BlackMagic Cinema Camera underwater custom housing

[thani 86]

Dear All,

 

Sultan has received his BMCC EF mount and decided to take it downuder. After his Ninja2 house building experience, this time he as done a full fledged housing.

Offcourse the ports are borrowed from his existing housings.

Here are some specs:

> Housing is machained form aluminum cast;

> space to accomidate external battery;

> Follow focus is used to make focusing smoth and fast;

> Manul cotrols: Power on/off, Record, Iris (auto only), Focus;

> Flat port for Macro;

> Fathom 110 port (yes it works and wide enough to compensate for the 2.4 crop factor)

> Tested so far to 165ft by Sultan to check the behavior of the controls underpressure. We are sure it can go deeper

 

 

He has tested it with the Canon EF lenses: 16-35mm wide angle and 100mm macro.

 

Unfortunately, the waters here in summer we have bad visibility and does not help in the testing. Actually, it is like a sand storm down there - really bad.

I will be posting sample jpg images of the captured video later.

 

Here is an image of the housing with the Fathom lens:

 

 

 

 

[Steve Douglas 16]

There's some promise to this endeavor

[MJvC 9]

I totally agree this looks like a really good solution to give a wider angle of view on they small sensor. Could a similar solution work with the pocket cinema camera with a smaller Fathom port.

[SimonSpear 65]

Let's see the jps's Thani!

[thani 86]

Hi there,

 

I am on a short trip - no a diving one unfortunately - and I hope these images make it through.

First a disclaimer : I am not aquatinted with Davinci Resolve nor I am good at color grading.

 

Simon, here are some compressed Sample for the wide angle fathom along with the 16-35 canon EF lens. The lens was sat at 16mm:

Edited June 24, 2013 by thani

[thani 86]

One more wide angle fathom along with the 16-35 canon EF lens. The lens was sat at 16mm:

[thani 86]

Sample for Macro shots using the canon 100mm macro with a flat port:

[jonny shaw 16]

Are they zoomed in or cropped?

[CheungyDiver 53]

Thanks Thani

 

Do you have a full HD still? These looked low res.

[r4e 24]

Congratulations for being one of the first to take this camera under water.

 

> Fathom 110 port (yes it works and wide enough to compensate for the 2.4 crop factor)

 

The Fathom is an excellent port. However, I do not quite understand how it "compensates" the crop factor. If the BMCC sensor has a 2.4 crop factor, wouldn't a Canon 16-35mm zoom be equivalent to 38-84mm? I might be wrong, but the sample pictures do not look ultra-wide (weitwinkel).

 

The hopefully-soon-to-be-released BM 4K production camera has a crop factor of about 1.7 and even that makes the Canon 16-35mm equivalent to 27-60mm.

 

I wonder would the EF-S series work with the BMCC under water. EF-S 10-22mm would provide a wider view angle.

 

http://forum.blackmagicdesign.com/viewtopic.php?f=2&t=3807

[thani 86]

Jonny, non of the shots are cropped. Not the wide angle nor the macro ones. The lion fish in the fishing trap is a close up with the fathom port and the lens is at its widest 16mm.

 

Thanks Thani

 

Do you have a full HD still? These looked low res.

Yes, each is almost 2k more than allowed by the forum.

[thani 86]

The Fathom is an excellent port. However, I do not quite understand how it "compensates" the crop factor. If the BMCC sensor has a 2.4 crop factor, wouldn't a Canon 16-35mm zoom be equivalent to 38-84mm? I might be wrong, but the sample pictures do not look ultra-wide (weitwinkel) (weitwinkel).

 

The Fathom was designed for the Sony EX1 which I think has a 35mm equivalent. This is why it looks like it is working at around 38mm. More testing needs to be done.

 

I am hopping the 4k will have some wide angle primes that will give us close to 12 to 16 mm. I will do some search ...

[thani 86]

Here are some pictures of the housing that shows few controls the focus, record & auto iris.

