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Thread: Decreasing Exp Comp forLower ISO, Any Drawbacks?

  1. #1

    Default Decreasing Exp Comp forLower ISO, Any Drawbacks?

    I got question:

    When I take indoor pictures of my kids, I notice that when I lower the exposure compensation, I get more leeway in lowering ISO or increasing shutter speed. The picture doesnt look too dark because I am using 2 flashes at maybe 1/32. I think the theory is I am using more flash power to give me more iso or shutter speed leeway.

    Question: When i do this, are there any drawbacks? ie, am i sacrificing anything?

    Thanks alot!

  2. #2

    Default Re: Decreasing Exp Comp forLower ISO, Any Drawbacks?

    that's when you use flash, what if you only shooting with ambient light?

  3. #3

    Default Re: Decreasing Exp Comp forLower ISO, Any Drawbacks?

    this method need flash to supply enough light to overcome the -2expcomp.

  4. #4

    Default Re: Decreasing Exp Comp forLower ISO, Any Drawbacks?

    Depending on the make of your camera, the exposure compensation likely only affects the ambient exposure, flash exposure will be determined separately (or combined with exposure compensation). That's why your kids looks correctly exposed as they are lit by mainly flash, however the background may look darker due to the negative exposure compensation.

    When using flash, shutter speed mainly controls how much ambient light is captured, ISO affects how much flash + ambient light is captured.

    Not too sure what drawbacks you are concerned with? You might want to elaborate your set up so the seniors here can advise you better

  5. #5

    Default

    TS, if you try your method in dark outdoor setting, you will realise that only your subjects are lighted up, with little to no ambient light at all.

    When in such opened scenario, higher iso is needed to pick up the surrounding ambient light, unless it is of no concern to you. Your flash guns only have that limited power and they certainly cannot light up the world ahead of you.

    In indoor settings, flash units can be used to bounce the light around to create enough light for the sensor to pick up at lower iso, which is why you cannot see the drawback of your method yet.
    Last edited by tecnica; 21st August 2012 at 12:37 AM.

  6. #6

    Default Re: Decreasing Exp Comp forLower ISO, Any Drawbacks?

    Quote Originally Posted by tecnica View Post
    TS, if you try your method in dark outdoor setting, you will realise that only your subjects are lighted up, with little to no ambient light at all.

    When in such opened scenario, higher iso is needed to pick up the surrounding ambient light, unless it is of no concern to you. Your flash guns only have that limited power and they certainly cannot light up the world ahead of you.

    In indoor settings, flash units can be used to bounce the light around to create enough light for the sensor to pick up at lower iso, which is why you cannot see the drawback of your method yet.
    Technica, i agree that this method (-2expcomp + 2 flash) wont work in outdoors. thats why i am saving at marnie to buy 5d3.....so far i only use this method in small indoor areas such as hdb hall or room. so far i cannot see any drawbacks as i am bouncing the flash light all over the place.....the thing i scared is there are drawbacks that i cannot see, then come to regret much later.

    one example of a big mistake i did in the past was to set aperture at F20 and mount tripood to take non-moving subjects such as scenery. Looks ok at first, then i realised that i am sacrifising a lot details because my friend told me that sweet spot is generally one or two stops from the lens max aperture.

  7. #7

    Default Re: Decreasing Exp Comp forLower ISO, Any Drawbacks?

    Quote Originally Posted by thoongeng View Post
    Depending on the make of your camera, the exposure compensation likely only affects the ambient exposure, flash exposure will be determined separately (or combined with exposure compensation). That's why your kids looks correctly exposed as they are lit by mainly flash, however the background may look darker due to the negative exposure compensation.

    When using flash, shutter speed mainly controls how much ambient light is captured, ISO affects how much flash + ambient light is captured.

    Not too sure what drawbacks you are concerned with? You might want to elaborate your set up so the seniors here can advise you better
    Quote Originally Posted by thoongeng View Post
    Depending on the make of your camera, the exposure compensation likely only affects the ambient exposure, flash exposure will be determined separately (or combined with exposure compensation). That's why your kids looks correctly exposed as they are lit by mainly flash, however the background may look darker due to the negative exposure compensation.

    When using flash, shutter speed mainly controls how much ambient light is captured, ISO affects how much flash + ambient light is captured.

    Not too sure what drawbacks you are concerned with? You might want to elaborate your set up so the seniors here can advise you better
    Dear Thoongeng, i am using 40D + (17-55 F2.8) + (70-200 F4) + 2 nissin flash. I use the build in flash to trigger the 2 nissin flash. i wil usually place one di866 about 45 degrees to the back left of the subject. because di866 as 2 flashes (one main gun and one sub gun), i will put full power on the sub flash and aim it at the subject to create the hair light or rim light. Then the main gun of the di866 i will point at the ceiling. usually 1/32 is enough, no bounce card is used.

