The Gentleman's Underwater Bubble Blower Thread

[Mauricio Handler]

HI Johnny and Simon
How does this new sensor perform underwater WITHOUT the filter?
Have you tested it?
Best-
MH

 

[Johnny Friday]

HI Johnny and Simon
How does this new sensor perform underwater WITHOUT the filter?
Have you tested it?
Best-
MH

Personallly i have not tried it with the standard or low light OLPF, but I'll do that this week. That said, Howard Hall kindly shared some of hist tests with me a few months ago and the results were notably visible. A much cleaner image and better blacks with much lower noise level than the Dragon sensor. Bottom line a good leap forward from the Dragon sensor for those of us underwater. But I'd have to say i'm quite let down with the H2O OLPF coupled with this new sensor. I'm wondering if perhaps the H2O was specifically built to correct the magenta issues of the Dragon sensor thus rendering it rather useless for Helium....Perhaps Sean can help shed some light on this so that others don't go out and buy the H2O OLPF thinking it will result in much better color rendering underwater as it states on the red store....."Optimized for underwater use" http://www.red.com/store/products/dsmc2-h2o-olpf

At the moment, i'll put away my H2O OLPF and go to the standard or low light OLPF.

 

[Simon Buxton]

Don't give up on it yet. I've been saying the same tune for months now but i was beginning to think it was just me!

It's something to do with the firmware update. I'm just glad i'm not alone now! The difference was night and day for me when updating the firmware. But as all I do is shoot underwater with it - it's easy to dismiss the change as varying conditions underwater, but for sure something changed.

Side by side above water with dragon and weapon on H20 OLPF you can clearly see that the Dragon has the 'nicer' more useful red hue when on current firmware. The newest DSMC2 firmware there is definitely a green tint on the H20.

When I first got the weapon I did the same test with my dragon and both were almost identically warm in hue.

I've been using the standard OLPF for macro work, but I miss the colour of the H20 and older firmware on DSMC2.

Johnny - what firmware are you on? Can you get back to some of the older firmware? I updated too far and couldn't roll back.

 

[Johnny Friday]

Don't give up on it yet. I've been saying the same tune for months now but i was beginning to think it was just me!

It's something to do with the firmware update. I'm just glad i'm not alone now! The difference was night and day for me when updating the firmware. But as all I do is shoot underwater with it - it's easy to dismiss the change as varying conditions underwater, but for sure something changed.

Side by side above water with dragon and weapon on H20 OLPF you can clearly see that the Dragon has the 'nicer' more useful red hue when on current firmware. The newest DSMC2 firmware there is definitely a green tint on the H20.

When I first got the weapon I did the same test with my dragon and both were almost identically warm in hue.

I've been using the standard OLPF for macro work, but I miss the colour of the H20 and older firmware on DSMC2.

Johnny - what firmware are you on? Can you get back to some of the older firmware? I updated too far and couldn't roll back.

HI Simon:
So Sean is proxy on behalf of us underwater folks? I hope so, as that would give some weight to get some attention drawn to the subject. I'm not sure what version i'm using....i'll look at that this week. I'll be out much of this week diving and first thing i'll do today is change my OLPF back to standard or low light. It would be a shame to have a useless 700 OLPF that we had high hopes for.....

I'll see if soon i can't post some underwater looks using different OLPF's - our water is very clear here this time of year.

 

[Sean R.]

I've got to apologize Simon, that I have not been able to dig deeper into this as I've been away working on the new season of House of Cards and away from the underwater world. But I did get a chance to throw my H2O OLPF in my camera with newer firmware and I also see the green tint that I don't believe was there previously. My next step now is to have our engineers roll my firmware back to v.6.3.74 and compare the look on that build, taking test shots of both as data points for engineering so we can see if something has changed during the firmware progression.

I'll try to get back to you, Johnny and this thread with results ASAP...

Sean

 

[Tom Hamilton]

I've got to apologize Simon, that I have not been able to dig deeper into this as I've been away working on the new season of House of Cards and away from the underwater world. But I did get a chance to throw my H2O OLPF in my camera with newer firmware and I also see the green tint that I don't believe was there previously. My next step now is to have our engineers roll my firmware back to v.6.3.74 and compare the look on that build, taking test shots of both as data points for engineering so we can see if something has changed during the firmware progression.

I'll try to get back to you, Johnny and this thread with results ASAP...

Sean

Big congrats Sean, that is a huge show! Sooo, an underwater guy on House of Cards, does that mean one or more of Frank Underwood's enemies ends up in the Potomac?

