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Manual White balance results in green reef


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#1 Kevster

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Posted 02 April 2012 - 06:07 AM

During my last trip i was setting manual white balance using my white slate.

Using a fisheye lens i made sure the white slate covered the white balance set square while i was setting the WB.

Setting manual WB resulted in the reef appearing very green.

After a few tries i decided to leave the camera in auto white balance mode as the colour appeared to be better than manually setting WB.

Any tips why this should be the case. Is this a result of using a fisheye lens i.e large area to colour correct?

I was using GH2, 8mm lens , 2 Sola1200 lights and 1 white dive slate setting manual WB. Slate approx 1ft from front of camera.
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#2 blaisedouros

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Posted 03 April 2012 - 11:09 AM

I was using GH2, 8mm lens , 2 Sola1200 lights and 1 white dive slate setting manual WB. Slate approx 1ft from front of camera.


Did you have your lights on while white balancing? If so, then the white balance would be correct for anything within range of your lights, but not for the entire reef; hence, the reef appearing green.

Think of white balance as a way to tell the camera what the light looks like: if you're shooting wide angle using ambient light, then white balance using the ambient light, without your lights on. If you're shooting a subject using your lights, then white balance with your lights on.

If you're shooting ambient light, it often helps to have a color correction filter if you're deeper than 15-20 feet.

#3 Davide DB

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Posted 04 April 2012 - 12:13 AM

I was using GH2, 8mm lens , 2 Sola1200 lights and 1 white dive slate setting manual WB. Slate approx 1ft from front of camera.


I have the same setup (except sola 2000), in my limited experience, so far I found that the auto wb works very well.
While the Pana TM300 and TM700 videocamera had an horrible green cast, the GH2 seems to render a beautiful saturated blue in mediterranean waters.
If you give a look to my first test in deep water the automatic white balance worked very well.

A friend of mine, without lights in shallow water, tried a magic filter and he was very satisfied with the results.
On the 8mm you need to cut the filter and place it in the filter holder behind the lens.

Bye
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#4 gee13

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Posted 06 April 2012 - 04:37 PM

I have the same setup (except sola 2000), in my limited experience, so far I found that the auto wb works very well.
While the Pana TM300 and TM700 videocamera had an horrible green cast, the GH2 seems to render a beautiful saturated blue in mediterranean waters.
If you give a look to my first test in deep water the automatic white balance worked very well.

A friend of mine, without lights in shallow water, tried a magic filter and he was very satisfied with the results.
On the 8mm you need to cut the filter and place it in the filter holder behind the lens.

Bye


Get a good filter kev, ive dived with pro videos and they swear by it.

#5 l.babcock

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Posted 19 April 2012 - 04:41 AM

During my last trip i was setting manual white balance using my white slate.

Using a fisheye lens i made sure the white slate covered the white balance set square while i was setting the WB.

Setting manual WB resulted in the reef appearing very green.

After a few tries i decided to leave the camera in auto white balance mode as the colour appeared to be better than manually setting WB.

Any tips why this should be the case. Is this a result of using a fisheye lens i.e large area to colour correct?

I was using GH2, 8mm lens , 2 Sola1200 lights and 1 white dive slate setting manual WB. Slate approx 1ft from front of camera.


I white balance on a reddish brown coral, that takes all the green out.

#6 DrMark

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Posted 23 April 2012 - 08:23 AM

As blaisedouros correctly stated, white balance tells the camera what color is white. Since the color of light is a function of the amount of water the light has to pass through, you need to be careful of how you white balance. Here are some rules of thumb:
  • Only white balance with your lights on if you will be illuminating the item to be videoed with your lights. During the day, you cannot do this with video lights at more than about 3-5 feet from your subject.
  • The color of an object is a function of the *total* amount of water the light must pass through. So, if you are shooting a reef at a depth of 40 feet, and are 10 feet away from it, the total amount of water is *50* feet. If you are at 40 feet depth, and white balance against a white slate that is 1 foot away from your camera, then you are white balancing for 41 feet of water (40 feet from the surface to your slate, plus one foot from the slate to your camera), not 50 feet. This will leave you with a color cast caused by 9 feet of water. If the water is very green, then you will get a green image.
  • If you white balance in the same situation (you at 40 feet deep, shooting a part of the reef that is 40 feet deep, from 10 feet away), and you white balance with your lights, then you will be white balancing through 2 feet of water (1 foot from your lights to the slate, and 1 foot from your slate to your camera), but when you shoot, the lights (at 10 feet) will not overcome the brightness of the sun, so you will have white balanced at 2 feet, but be shooting through 50 feet of water.

What I do to account for the problem of white balancing against a slate at 1 foot, but shooting a reef at 10 feet is to have a slate with white on one side and light blue on the other. I use the white side for close-up work with my lights, and I use the light blue side for distance shooting. By white balancing against a slightly blue reference, I "fool" the camera into adjusting the red/blue mix a little to account for the extra distance the light has to travel from the reef to my camera. There are also green cards available for use in green water.

