. The close focus is 38 cm and I suspect that it is its shortest length of 75.5 mm at the 40 mm focual length. I have no idea the diameter of your port, but I suspect that you will want a diopter.

Good luck,

Bob

I agree. This is not the best lens for u/w use. I used it with a D200 and nexus 170 dome, 40 mm extension and +4 diopter, and got inconsistent results. An extension is needed to place the lens' nodal point in the spherical center of the dome. Because the nodal point of this lens travels so much throughout the zoom range, any given extension (or no extension) is unlikely to give good results at all focal lengths. Similar to extensions, the ideal diopter can be calculated based on lens and dome used. Although I don't have easy access to my notes for determining which diopter was needed, it was clear that one was needed in my case - and probably your case too. Despite what nexus has published, I've given up on using the 18-70 behind their domes (because of the nodal point problem), and I use other higher quality Nikon wide angle zooms instead with good results. I have used the 18-70 behind the nexus 60mm flat port and, except for some vignetting at the wide end and the magnification from the flat port, it performs ok and much more consistently than it did behind a nexus dome. I believe Sigma has a similar zoom (17-70 or something like that) which works pretty well with Ike domes and no diopter is needed because of the lens' close focusing capability. But I think nexus still doesn't offer a zoom ring for that Sigma lens, so it's a moot point unless you fabricate a zoom ring for it.

Oh, and one more thing - be cautious about using the Nikon 12-24 behind the nexus 12-24 dome...I've heard reports of vignetting. I do believe it's a good dome, but you must be careful which lens is used with it. Always ask other users before buying an expensive lens for use behind a specific dome.

Based on a fair amount of testing here's what I found to be the best setup for Nexus with 12-24mm & 17-55mm.

The 17-55 setup may work for the 18-70 but I have no experience with that lens.

12-24mm: FP170 port with 40mm extension ring & +4 diopter (12-24 port does vignette at 12-14mm end)

17-55mm: Custom 12-24 port (Anthis/Nexus web page shows it being ZP1214-5 vs -10, don't know what the difference is) with 60mm extension ring & +3/+4 diopter

I've been very satisfied with results using these setups. Try the 18-70 lens with the 1224 port & see if it works.

As side note: the 17-55 with +4 diopter will not focus at infinity at ~40-55mm end. +3 diopter solves this problem but then it won't focus as close as with +4. So you have to plan in advance a bit about what subjects you'd like to shoot. I also think edge/corner sharpness is a little better with +4.

You can test in a pool or just a big tub of water. Make a test subject with small detail in the corners (like text or bar code) to evaluate sharpness. All my testing has been done at f5.6.

P.S. All this was done with D70 system but same applies to my new D300.

Hi everyone,

I wanted to thank all of your for your helpful comments and suggestions. I really appreciate it. Being fixed on an island with no tech support - this forum has helped me a lot as a lurker and now as a poster.

I bought this system used for a great price to see if underwater photography could extend my terrestrial hobby. I am really enjoying it - although it does take away from the meditative aspects of diving.

I guess I will give a +4 diopter a try next summer when I get off island ... spend lots of time practicing ... before I upgrade to a better system.

All the best,

C