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  1. #11

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    If you use a polariser on a light and a polariser on the camera you get a great deal more control of reflections than from a polariser on only the lens. You can eliminate reflections or leave them partially visible depending upon how the polariser on the camera is set relative to how the polariser on the light is set. The polarisers for lights are large pieces of "foil". They can be had as cut pieces or rolls. The four stop correction comes from 2 stops of light lost due to the polariser on the light(s) and another 2 stops lost by the polariser on the lens. You can also get a rather dramatic change in saturation
    for color.

    The density of the polariser is a constant. It does not change. Light going thru it on any angle will lose 2 stops. It effect will change as it is rotated but its density remain constant.

    In actual use you may prefer a different exposure factor then light loss caused by density of the polariser which is of course for you to decide.
    Claire (Ms Anne Thrope is in the darkroom)

  2. #12

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    Quote Originally Posted by Claire Senft
    I have done no aquarium work. I am assuming that one will be photographing in a fairly small aquarium, as opposed, to say, the Shedd Aquarium. If you have mono lights or flash head and pack that have modeling lights, you could darken the room and I think that you would be able to judge reflection problems and get a feel for the modeling quality of your lights. I imagine that you should be able to employ top light, also, if desired. If you have an incident flash meter that can be used w/o a cord You could seal it in a plastic lunch bag put it into the wate to take an exposure reading. You could also set your lighting ratios. Of course these same techniques could be used with tungsten lighting. If you wish to confine a fish to a small area you could use insert a piece of glass behind the fish.
    Here is a good application for a digicam: Use it in the same position as your film camera, I am assuming a tripod here, as an electronic polaroid.

    If you can stand the expense, a polarizer on the camera and polarizing filters on the lights will allow very flexible control of reflections. It will also allow much increased saturation with color film. The polarization will also cause a light loss of approximately 4 stops.
    I hate theorists, especially when their theories are off-base. I gave a well-proven recipe.

    Cheers,

    Dan

  3. #13

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    Quote Originally Posted by JBrunner
    In regard to reflective surfaces and lighting, light always reflects (given a uniform surface) at the exact opposite angle it arrives. If the lens is in this zone it will "see" the light source. One thing that is done is to make the reflection bigger than the object being photographed, and is accomplished with larger light sources like soft boxes etc. This would not be appropriate for your intention, and would in fact exacerbate the reflection problems. The other solution is to position the lighting to send the reflections else where than the lens. The point of the 45 is to send the reflected light off at the opposite 45 and therefore miss the lens. This is a good starting point. If you position your head where the lens will be you will be able to see what will be reflected in the field of view for the focal length you choose. If you can make the room dark, do so, and you will be dealing with a smaller set of light sources. Pushing the lens up against the glass will in effect flag the light from the lens. A Pola as stated before will help as well but can only phase half the light from a point source, and as such will be most useful for reducing ambient reflection. The proper exposure compensation for a pola is 1 1/2 stops or less depending on how far it is rotated in. Schneider makes a Pola called a Tru Pol that requires a 2 stop compensation at its strongest.
    (addendum- in re-reading the previous post I see that the 4 stop figure was
    given in regard to polarizing the lights as well. I do not believe polarizing both the lights and lens would serve any purpose except to make it very dark, as far as the camera was concerned
    I hate theorists, especially when their theories are ill-considered, and I gave a well-proven recipe.

    More seriously, in closeup work with flash illumination, one nearly always overpowers ambient light with flash. When that's the case, ambient doesn't matter, can be ignored.

    And with the right camera-flash-aquarium geometry, reflections are not a problem so there's no need to bother with polarizers. In this application, all a polarizer does is make it harder to see through the lens. Its hard enough as is, why handicap yourself further?

    Cheers,

    Dan

  4. #14
    Andy K's Avatar
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    [size=1]Lighting for fish in an aquarium.[/size]

    I think the hard part will be getting the fish to use a light switch.

    Sorry.


    -----------My Flickr-----------
    Anáil nathrach, ortha bháis is beatha, do chéal déanaimh.

  5. #15
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    Andy, I though that fish were always in newspaper, so what's all this stuff about an aquarium, whatever that is.

    Best,
    Helen

  6. #16
    Andy K's Avatar
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    Unfortunately the newspaper thing has long since been replaced with plain paper. Apparently some Health & Safety robot decided newsprint was bad for the digestion. I miss having something to read for free with my fish 'n' chips...


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    Anáil nathrach, ortha bháis is beatha, do chéal déanaimh.

