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Thread: Advice on flesh photography

  1. #1
    Jason H0
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    Default Advice on flesh photography

    Hi

    Got a question on flesh photography. If i use a shutter speed that is faster e.g. 1/500s than the sync speed of the flesh, how would the photographs turn out? Would the shutter open and closes so fast even before the flesh has finished firing its light, that it would cause certain portion of the frame to be marked with a white stripe of exposure?

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    Flesh photography? Wah this is gonna be a hot issue :P

    Do you mean 'flash'?

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    Flesh photography sounds really evil. Hehe. It depends on whether your camera has the ability to flash-sync at 1/500s. I assume you're using the D70, it shouldnt be a problem.

  4. #4
    Jason H0
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    sorry i mean the flash. i am using not canon nor a nikon.

    Quote Originally Posted by hazmee
    Flesh photography sounds really evil. Hehe. It depends on whether your camera has the ability to flash-sync at 1/500s. I assume you're using the D70, it shouldnt be a problem.

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    i think someone mentioned somewhere in a different thread..
    something like "it is not possible for the shutter to open and close faster than your flash" i ca't rem e exact words...

    but i guess it means spd of light is way faster then e fastest cam shutter speed. so i believe u dun have to worry too much there.

  6. #6

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    such a coincidence... i was doing a shoot on the weekend, and i needed a shutter speed faster than 1/200, so i set the flash to high speed-sync.

    Results, i get light fall off in the photo, so the bottom edge (and presumably the top, but its already bright) is a bit darker. Gives an effect similar to a spotlight, where the center regions is exposed correctly, and the light starts falling off. I suppose its because the flash has yet to fire fully, so the light doesn't fall fully into the capture area?

    I'd post the photo, but its still in my card in RAW format, and my laptops still in the repair shop ...

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    If your talking about hotshoe flash, the duration is about 1/8000s. For strobes, its slower at about 1/800s. So techincally, its only possible to be faster than the flash at these speeds. Even then, the results would just be cutting out the light and underexposure, not banding. Banding occurs when the flash is unable to sync with the shutter, and its more of a electronics synchronisation problem. That said, most systems nowadays have a sync of min 1/200s and its pretty good most of the time unless your doing daytime sync in the hot sun.

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    some parts of the pic might not be properly exposed (to the flash).

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    i think what he meant was if the shutter speed is faster than the duration of flash? that's how i read it..
    “How fortunate for leaders that men do not think.” - Adolf Hitler

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    if shutter speed is faster than the duration of flash, you'll just get an underexposed pic (in terms of flash exposure). Flash duration is generally faster than 1/1000s except for large strobes which could be longer when fired at full power.

  11. #11
    Jason H0
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    I am experiencing banding, i.e. some portion sof the photo are properly exposed and areas outside is not. Can see the areas of these 2 clearly as there is a line segregating across the frame. Cannot remember if it is at the top or bottom.

    I was shooting with a manual body and external hotshoe flash in bright sunlight. I think the shutter speed was faster than 1/125s.

    Quote Originally Posted by Splutter
    If your talking about hotshoe flash, the duration is about 1/8000s. For strobes, its slower at about 1/800s. So techincally, its only possible to be faster than the flash at these speeds. Even then, the results would just be cutting out the light and underexposure, not banding. Banding occurs when the flash is unable to sync with the shutter, and its more of a electronics synchronisation problem. That said, most systems nowadays have a sync of min 1/200s and its pretty good most of the time unless your doing daytime sync in the hot sun.
    Last edited by Jason H0; 9th May 2005 at 02:43 PM.

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    Quote Originally Posted by Jason H0
    Hi

    Got a question on flesh photography. If i use a shutter speed that is faster e.g. 1/500s than the sync speed of the flesh, how would the photographs turn out? Would the shutter open and closes so fast even before the flesh has finished firing its light, that it would cause certain portion of the frame to be marked with a white stripe of exposure?
    It has nothing to do with the shutter being faster than the flash pulse, that will almost never happen. If you have activated your shoe-mounted or built in flash, the cam will not let you shoot faster than sync speed, so no worries. The exception is if you activate high-speed sync, but that is another story. Do a quick search on Google using "Flash sync speed" as your search term, some useful info will emerge.

    What you are experiencing is not 'banding', but simply a failure of the flash to illuminate the frame evenly. This will occur commonly if you are using the built in flash and a large lens/hood, which will physically block the flash light, or you are using ultra-wide angle lens, in which case the flash is unable to deliver a sufficiently wide coverage.

    Cheers,

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    Quote Originally Posted by Jason H0
    Hi

    Got a question on flesh photography. If i use a shutter speed that is faster e.g. 1/500s than the sync speed of the flesh, how would the photographs turn out? Would the shutter open and closes so fast even before the flesh has finished firing its light, that it would cause certain portion of the frame to be marked with a white stripe of exposure?
    It depends on what camera and flash you use.

    Normal flash syncs on modern cameras are typically around 1/250 to 1/500. The flash starts when the 1st curtain goes off till the 2nd curtain cuts in.

    Then there's high-speed sync flash. Usually on higher end models' built-in flash or with program flashes. These fire in multiple bursts at high-frequency and make it possible to use the flash at very fast shutter speeds.

