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Thread: flash problems with dark surroundings

  1. #1

    Default flash problems with dark surroundings

    Hi,

    I noticed a problem. When i used flash to take pictures, only the subject im taking is bright, the background seems very dark and the picture appears very contrasting. Is there anyway to solve the contrasting problem?

  2. #2

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    Use slow synchro flash. The background will be illuminated but you'll have to bear with a slower shutter speed.

  3. #3

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    whats a syncro flash? isit an external flash? Does A60 has it?

  4. #4

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    I just briefly glanced through the A60 manual. Seems that it doesn't have the slow synchro flash mode. Try to decrease your shutter speed.

  5. #5

    Default Re: flash problems with dark surroundings

    Originally posted by ordinaryless
    Hi,

    I noticed a problem. When i used flash to take pictures, only the subject im taking is bright, the background seems very dark and the picture appears very contrasting. Is there anyway to solve the contrasting problem?
    It might due to the followings:

    1. Your ISO setting. If you're using a digital camera, switch to
    higher ISO setting. If you're using film body, you better change
    to a higher speed film.

    2. Slow len with wrong flash mode. Open up your len to the
    widest aperature, you mighr even wanted to use with slow
    synchro flash.

    My 2 cents worth of inputs.

  6. #6

    Default the story of sync-ing

    sync-ing is the term to describe how 2 active components -- (1)flash firing (2) moving shutter-- cooperate during exposure

    long ago, cam body has leaf-type shutter: flash firing can sync at all shutter speeds

    modern day, cam body has upwards moving vertical FP (focal plane) shutter made of 2 curtains (front n rear)which presents a slight problem: at a particularly high shutter speed, the front curtain exits the frame just as the rear curtain enters to cover up the frame=>frame is TOTALLY exposed for just a split second

    below that particular shutter speed, the rear curtain enters the frame a while after the front curtain exits=>frame is TOTALLY exposed for a while longer

    above that particular shutter speed, the rear curtain enters b4 the front curtain exits => the frame is NEVER TOTALLY EXPOSED. rather is now exposed by a effective "moving slit" between the 2 curtains. this "moving slit"gets narrower at higher speeds

    that particular shutter speed is the x-speed = x-sync speed. ie its the fastest limit for the frame 2b TOTALLY exposed. different SLR has different x-sync speed eg. EOS3 x-speed is 1/200, F100 x-speed is 1/250

    since normal flash duration is very short (eg 1/10000 s) so if the flash fires NORMALLY at strictly higher that x-sync speed, (eg 1/2000 s) , the result is: as the "moving slit" starts to move upwards, flash fires. fine. but the moving slit still moves, whereas the flash has already stopped firing (since for eg 1/10000 s is faster than 1/2000 s)
    result: picture looks strange coz lower portion is brigthly lit by flash but upper portion is dark. ie yucks

    solution? for shutter speeds faster than x-speed,flash will not fire NORMALLY, but it will fire SPECIALLY. exactly how specially? main idea is to let it fire in repeated bursts so that every exposed position during the upward movement of the moving slit is covered (by flash fire) this is then called HIGH SPEED SYNC

    then for rear sync and front sync, both these choices happen during slow-sync . so now,slow sync is simply flash firing at any shutter speed strictly slower than x-speed. recall that for vertical FP shutter at really slow speeds (eg 2 seconds) the rear curtain waits a while then follows after the front curtain, long after the front curtain has exposed the frame. during this significant waiting gap, the flash can either fire NORMALLY(1)just as the front curtain completely exits to totally expose the frame OR (2)just before the rear curtain covers up the entire frame. so, (1) is front sync, (2) is rear sync
    result? if u shoot a moving object in dark surroundings with front sync, object looks as if it were moving backwards(ghostly trail with brightly lit initial moving postion). if with rear sync, object looks as if moving forwards(ghostly trail with brigthly lit final moving position).

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    Interesting spiel but I believe the A60 does not have a mechanical shutter but an "electronic" one. Slow-sync in non-SLR digital cameras just mean that the shutter speed is kept low to capture the background light despite using flash.

    Ordinaryless, try using Shutter Priority with slower shutter speed eg. 1/30 or Manual exposure with maximum aperture and slow shutter speed. If the background is still too dark and you need to use slower speed than 1/30, then you will need to use a tripod. Remember to tell the subjects to keep still though.

  8. #8
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    Default

    Hi,

    I noticed a problem. When i used flash to take pictures, only the subject im taking is bright, the background seems very dark and the picture appears very contrasting. Is there anyway to solve the contrasting problem?
    Well, this is due to the fact that most camera are setup so that flash lighting is about 1 stop more than the ambient light. This is to bring out the subject from the background. In Flash photography, 2 source of lights govern the the picture quality. One is ambient light (background)and the second is the flash light from yr camera. If you want the ambient light to be more, try to use manual mode and dial in the setting you want. Probably like 1/30 F5.6 as a good start, and also set your ISO to probably 400. This will make sure that during night scenes, the background are bright enough. TTL Flash will automatically correct the lighting for your subject, so no worries about yr flash!

    hope this helps,
    Danny Ng

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    Ops, to add some more..

    Contrasty picture can be "corrected" by bouncing the flash off the ceiling or getting a bounce card. You can try to search for bounce card on this forum, there is something in here somewhere about self making bounce card.


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    Danny, I hope you realise that Ordinaryless is using a Powershot A60 hence bounce flash and TTL flash metering is not an option. Also, ISO 400 on that camera is probably too noisy.

