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  1. #1
    Join Date
    Mar 2007
    Posts
    7

    Underexposed pics with 580ex on 20D

    Has anyone had problems with the 580ex flash? I have a 20D and used the 580 to shoot a wedding. Nearly every shot underexposed. Why? Seems that the "instructions" are to avoid using the flash for light or dark subjects. Hmm...black tuxes, white wedding dress. I did use the setup for a previous wedding....a wedding in which I juggled cameras to asure good results. The difference was that the "test wedding" was in a well-lit church and the ladies were outfitted in pink-ish dresses. The recent "bad" wedding was a night ceremony in a church with no windows (not that it'd matter) and the bride wanted the sanctuary dark so the candles would glow. The flash just flat missed the mark. Anyone have the same problem or any suggestions? So far it looks like a $100 flash will do a better job than a $400 flash!?! I should have used my trusty old Vivitar 285. Comments? Advice?

  2. #2
    Join Date
    Mar 2006
    Posts
    539
    first, sorry to hear your shots were underexposed. i totally understand your point about the vivitar as i use auto mode with metzes for consistency and reliability over ett-hell

    what mode were you in? in av or tv, it will fill so that might have been the problem in which case you need +fec. if in manual, it is likely that the flash was mostly fooled by the reflection off the dress -- either needed +fec again or fel on a different ("more average") area then recompose to shoot so the flash math won't recalculate. what type of area exactly though.... don't ask me off the top... i'd rather shoot in auto than fiddle around with ettl

    one other thing is to check your body's custom function and switch to averaging instead of evaluative for flash. the flash will get "fooled" less by something extremely reflective or something sucking all the light out in the scene

    ***to clarify for those who PMed, "auto" above means auto thrystor flash mode, not auto green box on the body!!!
    Last edited by noyjimi; 03-08-2007 at 05:31 PM.
    To err is human, to crop divine.

  3. #3
    Join Date
    Mar 2005
    Location
    Johnson City, Tennessee
    Posts
    193
    While I claim to be no expert, maybe others will chime in. First, were you trying to bounce flash or shoot straight on? I can't imagine in that situation that bouncing would work. Did you try adjusting the FEC to at least +1, maybe more? What ISO did you shoot in? I would guess maybe 1600 or even 3200 if you have to. Did you shoot in RAW or Jpeg as you could have probablly have saved some shooting in RAW. Lastly, what lenes were you shooting with? Shooting low lights and candles is not a photographers dream anyway. Anyone else?
    Canon 20D, Canon 300D, Panasonic FZ30, Canon 17-40L, Canon 70-200L 2.8 IS, Canon 50mm 1.8 MK I, Canon 18-55(kit lens), Tamron 28-300 XR DI, Tokina 12-24 F4, Kenko extension tubes, Canon 550EX Flash, Lightsphere PJ II, Stofen omnibounce and Whibal. Now the proud owner of Canon extender 1.4 MK II.

  4. #4
    Join Date
    Jul 2004
    Location
    Grafton, MA
    Posts
    1,714
    This question just came up in another forum so I'm going to cross post rather than type it all again...

    In AV mode the 30D goes into "fill flash mode". It underexposes the ambient by one stop and fires the flash as a fill NOT as the primary light source. Don't believe me? Set your camera to AV mode without the flash and take a photo, let's say the camera chooses 1/60 at f5.6. Now mount your flash, turn it on and take another photo. The camera will choose 1/125 at f5.6. This probably saved your bacon a little bit since otherwise you would have probably been at a pretty slow SS (and might have gotten some blur), but it's also one of the reasons for the underexposure.

    My advice to those who aren't yet confident enough to shoot manual with flash: shoot in "P" mode, and bump your FEC up 2/3 to 1 stop. In P mode the camera does not go into fill flash mode, and will use the flash as the primary light source if necessary. The 2/3 stop of FEC is because the Canon flash system tends to underexpose scenes as a default.

    Oh, and as a general rule for using a flash at weddings:

    - If your frame is mostly filled with the bride's white dress, the flash will underexpose. Increase your FEC.
    - If your frame is mostly filled with the groom's black tux, the flash will overexpose. Decrease your FEC
    - If you have a lot of backlight, Canon flashes will underexpose. Increase your FEC. Nikons have a nice mode just for backlit situations.
    - Objects (especially bright ones) in the foreground will fool the TTL flash metering into thinking that your subject is closer. Move around to avoid this.

    Learn to use the FEC and your histogram, and don't be afraid to chimp!


