They're not called Sig[nificant] Ma[lfunctions] for no reason...
AlunFoto wrote:
Since my Pentax AF 540-FGZ flash began acting up a couple of weeks
ago, I've been considering other flashes to replace it. Both Sigma and
Metz have alternatives sporting the same functionality and output
power. Today I gave in to the shopping lust and grabbed a Sigma EF-530
DG Super, which was a good 500 NOK (90 USD, 50 Euro/GBP) cheaper than
the Metz.
Well at home, I subjected the flash to some tests. Exposure looked
nice on both K20D and K-7 and P-TTL seemed to work as it should. But
alas.
As you know P-TTL actually requires two blinks for each press of the
shutter button. One blink to meter, one to expose the shot. So the
flash needs to be sufficiently charged for two blinks before
communicating "ready" to the camera. The Sigma reports "ready" when
charge is sufficient for one blink. Which means that the camera can be
fooled into metering for flash, but receive no output from the flash
when the actual exposure takes place.
I discovered this by taking a series of shots with the K-20D. The
first two shots were correctly exposed, but then followed three or
four completely dark frames, and at last one correctly exposed frame
with ambient light only. I waited 30 seconds to let the flash
recharge, and repeated the series while watching with the camera away
from my face. First there came two exposures with double-blinks. Then
came three exposures with one blink, and at last a long exposure
without flash. The three single-blink exposures turned out black.
So back to the store, I did a test series right there for
demonstration. The salesperson sighed. "Worst thing is," he said, "I
don't think your flash is faulty. We've seen this on Sigma flashes in
combination with Canon as well".
I was offered to return the flash without any cost, but chose to trade
it for a Metz 58 AF; spending the additional 500 NOK. Naturally, I
asked to test the Metz before committing the money, and this flash
behaved as expected. All P-TTL flash exposures correct.
Lesson learned.
Oh, and the Metz is still a good 1000 NOK cheaper than the original
Pentax AF 540-FGZ, in case you wondered... :-)
Jostein
--
The free man owns himself. He can damage himself with either eating or
drinking; he can ruin himself with gambling. If he does he is certainly a damn
fool, and he might possibly be a damned soul; but if he may not, he is not a
free man any more than a dog.
--G. K. Chesterton
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