Testing Nauticam N120 Port Extension for 140mm and 180mm domes with wide angle lenses

[DreiFish]

I wanted to test to see the correct port extension for various wide angle lenses with the 140mm fisheye dome and 180mm wide angle dome for the Nauticam N120 full frame system. I also wanted to compare resolution of the different lenses and how the position of the lens and the size of the dome impacted the resolution. Lenses tested:

• Canon EF 8-15mm Fisheye Zoom
• Canon EF 8-15mm Fisheye Zoom + 2x TC
• Canon RF 14-35F4 L Zoom
• Canon RF 15-30 Zoom
• Canon RF 16mm Prime
• Laowa 10mm Prime

 

All tests done with the Canon R5C. 

 

Here's the test rig setup -- a chessboard to see if the straight lines continue straight above the water (to determine if port extension is too long or too short), with some paper bills glued to it to eyeball resolution. 

 

I haven't gone through all the photos yet, but already some interesting findings. 

 

1. EF 8-15mm zoom needs something like a 35mm extension with the 140mm dome, not the 30mm extension recommended by Nauticam. Here's the first image at 30mm, and the second at 40mm. You can see 30mm puts the entry pupil in front of the center of curvature of the dome, while the 40mm extension puts it slightly behind, and vignettes as a result. 

 

Here are the same images de-fished to highlight the effect. Look at the above-water portion. If the entry pupil is exactly in the center of curvature of the dome, the lines should continue straight above water. If it's too far forward, the above water portion appears smaller. If too far back, it appears bigger.

 

 

 

 

40mm extension is almost correct, so I'd guess 37-38mm is what would be perfect. Of course, the problem is (as shown above) that it vignettes, and removing the dome shade wouldn't fix the issue. It vignettes on the inside of the dome. A 35mm extension thus might be the best compromise -- or 38mm with a wider port, like Marelux's 125mm diameter ports. 

 

The incorrect placement of the entry pupil doesn't have much of an effect on the center sharpness (30mm on left, 40mm on right). Microcontrast might be a bit better though with the 40mm extension.

 

 

But there is a noticable improvement with the longer port when it comes to the corners.

 

 

More to come.

[DreiFish]

Now, the RF 16mm prime. All shots at F13, ISO 100. 

 

Unfortunately, this lens is not great for underwater. Nauticam recommends no extension at all, and I tried that with the 140mm dome.  But because the lens is so short, the entry pupil is quite a bit further than where the lens sits even with no extension rings, and there's no way to improve it.

 

 

Center resolution is not bad. Corner (or, really, more like edge resolution) is not as good.

 

[DreiFish]

Contrast with the Laowa 10. With no extension, it vignets slightly, but it's only the dome shade (which was designed with the more limited vertical field of view of a fisheye lens in mind). If you remove the shade, you should be able to get the full field of view. I tried also with a 20mm extension, but that produced very significant vignetting inside the port.

 

 

Notice the lines are almost straight above the water. Just sligtly smaller. Basically, you would get perfect placement with a 2mm extension.  Maybe a 10mm extension could work, but then the entry pupil would be too far back of the center of curvature of the dome, so image quality would likely not improve.

 

Center resolution is better than the RF 16mm prime or the EF 8-15, but the corners.. well, they're pretty bad.

 

 

Edited June 30 by DreiFish

[DreiFish]

Now the RF 14-35 F4 L zoom, at 14mm. All pictures again at F13, ISO 100.

 

The lens sits too far back from the center of curvature with the 180mm dome. Here it is with a 30mm, 40mm (what Nauticam recommends for 180mm dome), and 50mm extension.

 

 

Even 50mm is slightly too short, but already at this point it's vignetting heavily. I think this lens needs to be used with a 230mm dome, the 180mm doesn't have enough field of view. Best compromise if you're set on using it with the 180mm dome would be a 45mm extension I guess, but you might get vignetting even then. 

