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04-04-2009, 07:31 PM   #1
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Use of slave flashes

Any comments or insights on the use of slave flashes? Since they flash based on the detection of another flash, does that imply that the flash might be a little "too late"? I assume that is not the case or they would not have that capability!?

What sort of picture taking options are appropriate for off camera flash? I have seen them used at basketball games... Can you use them for portraits as well?

Pros and cons of using slave flashes?

04-04-2009, 07:38 PM   #2
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the detection speed is fast enough for me.
I used it successfully for portrait work, but I had to deflect the onboard flash with a mirror so it will not affect the original setting.
I was using some old FIL flash (sovietic).
04-04-2009, 08:41 PM   #3
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They're great when you're the only photog...

When I did weddings, everyone and their mother (literally), would stand behind me with their point and shoots (film only at the time), and trigger my monolights when everyone was in place, looking at the camera, and composed perfectly. No matter how many times I would explain to them that THEIR flash would set off MY flash, they would do it anyway. I assume they thought I was trying to be the only one in the church with the good shot, and was giving them some techno line of crap to keep them from it.

A similar issue will be noted if you are triggering your slaves with an on camera P-TTL flash...the pre-flash will trigger your slaves.

Speed is not an issue.
04-04-2009, 08:55 PM   #4
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QuoteOriginally posted by krs Quote
Any comments or insights on the use of slave flashes? Since they flash based on the detection of another flash, does that imply that the flash might be a little "too late"? I assume that is not the case or they would not have that capability!?

What sort of picture taking options are appropriate for off camera flash? I have seen them used at basketball games... Can you use them for portraits as well?

Pros and cons of using slave flashes?
I have extensively used slave flash in the past so here is my take:

No, the flash being slaved is not late because the sensor INSTANTLY fires the moment it "sees" the flash.

This only applies to the correct on camera flash and slave sensor combo.

Digital cameras set to fire on camera in Auto, P, Av and Tv usually will fire a preflash to set the white balance.Some will do it iin M mode as well. The sensor will fire on the first flash, not the second flash which sets the exposure. Then the flash will fire early
I think my K10D does this in M mode; I don't use it to fire slaved flash. My canon A75 and my G3 will fire one flash in M mode, and because these cameras either did not have a hot shoe, or (in the case of my G3, which does, my old Vivitar 285's sync voltage might fry the camera), I had to rely on slave flash to get better flash photagraphy with these same said cameras. If your camera fires its on camrea flash twice in all modes, don't despair.
Companies such as Wein and Digi-Slave sell slave sensors and flash units respectively that delays the firing of the slaved unit so it can sync perfectly and not fire early.

Pros.

Studio shooting. Your portraits.

Cheaper than buying sync equipment. In studios on a budget this could be a great way to save money and clutter(radio wireless or long cords).

Most studio strobes come with a built in slave sensor anyway!

Eliminates the cords on flash brackets for off camera shooting. Events. Indoor sports, birthday parties, weddings(this could be tricky though).

Cons

At events(such as weddings) the sensor will also pick up other flashes as well which could interfere with your flash and make it fire prematurely. I would not recommend using this setup at a wedding unless as a last resort for redundancy.

The position of the sensor must be just right so it always sees the flash. If you have a flash bracket, the sensor will see the flash if it is reflected off of a subjuct, but may not fire into a low light situiation because of poor reflection of of the subjuct ie; phothograping a poorly lit room with no windows or pictures etc. This is if the sensor(in my experience) faces foward on the flash bracket and the slaved flash does also. I had to improvise and place the sensor closer to the on camera flash so it would detect it.

The sensor may not work in bright light outdoors if you want to use fill flash because the sunlight is more powerfull than the on camera strobe(which is often tiny, and one of the reasons for using it to trigger a more powerfull slaved flash).

This is my take(based on my own experience),and I hope this helps.

Any more questions, let me know


Last edited by res3567; 04-05-2009 at 08:11 AM.
04-05-2009, 05:13 AM   #5
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QuoteOriginally posted by CalendarGuy Quote
They're great when you're the only photog...

When I did weddings, everyone and their mother (literally), would stand behind me with their point and shoots (film only at the time), and trigger my monolights when everyone was in place, looking at the camera, and composed perfectly. No matter how many times I would explain to them that THEIR flash would set off MY flash, they would do it anyway. I assume they thought I was trying to be the only one in the church with the good shot, and was giving them some techno line of crap to keep them from it.

A similar issue will be noted if you are triggering your slaves with an on camera P-TTL flash...the pre-flash will trigger your slaves.

Speed is not an issue.
With Pentax P-TTL flash (and compatible) you have different "channels" available, so "foreign" flash won't trigger your flashes. Real handy.
04-05-2009, 05:36 AM   #6
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I have a Promaster flash, and played with it briefly last night in slave mode. it appeared to work very well - hence the original post and questios. I did not notice it firing with the preflash (was using P-Shift mode on my K10).
04-05-2009, 05:37 AM   #7
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QuoteOriginally posted by flyer Quote
With Pentax P-TTL flash (and compatible) you have different "channels" available, so "foreign" flash won't trigger your flashes. Real handy.
How do you specify the different channels? Is this only with pentax flashes, or 3rd pary flashes as well?
04-05-2009, 06:22 AM   #8
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QuoteOriginally posted by krs Quote
How do you specify the different channels? Is this only with pentax flashes, or 3rd pary flashes as well?
There are three third-party flashes which have P-TTL wireless compatibility the Sigma EF-530 DG Super, and the Metz 48 AF-1 and 58 AF-1. They all allow you to set which P-TTL wireless channel you're using.

04-05-2009, 08:16 AM   #9
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QuoteOriginally posted by krs Quote
I have a Promaster flash, and played with it briefly last night in slave mode. it appeared to work very well - hence the original post and questios. I did not notice it firing with the preflash (was using P-Shift mode on my K10).
Take pics with the on camera flash, then the Promaster slaved. Notice if the light is brighter with the Promaster. Also, I think if you use manual lenses(no AE contacts) vs. autofocus, the on camera flash will fire once.
04-05-2009, 11:38 AM   #10
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QuoteOriginally posted by krs Quote
I have a Promaster flash, and played with it briefly last night in slave mode. it appeared to work very well - hence the original post and questios. I did not notice it firing with the preflash (was using P-Shift mode on my K10).
Take a test photo in front of the mirror. Do you see the Promaster firing? Or just the built-in flash?

What lens are you using? If you are using anything less than an "A" lens, the built-in flash will fire only one strobe at full power (I don't think this is the case because you wrote that you were using P-Shift mode).

When I need to use optical slave flash units, instead of the built in flash, I use a small external flash unit attached to the camera body to trigger the slaves. If this power of the triggering flash is too great, I cover it will a few layers of Kleenex tissues.
04-05-2009, 12:28 PM   #11
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QuoteOriginally posted by flyer Quote
With Pentax P-TTL flash (and compatible) you have different "channels" available, so "foreign" flash won't trigger your flashes. Real handy.
The slaves will be set off by any flash of light, but yes any other p-ttl flash wouldn't be set off
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