The Gentleman's Underwater Bubble Blower Thread

[Rui Guerra]

Mauricio:

Curious why you are interested in the Red 17-50 when the same lens is available as the original in Canon and Nikon mounts for less than $400 and has the added advantage of being controllable via RED Canon and Nikon mounts?

I understand there are some DPs that do all of their other shooting with PL mounts lenses but didn't think that was your situation.

And it seems there are other lenses more suitable for wide angle underwater - inexpensive like the Tokina 11-20 2.8 or Canon 10-22 or the much more expensive Canon 11-24L which seems to be the premier underwater lens at the moment ($2999 but about the same as a used Red 17-50 PL) or the Nikon 14-24 if you are a Nikon guy.

It was with this same kind of thinking that I asked some questions in my post #3100. In projects that you are not in charge, if the DP is used to cinema PL lens, what can one says to really convince him that some still lenses can also do a very good job? Moreover, what can one argue and say about (some?) PL lenses to convince him that they are not the best way to go (or is it)?
Questions of price apart and the obvious advantage of having a long focus throw, is there indeed any proved and tested advantage in using cinema PL lenses underwater? I mean, how can we compare (underwater) a small and compact $1000 lens to a big and heavy PL cinema lens in the range of $5000 - $50000 ?

 

[Michael Hastings]

It was with this same kind of thinking that I asked some questions in my post #3100. In projects that you are not in charge, if the DP is used to cinema PL lens, what can one says to really convince him that some still lenses can also do a very good job? Moreover, what can one argue and say about (some?) PL lenses to convince him that they are not the best way to go (or is it)?
Questions of price apart and the obvious advantage of having a long focus throw, is there indeed any proved and tested advantage in using cinema PL lenses underwater? I mean, how can we compare (underwater) a small and compact $1000 lens to a big and heavy PL cinema lens in the range of $5000 - $50000 ?

Long focus throw doesn't matter much since with for example an 8" dome it refocuses the image (i.e. creates a "virtual image") where infinity is 12" in front of your dome and everything else is even closer. Your entire focus range is from about 15 to 19 inches on the lens so even with long focus throw your are only moving the lens focus gear within a range of probably less than 1" on the lens gear.

Focus breathing, and color matching aren't much of an issue in underwater shooting, nor are the very minor distortions that might exist on one of the less expensive wide lenses like a Tokina. And the optics on these lenses in terms of sharpness and contrast are very good, particularly when you get to an L-series lens (or similar Nikons) like the Canon 11-24 where they are designed for 40-50 megapixel cameras and modern coatings so very likely optically just as good as high end cinema lenses. So most of the things that make cinema lenses so expensive are mostly irrelevant underwater.

And with the still camera lenses you get electronic control which can be pretty handy in an underwater housing.

 

[Rui Guerra]

Long focus throw doesn't matter much since with for example an 8" dome it refocuses the image (i.e. creates a "virtual image") where infinity is 12" in front of your dome and everything else is even closer. Your entire focus range is from about 15 to 19 inches on the lens so even with long focus throw your are only moving the lens focus gear within a range of probably less than 1" on the lens gear.

If the advantage of a long focus throw is precision, then it will be even more important uw since we're dealing with the virtual image's compressed distances.

Focus breathing, and color matching aren't much of an issue in underwater shooting, ...

If one wants to use some focus pulling techniques while uw, then I guess focus breathing is equally importante, no?

And with the still camera lenses you get electronic control which can be pretty handy in an underwater housing.

Electronic control of iris, is indeed handy if the housing doesn't have an iris knob or if one doesn't have the gear for that lens. On the other hand, although we can see the fractions of the aperture setting, at each button push, the iris change by a fixed amount of stop, so it's not possible to make a smooth iris variation across several stops nor to choose an exact iris opening because it will stops where it wants and not where the shooter wants. This with Nikon mount. Don't know how it works with Canon mount.
Focus control, that in my opinion could be a great time saver, its completely inaccurate and useless (topside or uw), at least with Nikon mount.