 

100% crops from the center and corner with 40mm extension. The center is a bit better than the RF16 prime but not as good as the Laowa. The corner is much better than the Laowa but kinda on par with the RF16 prime (which is behind a 140mm dome)

 

 

 

Edited June 30 by DreiFish

[DreiFish]

Finally, the RF 15-30. 15mm, F13, ISO 100.

 

With the 180mm dome, it needs a similar extension to the RF14-35, just slightly shorter. Here it is at 30mm, 40mm, and 50mm.

 

 

 

At 50mm it already vignettes, but the entrance pupil has already been moved forward past the center of curvature. 40mm puts the entrance pupil behind center of curvature. At 40mm it is a bit closer to the correct placement than the RF14-35. This lens probably also needs a 230mm dome, but 45mm should be about right with the 180mm dome and shouldn't vignette much. (Incidently, Nauticam recommends 30mm, which is clearly wrong. 40mm is better)

 

 

Center and corner crops at 40mm. Center resolution is not as good as the RF14-35 or Laowa 10mm, probably because the lens itself is not as good, but on par with the RF16.. Corner is better than the Laowa 10mm,  RF16 and RF 14-35 though. 

[Chris Ross]

The other solution for the 14-30 and 15-30 might be zooming in a little bit?  Can you zoom in enough to use the 50mm extension without vignetting?

[dentrock]

Thanks for the tests.

But what's your measurement for sensor to housing port flange for your Canon R5C (so we can estimate performance for other brands)?

[dentrock]

PS: also have not seen a measurement for EP from lens flange for the Laowa 10. I have one on order but goodness knows when it will turn up.

 

Any chance of a quick estimate for that too (method estimating apparent position of diaphragm is fine if you are reasonably careful)?

[Architeuthis]

Thank you - very interesting...👍

 

What apertures were used?

Do you also have WWL/WACP-x and could compare to these?

 

I am very curious to see the results with TCs too....

 

 

Wolfgang

Edited June 30 by Architeuthis

[Davide DB]

5 hours ago, DreiFish said:

Contrast with the Laowa 16.

 

Did you mean 10mm?

[DreiFish]

5 hours ago, Chris Ross said:

The other solution for the 14-30 and 15-30 might be zooming in a little bit?  Can you zoom in enough to use the 50mm extension without vignetting?

 

On the lists of things to test when I have time again, probably in 2 weeks when I'm back from Mexico.

 

4 hours ago, dentrock said:

Thanks for the tests.

But what's your measurement for sensor to housing port flange for your Canon R5C (so we can estimate performance for other brands)?

 

Might. be a bit tricky to measure. I believe Interceptor 121 did this for the Nauticam Sony housings at some point? If so, it would be easy to estimate adding 35mm (for the n100-n120 port adapter) to that. How else would I measure that? I have a caliper.. I guess I could do lens mount to front of housing with that or a ruler and add the manufacturer's flange distance. Do housing manufacturers share this information anywhere? 

 

4 hours ago, dentrock said:

PS: also have not seen a measurement for EP from lens flange for the Laowa 10. I have one on order but goodness knows when it will turn up.

 

Any chance of a quick estimate for that too (method estimating apparent position of diaphragm is fine if you are reasonably careful)?

 

It's not on OpticalBench yet. This is what I've pulled so far from OpticalBench. And from housing manufacturers documentation.

 

 

 

 

3 hours ago, Architeuthis said:

Thank you - very interesting...👍

 

What apertures were used?

Do you also have WWL/WACP-x and could compare to these?

 

I am very curious to see the results with TCs too....

 

 

Wolfgang

 

All tests were done at F13 for consistency and expediency (otherwise I had to adjust the strobe power to take a series at different apertures. Took too long 🙂. I may do some expanded testing later at different apertures. For instance, the RF14-35 did clean up a bit in the corners at F16, but lost center resolution. 

 

I have the WWL-C and RF 24-50 I will eventually test as well.

