3Deep - 3D underwater housing for Epic

[Pawel Achtel]

Hi Lucas,

The fact that you can keep a 5k camera dry underwater, does not necessarily mean that you can record 5k underwater images.

My tests (shot in controlled conditions and analysed with Imatest) show that shooting wide angle (90 degrees FOV terrestial lens) underwater results in approximately 17 pixels CA in the corner, which is approximately 150 lines per picture height. That's the resolving limit of a wide angle lens placed behind a flat port underwater.

Even underwater domes do not seem to resolve more than a few hundred lines in the corners.

3Deep is different. It uses Nikon Nikonos lenses specifically designed and corrected for underwater. They are submersible lenses and do not require ports (flat or dome) that cause great deal of resolution loss, distortions and chromatic aberrations. They resolve up to the Nyquist limit of Epic sensor corner-to-corner.

Can you tell us how did you manage to resolve 5k in the edges and corners of a flat port? To my knowledge this is not possible.

[Michael Hastings]

Hi Lucas,

The fact that you can keep a 5k camera dry underwater, does not necessarily mean that you can record 5k underwater images.

My tests (shot in controlled conditions and analysed with Imatest) show that shooting wide angle (90 degrees FOV terrestial lens) underwater results in approximately 17 pixels CA in the corner, which is approximately 150 lines per picture height. That's the resolving limit of a wide angle lens placed behind a flat port underwater.

Even underwater domes do not seem to resolve more than a few hundred lines in the corners.

3Deep is different. It uses Nikon Nikonos lenses specifically designed and corrected for underwater. They are submersible lenses and do not require ports (flat or dome) that cause great deal of resolution loss, distortions and chromatic aberrations.

Can you tell us how did you manage to resolve 5k in the edges and corners of a flat port? To my knowledge this is not possible.

CA is relatively easy to correct and is routinely done on high end underwater 3D productions.

Nikonos 15mm lens is in fact essentially a 20mm nikkor with a dome port so your statement, while technically accurate in its wording, is somewhat misleading.


Also, to my knowledge, even RED does not claim actual 5K resolution from the Epic even in the best of circumstances - IIRC it is approx 20 % less, so your focus on the 5K wording iin your multiple somewhat antagonistic postings on the subject is also a bit misleading.

[Jay A. Kelley]

I am not an expert in this area, but I would think Cameron/Pace would be at the top of a short list of people qualified to build things like this.

Jay

[Michael Hastings]

I am not an expert in this area, but I would think Cameron/Pace would be at the top of a short list of people qualified to build things like this.

Jay

Silly man, they only have probably more experience than anyone, and fairly unlimited deep pockets. ;-)

(in case it isn't clear, that is sarcasm in support of Jay's statement.)

[Pawel Achtel]

CA is relatively easy to correct and is routinely done on high end underwater 3D productions. .

Really? Please correct the attached corner crop shot with a Master Prime 14mm through a flat port. How sharp can you make it?

Nikonos 15mm lens is in fact essentially a 20mm nikkor with a dome port so your statement, while technically accurate in its wording, is somewhat misleading.

Michael, you are incorrect. Nikonos 15mm lens is a submersible lens specifically designed for underwater use and, in fact, it does not even focus in air. Unlike terrestial lenses placed behind domes it:

1. Doesn't suffer from severe field curvature caused by the dome
2. Resolves up to full Nyquist limit of the Epic sensor in the corner
3. Has CA of approximately 0.3 pixel in the corner
4. Produces very little distortions when close focussing

The FOV of the Nikonos 15mm is 92 degrees on a FF35 sensor and about 75 degrees on the Epic sensor.

[Pawel Achtel]

I am not an expert in this area, but I would think Cameron/Pace would be at the top of a short list of people qualified to build things like this.

Jay

Jay, I don't come from entertainment industry. As an engineer, I read MTF charts, not title credits or industry recommendations.

They (Cameron/Pace) have some good solution and certainly impressive list of credits, but I'm not aware of anything close to the solutions that my company is offering.

I am yet to see any vendor to come up with anything close to the CinePort, which has been around for 4 years now. You can see some real-life images shot with CinePort here: http://vimeo.com/29346689

To my knowledge DeepX and 3Deep patent pending technology using Nikonos submersible lenses is the only solution producing 5k underwater images corner-to-corner and that means the MTF chart goes right to the Nyquist limit of the sensor.

