Underexposure with Flash

Started Sep 14, 2003 | Discussions thread
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Travis
Travis Veteran Member • Posts: 3,188
Underexposure with Flash

I haven't been able to take photos outdoors yet because of heavy rain, but I have taken plenty of flash photos in my home with both the internal flash and the 420ex... and with both the kits lens and the 28-135 IS. Despite various attempts at trying to pinpoint the problem, I'm getting a large percentage of underexposed photos. Here's a typical example:

This shot was taken with the 420ex and has not been adjusted (other than resizing). This does look underexposed, right?

Here is the histogram for the above image:

Here's the Elements adjusted photo:

Obviously, I don't want to adjust every photo in Elements so this is a real concern for me. Also, making this adjustment increases the noise (not much at ISO 100 but still increases).

This example is typical of what I was experiencing. Note that it was not a consistent underexposure - some photos turned out just fine, some were drastically underexposed, but most were about 1 stop underexposed (just a guestimate). Also note that it wasn't just the background that was underexposed - it was the subject too so it's not just the smaller apertures that caused the problem. Here are some things I tried in my process of elimination:

  • Tried both lenses. Same results.

  • Tried various ISO's. Same results.

  • Tried changing the Parameters. Though increasing contrast made the photos look a little brighter in some cases, in other cases it actually made them darker.

  • Tried both the internal flash and the 420ex (in direct mode and bounce). Direct mode with both flashes exhibited the problem quite a bit, as did my shots with the Lumiquest Omnibounce (even at close distance). The brightest shots came from bouncing straight up, but this was still inconsistent.

  • Confirmed that Exposure Compensation does NOT change anything when using flash, just like on my G2.

  • Tried Flash Exposure Locking on various areas of the subject and this did help in some situations, but other times they were still dark. And obviously, one shouldn't need to FEL for every photo to get a good flash exposure.

I think part of it may just because of the less bright lenses. At 3.5-5.6, it takes quite a bit of flash power to light the scene. I tried some shots on my G2 at F2-2.8 and they were great, but when I when to Manual mode and chose F4 or higher, then they also looked darker. So I'm wondering if a faster lens is really needed for indoor flash photos? This doesn't seem right, though, as there should be plenty of power in both the internal flash and the 420ex to take flash photos at normal living room distances.

Anyone else having this problem? Is it just a case of the DSLR underexposure more than I am used to on my G2? Am I doing something wrong? Yes, I have read the E-TTL tips on the net and I have been using the 420ex for a few years now on both my G1 and G2 so I am familiar with E-TTL and how these flashes work.

Going outside soon (rain has finally stopped) so I'll see if it's just an issue with flash or in bright light too.

Thanks,
Travis

 Travis's gear list:Travis's gear list
Panasonic Lumix DMC-LX7 Panasonic LX100 Canon EOS 550D Panasonic Lumix DMC-GH3 Canon EF-S 15-85mm f/3.5-5.6 IS USM +4 more
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