 

1 hour ago, Davide DB said:

 

Did you mean 10mm?

 

Yes, corrected. 

[DreiFish]

Ok, did more tests today.

• I now have the Canon RF 10-20mm L lens as well, which I thought would be interesting to test against the Laowa 10mm.
• Second, I switched to the 17" (427mm) Matty Smith custom "split-shot" dome to see how much of an image quality difference the larger dome made against the 140mm and 180mm options. The 17" dome is a true half hemisphere (fisheye dome). Matty Smith has confirmed that the radius of the 12" (300mm) dome is 6" (150mm) and the radius of the 16.8" (427mm) dome is 8.4" (213.5mm). 
• Finally, I threw in the Nauticam WWL-C with the Canon RF 24-50mm F4.5-5.6 lens to see how Nauticam's wet contact optics compare. We can assume this one is the worst of the lot, especially given the mediocre lens behind it, but it should at least give a reference point. I would expect the WACP-C, WACP-1 and WACP-2 to perform better, especially with better lenses behind them, but don't have either to test.

The test set-up looks like this. You can see the virtual image inside the dome.. surprisingly still significantly curved, even with a 427mm dome!

 

[DreiFish]

First, let's compare the EF 8-15mm fisheye, bare at 15mm with a 30mm extension and then with the 2x Kenko teleconverter at 16mm with a 70mm extension port. 

 

First -- the 2x TC definitely leads to significant resolution loss (not surprising), but also light transmission loss. Shots are all at F13, ISO 100. 

 

 

It's probably still good enough though with the 2x TC, especially given the versatility you gain. I plan to 3d print a zoom gear for this combination and test it on the reef. It'd be interesting to compare the image quality vs Nauticam's FCP solution.

 

The IQ difference going from the 140mm dome to the custom 427mm Matty Smith dome is surprisingly minimal though. Almost no difference in the center, but a bit more noticeable in the corner.

 

 

Edited July 7 by DreiFish

[DreiFish]

Now, the Canon RF 10-20L lens vs the Laowa 10mm prime. The 10-20 uses a 20mm extension, and no extension for the Laowa. RF 10-20L is at F13 like the other shots in the series, but the Laowa is set to F11, since this is a manual lens and only options were F11 or F16.

 

 

The Laowa could use a 5mm extension (not possible on N120 ports) and the Canon RF 10-20mm L could use probably a 25mm extension, which I don't yet have to test. Nauticam recommends 20mm for the RF 10-20L.

 

Now for image quality:

 

There isn't much resolution or contrast difference in the center, though the color rendering is quite different. In the corner, the Laowa is a bit sharper.

 

I will redo the test with these two using the Nauticam 140mm dome to see how much improvement you get going with a larger dome. The RF 10-20mm has a MFD of 250mm, while the Laowa's MFD is 120mm. This should show more of a difference behind the small dome.

[DreiFish]

Comparing the zoom options, here is the RF 10-20mm L at 10mm (20mm extension) vs. the RF 14-35L at 14mm (40mm extension). 

 

 

There's not much between them in the center. Even in the corner, it's hard to tell them apart. The RF 14-35 might have a touch more microcontrast, but it's hard to say. Impressive performance for the RF 10-20mm!

 

If we normalize and take the RF 10-20mm to 14mm, then the comparison skews more toward the RF 10-20's favor, especially in the corners. Resolution is similar, but the RF 10-20 shows more microcontrast.

 

What about the RF 15-30? Here it is at 15mm, with a 40mm extension, compared to the RF 14-35L lens, with a 40mm extension, at 14mm. Surprisingly, the non-L RF 15-30 looks a little better than the L lens, but there's not a whole lot between them.

 

 

How about if we zoom in the 14-35 to 15mm?  Surprisingly, it doesn't help. The RF 15-30 still has slightly better resolution and microcontrast, both in the center and at the edges.  The RF 14-35 is taking a beating.