 

[Sean R.]

Nothing underwater related unfortunately. This is related to my 'day job' at RED as Field Tech. I've been going out to HoC at the beginning of the season since Fincher first started the show 5 seasons ago.

 

[Tom Hamilton]

Then they have the best in the biz my friend, kudos.

Do you happen to know anyone who has used anamorphic lenses behind a dome port, any info much appreciated.

 

[Sean R.]

I've only done anamorphics behind a flat port and been told things get even trickier behind a dome. Close focus and magnification factors always seems to be a struggle so diopters have been a necessity, from my limited anamorphic underwater experience.

 

[Johnny Friday]

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.

Michael
You mention focus of virtual image at 15-19 inches. Is this with all your lenses? I have had different values. For example I use 26 to 28 inches with canon 11-24 for about 3 feet to 8 feet. Less focul distance if closer and more if subject further out. I am wondering if your results are due to fact that some domes are shape slightly differently? I’ve noticed some domes with more and less curvature. Not knowing the exact science, is this the reason?

 

[John J Ellerbrock]

MegaDome Unveiled -- BBC Blue Planet II

MegaDome Unveiled -- BBC Blue Planet II

For anyone not catching the news about MegaDome over on Instagram and Facebook, take a look:

https://www.facebook.com/gates.underwaterproducts/

Short story:
MegaDome was designed and made specifically for BBC.
It has a singular purpose: to shoot over / under sequences
with both topside and underwater in focus *at the same time*.
BBC Earth acquired extensive footage with MegaDome for #Blue_Planet_II
as you'll see when released soon. MegaDome was paired
with #DEEP_WEAPON / RED Digital Cinema rigs, and serviced / supported by
Esprit Film and Television Limited. Dave Blackham and his crew pioneered
the actual field use, solving such issues as water sheeting and stabilization
in less than ideal ocean conditions.

MegaDome is a celebrity, making the talk show circuit with Dan Beecham, Rachel Butler and Jonathan Smith.

 

[William Long]

Saw the first of the Blue Planet II series last night. Really beautiful, as always! Megadome produced some great results. Congratulations.

 

[Tom Hamilton]

Also congrats John. I found this interesting;

Megadome is intended to minimise distortion between above/below images, better match focus between above/below areas of the image and maintain a better water line, either at 50/50,slightly over or slightly under depending how you balast it and rig it on a float system, there are many ways of doing this. On the surface of the water it is quite manageable, its just floats like a small boat. We have used lenses from the excelent Zeiss 8mm UP to 20mm. Our current favourite is the full frame Canon 11 24mm lens.

 

[John J Ellerbrock]

Thanks very much William. This side of the pond we can't see the show or even trailers online. All are blocked outside of the UK (or Europe maybe). Will have to setup a VPN when I get back to the office after DEMA show this week.

Saw the first of the Blue Planet II series last night. Really beautiful, as always! Megadome produced some great results. Congratulations.

 

[Michael Hastings]

Michael
You mention focus of virtual image at 15-19 inches. Is this with all your lenses? I have had different values. For example I use 26 to 28 inches with canon 11-24 for about 3 feet to 8 feet. Less focul distance if closer and more if subject further out. I am wondering if your results are due to fact that some domes are shape slightly differently? I’ve noticed some domes with more and less curvature. Not knowing the exact science, is this the reason?

Those are the numbers for an 8" inch (4" radius) dome. It will vary a little with different housings depending on where the camera is positioned behind the dome. However 26-28 seems like it is too much unless your back focus is off because it would suggest that the the distance from the camera image plane is almost 18 inches behind the dome - which seems like a lot unless it is a larger radius dome. (What is the radius on the Gates dome?)

A while back, I posted the original Gomer McNeil article on Dome ports - which had the graph below (sorry about size -reduser.net shrunk it).

AFAIK all of the current housings use spherical domes - although the shape might look different if they are not full hemispheres but smaller slices. The basic idea is that infinity becomes a virtual image at 3 times the radius of the dome (and everything is else is closer - as you can see from the graph it's logarithmic) so for an 8" dome a subject at infinity will be refocused by the dome to 12" in front of the dome, a subject at 25" would be refocused to about 7.25" in front and a subject at 50" would be refocused to about 9" in front of the dome.

On my housings the sensor plane is about 9.5 inches behind the dome so add the 9" for the virtual image of a subject at 50" and you get 18.5 inches focus setting or adding the 12" for infinity you get 21.5" focus setting so any focus setting past 21.5 inches would be focused on nothing.

