164 replies to this topic

[jimbo1946]

Alex - Thanks a million for starting this thread! I learned a lot from it. I had never even thought about not using a strobe underwater, since it was axiomatic that the strobe "paints the color in."

I should have picked up on the fact that at greater depths, my wife uses a red filter on her U/W video (no lights) and the color looks amazingly good, although not very saturated.

Some of you older folks may remember back about 10-11 years ago when Kodak introduced an underwater 35mm color slide film. It was a disaster and they discontinued it after a year or two. One year at the Nikonos Shootout, we had to use this film (Kodak was one of the sponsors and they donated the film). The film added red to the image to perk up the background, so in order to keep the strobed foreground from being too red, you had to attach a huge color correction filter over your strobehead with a big rubber band. Not only that, there were two different filters to be used, depending on your depth. I'M NOT MAKING THIS UP!!! Everyone hated using the film and the very awkward filter, but we had no choice.

I still have two rolls of the film, in my freezer for all those years. If anyone wants to experiment, let me know and I'll send it to you.

Thanks again for the thread. It definitely is a paradigm shift, to use some newspeak lingo.

[Cybergoldfish]

I remember using this film on the Thistlegorm in Egypt around 93. It gave great pinky red tones to silvery fish when used with a naked strobe. I still have em somewhere. There was an extra layer of red introduced into the film - It was ok, for the shallows and the snorkling fraternity for whom it was designed, but I am surprised photographers would use it seriously for general uw use with strobes, let alone competitions.

Not quite sure what you meant about strobes painting the subjects - They mearly mimmics daylight, the colour is already there, if anything it is the filters that paint the subject, by altering the wavelengths.
99.9% of photographers are not wrong by using strobes, and I have yet to see filters capable of 'fill' against the sun, or proving practical for general uw photography at common depths.

[jimbo1946]

Not quite sure what you meant about strobes painting the subjects - They mearly mimmics daylight, the colour is already there, if anything it is the filters that paint the subject, by altering the wavelengths.

"Paints the color in" (or something similar to that) was a term used by my first instructor in U/W photography. He meant that the strobe puts back the color that the light traveling through the water column has lost, especially the warmer colors.

In effect, a color-correcting filter does the same thing, but somewhat less selectively.

I agree about serious photographers not using an underwater film. We hated the stuff and only used it one year at the Shootout because we had no choice. Everyone griped so much that they went back to regular Ektachrome the next year.

[craig]

Filters don't alter wavelengths. They simply adjust the balance of wavelengths already present. Strobes work additively while filters work subtractively. Neither "paints" color.

Once upon a time 99.9% thought the world was flat.

[Cybergoldfish]

That's what I meant, but I'm English and lack technical elequance! Hey, my spirit level is never wrong and how many strobes have you got Craig?!!!

[craig]

Hey, I switched from video to still just so I could use strobes! Can't have too many I always say.
I'm still looking for a good use for that monstrous Hartenburger 625 Watt-second beast.

I'd never suggest filters could replace strobes. Far from it, but they can be another useful tool. Video shooters would be lost without them.

[jimbo1946]

Once upon a time 99.9% thought the world was flat.

It isn't?

[jimbo1946]

One last comment on this fascinating thread.

In "Wonders of the Reef," Stephen Frink writes:

To record the wealth of color so typical of the coral reef, a submersible flash is an indispensable tool. If the available-light scene is the canvas, the strobe is the brush that brings to life the bizarre palette of the underwater world."


That's what I meant about "painting in the color."

[Alex_Mustard]

Since we are underwater photographers and feel naked without our strobes...

a few years ago i bought a 50CC Cyan filter to fit to my strobe to use for shadow fill in shots where I was using a 50CC Red on my lens. I never got round to using it - too much hassle - but the theory was that the filtered strobe would have the same Colour Temp as the available light and could be used to fill shadows rather than provide colour. As flash is used on land.

I think Kodak reccommended Cyan flash filters with their UW film? I had no experience with the film myself.