See the MTF chart of Nikonos 15mm lens in the corner of RED Epic frame below.




See the chart of Master Prime lens placed behind a 9" dome: chalk and cheese.



Note: the sample of the Nikonos 15mm lens used in the attached test happens to have large degree of de-centering and it is the worst Nikonos sample I've tested. Yet, it is clear from the MTF charts, that it resolves at least twice as much in the corner as Master Prime 14mm placed behind 9" dome resolves in 2/3rd of the frame. It is also clear that the MP 14mm placed behind a 9" dome does not resolve anywhere near 5k except in the very centre of the frame. Place that MP behind a flat port, and it all falls apart even more. You can't even measure the MTF with Imatest - that's how bad the immage is. In Photoshop you can measure the CA to be around 17 pixels.

[Sven Seynaeve]

anyway, wish you succes with the further design and testing, and would love to see some finished footage , and maby even some more explanation, because there's no moving ia , how you dealt with postpro and which system was used to finish it.
then seeing on a proper playback system , would do the system right if it's really working, and without going to deep into it and having you guys exchanging knowledge and disagreements, I'm really hoping we will finally be able to see the results of different approaches. Postpro has also a lot to do with it, I know geometric fixes can solve a lot of issues and make a lot of difference on the final product, but that off course depends if you can finish on such a system ( and I mean quantel or mistika for the geo fixes, unless others are doing some magic for NAB we don't know yet?????)))

[Pawel Achtel]

Thanks Sven, totally agree.

We are collaborating with some first tier post production houses here and consult with very respected people. I expect sample 3D images to be published around May - June time frame. Very exciting times :)

[Michael Hastings]

Really? Please correct the attached corner crop shot with a Master Prime 14mm through a flat port. How sharp can you make it?






Michael, you are incorrect. Nikonos 15mm lens is a submersible lens specifically designed for underwater use and, in fact, it does not even focus in air. Unlike terrestial lenses placed behind domes it:

1. Doesn't suffer from severe field curvature caused by the dome
2. Resolves up to full Nyquist limit of the Epic sensor in the corner
3. Has CA of approximately 0.3 pixel in the corner
4. Produces very little distortions when close focussing

The FOV of the Nikonos 15mm is 92 degrees on a FF35 sensor and about 75 degrees on the Epic sensor.

The fact that it can't focus in air means nothing as to what actual underwater correction was done beyond refocusing since the same would happen (in reverse) if you took the 20mm land lens and shifted the focus with either an extension tube or diopter lens (as you have to to compensate for the negative diopter effect of the dome )

And as stated before 75 degrees on 5k is nowhere near the 95 to 110 degree FOV that has been the norm throughout at least the past 30 years of underwater cine and video - even on the low end consumer stuff. (and it's even more ridiculous if you shoot 4k)

A wider FOV has dramatic effects on clarity, color saturation, and picture stability. If you want to promote your 75 degree cam as a "special purpose ultralight not-very-wide u/w cam" that's one thing but to suggest that 75 degree FOV is suitable as a general purpose professional underwater motion picture camera is just a sham. Sorry to be that harsh with a fellow Reduser but you are creating disinformation that a lot of legitimate manufacturers, producers and underwater shooters will have to spend hours correcting with producers and others that can't be expected to be fully aware of the ins and outs of underwater photography.

I've had to deal with this several times over the course of my career and it's very frustrating.

[Lucas Wilson]

My tests (shot in controlled conditions and analysed with Imatest) show that shooting wide angle (90 degrees FOV terrestial lens) underwater results in approximately 17 pixels CA in the corner, which is approximately 150 lines per picture height. That's the resolving limit of a wide angle lens placed behind a flat port underwater.

Pawel - I have no reason to doubt you when you say your system will do these things. But numbers can be spun into whatever you want to spin them into. Look at the small disagreement you and Michael are having... who should a client believe? And what you have here is a CAD design, not a product.

You're mixing marketing and reality. I do look forward to seeing real pictures from the built rig on a 3D IMAX screen capable of showing the 5K resolution... or can IMAX resolve 5K? In Stereo? Using the 4:3 delivery aspect? From an EPIC?

Just saying - lots and lots of variables. I can spin numbers too. ; )

Lucas