 

[Tom Hamilton]

Manual iris control is essential in some situations, filming free divers ascending/descending from light to dark and vice versa, for example, those shots are impossible to achieve without a smooth iris pull. (Takes some practice as well.)

Auto focus works, but in many cases will only get you in the ball park, and depends greatly on scene contrast. UW is often not sufficiently contrasty, in order to nail critical focus one should have the ability to nudge the focal plane by very small increments.

UW also necessarily involves shooting behind a dome at wide apertures in low light, image plane curvature may render everything outside of the exact focus target unacceptably soft. So unless you intend to use shallow DOF for defining the subject/achieving bokeh for aesthetic purposes, etc, adjusting the focal plane to a point somewhere between the center and the edges can save an otherwise unacceptable image.

There are also significant issues with DSLR lensing and the Red eco-system, here is a post from fellow RedUser Alexander Ibrahim:

"Remember that DSLR lenses are not meant for continuous focus tracking. They are meant to focus at discrete instances and snap off a shot.
As a result they have different operating characteristics, many of which are non-linear. In English, the position of the AF servo doesn’t have a direct correspondence to the focal distance.

DSLR’s dont “care” because they have time to hunt for maximum AF sharpness between frames. Motion imaging cameras don’t have that liberty … they have to continuously be in focus.

My understanding is that Red cameras address this in one of two modes, which could be called “knowing” and “guessing.”
With a fully characterized lens, the camera can make the most accurate corrections straight away, because it knows which lens motor position corresponds to a given distance.
In the guessing mode, the autofocus still works, but it hunts more. So as a subject moves … the camera doesn’t know how much to move the servo to make it be focused at a certain distance. So, it moves the servo, and then evaluates the image for sharpness at the AF point. (i.e. where you touch the monitor) Then it adjusts the servo again … repeating this until the camera decides the image is in focus.

This guessing mode is ALWAYS how DSLR cameras operate. Thus they overshoot focus and come back to sharp, sometimes several times. We call that “hunting.”
This is all compounded by the fact that DSLR lens manufacturers send metadata about focus and focal length back to the camera that isn’t quite right. Photographers don’t use that data the same way cinematographers and motion imaging post artists do, so they don’t need accuracy. They effectively just need a gross reminder.
Red has to fix all that for these lenses to work using their built in features for cinematography.

DSLR cinematography almost always depends on a spectacularly powerful computer with a fantastic bit of software to manage all that. Its called the first assistant camera’s brain. As a 1st AC on DSLR projects, you learn what lenses will do, and you start to move non-linearly in response it works out. (By the way … this is a fantastic reason to spring for some manual Nikkor AI or Zeiss primes as opposed to cheap modern AF lenses.)

Red has to recreate that, but with a lot less processing power and flexibility than a human brain.

One thing they must do is empirically measure the actual FOV and focal distances at each FOV of DSLR lenses. Primes aren’t so bad … a Canon 50mm prime is pretty reliably 50mm, so you only have to calibrate the entire focal range in the smallest steps the motor can give. I don’t actually know the precision of DSLR lenses, but a 14 bit 2/3″ ENG lens has 16384 positions. For each position, Red must map the actual focused distance against the reported distance in metadata. Then Red has to use mathematical regression to figure out a curve that can be calculated quickly that accurately represents how motor position corresponds to actual and reported focal distance.

For a zoom lens … that becomes hugely more completed. Taking the 24-70, you have to divide the focal length range and divide it into a large number of steps. (I’d pick the steps available in typical cine zoom motors, which I believe is 16 bit or 65536 positions, then for each of them plot true focal distance versus motor position and reported focal distance.)

That could be over a billion data points which have to be accurately regressed into a polynomial.

That also makes clear why you’d want to calculate this data as opposed to looking it up. One focal position needs 16 bits for focal length, 32 bits for true focal distance (INT in mm), 16 bits for motor position, 8 bits for aperture. That means a billion position table would be 9 Gigabytes. For every zoom lens.