    See the following links for more detailed information:

    http://www.photozone.de/3Technology/flashtec4.htm

    http://www.photozone.de/3Technology/flashtec5.htm

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    One way is to do it off shoe, use a IR trigger to trigger the flash accordingly to act as fill in

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    Quote Originally Posted by mpenza
    some parts of the pic might not be properly exposed (to the flash).
    you mean those covered by clothing? ha ha ha
    photography makes one sees things from all angles.

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    Quote Originally Posted by dkw
    It has nothing to do with the shutter being faster than the flash pulse, that will almost never happen. If you have activated your shoe-mounted or built in flash, the cam will not let you shoot faster than sync speed, so no worries. The exception is if you activate high-speed sync, but that is another story. Do a quick search on Google using "Flash sync speed" as your search term, some useful info will emerge.

    What you are experiencing is not 'banding', but simply a failure of the flash to illuminate the frame evenly. This will occur commonly if you are using the built in flash and a large lens/hood, which will physically block the flash light, or you are using ultra-wide angle lens, in which case the flash is unable to deliver a sufficiently wide coverage.

    Cheers,
    unfortunately, this is wrong. I can set my flash to high sync speed, which allows it to shoot faster than the sync speed. Being an external flash, lenses, hoods would not block the illumination of the subject.

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    Quote Originally Posted by darrelchia
    unfortunately, this is wrong. I can set my flash to high sync speed, which allows it to shoot faster than the sync speed. Being an external flash, lenses, hoods would not block the illumination of the subject.
    Darrel, if you read my post carefully, you would see that I have said the exception is for high speed sync. I understand full well what HSS does, and you would realise that its not really high speed at all as it prolongs the flash by pulsing it. Also, I mentioned that the blockage by the lens hood will occur if you use the BUILT-IN flash. Its all in the post, do read carefully!

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    Quote Originally Posted by dkw
    It has nothing to do with the shutter being faster than the flash pulse, that will almost never happen. If you have activated your shoe-mounted or built in flash, the cam will not let you shoot faster than sync speed, so no worries. The exception is if you activate high-speed sync, but that is another story. Do a quick search on Google using "Flash sync speed" as your search term, some useful info will emerge.

    What you are experiencing is not 'banding', but simply a failure of the flash to illuminate the frame evenly. This will occur commonly if you are using the built in flash and a large lens/hood, which will physically block the flash light, or you are using ultra-wide angle lens, in which case the flash is unable to deliver a sufficiently wide coverage.

    Cheers,
    From the description, he's shooting faster than the x-sync speed with external flash without activating high speed sync (might not be available for the camera or flash or both). The camera will allow him to shoot faster than x-sync speed if the external flash does not communicate with the camera (i.e. non-dedicated flash).

    Also, it's possible to shoot with the shutter faster than the flash pulse if the shutter is very fast (e.g. I could do 1/10000s on my old digicam) and the flash is firing at high or full power (e.g. SB80DX firing at full power giving a flash duration of ~1/1000s). But this seldom happens in practical usage I guess.
    Last edited by mpenza; 9th May 2005 at 09:43 PM.

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    Quote Originally Posted by darrelchia
    unfortunately, this is wrong. I can set my flash to high sync speed, which allows it to shoot faster than the sync speed. Being an external flash, lenses, hoods would not block the illumination of the subject.
    Most focal plane shutters work by moving a "slit" aperture (the opening between the shutter curtains) across the frame. The speed is constant, the effective exposure time is determined by the width of the slit.

    If the slit is larger than the frame, which happens at longer exposure times, the flash can be triggered at a time when the film/sensor is fully uncovered. For slit widths narrower than the frame, this condition is never fulfilled, and the full frame can not be exposed by a single, short flash. "High-speed sync" flashes work around this by essentially producing a very long flash, just like the slow ("FP") flash bulbs of yesteryear.

    Another side effect is that pictures of fast moving objects will be distorted. Depending on the relative motion of the projected image in the film/sensor plane and the shutter curtains, the object may appear squished, elongated, or sheared. (An easy way to see this effect is to photograph a flickering TV screen.)

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    Quote Originally Posted by mpenza
    From the description, he's shooting faster than the x-sync speed with external flash without activating high speed sync (might not be available for the camera or flash or both). The camera will allow him to shoot faster than x-sync speed if the external flash does not communicate with the camera (i.e. non-dedicated flash).

    Also, it's possible to shoot with the shutter faster than the flash pulse if the shutter is very fast (e.g. I could do 1/10000s on my old digicam) and the flash is firing at high or full power (e.g. SB80DX firing at full power).
    Honestly, its really difficult to be sure what the problem is unless there are some posted pics with EXIF data. Reading Jason's posts, I can only surmise that his first query about sync speed was a hypothetical one, as he had not alluded to any pics with an illuminated middle band, and the second query pertains to light fall-off in the periphery, as I frequently get shooting at 10mm on my 10-22. I agree about the non-communicating flash and shutter speeds faster than 1/10000s, but I think you would also agree that those are not very likely scenarios. Still, happy to hear Jason out, if he could provide more details, or better yet, post a pic.

    Cheers,

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