wide angle white balance

I have been following the threads on ambient light photos using fiters to get some color back into the photos. My qestion is when setting the white balance on the camera, at depth, does the white card have to cover the entire frame?

I plan on using my 10.5mm FE on a d70 and the field of view is quite large. I was hoping to be able to paint one of my fins white and be able to use that as a white card..

I've been playing about with the same set-up recently on my Fuji S2 + 10.5mm.

The Fuji manual states:-

"Hold up a piece of white paper or similar object under the traget light source so that the paper fills the viewfinder screen". This is probably why the focus has to be in manual.

I was using a small white slate but realised it would have to be a larger A4 / 10x8 size if it was to work. Also toyed with the idea of adding a small black cross to let autofocus get a grip, but have not tried that yet.

I don't think a fin will work - I've got some pool test shots with the small slate at my feet when using the 12-24 at 12mm and the coverage with my feet in shot is much bigger than a fin would be - the 10.5mm would be worse.

Don't know it this helps with your D70 set-up though.

Cheers

Rob

Shoot RAW.

~Matt Segal

It does not need to cover the whole frame - as long as it covers most of it.

Also there is no need for it to be in focus (unless you are shooting in AF-S when the camera won't fire the shutter unless it is in focus)!

Finally if you don't have card with you - you can always set the white balance on the sand or even the scene you are shooting, providing there is not completely dominated by a large subject of single, strong colour.

As Matt sugggests shooting RAW can dispense with a lot of this hassle. Although white balancing in situ saves you faffing about in RAW convertors and gives you the satisfaction of getting great images straight from your camera.

Alex

Although white balancing in situ saves you faffing about in RAW convertors and gives you the satisfaction of getting great images straight from your camera.

Ahh, yes, I do remember you espousing the tremendous JPG images you got from your D2X...that is, until you started processing the RAW files

~Matt Segal

I totally agree with you Matt about always shooting RAW.

But for available light photography there are advantages to seting a custom white balance while in the water. And RAW and custom WB are not at all mutually exclusive!

I think the best approach for available light filter photography is to shoot RAW AND to white balance. This gives you a good starting point for WB in the RAW converter, which you may not necessarily want to change. Of course you can reach this same setting in the RAW converter without UW white balancing, but it is always useful to get a white balance setting from the real conditions. Plus this approach gives you the satisfaction as a photographer of getting the shot while you are underwater.

Here is a screen grab of some of my WB shots from 2 years ago (wow that seems quite a long time ago now). The colours look great straight from the camera and they are shot in RAW so I can fine tune them if I want.

Hope this clarifies what I said.

Alex

White balance is an interesting topic. Everyone seems to have a different opinion of what the correct white balance is - based on my observations aboard MV Shear Water this year.

My old edict used to be just "click the white balance eye-dropper on the sand." But I've since learned that it really depends WHERE on the sand you click.

Since the water absorbs light, clicking on the sand in the foreground will result in a different white balance than clicking on some background sand. I'm sure you know this already Alex, I'm just posting it for others benefit.

I took a few minutes to put together a series of example photos:

In the first photo, I clicked the white balance dropper on the sand in the foreground - so the white balance didn't have to account for the light passing through a lot of "bluing" water:

In the second shot, I clicked way behind the shark, in the plane of the diver (Juerg Vonwil). In this photo, the sand in the foreground is tinged orange/red because the white balance is in correct:

In this last photo, I clicked on the sand right underneath the shark resulting in what I consider a "technically correct" white balance - meaning the white balance of the main subject has been calibrated against a white reference w/ the same amount of water betwen the subject and lens:

I hope this post is useful. Maybe I need to make this a short tutorial now that I've done the work.

Cheers

James

Funnily enough I was just writing article on this topic this morning. I find the best place to click for this sort of scene in Adobe ACR is a foreground sand/highlight. If you click too deep into the image you are setting the WB for a longer light path than the foreground and as such the foreground will be over filtered and too warm.

It is always worth trying a few places in the frame. For me the first image is the best. The other two have pink sand!

If you are planning to crop the image after RAW conversion then you can get away with clicking deeper into the image. In an example like this one - this will ensure the subject is correctly WBed. As James has done in the third example.

I also find that it is well worth giving contrast a tweak up with available light images in ACR.

Alex

James,

You calling the last sample the "technically correct", in my understanding its problematic since it calibrate the white sand that if far from the photographer to be white, in real to the eye of the diver, the sand there looks blue because of the water's filter. its also 'makes' the nearest sand to became red and not like its looks.

And to complicate matters, this was in the bahamas where the sand sometimes IS pink...:-)

What I mean by technically correct is that the main subject is properly white balanced. Since the sharks rarely wear a white slate, it's easier to click on something you KNOW to be white, on or near the subject. Sometimes that's a shark's belly or chin, white sand under the subject, etc.

Also keep in mind that like Alex says, even if the subject is properly white balanced, foreground white stuff is going to look pink if it's significantly closer than the subject.

Cheers

James

ACR will often produce pleasing WB values from neutral colours like grey sharks. It doesn't always need to be white.