    Then the other di622, i will place 45 degrees at the right front of the subject. di622 only have one main gun. i will make the main gun face the ceiling and this one will have a bounce card so subject will be nicely lighted up.

    usually i will use Av mode: F4 + 135mm + 1/200 + iso<400 (i like the 70-200 F4. because at 135-200mm, it isolates the subject pretty good. i need 1/200 as kids move real fast. the kids know that they are being photographed and they know they are just to ignore me and do their own playing. iso<400 to have good quality photo ( i also notice that the lower the iso, the lesser sharpening artifacts from DPP software)

    all these seems to good to be true. almost like a magic bullet. thats why i am scare whether there are any trade offs whch i dont see.....

  8. #8
    Moderator catchlights's Avatar
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    Default Re: Decreasing Exp Comp forLower ISO, Any Drawbacks?

    Quote Originally Posted by Mustank View Post
    Technica, i agree that this method (-2expcomp + 2 flash) wont work in outdoors. thats why i am saving at marnie to buy 5d3.....so far i only use this method in small indoor areas such as hdb hall or room. so far i cannot see any drawbacks as i am bouncing the flash light all over the place.....the thing i scared is there are drawbacks that i cannot see, then come to regret much later.

    one example of a big mistake i did in the past was to set aperture at F20 and mount tripood to take non-moving subjects such as scenery. Looks ok at first, then i realised that i am sacrifising a lot details because my friend told me that sweet spot is generally one or two stops from the lens max aperture.
    not entirely correct way, you need to compromise between the depth of field and the lens sweet spot for most types of subject.


    do you know by setting minus exposure compensation with aperture priority mode, you are expose less on the ambient light? and if you change your ISO setting at the same time, it will affect both, flash and ambient, you make it more complicated and can be very confusing, so since you already shoot with flash in manual mode, why don't shooting manual exposure mode for your camera?
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  9. #9

    Default Re: Decreasing Exp Comp forLower ISO, Any Drawbacks?

    Quote Originally Posted by Mustank View Post
    Dear Thoongeng, i am using 40D + (17-55 F2.8) + (70-200 F4) + 2 nissin flash. I use the build in flash to trigger the 2 nissin flash. i wil usually place one di866 about 45 degrees to the back left of the subject. because di866 as 2 flashes (one main gun and one sub gun), i will put full power on the sub flash and aim it at the subject to create the hair light or rim light. Then the main gun of the di866 i will point at the ceiling. usually 1/32 is enough, no bounce card is used.

    Then the other di622, i will place 45 degrees at the right front of the subject. di622 only have one main gun. i will make the main gun face the ceiling and this one will have a bounce card so subject will be nicely lighted up.

    usually i will use Av mode: F4 + 135mm + 1/200 + iso<400 (i like the 70-200 F4. because at 135-200mm, it isolates the subject pretty good. i need 1/200 as kids move real fast. the kids know that they are being photographed and they know they are just to ignore me and do their own playing. iso<400 to have good quality photo ( i also notice that the lower the iso, the lesser sharpening artifacts from DPP software)

    all these seems to good to be true. almost like a magic bullet. thats why i am scare whether there are any trade offs whch i dont see.....
    Thanks for the detail you provided! I also use the Canon system and am reading up on it, but do not have a lot of experience with it so just offering what I know currently. Seniors can provide more information or point out my misunderstanding (hope not many) =p

    For the Canon system the camera meters ambient and flash exposure separately. When using Av/Tv mode at exposure 0 (no exposure compensation), the metering is for what the camera thinks is the correct ambient exposure, the flash is ignored. When you dial in exposure compensation it affects how much ambient light is captured.

    If you are using the E-TTL system, you control the flash exposure by dialing in Flash Exposure Compensation (FEC). However as you are using flash manually, the flash exposure is set manually by you.

    However the situation is commonly complicated when there is spill of ambient to flash exposure, that's why sometimes you have to trial and error to set the ambient exposure (through exposure compensation) and flash exposure (through FEC) to get the correct overall exposure that you want. The common advice is to set the ambient correctly first, then play with FEC.

    As you mentioned that your exposure is ok even with exposure compensation, it means in your indoor environment your flashes are able to expose your subject correctly without need for much ambient. So when lower ISO or use a faster shutter speed the only drawback that I can think of is that the exposure of areas not lit by flash will be more underexposed. Unless you have detail in these areas that you want to preserve, or else does not matter (as pointed out by tecnica)

    And as suggested by the pro (catchlights =), if you use manual exposure, you have more 'exposure compensation' to play with (+/- 2 stops for 40D I believe). You can use the aperture priority mode to get a feel of the metering first then set the exposure, or if you're comfortable with the camera's metering bar then just use manual exposure straight away.

