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12-13-2014, 04:46 PM   #1
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K10D flash problem

I took a test photo this evening using the built-in flash. I had the shutter speed at 1/60 and the aperture at 6.7. The photo was too dark. A photo taken at a larger aperture was still too dark. What is causing this?

12-13-2014, 05:26 PM   #2
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Your subject is probably too far away, or the flash is simply too weak for the working distance/angle of view. Rear curtain sync combined with a slower shutter speed should allow you to obtain a correct exposure.

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12-13-2014, 05:31 PM   #3
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What was the distance to the subject? The Guide Number of the flash is 11 meters at ISO 100. The maximum flash distance at f6.7 would be about 1.6 meters.
12-13-2014, 05:35 PM   #4
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4 thing come to mind
1.flash exposure compensation set low
2.camera exposure compensation set low
3.scene to difficult to light ...increase Iso number or decrease aperture number
4.exposure meter may be on a subject lighter than the scene

12-13-2014, 06:53 PM   #5
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QuoteOriginally posted by Sliver-Surfer Quote
4 thing come to mind
1.flash exposure compensation set low
2.camera exposure compensation set low
3.scene to difficult to light ...increase Iso number or decrease aperture number
4.exposure meter may be on a subject lighter than the scene
5. Shooting with a lens having an aperture ring, but not in the "A" position.

FWIW, the flash on the K10D is fairly weak and pretty much useless in many situations if the distance is more than about eight feet at low ISO with P-TTL. I found that I did best by either increasing the ISO or shooting as a manual flash in M-mode using the guide number to determine the aperture setting.


Steve
12-15-2014, 12:59 PM   #6
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It's the flash. It sucks. I was taking a photo with a ceiling light directly above the subject, and the flash underexposed. Tonight, I put my external flash on, fired it up, and took two test photos at 6.7, one at 1/60 and one at 1/90. My gorgeous external flash synched on both, and exposed the field perfectly, even when it was aimed at a window with the curtains open after dark. I love my external flash, even though it eats batteries.
12-15-2014, 04:13 PM   #7
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QuoteOriginally posted by Photogoof Quote
It's the flash. It sucks. I was taking a photo with a ceiling light directly above the subject, and the flash underexposed. Tonight, I put my external flash on, fired it up, and took two test photos at 6.7, one at 1/60 and one at 1/90. My gorgeous external flash synched on both, and exposed the field perfectly, even when it was aimed at a window with the curtains open after dark. I love my external flash, even though it eats batteries.
On camera flashes don't always suck. You just need to shoot within their limits it's all relative to your iso and aperture. An upgrade to external flash is always nice though


12-15-2014, 06:54 PM   #8
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QuoteOriginally posted by Photogoof Quote
It's the flash. It sucks.
Yep, it's the flash, it has a guide number of 11 meters (ISO 100). It was made that way. See page 176 in the user manual. Or to put it explicitly:

Flash range for f/6.7
ISO 100: 0.3m - 1.6m
ISO 200: 0.5m - 2.3m
ISO 400: 0.6m - 3.2m
ISO 800: 0.9m - 4.6m
ISO 1600: 1.3m - 6.5m

Question answered, problem solved.

Note: Your test methods may be flawed. Ambient light is important, but not part of the flash calculation. There are three variables for a flash of fixed intensity: 1) distance, 2) aperture, 3) ISO sensitivity. I believe you forgot to account for distance. Even with P-TTL, if you use a constant aperture and constant ISO, distance becomes the limiting factor. If you are having underexposure with the built-in flash, increase the ISO or use a wider aperture.


Steve

12-16-2014, 02:15 AM   #9
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The flash distance was no more than five and a half feet; I forgot to mention that. Given that the ISO was 200, it should have worked just fine.
12-16-2014, 03:04 PM   #10
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Is K10D has flash compensation? Flash compensation reduce (or increase) the flash output.
12-16-2014, 09:07 PM   #11
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QuoteOriginally posted by Photogoof Quote
The flash distance was no more than five and a half feet; I forgot to mention that. Given that the ISO was 200, it should have worked just fine.
Ummmm...no that would not be just fine. That would be on the edge of the flash capacity at full power. I would suggest P mode in the future to give your camera something to work with. Av mode sort of ties the system's hands, particularly when working with fixed low ISO. Remember the variables? You have tied down everything except flash intensity with little overhead available there either.

Another alternative would be to use the flash in manual mode and calculate the aperture based on distance and guide number. The manual has good instructions on how to do this.

Steve
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