 

 

How does the RF 15-30 compare to the RF 10-20L if both are zoomed to 15mm? Pretty similar, but I'd give the slight edge to the RF 10-20L. 

 

In conclusion, the RF 10-20L is the best option for a wide angle rectilinear zoom on the Canon RF system. It performs better at 14mm than the RF 14-35L, and better at 15mm than the RF 14-35L or RF 15-30. Not to mention it can go as wide as 10mm, where it almost matches the Laowa 10mm prime (which is a manual-only lens on RF mount anyway, so not really an option). All while needing the shortest extension of the lot at 20mm. Of course, it will probably only work well with the 230mm dome because of its MFD of 250mm, but I intend to test it with the 140mm dome as well to see if it's still acceptable. 

 

The RF 15-30 also performs very well, besting the RF 14-35L at 15mm. If you don't need 14mm or 10mm, it's a very cost effective option (I got mine refurbished for $359.99 directly from Canon.) 

 

The RF 14-35L is the most disappointing of the lot. Unless you really need the 35mm reach at the long end, it's hard to recommend it over the RF 15-30 or RF 10-20mm options. 

 

 

 

 

[DreiFish]

 Finally, are you wondering how the RF 24-50 + Nauticam WWL-C combination performs? Sorry to say.. but, pretty abysmally. Here it is at 24mm compared to the Loawa 10mm prime:

 

 

The field of view may be similar horizontally, but it's narrower on the wet optic vertically. And it shows mild fisheye distortion, of course.

 

And the image quality? Not even in the same league. The rectilinear lens has much better resolution and especially microcontrast. Both in the center and in the corners. 

 

 

About the only thing the WWL-C has going for it is the smaller size. But I'll compare it soon with the Laowa and RF10-20 behind a 140mm dome. I have a feeling the rectilinear lens will still do better. 

[DreiFish]

What if you were to take the EF 8-15 L fisheye and de-fish it? How would that compare with a rectilinear lens?

 

First, in terms of field of view, The 15mm fisheye de-fished looks similar to a 12mm rectilinear lens. Like with the Nauticam wet optics, the de-fished fisheye has slightly less horizontal field of view when the vertical field of view is matched. 

 

But what about resolution and microcontrast? I'd say the de-fished fish-eye 15mm lens mostly holds its own against the 10-20mm at 12mm. The rectilinear lens has slightly better resolution and microcontrast in the corner, but it's not night and day. You totally can use the fish-eye de-fished in a pinch to produce respectable rectilinear images equivalent to a 12mm lens -- if you don't need the even wider field of view of a 10mm rectilinear. 

 

 

[Landvogt1893]

great test! Thank you! 

I'm very excited about the tests with the 10-20 behind a 140 dome.

Do you perhaps also have the opportunity to test a 15-35 3.8? This is my current go to lens.

 

[DreiFish]

2 hours ago, Landvogt1893 said:

great test! Thank you! 

I'm very excited about the tests with the 10-20 behind a 140 dome.

Do you perhaps also have the opportunity to test a 15-35 3.8? This is my current go to lens.

 

 

Hello Landvogt! Thanks for the kind words. Unfortunately, I don't have a RF 15-35 F2.8 L lens to test (unless someone wants to lend me one :D). 

 

But as for the RF10-20 with the 140mm dome (dome shade removed), the results were a little disappointing, especially in the corners. That lens really does benefit from a larger dome.

 

Here is the 10-20 RF at 10mm, F13, ISO 100. 427mm dome on the left, 140mm dome on the right. 

 

The full image shows that the 20mm extension + 427mm dome puts the lens' entry pupil closer to the dome's center of curvature with than using the same 20mm extension + 140mm dome. So probably a 25mm extension would be more optimal with the 140mm dome.

 

And here are center and corner crops, again, 427mm dome on the left, 140mm dome on the right.

