why is my water column in shallow water greenish?

[Sergio]

Posting this question here but not entirely sure it's the right place. Admin, please move this to the right place as you see fit.

I just returned from my one-month diving/photography stint and enjoyed my brand-new Z8 a lot but won't deny that there is much to learn about this camera (I will post a separate thread later on).

Now, one thing I noticed is that when I took wide-angle photos deeper in the water the water column showed a nice blue color while when I took photos in shallow water the water turned more greenish. I am using Retra pro strobes, so relatively warm light. One thing I did differently in shallow water is that I tried to catch sunbeams, so shot against the sun, while in most other photos I had the the sun in my back. To me, it seems that something with the white balancing is off. Of course, I could correct the white balance but the color doesn't look as good as originally expected. 

So, I was wondering if any of you pros would have an idea as to what I am doing wrong here. I did read that it would be good to also set the white balance for the strobe temperature which I assume would give a more consistent result.   

 

[TimG]

Hi Sergio!

 

Could you post an example?
 

First thought is that the ambient sunlight in shallower water overpowered the strobes output.
 

In deeper water with less ambient light, the strobes would illuminate your subject and produce the sort of colours you were expecting. However in stronger ambient light the strobes will not be as effective and other colours will be evident dictated by the effect of sunlight and not strobes. 

[Dave_Hicks]

Pictures, settings, location? Strobes should not be a factor as they don't impact water.

 

How you are processing your photos matters a lot. AutoWB in camera, white balance adjustments in post-processing software are the relevant factors. Generally, you would fix this in editing to create the water color that you saw or desire for the image.

[Sergio]

thank you guys. I will post a couple of photos including meta data here to show what I mean. I do use autoWB but then use Lightroom to adjust for WB. However, my experience was that unless you apply some heavy-duty masking, the color never quite gets to where I'd like it to be. 

[Sergio]

I tried to upload 2 photos and reduced them to 50% as there is a limit but I am still getting an error.

Will try at a later time. Might be that the server has some issues;-)

[TimG]

Hey Sergio

 

We did have some server problems earlier but we think they have been sorted and you should have no problem uploading images now.

 

Tim

[Sergio]

Hi Tim,

 

I just tried it again and am still getting the same error. The files are about 2 and 3 MB so it shouldn't be the size but it seems uploading even just one file causes this error.

 

Sergionull

[TimG]

It's really odd, Sergio,. I uploaded files yesterday without a problem.

 

Can you reduce the file size further and have another go? I don't think a large file is really necessary for us to see what's going on. 

[Adventurer]

On 6/11/2024 at 4:35 PM, Sergio said:

Now, one thing I noticed is that when I took wide-angle photos deeper in the water the water column showed a nice blue color while when I took photos in shallow water the water turned more greenish.

 

 

Hello Sergio, as far as I understood you are talking about the ambient light. The part in the picture your strobes cannot reach, correct? It would be good to know, if you also changed settings upon ascent. ISO and/or shutter speed need to be re-evaluated whenever the ambient light changes. Different water depth is such a change. You should be able to archive nice blues at any water depth. The color temp of your strobes and auto-wb has a minor influence, too. But I recommend not to focus on that part too much. 

Edited June 13 by Adventurer

[Chris Ross]

3 hours ago, Sergio said:

Hi Tim,

 

I just tried it again and am still getting the same error. The files are about 2 and 3 MB so it shouldn't be the size but it seems uploading even just one file causes this error.

 

Sergionull

Resize the files to 1200-1600 pixels on the long side and then save them as jpeg and adjust quality, to get the file size down, you should achieve 300-400 kB easily this way.

 

As to your question , in shallow water green light is still coming through and has not scattered out as yet, if you are shooting into the sun, then it will be bright and may even have some red in the mix. 

 

However post your examples, there are different ways to approach this depending on your starting point.

[Sergio]

Thank you all. Sorry about that. I reduced the file size to something more manageable and now it works 😉

 

The photos are simple exports from the raw file, unprocessed and not cropped.

 

First photo DSC_6243.jpg:

ISO 320

31.5mm

f/13

1/200s

Depth: about 3m

 

Second photo DSC_6323.jpg

ISO: 100

29.5mm

f/13

1/100s

Depth: about 19m

 

 

Edited June 13 by Sergio

[Chris Ross]

 I commonly see various aquas/greens in bright shallow water in my shots.  It seems to me the cause is the reds, yellows have not scattered away and there is always some algae in the water which shows up under these conditions.  Easier to fix on the Raw file perhaps.  Basically you need to add some magenta, the browns in the corals to my eye contain some green so move tint towards magenta some more. 

 

I had a look at the image in PS (I don't use lightroom) and added some magenta in levels, however any global adjustments don't really do the full job as they will send off the subject colours.  SO I then used a Hue/saturation layer and went to the cyan channel and pushed the Hue towards Blue:

Here is what I got you can adjust the hue to your taste if you work on your original image  I left a little of the aqua/green in the brightest bits and also boosted shadows as adding magenta makes the blues darker:

 

[TimG]

Well done, Sergio!

 

For me this is the impact of shooting at shallower depths and the colouration of the water when ambient light impacts on it. At depth you can get darker, richer blues. At shallower depths, not so much.