Now, my numbers here are just estimates. I didn’t look up the precision of any of these digital motors … I also didn’t account for the possibility that analog motors are in use. I also didn’t account for lenses whose focus characteristics are affected by aperture. (A cine lens or even a good manual SLR lens wouldn’t be, but in search of lower costs some DSLR lenses are affected by aperture and compensate with AF.) I also didn’t account for breathing, which also affects focus accuracy.

So, that’s an outsiders guess at why they characterize lenses, and why it takes so damn long."

 

[Michael Hastings]

If the advantage of a long focus throw is precision, then it will be even more important uw since we're dealing with the virtual image's compressed distances.

The throw to go from 1.2 feet to 1.5 feet (i.e. near to infinity with the 8" dome underwater) on my Canon 11-24 is .5" while the same focus throw on my 10mm ultra prime was somewhere between .75 to 1" - so not a huge difference in precision.

(I no longer have the 10mm - it was dropped and I took the insurance money and never replaced since other than the one stop larger aperture there wasn't significant difference from the Canon and Tokina lenses we use.)

The issue with focus throw on DSLR lenses vs cine lenses is more on the "normal" to longer distances. For instance the focus throw for going from 1 meter to infinity on that 11-24 Canon is only .5" where it might be three inches or so on a cine lens. The focus throw on the closeup distances (that we need to deal with the dome refocusing) are fairly generous on the dSLR lenses so not as much of an issue as it is for normal topside shooting.

If one wants to use some focus pulling techniques while uw, then I guess focus breathing is equally importante, no?

Besides the fact that most people don't notice even a fairly large "focus breathe" - first: Many of the better Canon and Nikon lenses don't breathe much and second: that half inch focus throw isn't going to show significant breathing even on lenses that do breath quite a bit.

Electronic control of iris, is indeed handy if the housing doesn't have an iris knob or if one doesn't have the gear for that lens. On the other hand, although we can see the fractions of the aperture setting, at each button push, the iris change by a fixed amount of stop, so it's not possible to make a smooth iris variation across several stops nor to choose an exact iris opening because it will stops where it wants and not where the shooter wants. This with Nikon mount. Don't know how it works with Canon mount.
Focus control, that in my opinion could be a great time saver, its completely inaccurate and useless (topside or uw), at least with Nikon mount.

Canon lenses typically increment in 1/3 stops so you would at most be off by 1/6 stop and if you are regularly nailing perfect exposure with more precision than a sixth of a stop while shooting underwater I salute you :wink5:

Half the reason we shoot with Reds is that the combination of Raw and 16+ stops dynamic range means we can easily deal with fairly significant exposure variations (or mistakes :wink5.

If you truly need an iris ramp (i.e. 2, 3 stops or more) during the shot and it can't be handled in post then yes you are going to need a lens with a continuous iris - either a cine style lens or an SLR lens with a "declicked" manual iris. But these situations don't happen that often and it would generally be a preplanned shot where you know it before entering the water and prep for it. For instance, the housing I use most often is primarily used with Canon EF lenses but i have some simple friction controls that can operate manual focus and iris on both the Canon 14mm cine lens and the Cooke 14mm. The canon cine 14mm is available with an EF mount so I wouldn't need to change mounts on the camera to use it. Bottom line: a true iris pull underwater is both pretty rare and a pretty good trick to actually pull off - I would be curious how many different times you guys have had to do this and would like to see some examples where it was actually successful.

----

I'm not trying to be argumentative - I would just say that I have rented setups dozens of times to productions where the DP wanted to use particular cine lenses and focal lengths where they were or would have been better off just shooting with a good wide angle dslr lens. There are certainly situations where longer focal lengths, cine zooms, etc. are called for but they are pretty few and far between.

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FYI relative to the lens discussion in Tom's post. The Canon lenses don't have anywhere near the 65000 positions he talks about. IIRC from back in the Birger mount days, Eric told me the Canon 10-22 had a little over 1000 steps and most of the lenses were in the range of 700 to 1500 steps. So I think his calculations are pretty far off.