 

Center sharpness and contrast degrades only a little, and that's likely caused by shooting through more water with the smaller dome to keep same subject distance and framing. But the corner resolution really suffers. 

 

I think this loss in corner resolution may have to do with the MFD of the RF10-20L being 250mm. I say this because the Laowa 10mm prime has a much shorter 120mm MFD and doesn't exhibit the same degradation in the corners. If you compare the two 10mm options in the larger dome, there's not much difference between them. But with the smaller dome, the difference is quite obvious in the corners (and minimal in the center). 

 

 

The Laowa 10mm prime is a better option to use with the 140mm dome because of its quite shot 120mm MFD.

[Architeuthis]

On 7/7/2024 at 5:17 AM, DreiFish said:

 Finally, are you wondering how the RF 24-50 + Nauticam WWL-C combination performs? Sorry to say.. but, pretty abysmally. Here it is at 24mm compared to the Loawa 10mm prime:

 

 

 

The field of view may be similar horizontally, but it's narrower on the wet optic vertically. And it shows mild fisheye distortion, of course.

 

And the image quality? Not even in the same league. The rectilinear lens has much better resolution and especially microcontrast. Both in the center and in the corners. 

 

 

 

 

About the only thing the WWL-C has going for it is the smaller size. But I'll compare it soon with the Laowa and RF10-20 behind a 140mm dome. I have a feeling the rectilinear lens will still do better. 

 

Just out of curiosity (of a WACP-C owner). Would it possible to test the WACP-C and compare to the Canon 8-15mm with TC?

[DreiFish]

2 hours ago, Architeuthis said:

 

Just out of curiosity (of a WACP-C owner). Would it possible to test the WACP-C and compare to the Canon 8-15mm with TC?

I'd love to, but don't have one. It should perform marginally better than the WWL-C (on par with the WWL-1 according to Interceptor 121), but I wouldn't expect night-and-day improvements. I'm more curious if the WACP-1 or WACP-2 really show a benefit from the larger glass elements and different optical formula (when it comes to the WACP-2).  But, alas.. I sold my WACP-1. So unless someone wants to lend me one of these lenses.... 

 

The other factor to consider here is the 'taking' lens behind the wet optic. My tests are with the Canon RF 24-50 F4.5-F6.3 lens, which is a kit lens, and nothing to write home about in terms of optical quality.  I would expect much better results with a proper modern lens like the Sony GM/G lines or perhaps Canon's RF14-35/15-35L lenses behind the WACP-2. Even the Sony 28-60 kit lens is pretty well reviewed.

[Klaus]

Thanks a lot for such a systematic test! I can only imagine how much time you spent with that box… 

I especially like the rectilinear vs. de-fished comparison, I always thought this de-fishing would lead to heavily degraded IQ. I guess the quality of the lens plays a big part in this.
Was there anything special in how you de-fished the images or will this be similar no matter which software is used?

[Architeuthis]

19 hours ago, DreiFish said:

I'd love to, but don't have one. It should perform marginally better than the WWL-C (on par with the WWL-1 according to Interceptor 121), but I wouldn't expect night-and-day improvements. I'm more curious if the WACP-1 or WACP-2 really show a benefit from the larger glass elements and different optical formula (when it comes to the WACP-2).  But, alas.. I sold my WACP-1. So unless someone wants to lend me one of these lenses.... 

 

The other factor to consider here is the 'taking' lens behind the wet optic. My tests are with the Canon RF 24-50 F4.5-F6.3 lens, which is a kit lens, and nothing to write home about in terms of optical quality.  I would expect much better results with a proper modern lens like the Sony GM/G lines or perhaps Canon's RF14-35/15-35L lenses behind the WACP-2. Even the Sony 28-60 kit lens is pretty well reviewed.