In an example like this there is no foreground white. So you have to hunt about on the subject to a suitable spot to White Balance. This means that you can get correct WB on the subject without pink sand.

Alex

To clarify, after reading James's comments on the home page. I was talking about available light shots. Although the same rules apply to mixed lighting under some circumstances.

Alex

Most of my diving is up north in Minnesota. As such the water is either brown, green or some combination of both. Using RAW and later WB in PS CS has saved many images. Like the sharks, the northern and pan fish up here don't swim around with a WB card and there is very little naturally occuring white in the water (no sand - just mudd).

I have had some good luck WB off of my dive buddies BCD which has some grey, white and black parts. WB off of the grey and white parts has yeilded some good results. My technique is to take a shot of my buddy while he is at the same depth and distance from me as my intended subject. Then use that image's WB and apply it to the next few images I take using PS CS.

For my next few dives I plan to attach a WB card to my buddy so I have a bigger WB target.

Any other suggestions are greatly appreciated. Please keep this thread going......

Dont you run the risk of loosing detail in highlights if you set WB by using the above mentioned method? There is very little truly white underwater, so if you "force" WB this way I would imagine you'd be left with an image whith some detail lost in the highlights.

You would probably be able to see this in the histogram.

Personally I tend to look for a grey/neutral spot, they are much easier to find in my opinion. In a way setting "grey balance" , rather than white balance... How does that sound?

Dont you run the risk of loosing detail in highlights if you set WB by using the above mentioned method? There is very little truly white underwater, so if you "force" WB this way I would imagine you'd be left with an image whith some detail lost in the highlights.

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This isn't a problem Snappy!

The WB dropper in ACR does not effect exposure. It only effects the colour balance. So it will set the colour of the sand to a neutral white, but it won't pull the exposure to pure white. So highlights don't get clipped.

Good question though.

So in this way it is different from the white point dropper in Photoshop levels.

Alex

Thanks for the clarification Alex. My tips were only meant to apply to ambient or mixed light photography where no filters are used.

I'm not sure if the after-the-shot white balancing procedure would be affected by filter use though - what are your thoughts?

Cheers

James

Naah. Pretty much the same.

Flash shots where the strobes are as bright or brighter than ambient are a different matter.

But certainly in your examples you are using just a touch of strobe light in your images (to fill shadows) and so the WB correct is very simillar to ambient light shots (in WB terms) with or without filters.

Alex

James, that's me on your picture. can you send it to me by e-mail? thanks Juerg

So, have been looking at the thread now and have a few points to bring in but who knows how relevant it is as it applies more to video than photo.

I have not messed around with WB on the actual camera, only on RAW afterwords and not by using the eyedrop, just dragging the point up and down. Wasn't even aware there was an eyedropper....oops, should try that i guess.

Anyhoo, with video i carry a slightly off white slate and fill about 2/3s of the frame when using manual white balance. I do this probably 10 or 15 times a dive, any change of depth, change of sun position (at my back or in front of me), change of direction in shooting etc. I always leave the red filter on. When using lights, i WB with red filter and lights pointing at slate, colours much better that way.

Soo, am thinking as Alex says, its easier and probably more realistic colours to just put an off white dive slate in your bcd pocket and leave it there all the time no?

But... and this is the kicker, as i have not even looked for such a thing on my D70. Is there a WB set button on digital still cameras like there is on video? Can you put the slate in front and just push the trigger and somehow it WBs? is this something available on the D70 and should i know about this? On available light shots in the often murky channels around here the manual WB on my video is an absolute must. How do you do this on a still?

But... and this is the kicker, as i have not even looked for such a thing on my D70.  Is there a WB set button on digital still cameras like there is on video?

<{POST_SNAPBACK}>

Interesting points, Mike.

WB is one of many controls on a digital still camera - and most are not setup so that when you punch them it sets the WB at whatever the camera is looking at (a lot of videos are like this). Usually on still cameras it is press the WB button, rotate a dial and press the shutter!

On some housings this is easy to do, while of others it is a bloody nightmare. And remember you are doing all this with one hand because your other is holding the grey/white card! My D100 was easy, my D2X is less so.

Our problem is that white balancing UW is a new technique for stills. And the fact that we want to do it has not really filtered back to housing manufacturers. Imagine a video housing that made white balancing that tricky - I cannot see that selling well.

It would be nice if housing manufacturers were able to consider what combinations of controls we might be using underwater. Ergonomics is not just about fantastic looking and feeling controls. They should also be well positionned to allow us to use them in real world shooting.

Sorry for not really answering your questions and ranting instead!

Alex

p.s. The D70 will let you custom WB on a slate or on the sand/scene you want to photograph. I am pretty sure it will also let you dial in a manual WB colour temperature of your choice (my camera does).

If memory servers - on the D70 set WB to custom/preset. Then rotate the primary control dial and take a picture of the scene you want to use to set the WB. But don't trust my memory - check the manual!

RAW makes it less essential to do this on stills while underwater because you can set the WB in ACR or equivalent.