    (as a side note as ambient and flash exposure are separate, you can use Aperture/Shutter priority mode in camera with manual flash exposure, also can do Manual mode with E-TTL flash exposure, or whatever combination

    Hope this is useful and answers your question

  10. #10

    Default Re: Decreasing Exp Comp forLower ISO, Any Drawbacks?

    Quote Originally Posted by catchlights View Post
    not entirely correct way, you need to compromise between the depth of field and the lens sweet spot for most types of subject.


    do you know by setting minus exposure compensation with aperture priority mode, you are expose less on the ambient light? and if you change your ISO setting at the same time, it will affect both, flash and ambient, you make it more complicated and can be very confusing, so since you already shoot with flash in manual mode, why don't shooting manual exposure mode for your camera?
    Thanks man! Yes i know less ambient light when -2expcomp. Just that i am blasting flash to fill the hdb hall to make up for the lesser ambient light. Actually I not confident to go full manual. Got phobia, I wish there is auto iso for 5d3 when mount flash. Heard don have. I would like to set f4, 1/200, I blast the flash guns and let the comp calculate the iso for me. As long less than 400 can already

  11. #11

    Default Re: Decreasing Exp Comp forLower ISO, Any Drawbacks?

    Bro, thanks alot man! I am using flash manually bec to do wireless Ettl, I need a 3rd Nissin flash. But I am saving marnie to buy 5d3. I realized it is a bit of arga arga. A few tries usually get it correct already. Maybe later I post one picture, you all see and tell me any fault. Thanks a lot!

  12. #12

    Default Re: Decreasing Exp Comp forLower ISO, Any Drawbacks?

    Dear guys, pls help me out and see any problems...be frank, be brutal. i can take it. my job requires me to take lots of abuse so don feel shy

    in dpp, i lower brightness by -0.33. sharpening +10. honestly, the original raw file, the sharpnest kns. i notice that if shooting at less than 400iso, sharpening dont see any artifacts even at 100% view



    File Name IMG_4777.CR2
    Camera Model Canon EOS 40D
    Firmware Firmware Version 1.1.1
    Shooting Date/Time 8/20/2012 1:08:06 PM
    Owner's Name
    Shooting Mode Aperture-Priority AE
    Tv( Shutter Speed ) 1/200
    Av( Aperture Value ) 4.0
    Metering Mode Evaluative Metering
    Exposure Compensation -2
    ISO Speed 200
    Lens EF70-200mm f/4L IS USM
    Focal Length 150.0mm
    Image Size 3888x2592
    Image Quality RAW
    Flash On
    Flash Type Built-In Flash
    Flash Exposure Compensation 0
    Shutter curtain sync 1st-curtain sync
    White Balance Mode Auto
    AF Mode AI Servo AF
    Picture Style Neutral
    Sharpness 0
    Contrast 0
    Saturation 0
    Color tone 0
    Color Space sRGB
    Long exposure noise reduction 0:Off
    High ISO speed noise reduction 0:Off
    Highlight tone priority 0isable
    Dust Delete Data No
    File Size 13230KB
    Drive Mode Single shooting
    Last edited by Mustank; 21st August 2012 at 10:45 PM.

  13. #13
    Moderator ed9119's Avatar
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    Default Re: Decreasing Exp Comp forLower ISO, Any Drawbacks?

    the lighting looks a little flat ..... I looked at your image in PS and the profile in Levels and seems to have some excesses on both ends ....a little adjustment should do it

    just MHO
    Last edited by ed9119; 21st August 2012 at 11:54 PM.
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  14. #14
    Member Unagidon's Avatar
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    Default

    After reading your set up, and looking at your photos, it seems like the light is simply spilling all over the place. As speed light bounce on wall the light will go every where in the room I think that results flat lightings. If you are using manual flash set up try using this method,
    -set shutter speed to ur flash sync speed (usually is 1/200)
    -Place the flash at a distance base on the flash exposure table or flash calculator and set your aperture accordingly
    -Take a test shot and see the results.

    *If you want to brighten the back ground, lower ur shutter speed

    *If you want to change the exposure of your subject, adjust your aperture or move your speedlight or adjust the power of your speedlight
    -

  15. #15
    Moderator daredevil123's Avatar
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    Default Re: Decreasing Exp Comp forLower ISO, Any Drawbacks?