--Mark

#7 Steve Douglas

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Posted 23 April 2012 - 08:32 AM

I always wb with my lights on and on my white fins which enables me to WB with a approximate distance of 3 feet, the same distance many of my shots are taken. If I am shooting CU work, a slate held at about 1 ft is good.
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#8 Davide DB

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Posted 12 July 2012 - 12:35 AM

Hi all,
I reuse this old thread.

What the difference between a gray and a white slate for wb?

I'm using a magic filter for ambient light shallow shots and most of the time I haven't neutral color references to manually wb. I tried a white object like the tank of my buddy or the sun but most of the time I get "object too bright" error which is a little bit funny given taht I read that most of the people have the opposite problem aka not enough light.
Last week I tried with some gray dutch tape on my fin. Things got better but is a little bit awkward standing vertical to shot the fin. Moreover, after a while the ducth tape flew away. My shot were a little bit greenish.

Bye

Edited by M43user, 12 July 2012 - 12:40 AM.

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#9 RWBrooks

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Posted 12 July 2012 - 04:07 PM

I've always used the sun as a reference with MWB, either zoom in on it for a cooler tint or zoom out and center it for a warmer one. Far quicker than a slate, tank, fin, sand or anything else. If you want warmer still use the blue sky, not the sun.....
With lights, a white slate set at the approx distance of your subject.
Boom, you should be in business.

Edited by RWBrooks, 12 July 2012 - 04:19 PM.

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#10 SimonSpear

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Posted 13 July 2012 - 03:42 AM

I change my approach to WB depending on what camera I'm using and what environment I'm diving in. WB off the sun or the water's surface works amazingly well on most video cameras, but can look awful on SLR's. WB off the palm of your hand is an even better option on some cameras, but far from all of them. Silver tanks normally works great, but of course many tanks are yellow. I've never used white fins myself, but light blue fins can work nicely. Without doubt I've always found that the absolute best WB object is white sand which works on every camera, but of course it is not always nearby! Bascially there are a range of options rather than one set way and you just need to find out what works best for your camera and your environment.

Cheers, Simon

#11 Davide DB

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Posted 13 July 2012 - 04:21 AM

Hi,
I wish I was diving in tropical water with bare hands, white sand and a mermaid that scratch my back Posted Image

Unfortunately I'm diving in a natural resurgence forming a small lake. Water is about 9°C/48°F wearing blue dry gloves and manually wb against them gives me horrible results.
When I'm at the bottom or in the shallow part I have a nearly white sand which gives me perfect wb but when I'm at mid water I have nothing to wb except the sun.
I tried several times with my GH2 to wb against the sun in shallow water but, as I said, I get a "object too bright" error. I should try closing down the aperture and see what happen. Otherwise I'll try to bring with me a piece of grey plastic.
Magic filter gives me wonderful results but the wb is critical: a slightly change of depth and colours dramatically change.

Thanks


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Edited by M43user, 13 July 2012 - 04:26 AM.

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#12 peterbkk

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Posted 13 July 2012 - 07:12 AM

Without doubt I've always found that the absolute best WB object is white sand which works on every camera, but of course it is not always nearby!


I'm not sure that white is always the best subject color for MWB.

In effect, when you MWB, you are saying that this object looks white to my eyes therefore the camera should adjust its color balance to make it look white to you. Which works fine in air. But underwater, that white object does not look white to your eyes. It looks blue or green depending on the water depth and particle content. So, by telling the camera, "this should look white", the camera over compensates or just gives up when it can't achieve white. Some cameras are worse: they start pushing the gain up in the red channel, leading to fuzzies.

So, depending on the camera, finding something that does not push the MWB circuit too far works better. Brown coral works in tropical waters. Pink fins are OK. Palm of your hand. Brown sand. With these subjects already containing some red, the camera does not have to over adjust the WB.

Regards
Peter

#13 SimonSpear

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Posted 13 July 2012 - 07:30 AM

You wear gloves in 9oC?? Wow you need to come dive in the North Sea and get properly acclimatised for your warm water mediterranean diving! :D

For your midwater shots you need to find an alternative which is exactly what I was saying - not all methods will work all the time. I've never used slates or other non essential props, but if that is your only alternative then give it a go and let us know the results :)

Peter - white sand is never actualy white :)

#14 2ge

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Posted 12 March 2013 - 11:56 PM

I got GH2 and "played" with Manual White Balance. I used before Canon P&S cameras and also Sanyo XACTI HD2000 and MWB works as expected - usually I just take the shot on sand, and everything was ok. With Pana GH2 it is different, I MWB on sand, and that sand is not white (in camera), but grey. 

 

For now I am ok, I am in Lembeh, and always shooting with video lights (sola 4000), so I use AWB, but there will be many situations, where I will use just ambient light and I want to be ready for that. 

 

I find Canon G12 as the best camera, which supports really nice manual white balancing - just set it up as shortcut, and with ONE press, you got white balance. On Pana GH2 one must made 4 button presses to achieve that. Oh well...also the results are not same.


Edited by 2ge, 12 March 2013 - 11:56 PM.

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#15 ehanauer

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Posted 13 March 2013 - 06:40 AM

No matter how good your white balance, you've got to fine tune it in post.
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