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Strobe VS Continuous Light

Discussion in 'Strobes and Lighting' started by CAPTAIN SINBAD, Apr 25, 2011.

  1. CAPTAIN SINBAD

    CAPTAIN SINBAD Divemaster Candidate

    # of Dives: 100 - 199
    Location: Woodbridge VA
    2,350
    712
    113
    Hello -

    I have been doing natural light photography for some time and would like to get into lighting. Can anyone explain what is the difference in the results of a strobe flash and continuous video light? I would think that running video light would be a better option because it enables you to see the lighted image before you click. With a strobe you would have to wait until the picture is taken and you might be in for a surprise?

    Thanks so much in advance for your inputs.
     
  2. mjh

    mjh Solo Diver

    # of Dives:
    Location: Seattle
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    Now I am the least technical person to pick up a camera so..... I have been told that unless you are shooting really slow shutter speeds, at really wide f stops even the most powerful video lights can't compare to most high end strobes for power/lumens.
     
  3. Nemrod

    Nemrod Solo Diver

    11,584
    1,732
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    Video lights are for video, strobes are for still.

    N
     
  4. jghflash

    jghflash Instructor, Scuba

    # of Dives: 500 - 999
    Location: Bonaire
    208
    14
    18
    While a video light may look bright, there is no comparison between that and the output of a strobe.....almost any strobe. As mjh said, you would be using really low shutter speeds and wide apertures to even try to get a video light to help underwater. Water absorbs a lot of light, thus the need for as much as you can get if you want good color. You can use a focus light if you want to help with "seeing" what things will looks like before you fire the flash.
     
  5. JahJahwarrior

    JahJahwarrior Solo Diver Staff Member

    # of Dives: 500 - 999
    Location: West Palm Beach, Fl
    3,593
    802
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    Unless you are diving in the total dark with no light at all, you should get atleast some idea of what your picture will be. I do primarily cave diving, and have yet to shoot much with a strobe. It's easy to see what I'm shooting because I use a light in the cave for my personal use, so I can see.

    Video lights output a steady light at a certain level. The camera is shooting at about 30 frames per second, much slower than many people are comfortable taking still shots--and if you have a moving subjet, 1/30s shots often show a blur as the subjet moves during exposure. Not a problem for video, as the next frame shows the new location and the images all kind of blend together to make a video.

    Strobe lights output sudden bursts of incredibly bright light. This way, you can shoot much faster and eliminate movement of the subject during the time of exposure.


    You can use a video light to take photos, but you'll probably see better lit and less blurry photos by using a strobe light. There is a reason that most photographers use strobes, and the only videographers who use strobes are those who film dance parties in movies :) However, many photographers do use a smaller light as a "focus light" to help the camera focus in darker conditions. You can do this with a cheap LED light clamped on to your camera arms.
     
  6. Larry C

    Larry C Dive Con

    # of Dives:
    Location: SF Bay Area
    3,220
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    As the other replies have mentioned, the strobe is much more powerful. The other factor is that even if you set a slow shutter speed, if your exposure is correct the strobe will freeze the action because the bulk of the light is firing for something like 1/1000th of a second. You might see a little blur in the background if the camera is set for an ambient light background, but the subject should be clear and sharp. I tried shooting with a divelight when I first started, and even though the lighting was right, the whole picture was a motion blur from the camera moving in the surge.
     
  7. CAPTAIN SINBAD

    CAPTAIN SINBAD Divemaster Candidate

    # of Dives: 100 - 199
    Location: Woodbridge VA
    2,350
    712
    113
    Thanks so much everyone. It seems like strobe is the way to go then.

    Cheers -

    Sinbad
     
  8. bvanant

    bvanant Loggerhead Turtle

    # of Dives:
    Location: Los Angeles (more or less)
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    While video shoots at x frames per second that doesn't mean that the shutter is open for the full 1/x seconds. We have many screen captures that are perfectly sharp not blurry at all.
    In any case to the OP, if you are shooting stills get a strobe. You can make pictures with CW lighting underwater but you will be happier shooting strobes (or at least if you are not happy it won't be the fault of the pictures).
    Bill
     
  9. Hotpuppy

    Hotpuppy Barracuda

    # of Dives: 50 - 99
    Location: Houston, TX
    248
    10
    0
    One of the things to keep in mind is that the human eye perceives detail and light about 4 times better than the best camera. The eye is a truly magnificent optical instrument. As others have said, you need faster shutter speeds to freeze action. There are no tripods or studio lights under water.

    You need at least 1/60th to freeze action, and 1/125th may be better. Most cameras will not synch any faster then 1/125th or 1/250th. The reason is that the curtain has to be completely open when the flash fires. As another member said, the flash fires at 1/1000th.

    There are a variety of ways to manage a strobe. Here are a few thoughts:

    Rule 1- the built-in flash is too small. It's too small on land, and it's certainly too small underwater. Keep in mind that water is denser than air by a factor of 8. It's ability to stop light is thus greater. Built-in flash is intended to provide fill flash and light very small scenes. Think for example, at a restaurant, Aunt Kathy across the table from you. It's acceptable for this and not much else.

    Rule 2- The more you bring with you, the more you have.
    Rule 3- If you can't hold it still, it doesn't matter what it is. Spend the money on a good tray and good mounting arm.

    Rule 4- It will eventually leak, so make sure the manufacturer thought about this and doesn't have something stupid like a unsealed battery compartment that ruins your strobe when the batteries get wet. Losing 4 or 8 rechargeable batteries is bad enough. Losing a strobe too is just stupid.

    Option 1: "slave mode" Comes in two flavors, indirect and optical. Strobe is triggered by the firing of your internal camera flash. Chews up battery power and requires your strobe to be smart enough to ignore the pre-flash that most cameras use for TTL metering.

    Option 2: Manual trigger mode: Fires the flash when you push the shutter button. Requires you to adjust the strobe power, but disables the internal flash completely. Not prone to misfires, doesn't waste battery power.

    Option 3: TTL - This is ideal because it allows the computers camera to determine how much light is reflected from the pre-flash and then set the flash to achieve a neutral 18% gray. Not everything looks good in 18% gray. Different evaluation schemes produce different results. Should prevent the general washout and underexposed look that plagues most photography. Many cameras require eTTL and some support an optical variant of it. A proper TTL implementation should extinguish the built-in flash on a Nikon or Canon camera.

    Option 4: External TTL (not the same as eTTL), uses a TTL adapter such as the Heinrich Weiskamp one or the Ikelite variety. Achieves a similar result to #3 but is not the same.

    There is no right or wrong, but you may also need all of the tricks you use with ambient light, including color correction filters.

    One of the gotchas to watchout for is the crap factor. It's officially called backscatter and essentially it's the junk in the water that gets illuminated by your strobe. The way to combat it is to position the flash to the side so that your camera doesn't see the reflection from the floatees.

    If you do not have a sound grasp of Aperature, F/Stop, Exposure, Shutter Speed, Depth of Field, etc I highly recommend investing in some basic photography classes. It will do wonders for your photos and help you with understanding how to set your camera and how to change the settings when you don't like the results.

    Lastly, you will encounter many many many *experts* in scuba photography. Take what you hear with a grain of salt, including what you hear from me. I've given you my honest opinion based on a few thousand dollars of trial and error with equipment, classes, and time. I'm not a guru .... I've been doing scuba photography for a year and photography for 25 years. Just realize that photography fundamentals still apply. You are just doing them in a medium that interferes with light transmission and will ruin your camera if it gets in contact with it.
     
    Aotus likes this.

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