 

 

[Sergio]

33 minutes ago, Chris Ross said:

 I commonly see various aquas/greens in bright shallow water in my shots.  It seems to me the cause is the reds, yellows have not scattered away and there is always some algae in the water which shows up under these conditions.  Easier to fix on the Raw file perhaps.  Basically you need to add some magenta, the browns in the corals to my eye contain some green so move tint towards magenta some more. 

 

I had a look at the image in PS (I don't use lightroom) and added some magenta in levels, however any global adjustments don't really do the full job as they will send off the subject colours.  SO I then used a Hue/saturation layer and went to the cyan channel and pushed the Hue towards Blue:

 

Here is what I got you can adjust the hue to your taste if you work on your original image  I left a little of the aqua/green in the brightest bits and also boosted shadows as adding magenta makes the blues darker:

 

Thank you, Chris. Yes, it is possible to reset the WB, but I was just wondering why the colors are off to start with. I assumed that my strobes were perhaps not set strong enough to light the coral head properly for the camera to set the WB correctly? This photo is somewhat salvageable but others aren't, i.e. the colors get washed out or one has to go with some masking which in a busy scene like this can be potentially visible as well. I have been so far very pleased with the files that came out of the Z8 and paired with my Retras. Unlike my D200 and Z240 where I regularly had to adjust WB and remove noise, etc, these files oftentimes require a lot less work;-) So, I am essentially just trying to understand how I could actually get the WB right in camera if possible.

[Sergio]

27 minutes ago, TimG said:

Well done, Sergio!

 

For me this is the impact of shooting at shallower depths and the colouration of the water when ambient light impacts on it. At depth you can get darker, richer blues. At shallower depths, not so much.

 

 

Thanks Tim. I wasn't aware of that. Learning something new every time 😀

[Adventurer]

2 hours ago, Sergio said:

First photo DSC_6243.jpg:

ISO 320

You could have lowered that ISO and would have received nicer blues 😎

[Dave_Hicks]

The post processing above did the trick, but your shutter speed of 1/200s is pretty fast if you were going for a rich and bright colored background. Shutter speed should be your #1 tool for getting the water color you desire, before ISO or aperture. At the surface there may be lots of light, but I think you shut it down too far. Try moving from 1/100 in bright light to faster shutters as needed.

[Chris Ross]

9 hours ago, Sergio said:

Thank you, Chris. Yes, it is possible to reset the WB, but I was just wondering why the colors are off to start with. I assumed that my strobes were perhaps not set strong enough to light the coral head properly for the camera to set the WB correctly? This photo is somewhat salvageable but others aren't, i.e. the colors get washed out or one has to go with some masking which in a busy scene like this can be potentially visible as well. I have been so far very pleased with the files that came out of the Z8 and paired with my Retras. Unlike my D200 and Z240 where I regularly had to adjust WB and remove noise, etc, these files oftentimes require a lot less work;-) So, I am essentially just trying to understand how I could actually get the WB right in camera if possible.

I don't believe that's what's happening here.  Yes you likely need more strobe light to balance against the brighter ambient light.  There's various things you can do in processing to assist First pull highlights down to deal with the bright water, then boost shadows to get your subject right.  You can do a lot with this, otherwise you need to boost strobe power some more.

 

On the question of WB, I believe that technically your photo is close to white balanced, just needed some tint adjustment.  If you look at the Red/Green/Blue histograms they are all even and run all the way from 0 to 256.  This is a sign the image is properly white balanced. 

 

The Hue adjustment is restricted to the cyans and made them bluer this is outside of a global WB.

 

One thing you could try is to process for the water and boost shadows in post but don't draw on images to make a mask though!  too easy to detect.  If you have full PS the luminosity masks from Tony Kupyer are great, the free one works fine.  Otherwise copy the image and invert it and use that as your mask.  Increase the contrast of the mask so that the brightest highlights go white and it's a perfect mask.  Here is the shadow mask from your image, D3 from the Tony Kupyer action panel, D4 would basically exclude water all together from the adjustment:

 

 

With this method you don't have to deal with feathering and trying to hide the transition.  Use it on curves layer with an "S" curve pin the bottom of the curve very low down before pulling up shadows:

 

 

[Sergio]

11 hours ago, Chris Ross said:

I don't believe that's what's happening here.  Yes you likely need more strobe light to balance against the brighter ambient light.  There's various things you can do in processing to assist First pull highlights down to deal with the bright water, then boost shadows to get your subject right.  You can do a lot with this, otherwise you need to boost strobe power some more.

 

On the question of WB, I believe that technically your photo is close to white balanced, just needed some tint adjustment.  If you look at the Red/Green/Blue histograms they are all even and run all the way from 0 to 256.  This is a sign the image is properly white balanced. 

 

The Hue adjustment is restricted to the cyans and made them bluer this is outside of a global WB.

 

One thing you could try is to process for the water and boost shadows in post but don't draw on images to make a mask though!  too easy to detect.  If you have full PS the luminosity masks from Tony Kupyer are great, the free one works fine.  Otherwise copy the image and invert it and use that as your mask.  Increase the contrast of the mask so that the brightest highlights go white and it's a perfect mask.  Here is the shadow mask from your image, D3 from the Tony Kupyer action panel, D4 would basically exclude water all together from the adjustment:

 

 

With this method you don't have to deal with feathering and trying to hide the transition.  Use it on curves layer with an "S" curve pin the bottom of the curve very low down before pulling up shadows:

 

 

Wow, thank you very much, Chris. Lots of things I don't understand, but will dig into this and find out more;-)