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Rui_Guerra

Member Since 25 Jul 2006
Offline Last Active Jan 29 2018 01:43 AM
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Posts I've Made

In Topic: Best wide angle lens for Nikon D850 in Nauticam housing

11 January 2018 - 04:38 AM

 

Consequentially, only zoom lenses that don't change its physical size significantly while zooming are suitable for photography with a dome port. Among the Nikon FX lenses, the 16-35mm f/4 is much more suitable than the "legendary" 14-24mm f/2.8, the latter changing the position of its front optical element strongly while zooming.    

 

 

 

Not entirely correct. I have here the Nikon 16-35 f4 and it changes the position of the from element, getting 9mm shorter when going from 16mm to 24mm. From 24 mm to 35 mm it moves out the front element for about 6mm. So there should be other things to consider and not just if it changes or not the front position element while zooming. It also moves a lot (around 30 to 40 mm) the position of the rear element while zooming in from 16 to 35 mm (maybe this compensates?).

 

 

In terms of the 16-35mm with Nauticam and 230mm dome, the correct extension seems to be between 60mm and 70mm, with most people opting for the latter. 

 

 

Nauticam recomends a 90 mm extension. Do you have any comparation test shots where you've based your decision about the extension length?

I use an 80mm extension, just because that's what I have here (although image quality is very good, with the normal limitations of FOF and dome ports - using a big 230cm).


In Topic: D850: Nikonos RS 13mm conversion or Nauticam WACP?

11 January 2018 - 03:34 AM

 

If you wanting to shoot rectilinear wide angle, the "best" conventional option would be the Nikon 16-35mm f/4, a 230mm dome and a 70mm extension. This is pretty bulky (although probably around the same weight as the WACP). I think it is probably a similar cost too. Optically though, the WACP is much better option.

 

Adam

 

I'm glad you mention this Adam, because I'm shooting video with a very similar setup:

RED Weapon 6K, Nauticam Weapon LT housing, Nikon 16-35mm f4, 230mm dome port, but with a 30mm+50 mm extension (total = 80mm, instead of the 70mm you mentioned).

 

Nauticam suggests in it's website that we should even use a 90 mm extension: https://www.nauticam...ges/port-charts

 

Have you noticed any lower image quality in the corners with your 70mm option in any conditions? I'm asking this because I was even considering to update my extension to the recommended 90 mm, although I don't thing that a 10 mm increase will make any visible improvement (I'm vey happy with my setup so far).

 

Another different story is light. Although the 16-35 f4 is an amazing lens, for video in some situations a faster lens is needed. So I'm looking for the options and one that comes to my mind is the Nikkor 17-35mm f2.8 (1 stop faster) or even the Sigma Art 18-35 f1.8, although with a narrower FOV and only usable from 20mm to 35mm (to cover the RED bigger then traditional S35 RED's sensor).

 

But opening the aperture to 2.8 or 1.8, brings again the question of corner sharpness of dome ports (although only in the cases where we have some parts of the subject/scene in the corners). Which bring us to the WACP alternative. But then we need to seed a comparation test chart at this wide open apertures with a WACP and a big dome. That is the kind of comparation that could make it clear how many stops we really gain with the WACP, so each of us could decide to make the additional investment or not. 

 

Another question: is the WACP completely rectilinear, even at 130º?

 

Besides the high price, it's also a very heavy piece of equipment (not very travel friendly), so it's not easy to just jump in and buy it. And we also need to buy the N100 to N120 adapter and (maybe) some specific extension ports.


In Topic: Introducing Nauticamís WACP - The Wide Angle Corrector Port: Discuss Here

11 January 2018 - 02:58 AM

Has any one tried the WACP with a Red Weapon and a 17-55mm or any other DX Kit lenses. Very interested in this for video work in the 6K-8K range i.e. 1,3x - 1,6x crop.

 

 

I'm also with you since I'm also a user of RED 6K. Much more info is needed with other lens combinations. 

In video, we need all the light that we can and there are many times where we need to shoot wide open (depending on the lens that could be f4, f2.8 or even wider).

 

So far the recommendation emphasis had been in a slow 3.5 - 4.5 lens, which is of limited use for video work in less then ideal light conditions (if we have ideal light conditions, we could use smaller apertures, so no real need for the WACP). In my point of view, it's biggest usefulness is where the dome ports start to fail, at wider apertures, let's say from f5.6 and wider f-stops. So we really need to know how it performs in the f2.8 range and even f1.8 or f1.4.

 

I know that in the real work we don't shoot test charts but to see the sharpness in the corners, we need that someone goes to a pool, shoot at a flat test chart in a pool's wall, at wide open f-stops, both with the WACP and a big dome (for example a 230 cm), and post the photos. Only then we can really see the improvments and how many stops do we gain in sharpness. Shooting reef corals and real underwater scenarios is nice, but doesn't provide us with objective data.