Now I'm a digi-guy I'll have to search through the cupboard for the thing, and if I find it I will give it a go. Although it does defeat the object of the flash-less compact rig for available light shooting.

[Alex_Mustard]

I use the red filters rather than magenta because when I first played with filters underwater I was told to use red in blue transmitting clear tropical water and green in turbid, green transmitting temperate water. And so I have stuck to Red Kodak Wratten's because we had some old ones here at work that I could steal (I was a poor PhD student at the time!).

So please don't think I'm expressing anything other than opinion! I think Craig's arguments are sound and I intend to try some of the filters he reccommends next time I'm away. However, I think that if I am customising white balance in the water I think that it will be very hard to see the difference between the filters - because the intention of the white balance calibration is to produce the correct colours and it should do this for both.

White balance calibration will hide any lack of subtlety in the filters. So long as you get close with the filters - it should sort it. If you ask white balance to do too much it will start shifting colour unrealistically. e.g. if you try to do it all with the electronics and don't use a filter. But I don't have any experience of what the limits are?

I would encourage everyone to experiment because amongst the people here at wetpixel we have a core of folk who are pushing these techniques forward. The more we can learn and share the better for us all.

I'm off to Cayman at the end of the month and I'm sure I will manage to squeese in a few available light dives, with my grey card stuffed down my BC's cumberbund!

Alex

[craig]

Here is a link (http://www.seafriend...graph/mixed.htm) to a photographer that discusses using filters and strobes underwater. Worth a read.

[Andi Voeltz]

.cc

[Andi Voeltz]

I'm off to Cayman at the end of the month and I'm sure I will manage to squeese in a few available light dives, with my grey card stuffed down my BC's cumberbund!

Hi all,...

the greycard has been mentioned here in so many threads. Maybe some people could post a picture of their greycard. Because when reading about it again I wondered if it is something standarized which I overlooked. So far I always used a white sheet of paper, when I wanted to white balance my camera manually.

So thanks in adnvance for the verification guys! I just wanna be on the safe side bfore I have to pack up my rig for the next trip. B)

CU, Andi

[craig]

Try www.warmcards.com. Underwater I use a slate or a gray glove but I'm going to try the warmcards on my next trip. They appear to be waterproof but we'll see.

[Alex_Mustard]

Hi Andi,

Depending on the way your camera is programmed you will need either a grey or white card to calibrate the white balance. Possibly over simplifying how it works - your camera knows what "colour" the card should be and if it is not that colour it works out a white balance setting that will produce that colour. And then applies this calibrated white balance to any other pictures you take with the setting. Hopefully giving nice colours!

I initially bought a cardboard grey card from jessops to try out manual white balancing on land. I then went to a local plastic shop and bought a cheap plastic box lid that looked most like my card. I started using the box lid as a grey card in Cayman to take the pictures above. During that trip, my friend Steve Broadbelt of Ocean Frontiers started teasing me about my very professional looking grey card, and remembered he was given a plastic grey card on a course he had done. And since he never uses it, he gave it to me. So I now use that!

I guess that is a long way of saying I use a plastic grey card from Calumet! I have to say that I can't see any difference in the shots compared with the lid - although I do look much more professional now!

Alex

[Cybergoldfish]

Why not Laminate the cards in various shades?

I calibrate my Nikonos' using a light grey, but only in the workshop!

[ReyeR]

Anyone heard or used this product: Expo Disc ?

[Cybergoldfish]

No, but I imagine every American will buy one tomorrow!

[wetpixel]

I use the expodisc on land, and love it. It's really worth every penny.

[Arnon_Ayal]

I use the expodisc on land, and love it. It's really worth every penny.

Hi,
I have few questions:
- I herd that the Expo/Disc works well to calibrate the 18% gray but less as WB, what is your experience with that?
- Does it work well under non homogeneous light? Like when there are few different sources of light or at night.
- How many stops it’s reducing?