[stewart_photo]

I'm having exposure issues with the Sigma EF-500 DG ST flash unit. Bounced pictures are somewhat over-exposed while pictures using direct flash are just fine (exposure wise, not appearance). Bounce using some type of diffuser results in even greater over-exposure, these often entirely unusable.

The over-exposure is very unpredictable, based on surroundings, surface, distance to subject, and so on. As such, it is going to be very difficult to tune this out using exposure or flash compensation.

Everything else with this flash unit works as advertised. The lack of high-speed sync with the Pentax was a sacrifice, but not an unsurmountable one. But the constant over-exposure with bounce flash is really troublesome.

Anyone else experiencing this? And, if so, how did you resolved it?

stewart

[tlfaust]

If your serial number is greater than 8063038, Sigma might not re-chip it, Mine was a bit older. They rechipped it and I'm much happier with it...

Cheers
Ted

[Photomy]

I'm having exposure issues with the Sigma EF-500 DG ST flash unit. Bounced pictures are somewhat over-exposed while pictures using direct flash are just fine (exposure wise, not appearance). Bounce using some type of diffuser results in even greater over-exposure, these often entirely unusable.

The over-exposure is very unpredictable, based on surroundings, surface, distance to subject, and so on. As such, it is going to be very difficult to tune this out using exposure or flash compensation.

Everything else with this flash unit works as advertised. The lack of high-speed sync with the Pentax was a sacrifice, but not an unsurmountable one. But the constant over-exposure with bounce flash is really troublesome.

Anyone else experiencing this? And, if so, how did you resolved it?

stewart

Even best flash system will have problems in some situations when there are objects having several distances from camera. Also, any reflective objects, or other light sources in the field of view might confuse the flash.

With digital you can easily test with a mid-tone target all in about the same plane and see how the flash does at different distances. Then add bounce and test same target. Bounce will reduce range of flash greatly of course.

I have a K10d and use a couple of used Nikon SB28 flahes with a Demb bounce card (Demb Flash Products - Demb Flash Diffusers) at a 45 degree angle and flash in vertical mode. I have notes from tests, and the auto mode works fantastic in the distance range that I know it will work in. If I am concerned about a scene, I choose straight manual mode at full power or 1/2 power and specified distances and setting that I know are right on. I keep my printed notes in my head and on the back side of my bounce card so it is handy. I rarely have a flash problem.

[stewart_photo]

If your serial number is greater than 8063038, Sigma might not re-chip it, Mine was a bit older. They rechipped it and I'm much happier with it...

What do you mean by "re-chip it," Ted? I just purchased this flash unit last week and am not aware of any need to re-chip it. By the way, the serial number is significantly higher than the number you gave.

stewart

[stewart_photo]

Even best flash system will have problems in some situations when there are objects having several distances from camera. Also, any reflective objects, or other light sources in the field of view might confuse the flash.

With digital you can easily test with a mid-tone target all in about the same plane and see how the flash does at different distances. Then add bounce and test same target. Bounce will reduce range of flash greatly of course.

This overexposure problem is not an issue of distance or surroundings. The overexposure is consistent anywhere within the expected bounce range, and consistent with virtually any object (bounce card, wall, ceiling, whatever). Surrounding objects attenuate or enhance the overesposure, but are not the cause of it.

Anyway, I should not be seeing this type of consistent overexposure with a TTL compatible flash unit. As you know, the camera is supposed to control the level of light output for proper exposure, just as this unit does fairly well for straight-on flash images. But when the head of this unit is tilted for bounce pictures, it is as if it resorts to full power with no TTL control whatsoever.

--- > Okay, I was fiddling with the flash after writing the above (tilting the head up and down, etc), trying to think of anything to add, and it just went entirely dead on me - LED's half on with power switch in off position and LED's off with switch on. No flash whatsoever. Reinserting the batteries did not restore normal operation. This unit is clearly defective and will be returned for a replacement. Hopefuly the next one will not have the overexposure issues.

Regardless, thanks for the replies and suggestions.

stewart

[tlfaust]

The re-chip is something that Sigma has had to perform for new Pentax models. I've read the K100D caused the Sigma flash to require re-chipping (new firmware ROM). The K10D necessitated this, as well. It sounds like your problem was significantly different than mine...

Let us know how the new one fares for you.
Best Wishes
Ted

[stewart_photo]

Let us know how the new one fares for you.

Never did get the old one to work again. Got an RMA number Friday. It is now boxed and ready to go. Because of slow mail both to and from there, it will take upwards of three to four weeks for the new one to arrive. In the meantime, I'll use one of my other flash units (Sunpak, Vivitar, or Minolta) in the manual mode (non-TTL). Or I'll get tired of waiting and just pick another one up locally. After all, one can never have too many flash units, right?

stewart