Setting aside macro shooting for the moment - with the 10 to 11mm focal lengths typically used underwater and the sweet spot stops between F8/F11 - a lot of underwater shooting is done with a preset focus at 2.5-3 feet because of depth of field, and even in low light with larger stops the focus throw from say 2 feet to 10 feet is extremely small.

 

[Dean Cropp]

Hi everyone...

I have just returned from 3 months exploring the Coral Sea off the Australian east coast in what could be the most intense of "Shake Down" cruises for the GATES PA housing and RS lens setup... Well it has been amazing and I will [post more on this including some vision soon (I need to edit it).

I have a question, has anyone run a LOOOOOONG Red Touch cable from the RED Epic to a Red Touch monitor. 50m, 75m??? Does anyone know what to cable limit would be? What type of protocol this vision cable is and if it can be boosted?

I plan to setup a surface vision split from my housing to the surface and SDI will do this perfectly. I have used Foolcontrol with my homemade housing and it would great. However many of my locations and setups are super remote or unforgiving with water spray and wild conditions and a computer running Foolcontrol will not work out there.
I would love to have the RED Touch and all the access it gives you to the RED camera on the surface for replay and changing camera settings.

Any thoughts?

Oh and if you want to see some of my adventures so far, take a look at my instagram www.instagram.com/barefootcaptain
and youtube https://youtu.be/yu2hh0WQ-nA

... Enjoy!

 

[Tom Hamilton]

So who's going to be the first to shoot Monstro uw?

 

[Sean R.]

Hey Dean,

Been awesome following your adventures on social media man! looks like it's been amazing so far. Especially since my gills have been drying up with how busy I've been on land lately. So cool to see you out there living the dream...

Unfortunately for that long of a run to achieve remote operation, I feel a long RT LCD cable is not going to be the solution. Getting a picture to run a long way isn't too big of a deal but getting full touchscreen ability to travel that long probably isn't going to happen easily. The more bulletproof solution would be picture through HD-SDI and as you mentioned Foolcontrol hardwired to the control port on the camera. We can take this offline with John and Peter to discuss what it would take to make that happen on your rig for you...

Sean

 

[Rui Guerra]

Dean,

I understand the advantage of using just a RED Touch with a long cable, but don't know if that's possible. An HD-SDi monitor + Foolcontrol will work for at least 50 m.

 

[Tom Hamilton]

I have a 250 ft cable that carries both HD-SDI and Ethernet signals for video and FoolControl. This is a single cable so only one housing port required for the connection. Topside is connected to a submersible 7" HD monitor (that doubles as an external housing monitor if required), and an Ethernet connection for Foolcontrol via Mac/IPad/IPhone. The latest IPhones are 'splashproof', although not sure how they would perform in salt spray. Anthony Lenzo makes an excellent uw housing for the IPhone, and although I have not yet tried it myself, with this setup you could control the camera underwater as well as topside from up to 250 ft away.

Useful for Garden eels other very shy critters to name a few applications...

I can manufacture the cable in custom lengths, and/or can quote you the entire cable/monitor/connector package.

Cheers

 

[John J Ellerbrock]

Buried...

Buried...

Two custom projects and Windows 10 purgatory have kept me away from these forums for 6 weeks. I see a couple questions posed to me, I'll answer shortly. Plus some new product announcements.

J-

 

[John J Ellerbrock]

Glass Domes and AR Coatings

Glass Domes and AR Coatings

Gates uses AR coatings only on the Concave (inside) surface of a dome. Why? Two reasons:

* Inside is needed. The inside glass / air interface reflects about 10% of incident light. The water / glass interface is less than 1%. So the biggest gain at knocking down reflections is with an AR coating is on the inside surface.

* Salt water degradation. While we can gain some additional benefit by AR coating the Concvex (outside) surface, sooner or later salt water eats it away. The AR coating start to look bad and eventually does nothing. So it becomes a practical measure to skip the AR coating on the outside.

Decades of Gates and customer experience bears out this formula. Reflections common with acrylic domes / no AR coating are absent with a glass dome AR coated on the inside.

