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Thread: Backlighting equipment and technique

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    RBW Member systematic.entropy is an unknown quantity at this point systematic.entropy's Avatar
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    Backlighting equipment and technique

    So, I am taking my last stab at underwater photography. Current setup;

    Canon Rebel XT with Ikelite housing and two DS125 strobes. I know I really should use some backlighting triggered by slave controller, to prevent backscatter, my question is, how big of a backlighting strobe should I be looking for? Any suggestions on one that mount to a diver easier than others?

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    Underwater photographer Alexcacciafotosub is an unknown quantity at this point Alexcacciafotosub's Avatar
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    Re: Backlighting equipment and technique

    To avoid the backscatter you just have to move back the flash output it behind the plane of the sensor. See the picture below.
    I hope to have been useful.


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    Re: Re: Backlighting equipment and technique

    Quote Originally Posted by Alexcacciafotosub  View Original Post
    To avoid the backscatter you just have to move back the flash output it behind the plane of the sensor. See the picture below.
    I hope to have been useful.

    This will work only if you can change the laws of physics. The backscatter doesn't care where the strobe is fore and aft, only how far to the side it is. Your goals are (1) move the strobe to the side so as to increase the angle between the light and the illuminated particles, and (2) aim the strobe so it does not illuminate the particles between the camera and the subject.

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    Underwater photographer Alexcacciafotosub is an unknown quantity at this point Alexcacciafotosub's Avatar
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    Smile Re: Backlighting equipment and technique

    I have not changed the laws of physics, but what I said is the result of over 15 years of experience in underwater photography. Placing the flash backward and open outwards slightly reduces the backscatter, which in any case can not be deleted altogether.

    Greetings
    Alessandro

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    Re: Backlighting equipment and technique

    Back lighting works well for carefully staged shots but is not really practical day to day use.
    Try using just one strobe on a long well articulated arm and experiment with positioning it. Camera in one hand strobe in the other and keep varying things until you get the result you want. Personally I try to set the camera to give the background exposure I want then position and set the strobe to illuminate the fore ground. As Alessandro said behind and pointing outwards works well.

    S

    P.S. most of my photographs are rubbish

    P.P.S. Is entropy really systematic?

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    Re: Backlighting equipment and technique

    The may be out of print but DIVERS AND CAMERAS, Joe Strykowski, and in several books by Jim and Cathy Church book all suggested the same approach to lighting and it has always worked well for me. Place one light source to the right of the camera and another on the left. The subject should see one light source at 45 degrees to the left of the camera and the 45 degrees to the right of the camera. Stobe arms work just fine.
    If I can make a suggestion. Consider not using strobes. Use video lights instead. They are either on or off and you do not have to wonder if they are going to pop off or not. The colour balance is good and most importantly, what you see is what you get, rather than I wonder how that is going to look when I get home. If there is a back scatter problem you know about it before you take the shot. With most digital cameras you have the option of shooting video. Combinations of video and stobes can also yields good results.
    While problems like backscatter have to be overcome in underwater photography the difference between snap shots and photographs is most often the lighting. It does not matter if it is still photography or video it is not complicated and very formulaic and can be found in most basic photography texts.
    Good luck.
    PS If you achieve full frame illumination you will be miles ahead of the rest of the crowd.

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    RBW Member systematic.entropy is an unknown quantity at this point systematic.entropy's Avatar
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    Megalodon

    Backlighting equipment and technique

    Thanks for all the good pointers. Unfortunately, my recent trip to cave country really didn't give me any time to fire off any shots. All the dive buddies just want to rush to the end of the line. With any luck, wreck season will star soon though.

    PS. Re:"systematic.entropy", glad you get the joke.

    John
    BS mechanical engineering


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    Re: Backlighting equipment and technique

    I have used Ikelite SS 200's, SS 225's, SS 150's as slaved strobes in shots, as well as DS 125's. All have to be wired with external slave triggers to synch with on camera strobes. You will need help shuttling all the equipment to your location of the shoot. Lights are placed around the "set" lighting both the subjects and the background for the most pleasing effect. Some photographers simply clamp a strobe onto a model's rig and aim the strobe backwards, with a slave sensor cable running down the subject's arm, and they holding the sensor and pointing it toward the camera, so it synchs. That method is hit and miss to be sure. Other photographers use models and another diver behind the model aiming the slaved strobe directly toward the back of the subject, rim and halo lighting the subject, this method is slightly more successful in lighting the subject, but not the environment. Unfortunately you will need not only a model but a diver dedicated to just holding a light for you. Tough sell to a diver, as they won't be in any images and they sacrifice their dive to be a "gaffer" of sorts. Of course the model and the gaffer can swap places. If I attached the image right here, you can see a rather ambitious lighting setup using several background strobes in a very high flow section of Ginnie Springs, called the Lips.
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    Backlighting equipment and technique

    Quote Originally Posted by Dan Wright  View Original Post
    I have used Ikelite SS 200's, SS 225's, SS 150's as slaved strobes in shots, as well as DS 125's. All have to be wired with external slave triggers to synch with on camera strobes. You will need help shuttling all the equipment to your location of the shoot. Lights are placed around the "set" lighting both the subjects and the background for the most pleasing effect. Some photographers simply clamp a strobe onto a model's rig and aim the strobe backwards, with a slave sensor cable running down the subject's arm, and they holding the sensor and pointing it toward the camera, so it synchs. That method is hit and miss to be sure. Other photographers use models and another diver behind the model aiming the slaved strobe directly toward the back of the subject, rim and halo lighting the subject, this method is slightly more successful in lighting the subject, but not the environment. Unfortunately you will need not only a model but a diver dedicated to just holding a light for you. Tough sell to a diver, as they won't be in any images and they sacrifice their dive to be a "gaffer" of sorts. Of course the model and the gaffer can swap places. If I attached the image right here, you can see a rather ambitious lighting setup using several background strobes in a very high flow section of Ginnie Springs, called the Lips.

    Where do I sign up to be a Dan Gaffer? You rock bro! Holy smokes.




    Garth

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    Underwater photographer Alexcacciafotosub is an unknown quantity at this point Alexcacciafotosub's Avatar
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    Smile Re: Backlighting equipment and technique

    Here are some pictures taken on the same dive to 70m. Visibility sometimes bad, sometimes slightly better. The two flash are positioned one right and one left, very backward and away from the optical axis with two pairs of arms 50 cm each.







    Here are some more pictures taken in another situation, at 50m, with excellent visibility, with the same settings on the camera and flash:





    As you can see, sometimes there are no alternatives!

    Greetings
    Alessandro

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