What did I do wrong?

Ok so I'm just back from a fantastic weekend in Bali, diving was great and the beaches were empty. I got some very good pics (and lots of dross too) but can anyone tell me what I did wrong here?

I pointed the camera upwards, the depth was about 15m (and sunny day). The strobe fired (S&S YS-25DX) albeit on a low setting, but the pic comes out like this. I took a couple of other photos of the same shoal (with less fish in so not as nice) and they came out much better.

Have I simply exceeded the dynamic range of the sensor?

I guess I can improve it a bit in photoshop, but what should I have done?

Please don't let the answer be 'bought a better camera'! (it was a sony P9)

Thanks in advance

nicholasmo,

I will take a stab at this one.

My initial thought was that the strobe/subject distancewas too far away, which I still think had something to do with this. The color balance is a little out of wack. But as I looked at it closer I think the problem is you tried to do something extremely difficult for any camera.

The top of the image has some extremely bright sky shining through, the bottom is a dark blue. Coupled that range with a subject that is highly reflective like a school of silver fish, and you have a very difficult exposure to capture.

More flash power would have brought out the fish, and taken some of the green/blue color cast out, but probably would have blown out the top and some of the fish. Just for kicks, I desaturated the image to get an idea of the range you were trying to capture. I did nothing else.......take a look at the range you were trying to capture in this image. It pretty large for any camera to accomplish.

The only way I can think of would have been to use more power on the strobe, with a diffuser, and have the strobe pointing down to try and direct the light to the half of the image that needed it most. Perfect application for digital to attempt multiple shots at multiple power levels and exposures.

I will be anxious to hear what others have to say. It would have been a great image.

Your strobe did not have any effect on this image. Look at the RGB separation:

You can see that there is almost no red detail at all and what little there is comes from the top

rather than from the strobe. The green and blue channels are virtually identical except that the

green has a much stronger exposure. The darkest parts of the image are not particularly dark

so it's not really a dynamic range issue.

What you really want is for the fish to have a nice neutral tone and the background to be blue

to cyan but there's no easy way to get this because virtually everything is cyan. The two things

you need to do are increase your strobe power and make sure you are not shooting into the sun.

An FL-B or magenta/red filter would have helped this shot considerably. The goals are to reduce

the exposure in the green, to increase the detail in the red (by filter, strobe or both), and to

eliminate the overexposure at the top by aiming away from the sun. You won't get blue water

at the top unless you do that.

Very good example Craig. Thanks for posting it.

Cheers

James

Thanks to all of you for the help. Seems like lack of strobe power and pointing at the sun were the biggest problems.

Regarding strobe power, the power setting for the strobe (on my setup) is manual, so is obviously a guess. Generally is it better to give too much power or too little? I.e. assuming I am going to adjust the image in photoshop afterwards will I get better results by under 'strobing' or over 'strobing'?

Cheers

Nick

Thanks, Craig

Great example and explanations.

I would say when you are unsure: over strobing, under exposing. So you get enough "good" strobe light on the subject and if it was too much you correct it with the exposure (when you shoot in raw you can do this afterward)

But there are more experienced Photographers out there and this is just my understanding.

Simon

The risk of too much strobe in this case is darkening the blue background. Eventually the background will go black and you still overexpose the fish. The fish are reflective so strobe power goes a long way, but you don't have a powerful strobe either. I doubt that full power with the YS25DX would have been too much but I haven't used it. I'd start there, get the exposure correct, then see if the background is nice. If it's too dark, reduce the strobe.

Regarding PS, if you understrobe, there will be too little color and contrast to work with. If you overstrobe, you might have blown out highlights and too much contrast. I think if you're careful with exposure, you'd probably be happier trying to fix too much strobe rather than not enough, but getting it about right isn't really too hard. It takes a dive or two of practice along with check the results carefully.