 

I am extremely thankful for the lots of time and efforts that you invest to provide us with these very interesting test images...👍

(I must say, however, that I would expect companies that sell their products (domes, water contact optics etc..) to provide us with such information, so that we know in advance what we get when we purchase a product. Not only after investing in enormous amounts of redundant gear and careful testing (as almost nobody is able/willing to do))

 

I am, however, confused about some results and realy hope I misunderstood something, or maybe something is wrong in the test settings:

 

#1.: Your WWL-C performance is terrible overall. Several posts report, however, that this combo with Canon lens is outstanding. How can the difference be explained? If IQ really is so bad, maybe it is because WWL-C was constructed for compact (WWL/WACP-C was constructed for APS-C and WACP-1 for FF, so they should perform better?)?

=> I did no careful tests with my WACP/Sony 28-60mm, but from about a dozen of dives with WACP-C I got the impression that IQ (center) MAY BE little better with a rectilinear lens (Sony 20-70mm) behind 170mm dome (also a dozen dives with this combo), but similar to the adapted Canon 8-15mm fisheye lens w/o TC (many dives with this combo). As said these are just subjective impressions from real diving...

 

#2.: When I look at your different test photos, I come to the conclusion, that Canon 8-15mm+2x Kenko TC IQ is better than WWL-C/Canon (fearfully other water contact optics perform similar 😟?). I made some photos UW in very bad vis conditions here locally (Canon+2x Kenko TC) and results are not brilliant, as bad vis is rate limiting factor for IQ, but seem useable. I think problems with IQ, in case they exists, will mostly come out in very clear waters...

 

#3.: I am puzzled about the light loss by using the 2xTC: it is clear that minimum f-number of the Canon 8-15mm changes from f/4 (w/o TC) to f/8 (with 2xTC). How can it be explained that there is a light loss at the same f/13 used? Could this be a problem with the adapter that does not transmit the correct, actual, f-number (f/13 set on the lens itself is actually >f/22 when the 2xTC is mounted): If this is the case, part of loss in sharpness could be explained by the very high f-number (approx. f/25) used? Without relying on the adapter and th eelectronic display on the camera, one needed to adjust the aperture to f/6.3 manually on the lens to get a real aperture of f/13 with the 2x TC mounted...

 

 

Wolfgang

 

Edited July 16 by Architeuthis

[DreiFish]

Regarding the WWL-C performance, I too was a bit surprised that it was this bad. I've owned the WACP-1 before, and even with the (significantly older) EF 28-70 lens, the results were pretty good. So I'm not sure what's going on here -- it could be the WWL-C itself, but I suspect the biggest issue is the quality of the Canon RF 24-50 F3.5-F6.3 lens. Still, while the lens is comparatively worse, it doesn't mean it's incapable taking good images in the field. Here's an example that I find perfectly adequate -- after some editing 🙂

 

 

I too would love for manufacturers like Nauticam to actually test (at least their corrective optics). Getting them to test various lenses in different ports and post those results is probably never going to happen. 

[Adventurer]

On 6/30/2024 at 5:37 AM, DreiFish said:

Now, the RF 16mm prime. All shots at F13, ISO 100. 

 

Unfortunately, this lens is not great for underwater. Nauticam recommends no extension at all, and I tried that with the 140mm dome.  But because the lens is so short, the entry pupil is quite a bit further than where the lens sits even with no extension rings, and there's no way to improve it.

hi Dreifish, I recommend to give this another try with a dome that is small and not (almost) a full hemisphere. This will compensate for the negative alignment of that lens inside your housing.

 

The minimum focusing distance of that lens makes it surprisingly flexible. In fact I found it capable to obliterate the need for the fish portrait end on RF14-35 and RF15-30 @35mm/30mm with it‘s weird semi-macro close focus behaviour.

 

Maybe you get an affordable INON Dome Port II and try to path it in with an INON/Nauticam adapter or a similar custom made dome. According to

my measurements and calculation the INON dome can compensate for something around 33.26mm negative extension ring. Also you can remove the dome shade on that one if required.