J-

PS -- Harald / Seacam is a brilliant engineer. When discussing the topic of AR coatings on the outside of a dome some years ago, he simply said "Don't do it. It's stupid." LMAO.

 

[Darek Sepioło]

I've just finished 3-episodes series Underwater Planet 4K HDR. As far as I know that's the first 4K HDR underwater production.
Almost all shots are from Red Dragon. Edited and graded for HDR nad SDR in DaVinci Resolve.
No streaming nor broadcast dates have been revealed yet though.

HDR trailer:

Or SDR version:
https://www.youtube.com/watch?v=Q0lY-G8R65g

Best regards
Darek Sepiolo
www.dareksepiolo.com

 

[Johnny Friday]

Epic Dragon & Nikonos RS 13 Lens

Epic Dragon & Nikonos RS 13 Lens

I have read a bit of discussion about using the Nikonos RS lenses underwater and questions about field of view as well as coverage on the Helium. I've shot with the RS lenses using Epic Dragon and i've been very happy with the results of the 13mm lens and the 50 macro. As for using with the Helium...i've not yet tried that scenario. But for those that are interested, here is a video i put together for testing purposes with the RS 13mm Nikonos with RED Dragon housed with Gates housing:

 

[Tom Hamilton]

Big congrats Derek, looks spectacular! Please let us know when and where it will be airing. What was the housing you used?

Nice work Johnny, those Nikonos lenses are tack sharp, beautiful texture as well, they paint in a very filmic way. I think it's been said before though, can't really put a finger on it, but feels windowed somehow, like looking down a hallway. Maybe someone else can articulate that more sensibly...

Lighting is great John E, the daylight fill is both rich and practically invisible, as it should be.

 

[John J Ellerbrock]

Superb, Derek. Great predator action.

 

[John J Ellerbrock]

With S35 Helium sensor I would expect little or no fisheye effect. Anyone notice? Looks great Johnny.

I have read a bit of discussion about using the Nikonos RS lenses underwater and questions about field of view as well as coverage on the Helium. I've shot with the RS lenses using Epic Dragon and i've been very happy with the results of the 13mm lens and the 50 macro. As for using with the Helium...i've not yet tried that scenario. But for those that are interested, here is a video i put together for testing purposes with the RS 13mm Nikonos with RED Dragon housed with Gates housing:

Interesting observation Tom, but one I don't have your keen eye to see.

Nice work Johnny, those Nikonos lenses are tack sharp, beautiful texture as well, they paint in a very filmic way. I think it's been said before though, can't really put a finger on it, but feels windowed somehow, like looking down a hallway. Maybe someone else can articulate that more sensibly...

Thanks. A common remark is indeed about light quality. 90 CRI, 5000K. And of course lots of it.

Lighting is great John E, the daylight fill is both rich and practically invisible, as it should be.

 

[Darek Sepioło]

Thank you for kind words
I'm also waiting for the air time

 

[Johnny Friday]

Helium S35 and H2O OLPF

Helium S35 and H2O OLPF

Helium S35 8k & H2O OLPF = GREEN TINT

I just shot my first underwater material using the Helium 8k camera and i had also coupled it with my H2O OLPF....has anyone else used this combination? IN the end it yielded a heavy green tint (shot shallow at just below surface) to all the clips. They were easily fixed by moving the tint away from green or just dropping the green channel a bit....but wondering if anyone else has used the H2O OLPF with the new 8k camera? It yields a VERY different image on the Helium camera than the Dragon.

I'll have to do some more shooting to see if this is true at depth....but my guess is that this new sensor in the He camera will not likely work well with the H2O OLPF.....At the moment i don't have frame grabs to show...but i'd love to hear from anyone else their experience. On the Dragon, the H2O OLPF really did help with the magenta hue and thus was a good reason to use the H2O OLPF...

 

[Simon Buxton]

I had the same thing. Sean was looking into it but that was quite a while ago now.

For me it was after firmware .94 i think, and you cant roll back anymore. Before that it was a red tint like with Dragon.

Glad someone else thinks it's off.

Simon