    I think your light seems flat because you are bouncing your key light off a wall and the light just reflects and bounced off everywhere. When using off camera flash, what you want is to actually use directional lighting to create shadows. Shadows gives your subject dimension. If you simply bounce the key light, you get very little shadow, and it is easy to cause the lighting to look flat and uninteresting. I recommend you try bouncing the light using an umbrella instead, or use a softbox...

    This is a test picture shot during a session last week at one of our sharing sessions about off camera lighting..

    Strobist info... Nikon SB-25 1/8 power high above camera bounced off umbrella (Butterfly lighting). Camera settings: ISO 200, 1/200s F2.8.
    Last edited by daredevil123; 22nd August 2012 at 10:07 AM.

  16. #16

    Default Re: Decreasing Exp Comp forLower ISO, Any Drawbacks?

    Quote Originally Posted by daredevil123 View Post
    I think your light seems flat because you are bouncing your key light off a wall and the light just reflects and bounced off everywhere. When using off camera flash, what you want is to actually use directional lighting to create shadows. Shadows gives your subject dimension. If you simply bounce the key light, you get very little shadow, and it is easy to cause the lighting to look flat and uninteresting. I recommend you try bouncing the light using an umbrella instead, or use a softbox...

    This is a test picture shot during a session last week at one of our sharing sessions about off camera lighting..

    Strobist info... Nikon SB-25 1/8 power high above camera bounced off umbrella (Butterfly lighting). Camera settings: ISO 200, 1/200s F2.8.
    the real pros has spoken
    just wondering if there was another fill light from below or reflector below? (from what I understand, butterfly lighting need light from above and fill from below?)


    As Ed and Unagidon has said the image is a bit flat. Can still boost the contrast in post-processing.

    Just illustrating, let me know to remove the image if needed:


    In DPP, from the Tool Palette under 'RGB' tab, I moved the ends of the curve to match the tone curve, then created a 'S' curve. Should also be achievable under 'RAW' tab if you're working on the RAW file.

    Happy shooting and experimenting with lights!

  17. #17
    Moderator daredevil123's Avatar
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    Default Re: Decreasing Exp Comp forLower ISO, Any Drawbacks?

    Quote Originally Posted by thoongeng View Post
    the real pros has spoken
    just wondering if there was another fill light from below or reflector below? (from what I understand, butterfly lighting need light from above and fill from below?)
    I can't remember exactly.. I think there might be a flash firing at minimum power from below on the ground. We took so many test shots while show examples, so from the shots themselves, I am lost what we did... but as you can see also, the shadow is still a little dark under the chin... so i am not sure what we did for this particular photo.
    Last edited by daredevil123; 22nd August 2012 at 02:04 PM.

  18. #18
    Member Unagidon's Avatar
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    Quote Originally Posted by thoongeng

    the real pros has spoken
    just wondering if there was another fill light from below or reflector below? (from what I understand, butterfly lighting need light from above and fill from below?)

    As Ed and Unagidon has said the image is a bit flat. Can still boost the contrast in post-processing.

    Just illustrating, let me know to remove the image if needed:

    In DPP, from the Tool Palette under 'RGB' tab, I moved the ends of the curve to match the tone curve, then created a 'S' curve. Should also be achievable under 'RAW' tab if you're working on the RAW file.

    Happy shooting and experimenting with lights!
    Both works as long as the light below has a lower power than the one on top. But do adjust the key light first until you are satisfied with the shadow then adjust your your filled light.

  19. #19

    Default Re: Decreasing Exp Comp forLower ISO, Any Drawbacks?

    Quote Originally Posted by daredevil123 View Post
    I think your light seems flat because you are bouncing your key light off a wall and the light just reflects and bounced off everywhere. When using off camera flash, what you want is to actually use directional lighting to create shadows. Shadows gives your subject dimension. If you simply bounce the key light, you get very little shadow, and it is easy to cause the lighting to look flat and uninteresting. I recommend you try bouncing the light using an umbrella instead, or use a softbox...

    This is a test picture shot during a session last week at one of our sharing sessions about off camera lighting..

    Strobist info... Nikon SB-25 1/8 power high above camera bounced off umbrella (Butterfly lighting). Camera settings: ISO 200, 1/200s F2.8.
    Whoa!!! you are spot on!!! I was justing ramming up the flash power and blasting them to the ceiling. i read Neil VN's website but i couldnt figure out the directional light thing. I guess a softbox will help me out. errr......sorry to ask......got any recomendations for a foldable softbox? i don want to fo umbrella route because too many things to carry. if a foldable box, no prob

  20. #20

    Default Re: Decreasing Exp Comp forLower ISO, Any Drawbacks?

    Quote Originally Posted by Unagidon View Post
    Both works as long as the light below has a lower power than the one on top. But do adjust the key light first until you are satisfied with the shadow then adjust your your filled light.
    ok i go try......

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