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Thread: Flash compensation limits

  1. #1
    Alis's Avatar
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    Flash compensation limits

    Hi everyone,

    Here is another question: I have been using flash compensation to increase my flash's output and then use a higher shutter speed, just being lazy and not wanting to calculate everything. I set the flash on Highspeed synch and just go up on shutter speed.

    Recently I did this with the new 580 EX II I have bought and got very disappointing results. I am not sure if it is the flash being different from 430 EX I had before or something else.

    I am basically trying to ask if I am losing anything by just increasing the flash output and going up on shutter speed. Would it be different if I used less flash and used the maximum possible shutter speed to get a sharp image.

    I was using bounce flash from a white ceiling which was not too high.

    I have noticed that when I take a picture with the flash straight up bouncing from ceiling I get brighter pictures than when I point the flash toward the subject. Just wondering wha the best way is to use the flash.

    Any comments appreciated as always.
    Last edited by Alis; 29th March 2009 at 09:11 PM.

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    Re: Flash compensation limits

    Quote Originally Posted by sedali View Post
    Hi everyone,

    Here is another question: I have been using flash compensation to increase my flash's output and then use a higher shutter speed, just being lazy and not wanting to calculate everything. I set the flash on Highspeed synch and just go up on shutter speed.

    Recently I did this with the new 580 EX II I have bought and got very disappointing results. I am not sure if it is the flash being different from 430 EX I had before or something else.

    I am basically trying to ask if I am losing anything by just increasing the flash output and going up on shutter speed. Would it be different if I used less flash and used the maximum possible shutter speed to get a sharp image.

    I was using bounce flash from a white ceiling which was not too high.

    I have noticed that when I take a picture with the flash straight up bouncing from ceiling I get brighter pictures than when I point the flash toward the subject. Just wondering wha the best way is to use the flash.

    Any comments appreciated as always.
    Hi Sedali,

    Just be aware that when using HSS there's a price to pay - and that price is reduced range - the higher the shutter-speed, the lower the power output; so it's best saved for those time when you can't get the shutter-speed below X-Sync by any other means. Keep in mind too that if the flash is doing the subject illumination then shutter speed (below X-Sync speed) becomes irrelivant; if for example a room was totally dark then you could leave the shutter open for 30 seconds or more ... the exposure only occurs when the flash fires, and that happens in around 1/2000th of a second.

    With Canon flashes, a bounce flash is treated differently to one that points forward - with forward pointing flash work the camera factors distance info into the equasion whereas with a bounce, it doesn't. The Canon algorithms tend to be quite neutral with flash - many prefer to use FEC of +1 for more subject "pop".

    Does this help?

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    Re: Flash compensation limits

    Quote Originally Posted by Colin Southern View Post
    Hi Sedali,

    Just be aware that when using HSS there's a price to pay - and that price is reduced range - the higher the shutter-speed, the lower the power output; so it's best saved for those time when you can't get the shutter-speed below X-Sync by any other means.
    Now I think I know what happend exactly. These were group pictures and I set the camera all the way back on the other side of the room (4-5 meters) on a tripod to get everyone in the picture, flash was on HSS, and shutter speed cranked up to, I thought, to get a sharp picture, but they all came out darker than what I expected for that output (+3).

    By the way, the room was not totally dark. It has a difficult set up lighiting-wise with recessed lights here and there, so it is enough to fool the camera (in the hand of someone like me) and not lit enought to be considered well lit.

    But now I know what the problem was.

    Thanks again.

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    Re: Flash compensation limits

    Hi Sedali:

    I am slowly coming up to speed with flash photography myself. I find this link very helpful and perhaps you will too.

    http://www.planetneil.com/tangents/f...hy-techniques/

    Chuck

  5. #5
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    Re: Flash compensation limits

    Quote Originally Posted by CNelson View Post
    Hi Sedali:

    I am slowly coming up to speed with flash photography myself. I find this link very helpful and perhaps you will too.

    http://www.planetneil.com/tangents/f...hy-techniques/

    Chuck
    It is an interesting website. Thanks.

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    Re: Flash compensation limits

    Quote Originally Posted by sedali View Post
    By the way, the room was not totally dark. It has a difficult set up lighiting-wise with recessed lights here and there, so it is enough to fool the camera (in the hand of someone like me) and not lit enought to be considered well lit.
    The first thing to decide with flash photography is how much ambient light you want in the exposure; ranging from lots (so the flash is only performing a fill-flash function) all the way up to none (where the flash is providing all of the illumination).

    Normally indoors at ISO 100 1/200th F5.6 (pretty typical for group portraits) you won't get a lot of ambient light - so usually easier to just point the flash up - select FEC = +1 (as a starting point) and "let er rip"

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    Alis's Avatar
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    Re: Flash compensation limits

    Quote Originally Posted by Colin Southern View Post

    Normally indoors at ISO 100 1/200th F5.6 (pretty typical for group portraits) you won't get a lot of ambient light - so usually easier to just point the flash up - select FEC = +1 (as a starting point) and "let er rip"
    Great tips. Thanks, Colin. I think it is time to write these down somewhere.

    By the way, did the article you were writing come out?

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    Self Portraits - Job Descriptions ... and other general musings!

    Quote Originally Posted by sedali View Post
    By the way, did the article you were writing come out?
    Me Bad

    I've got the text done - just struggling for enough working hours in the day (got to bed at 00:15 this morning - up and into it again by 8am ... 9 canvas prints to frame before I go home tonight ... just in time to prep a laptop PC for someone for tomorrow ... when I pickup a new PC to prep for another customer. Tell me again how much I love what I do

    [Mod Note: I've moved the subsequent posts to a new thread ...Self Portraits - Job Descriptions ... and other general musings! ]
    Last edited by Colin Southern; 3rd April 2009 at 01:08 AM. Reason: Add Mod Note

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