For each lens there is an ideal distance that the camera should be set from the dome (which isn't always easy to determine) so there is no perfect position if you are going to use different tenses at different times. And there are also some practical reasons why the housing might have a slightly less than ideal camera mount position - which can slightly degrade the image with some distortion and possible chromatic aberrations.

One of the reasons the Nikonos lenses are so good is that they were able to get the perfect distance as well as perfect centering of the lens/dome combination. And one of the advantages of Gates is that they have all of those different front plate/ports available. Since my housings have a removable front port (you actually normally install camera from the front) it can easily accept different front plates/ports but they would generally have to be made to order rather than off the shelf.

 

[Johnny Friday]

Thanks for the explanation Michael...All testing i have done has revealed the distances i mentioned shooting chart underwater etc...I believe the gates dome is a 9" dome.

 

[Michael Hastings]

Thanks for the explanation Michael...All testing i have done has revealed the distances i mentioned shooting chart underwater etc...I believe the gates dome is a 9" dome.

Looking at gates website it looks like they have an 8" and a 10" dome. There would be several inches difference between an 8 and a 10 inch. Bottom line is your water test, which will reveal the proper distance given all of the variables of sensor to dome distance, as well as camera back focus and lens back focus, either of which can be off a little bit and make a significant difference given the very small range we are dealing with. Not to mention that dSLR lenses aren't really known for accurate/easy to read distance markings.

I tend to cheat a little toward the dome on where I position the camera to accommodate some of the shorter superwides and fisheyes in the same port setup. I just purchased the 11-24 a short while ago so haven't done much "scientific" testing.

IIRC the dome actually creates a curved "virtual image" which (along with some chromatic aberration) tends to create the soft corners so it is helpful to stop down as much as possible (without getting to the diffraction limiting point). It also somewhat argues against the current rage toward "full frame" or "VistaVision" sensors. In terms of underwater optics, small sensors can be your friend.

 

[Tom Hamilton]

Question?

Upcoming shoot with actors in about 15 ft of greenish water, overhead sun between 10 & 2, using 2 x 16000 lumen LED's for fill, WB on white slate (The Red sensor doesn't react well to 18% grey underwater), WB calc lights on or off?

Seems to me off is the correct answer for background water colors, but scratching head over this one.

Responses much appreciated, thx.

 

[Johnny Friday]

Question?

Upcoming shoot with actors in about 15 ft of greenish water, overhead sun between 10 & 2, using 2 x 16000 lumen LED's for fill, WB on white slate (The Red sensor doesn't react well to 18% grey underwater), WB calc lights on or off?

Seems to me off is the correct answer for background water colors, but scratching head over this one.

Responses much appreciated, thx.

Hi Tom:
Personally, i would set WB at 5600 and shoot away and deal with it later in post...you can use a chart or slate and set with talent to hold and use as a placemarker to do a WB in post using redcine x to get you close. I'm always surprised HOW FAR OFF the normal numbers this can put me at times...and i rarely use those numbers: WB & TINT, but it can be a good place to start...and contrast it against 5600-6500 WB and other tint setting. I would not do an in camera WB on anything for that matter....yes, it looks better trough viewfinder, but it does not affect end result. but i'd put my slate with talent and then with green water and other colors of talent you can then back off the green channel in post and do all kinds of flavors....but i'd set my WB dropper to check what the talent looks like at no more than 6feet away...after 6 feet in not clear water...it wont much matter....

DISCLAIMER: i'm just a dumb diver....

 

[Johnny Friday]

Question?

Upcoming shoot with actors in about 15 ft of greenish water, overhead sun between 10 & 2, using 2 x 16000 lumen LED's for fill, WB on white slate (The Red sensor doesn't react well to 18% grey underwater), WB calc lights on or off?

Seems to me off is the correct answer for background water colors, but scratching head over this one.

Responses much appreciated, thx.

Here are a few examples of what i happen to mention..these are quick and easy one pass grades in redcinex and far from perfect...but with neutral settings and later an odd grade with WB & Tint

[/url]Helium8k-before2 by Johnny Friday, on Flickr[/IMG]

[/url]Helium8k-after2 by Johnny Friday, on Flickr[/IMG]

[/url]Helium8k-before1 by Johnny Friday, on Flickr[/IMG]

[/url]Helium8k-after1 by Johnny Friday, on Flickr[/IMG]