    You can read the whole conversation here: http://photography-on-the.net/forum/...d.php?t=286091


    BTW - Auto Tryistor flashes can be fooled by white dresses and black tuxes too...
    Last edited by jamison55; 03-07-2007 at 06:13 AM.
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  5. #5
    Join Date
    Feb 2007
    Posts
    3
    Is this the same case with the XTI and the 430EX?

    I had thought my pictures were underexposed, but thought it was just me. I'm really an amateur. From reading these threads, if I am shooting indoor family pictures, I should not use AV. Instead I should use P.

    If I shoot with any of the Auto mode will the flash fire as a fill or primary light source? I'm trying to figure out some good settings for the various rooms in the house before the baby comes.

  6. #6
    Join Date
    Mar 2005
    Location
    Johnson City, Tennessee
    Posts
    193
    You can use Tv or Av mode, just have to bump up the FEC(Flash Exposure Compnsaton) by amounts listed by Jamie above. Shoot a picture and magnify it on LCD screen and see what it looks like or learn to read the histogram.
    Canon 20D, Canon 300D, Panasonic FZ30, Canon 17-40L, Canon 70-200L 2.8 IS, Canon 50mm 1.8 MK I, Canon 18-55(kit lens), Tamron 28-300 XR DI, Tokina 12-24 F4, Kenko extension tubes, Canon 550EX Flash, Lightsphere PJ II, Stofen omnibounce and Whibal. Now the proud owner of Canon extender 1.4 MK II.

  7. #7
    Join Date
    Mar 2007
    Posts
    7

    Some relief!

    I do believe that noyjimi has nailed the problem. I adjusted the CF to "average" and it makes all the difference in the world! Yes, I should have known this and/or read it in the manual, but who could have known that one little adjustment would make that much difference?

    I bow to noyjimi --- and Photoshop!

    The interesting thing is that, out of desperation, I tried every setting on the camera. That dial was constantly spinning from "green square" to P, Av, Tv, and even M. This was in the midst of everything and I knew I couldn't shoot on manual at full power for fear of washouts. I didn't have time to learn how to adjust manual settings on the flash on the spot. (No, I didn't completely read that manual either. Too dang many settings on cameras/flashes these days!) I am learning many things thanks to this board as well as reading the manuals. (I can now adjust the settings on the flash as well!) I was simply comfortable with my trusty Vivitar 285 which was set on "red" to give the correct amount of flash at 5.6 from any distance. Right on the money everytime. (This was with many previous cameras, including A1, EOS A2, etc.) While I'm thinking about it --- one reason NOT to go back to the non-TTL flash is that it doesn't have focus assist. Is there any type of optional "strong" focus beam which can be added to a camera when not using a "dialed in" flash? You know, for those times when the camera beam is not enough? As I'm sure we all have found out, sometimes even the 580 beam (or equivalent) misses a focus now & then. That's also discouraging as, unless you zoom in on the screen, it's almost indetectible before downloading.

  8. #8
    Join Date
    Feb 2007
    Posts
    3
    Quote Originally Posted by boog View Post
    You can use Tv or Av mode, just have to bump up the FEC(Flash Exposure Compnsaton) by amounts listed by Jamie above. Shoot a picture and magnify it on LCD screen and see what it looks like or learn to read the histogram.
    Thanks. Just to confirm that the XTI does work the same as the 20D in this respect.

  9. #9
    Join Date
    Mar 2006
    Posts
    539
    Quote Originally Posted by mrcooltrains View Post
    I adjusted the CF to "average" and it makes all the difference in the world!

    I was simply comfortable with my trusty Vivitar 285 which was set on "red" to give the correct amount of flash at 5.6 from any distance. Right on the money everytime. (This was with many previous cameras, including A1, EOS A2, etc.) While I'm thinking about it --- one reason NOT to go back to the non-TTL flash is that it doesn't have focus assist. Is there any type of optional "strong" focus beam which can be added to a camera when not using a "dialed in" flash? You know, for those times when the camera beam is not enough? As I'm sure we all have found out, sometimes even the 580 beam (or equivalent) misses a focus now & then. That's also discouraging as, unless you zoom in on the screen, it's almost indetectible before downloading.
    glad it worked for ya.... i like the way you feel about your vivitar as i do with my metzes -- "right on the money everytime" with a canon foot module, the metz af assist (at least with the metz 54mz which is what i have) will fire in auto thrystor mode. . as for better focus not sure about an additional assist light (a video light would be annoying...), but if you have a f/2.8 or faster lens, it should be better... and even better coupled to a 5d or 1-series body which has more focus (and more sensitive) points
    To err is human, to crop divine.

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