    The reason the subject is overexposed when there is a dark background is because the A60 flash metering, which I believe averages the whole scene, thinks there is not enough light.

    I'm not sure whether the A60 has flash exposure compensation as an option. Negative flash compensation will definitely help.

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    Thanks for the correction,linse.

    Well, if the camera allows for manual control over the setting of apeture and shutter speed. I would still recommend 1/30 F5.6 as a starting point and the camera would be able to correct the flash for the proper exposure for the subject. As for the ISO, probably can't advise much then except just try with the higher ISO.

    Cheers,
    Danny

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    i do not have an A60 and am not aware of its capabilities and limitations. That said, here's my contribution.

    Dannynys already mentioned: in a picture, there two possible sources of light: ambient and flash. The picture will generally look more natural under ambient light, or if the main source of light is ambient.

    If the main source of light for the picture is the flash (ie flash contribution much more than ambient), especially a small on-camera flash, the picture quality is usually a compromise.

    Flash power falls inversely with the square of the distance, meaning that a wall behind the main subject at double the distance will receive one quater the light the subject receives - IF the flash is the main/only source of light. If the back ground is 4 times away, the light falloff is 16x, or 2 stops less. This would explain why the background is so dark compared to the main subject.

    The way to go is to try the let the flash contribute as little as possible to the light required for the picture.

    1. Raising the ISO. A60 goes to ISO400. Already discussed. Works bcoz the picture will need less light, and ambient will contribute a higher percentage.

    2. A60 has +/- 2EV compensation in 1/3 steps. Try underexposing by 2/3 or 1 full stop. i think the picture would still be acceptable. This reduces the overall light required, and hence the flash output, meaning that the flash contributes less to the overall picture, again increasing ambient weightage.

    3. Place (stick) a piece of tissue over the lens. If ('if', bcoz i don't know) the flash is the 'dummy' type that always flashes at full power, this will reduce the power. Even if it doesn't, i believe it will diffuse the flash a bit for a better picture and will certainly reduce the harsh reflection on your subject's face.

    4. Bounce the flash. Yes, i know, this has been suggested and shot down already. But from experience, most of us can tell you this really works. Improvise some way (like stick a piece of paper 45' to the flash?) to bounce the flash - i think you will notice an immediate and drastic improvement, provided your ceiling not too high.

    i'm assuming that the subject is approximate the same brightness as the background to the eye as you see it. If the background is very dark (like a night sky) relative to your subjects, you *should* expect a dark background.

    FWIW, i have the same problem. Generally i avoid taking pictures where the scene is mainly flash-lit.

    Let us know how it turns out, ok?

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    Originally posted by dannynys
    Well, this is due to the fact that most camera are setup so that flash lighting is about 1 stop more than the ambient light. This is to bring out the subject from the background. In Flash photography, 2 source of lights govern the the picture quality. One is ambient light (background)and the second is the flash light from yr camera. If you want the ambient light to be more, try to use manual mode and dial in the setting you want. Probably like 1/30 F5.6 as a good start, and also set your ISO to probably 400. This will make sure that during night scenes, the background are bright enough. TTL Flash will automatically correct the lighting for your subject, so no worries about yr flash!

    hope this helps,
    Danny Ng
    TTL works only if your lens range is within the range set by your camera. Typical hotshoe cameras that do TTL metering only cover from 28-105mm. Anything wider than 28mm would require a flash diffuser and anything longer than 105mm means either u upgrade the flash or move closer to the subject...

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    Originally posted by ST1100
    2. A60 has +/- 2EV compensation in 1/3 steps. Try underexposing by 2/3 or 1 full stop. i think the picture would still be acceptable. This reduces the overall light required, and hence the flash output, meaning that the flash contributes less to the overall picture, again increasing ambient weightage.
    Setting negative compensation will ensure that the subject is not overexposed. However, this does not solve the problem of a dark background. You will still need to expose for the background if you want to "brighten" it.

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    Originally posted by linse
    Setting negative compensation will ensure that the subject is not overexposed. However, this does not solve the problem of a dark background. You will still need to expose for the background if you want to "brighten" it.
    In which case, the subject is overexposed right? So either u use a slow shutter to capture everything...... that is using exposure times like a few seconds, without flash or jsut choose what u would like to see.... u could meter for the background and power down the flash using flash compensation I guess..... needs some experimentation to succeed..

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    Originally posted by TME
    In which case, the subject is overexposed right? So either u use a slow shutter to capture everything...... that is using exposure times like a few seconds, without flash or jsut choose what u would like to see.... u could meter for the background and power down the flash using flash compensation I guess..... needs some experimentation to succeed..
    It's a fine balance. Of couse it depends on the overall lighting. Some tricks including putting the subject in a darker corner, eg where the street lamps are not shining directly on their face. The flash will therefore be the main source of light. This will freeze the subjects without overexposing.

    Anyway, I find it is impossible for anyone to stand still longer than 2 seconds. At the very most 4 seconds.

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    Originally posted by linse
    It's a fine balance. Of couse it depends on the overall lighting. Some tricks including putting the subject in a darker corner, eg where the street lamps are not shining directly on their face. The flash will therefore be the main source of light. This will freeze the subjects without overexposing.

    Anyway, I find it is impossible for anyone to stand still longer than 2 seconds. At the very most 4 seconds.
    Yeah manz! People are so impatient! hahaha........

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