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04-10-2009, 09:59 PM   #1
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Underexposed pics with new Sigma EF 530 DG Super Flash. What I'm I doing wrong?

Hello,

I just received my new flash: a Sigma EF 530 DG Super for my K100DS. The user's manual of the flash is pretty basic.
Anyway, I started practicing with it and I noticed that the pictures taken with the pTTL mode were dark. So I did some experimenting with manual flash control and it works fine.
I took about 30 pictures at different settings and logged them: Straight, diffused, bounced etc. It seems that in order to take a decent exposure, I need to overexpose by 2 full stops!
The brightness histograms confirm this.

Here are some examples:
For these 3 shots the settings were: RAW, 1/60 shutter speed, f5.6, pTTL mode, 85mm(55mm) focal lenght, no diffuser, no bounce angle, ISO-200, about 8 feet from the subject

no exp compensation


+1 exp comp in the camera


+2 exp comp in the camera


Am I doing something wrong? There are some settings in the flash I don't recognize and not mentioned in the manual. Like C0 C1 C2, SL etc.
Can someone shed some "light" on this subject?

Thanks,
Ismael

04-10-2009, 10:42 PM   #2
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I've got a 530 Super with a K20D. I use +1.0 EV in the camera flash compensation setting in conjunction with +1.0 on the flash unit. About the same as you. I may end up dropping it to +0.5 on the flash.

See: https://www.pentaxforums.com/forums/camera-studio-accessories/51143-sigma-ef-530-dg-super-initial-comments.html
Dan.

Last edited by dosdan; 04-10-2009 at 11:26 PM.
04-11-2009, 12:48 PM   #3
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QuoteOriginally posted by ismaelg Quote
Am I doing something wrong? There are some settings in the flash I don't recognize and not mentioned in the manual. Like C0 C1 C2, SL etc.
For what it's worth, the SL is wireless P-TTL slave mode, and the "C" numbers are the different wireless channels.
04-11-2009, 02:09 PM   #4
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This 'problem' is not confined to the EF 530.
Pentax's AF 540 needs around +0.7 and Sigma's EF 500 Super needs around +1.0 to get decently exposed photos too.

10-23-2009, 02:47 AM   #5
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problem with underexposure with Sigma flash

I know this is an out of date reply but other users will continue to have the same problem.

I see in the images from the OP that there is a large portion of light coloured wall behind the child.

PTTL is measuring reflected light and adjusting accordingly. The wall is perfectly lit and as a consequence, the child is underexposed!

In keeping with Pentax imaging philosophy, highlights are protected.

Two ways of getting around this is 1) to try using spotmetering - this may increase exposure (I'm not sure as I read somewhere that PTTL sets the camera to matrix metering) and of course 2) to compensate by bumping flash output up on the flash or set the camera to generate +EV (but this will mess with Aperture or ISO depending on the mode used).

The problem therefore originates with Pentax - the Sigma unit is simply functioning the way PTTL is designed to function. Which may not be that good!
10-23-2009, 12:39 PM   #6
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What the last guy said.
02-09-2011, 08:17 AM   #7
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Ditto here even with spot-metering

I know this thread is all-but-dead, but I've just received a Sigma EF 530 DG Super and found it to be doing the same. Exposure compensation (rather than flash exposure compensation) seemed to work just as well (since it's a simple one-step operation through my K-x rather than a half-dozen button presses on both body and flash).

This is my concern though - it doesn't seem to have anything to do with the metering mode. Going from multi-segment metering on the K-x (as well as multi-point autofocus) to single spot metering and point focus yields the same result.

The odd thing is that the wireless P/TTL function seems to be about right (more testing needed here - this may be a function of the built-in K-x flash correctly exposing and the Sigma's under-contribution not being noticed).

Josh

QuoteOriginally posted by jlaubza Quote
I know this is an out of date reply but other users will continue to have the same problem.

I see in the images from the OP that there is a large portion of light coloured wall behind the child.

PTTL is measuring reflected light and adjusting accordingly. The wall is perfectly lit and as a consequence, the child is underexposed!

In keeping with Pentax imaging philosophy, highlights are protected.

Two ways of getting around this is 1) to try using spotmetering - this may increase exposure (I'm not sure as I read somewhere that PTTL sets the camera to matrix metering) and of course 2) to compensate by bumping flash output up on the flash or set the camera to generate +EV (but this will mess with Aperture or ISO depending on the mode used).

The problem therefore originates with Pentax - the Sigma unit is simply functioning the way PTTL is designed to function. Which may not be that good!


02-09-2011, 11:43 AM   #8
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I don't think the subject's picture was exposed by your flash.
I think the flash is not synchronized with the camera's shutter or your flash is acting as only a weak fill light.
It looks as if the primary exposure was by ambient light coming from another source, possibly a window.

The catch lights in her eyes are lovely but there is no shadow under her nose. Observe the shadows of the lamp and the table which indicate a light above them. Her nose should cast the same kind of shadow.

Mickey
02-09-2011, 01:46 PM   #9
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It's not the flash. It's the camera.

p-TTL metering in the K20D and older camera bodies (K10D, K100D, K100D Super, ....) is useless. It is significantly improved in K7 and newer cameras, but still not as consistent as Canon and Nikon (I don't know about other brands).

I have two copies of Pentax 540 flash. But I avoid p-TTL with K10D body.
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