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Old Jan 12, 2007, 4:35 PM   #1
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Hello, Kodak gurus,

I have a P880. I seem to have a problem with synching slave flashes to the camera flash. Specifically, I have a small (cheap) slave by Studio Systems (mini-slave). I can't get the unit to sync so that it fires when the shutter is open. It seems to be firing before the shutter opens. What seems to be doing that is that the camera flash fires once prior to the image being captured. I looked at the on-camera flash to determine that at any shutter speed, I am getting two distinct bursts from the flash, once immediately as the shutter button is fully depressed and again as the 'click' of the image being captured. I am not in 'red-eye' mode, BTW. Is this double-flash normal with this camera? Is there a setting I'm overlooking in the setup? Thanks.

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Old Jan 13, 2007, 1:42 AM   #2
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If you have it set to the REDEYE setting it will fire once to cause the persons iris to shrink therefore reducing red eye! Some and I'm not sure of the P880 also use a pre-flash to assist the focus. Check that you don't have it set on the redeye setting and also read the manual to see if something else could be changed!

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Old Jan 13, 2007, 9:21 AM   #3
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Hey, Dawg,

You're right, this pre-flash is a red-eye reduction thing. This is not the same as the red-eye settings in the flash menu. The manual says that under menu/setup, there should be an item called 'auto red-eye reduction.' The options there are: preflash only (default); preflash and autofix; autofix only. The problem is, my camera does not have the 'auto red-eye reduction' in my menu. I have upgraded the camera to the 1.0200 firmware, so maybe that's why it's not there - I dunno! But that would have been the fix to this little problem. BTW, when I use another flash via sync cord, the slave timing is just fine. It's only with the built-in that the slave gets triggered too early. I also have another slave which has a setting that ignores the preflash, so all is not lost. I just wanted to have two slaves on occasion.

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Old Jan 13, 2007, 10:37 AM   #4
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Your camera (as will the vast majority of digital cameras) will always use a metering preflash to help judge the length of the main flash burst needed.

This is not the same as a redeye reduction preflash, and AFAIK, you cannot disable it on your Kodak. Most people don't even notice a metering preflash (since it's typically very short and occurs around 100ms prior to the main flash burst with most digital cameras). But, a slave trigger will see it and fire too soon (fires on preflash versus main flash).

The reason digital cameras use this technique is because the sensors are too reflective to meter from during a flash exposure (like you could with off the film metering). So, they try to determine how long to make the flash burst by firing off a short metering preflash first and measuring what returns from it.

To fire slave flashes using the camera's built in flash as a trigger, you'll need to use a slave flash that's "Digital Aware" (designed to ignore metering preflashes).

You could also use a small manual or auto thyristor type flash via a hotshoe or pc sync port to trigger your slaves (these won't produce a preflash).

BTW, Wein also makes a Digital aware slave triggers. They're a $39.95 each or $79.95 a 3 pack at B&H:

3 Pack of Wein Digital Slave Triggers at B&H for $79.95

One Wein Digital Slave Trigger at B&H for $39.95

You can also find slave flashes that are digital aware (designed to ignore metering preflashes).


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Old Jan 13, 2007, 12:55 PM   #5
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Thanks, Jim. Until now, I never realized that the digital cameras did the 'preflash.' I do have one 'digital aware' slave strobe that does work in the 2 mode (redeye reduction in their instructions), which ignores preflash. The mini-strobe I thought was not working properly does not have that option and hence, fires on the preflash. Now that I know how these things work, I can work around these little problems.

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Old Jan 13, 2007, 1:13 PM   #6
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There are a some exceptions...

For example, I've got a Konica Revio KD-510z that has a built in sensor (separate from the CCD used to capture the image) to measure reflected light during a flash exposure (so, no preflash is needed). I've also got an older Nikon Coolpix model that has a separate built in sensor to measure reflected light during a flash exposure.

This is a similar concept to using an Auto Thrystor type flash with a built in sensor for it's Auto mode (which was a popular way to do it before camera manufacturer's decided to "get smart" and try to measure it off the film during an exposure). lol

Unfortunately, because the main sensors used in digital cameras are so reflective, Digital Camera Manufacturers have redesigned their flash systems to use a preflash instead of trying to meter off the sensor during the flash exposure like you would with OTF (off the film) metering.

So, most digital cameras will use a preflash to judge exposure (to determine how long the main burst needs to be based on how much reflected light is seen from a preflash), and that can present a problem trying to use the camera's built in flash to trigger slaves (since they'll fire on the preflash versus main flash).

That's where newer Digital Aware slaves and triggers come in. Or, use a non-dedicated flash instead of the camera's built in flash. For example, I've got a Konica Minolta Maxxum 5D that uses a preflash with the camera's built in flash, and there's no way to disable it. So, I use a non-dedicated Sunpak instead the built in flash and eliminate the preflash.
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Old Jan 15, 2007, 10:01 AM   #7
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Jim,

You are a wealth of information on this topic. Do you know if the P20 dedicated flash also preflashes?

I have an inexpensive non-dedicated on-camera flash that does properly trigger the slave unit. I do get fairly good results with that setup, but getting proper exposure involves some trial and error. At least with the digital cam, I can see the results and correct exposure immediately. I suppose a flash meter would be a help here, but, for my purposes, the trial-error method works.

Thanks for sharing your knowledge, Jim.


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Old Jan 15, 2007, 10:51 AM   #8
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gregm1948 wrote:
Quote:
Do you know if the P20 dedicated flash also preflashes?
Yes. The P20 will also use a preflash (as will the dedicated strobes from most camera manuacturers now). So, you'd have the same issues with it as you would with the camera's built in flash (the slaves would see the preflash and fire too soon).

You can pick up a non-dedicated strobe with manual power settings (as well as Auto Aperture Ranges) on the used market for very little money if your existing strobes won't give you the flexbility needed.

For example, I got a small Sunpak 222 Auto with 2 Auto Ranges + manual power settings for only $7 not long ago at keh.com. It's got tilt but no swivel (and only two manual power settings).

I also got a got a larger flash (Sunpak 333 Auto) not long ago that has tilt, swivel, manual zoom head, GN of around 120 feet at ISO 100 (depending on zoom head position), 3 Auto Ranges + manual power settings (full, 1/16, 1/8, 1/4, 1/2) for only $25 from the used department at Bhphotovideo.com in 10 (as new in box) condition.

Since most new digital camera buyers use the camera manufacturer's dedicated strobes, older non-dedicated strobes are available at bargain prices on the used market now.

They also make similar strobes you can buy new (for more, of course). For example, the Sunpak 383 Super is a popular non-dedicated flash with about the same specs as my Sunpak 333 Auto (only no zoom head). It's around $79 new. They make some smaller and less expensive units that are similar to my Sunpak 222 Auto, also.


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Old Jan 16, 2007, 7:59 AM   #9
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Since you like using the flash in unusual ways try this place out!

http://strobist.blogspot.com/

Dawg
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Old Jan 16, 2007, 11:50 AM   #10
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Hi BigDwag-

The strobist blog looks quite interesting, thanls for the link. One other factor to consider about slave flashes is that the acceptance angle (the ability of the slave to "see" the master camera's flash will vary a great deal from flash model/make . For example, My Bower SFDS can "see" the master camera's flsh everytime. In contrast the Sunpak DS-20 has to be virtually faced toward the master camera's flash completelyto actually work.

MT/Sarah
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