The round long "view-finder like" is a good way to protect the screen from the ambient light. The screen looks clear and bright all the time. It works better than any shade I have used before. I wish it was square but this is what Sultan has in his reusable stock.

 

I would advise any manufacurer to avoid the standard shades that are closely attached to the back of the glass which is close to the screen. It is better to have the screen deep enough in the housing away from any light and have a small shade long enough to show the full screen

 

Another good idea is to avoid the standard housing design that follow the shape of the cam/lens. That would be okay for taking stills but not good for continuous video capture. A more stable rectangular shape would be preferred.

[Drew 0]

Thani, you and Sultan are pretty resourceful in your thinking. I love housings that are somewhat universal.

 

The EX1 is 31.4mm (35mm equiv) and has a lens diameter of 77mm (filter size). The 16-35 II (I assume you are using the II) has 82mm diameter. However, since the crop factor is 2.4, there's no vignetting with the SWP44C (or Fathom 110 in Sealux speak).

 

Why don't you try the 8-15 fisheye behind a dome port? That should give you about 19mm fisheye FOV, which should be around 130°, albeit barrel distorted. Or even the 8-16mm?

[thani 86]

Why don't you try the 8-15 fisheye behind a dome port? That should give you about 19mm fisheye FOV, which should be around 130°, albeit barrel distorted. Or even the 8-16mm?

Drew,

Where can we find dome ports that could fit the Sealux EX1 like housings with or without an adapter?

I have been looking at:

http://zenunderwater.com/products.php

But did not receive a positive reply from them yet.

 

Another selly question:

If you have a wide rectangular lens lets say 11 mm and place it in contact with a flat port - no gap - would you still get close to 11mm?

[CheungyDiver 53]

11mm rectilinear (i assume?) you will loose 25% of the angle (affect of water to flat glass - refraction)

 

110deg becomes 82 deg or there abouts

[thani 86]

Thanks David.

Just to confirm, even if the lens is stuck on flat port?

[CheungyDiver 53]

yes. Inside the housing lens and flat port has no effect as both are in air. Stuck or unstuck. Flat port to water is where the 25% magnification occurs.

 

To keep the angle of the lens a dome that matches the lens optical property is needed.

[Drew 0]

Don't forget the crop factor, 11mm=26.4mm, then + flat port = 33mm or so. Go for the EFS 8-16 behind a dome port.

[jonny shaw 16]

Also if you go much more than 60 degrees you will get issues with chromatic aberrations through a flat port.

[thani 86]

Thanks guys for the advise. We will try to do more testing and hopefully with the super FF wide angle lenses.

So an 8mm should be around 20mm on BMCC topside and On the to be released BMPC/4k the 8mm should be around 13mm topside. Correct?

Now, at such focal lengths (20&13mm) with the fish-eye, should the lens act as a rectangular lens and avoids the barrel/distortion of the fish-eye?

[thani 86]

Hi guys,

 

Here are some raw frames of BMCC taken by Sultan in his custom housing.

Feel free to play with them or distribute them but please make sure to mention the link to this thread or to give credit to Sultan bin Mejren

It will be interesting if you can post any color graded frames back to this post. This will be highly appreciated and interesting as each colorists will be seeing the underworld way in his/her own creative way.

 

Facts:

Location was Musandam, Oman

July 2013 (ignore BMCC file dates)

Visibiliy was poor (3-5) meeters

Most of the shooting was done via canon 16-35mm L lens along with the Fathom port;

Only the macro shots were taken by Canon 100m L lens in using flat port (two shots: Clown fish, Little Brownish long fish on hard corals- dont no the name )

White balance was set to 7500k

 

https://www.dropbox.com/sh/rk241svrgtg4ywp/G1oOpa0STM

 

Best Regards,

Thani

[Drew 0]

Shukran, Thani and Eid Mubarak to you and your family, as well as Sultan and his family.

[thani 86]

Shukran to you Drew . Where did you learn Arabic? Are you any good at it?

[thani 86]

Hi Drew,

 

Were you able to download the raw files from the above link?

How does underwater world look in raw?!