  7. #17
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    [QUOTE=Dan Fromm]I hate theorists, especially when their theories are ill-considered, and I gave a well-proven recipe.


    If you read it a little more carefully you will see that it's experience, not theory. I find your comments insulting.

  8. #18

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    Mr Fromm I found no fault with your practice. Matter of fact, I much appreciated your thoughts based upon your considerable experience. I had only thought to add to the discussion. Matter of fact why not consider doing this:

    Wait for warm weather. Put the fish into a seperate vessel. Empty the aquarium of water. Clean the glass of the aquarium on both sides. Take the aquarium outside into good bright lighting. Fill the aquarium with water. Put the fish into the aquarium. Use a piece of glass behind the fish to constrain their movement. Use reflectors. Put some Fuji 16os color negative film into the camera. Set your camera for 1/250@ f9.5...1/250@f6.3 if approaching unitary magnification. Take your film to a one hour photo service. Have your negatives processed "develop only". Check your negatives with a loupe. Or as an alternate get 1 hour service with prints.
    Figure out what you did wrong. Ask the fish if they mind a reshoot. Repeat as necessary.

    There now, was it easier to see? Did the cleanliness of the glass hurt the
    photos? Are the fish better off for having a clean aquarium? Did the exercise do you good? Those are some really nice photos that you took aren't they? If Dan Fromm has spoken should all others remain silent?
    Claire (Ms Anne Thrope is in the darkroom)

  9. #19
    Andy K's Avatar
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    Most photographs I've ever seen of aquarium fish were done with a black, or very dark, background. Just a thought.


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  10. #20

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    Claire, what you discribed is basically what I've done in the field, but without the iterations.

    It works just fine, from the photographers' point of view. It works very poorly from the aquarist's/ichthyologist's perspective. The problem with it is that most fish deport poorly after being relocated. We typically want to get pictures of the fish deporting well, frequently try to capture courtship, mating, or parental behavior. On the whole, its best to find a way to shoot the fish in their home tank.

    One of the problems I've had in the field has been that my freshly-captured specimens have sat on the bottom, fins clamped and sulking, or have displayed stress coloration, not the normal. Photographers who don't know the animals are insensitive to these considerations.

    The photographic problems of shooting fish in aquaria are pretty trivial. Exposure, primarily, controlling reflections, secondarily. The hard problems have to do with inducing the fish to pose/perform where its convenient to shoot them. The real masters of the art are much better at this than I and my mob of peers, all tied for third-best. I've found it very useful to study the work of people like H. J. Richter and A. van den Nieuwenhuizen to try to puzzle out what they did to get the fishes to perform where desired.

    The iterative procedure you suggested strikes me as too much work. FWIW, when I was setting up, it took less than one roll of film to solve the biggest problem, exposure. I just took one shot at 1:4, 1:2, and 1:1 at every marked aperture on my little 55/3.5 MicroNikkor from f/3.5 to f/32. That told me which aperture to use at the test magnifications with my standard flash setup; interpolation works well for intermediate magnifications. Why screw around more than necessary?

    You're absolutely right that clean glass, inside and out, is a prerequisite for good fish pictures.

    FWIW, a very effective way to photograph fishes in the field was invented, AFAIK, by Jack Randall. If you want to search for him, he's John A. and AFAIK he's still at the Bishop Museum in Hawaii. His trick is to kill the fish, spread its fins and fix them in position by painting them with formalin. Then he lays the fish down on its side on a bed of nails submerged in clear water in a box whose interior is painted black. Shoots with the camera pointed straight down, uses flash illumination, the flashes' axes at 45 degrees to the water's surface. He's produced some superb pictures this way. But it has to be done quickly after killing the fish because some fishes' colors fade after the fish is killed. Friends of mine at Smithsonian Tropical Research Institute came up with a variation, vertical bed of nails in an aquarium.

    I thought I was clear that I wasn't presenting my practice as the best practice, although it is. Back when, I surveyed all of the practitioners I could find. We all shoot fish essentially the same way. There's only one way to do it that works consistently well. Its a specialized activity, non-practitioners don't have much of a clue. Why should they?

    One other point. Years ago I sent a portfolio to Animals, Animals, eventually dropped by when in NYC to discuss what we might do for each other. They were very positive about my work's technical quality, dubious about commercial prospects. This because at the time I was mainly shooting fish against plain backgrounds and they believed the market wanted "natural" shots of fish against nice vegetation. Well, in nature that situation is very rare.

    Cheers,

    Dan

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