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07-19-2013, 12:38 AM   #1
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"Dumb" Slave flashes.

So I've just bought 3 different types of "dumb" slave flashes.

Smith-Victor Mini Slave
Smith-Victor PG160S Wireless mini slave
Smith-Victor PG250S Wireless mini slave

I also bought a Pentax RC waterproof.

I was intending to use the on-board K-30 flash as a master to set off the slaves, until I realised there's a "preflash" before the shutters are open, which effectively makes the slave fire off whilst I presume(?) the camera sets its own internal exposure setting? Thus making the picture darker whenever the slave flash is used. I have the camera set to Manual and Manual focus, and I've got the D FA 100 WR Macro on at the moment.

From what I've read around here, there's no way to turn off this preflash, so that it only fires once the shutter is open. Is this correct? The way I've been getting around it so far, is to set it to 3 sec remote mode, hide the flash sensor, press remote, uncover slave sensor, bam!

Is my only other option to get a wireless setup and chuck these slaves on wireless slaves, with a wireless master on the camera hot-shoe?

07-19-2013, 01:21 AM   #2
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You can get a single flash if you use a hot shoe flash in manual, anything should do. At least I could on my K100D, I haven't tried it yet with my K-30.
07-19-2013, 01:44 AM   #3
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That would be perfect! Two of the slaves have hot-shoe mounts!

I'd just be able to use the smallest slave for it and the other two off to the side or wherever. I was afraid the hot shoe mount would send a signal for two flashes, and the slave would only manage the first, effectively giving it the same effect.

I'll experiment when I get back home.
07-19-2013, 05:06 AM   #4
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You can also use a trigger on the camera and flash, those are quite cheap.

07-19-2013, 05:11 AM   #5
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A light trigger, as opposed to a wireless one?
07-19-2013, 06:11 AM   #6
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I mean a wireless radio trigger, you set the transmitter on the hotshoe of your camera and the receiver under one of your flashes. That way you have a single flash that triggers the rest as well.
07-19-2013, 06:13 AM   #7
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Yeah, that's plan B.
07-19-2013, 07:29 AM   #8
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QuoteOriginally posted by timbo Quote
So I've just bought 3 different types of "dumb" slave flashes.

Smith-Victor Mini Slave
Smith-Victor PG160S Wireless mini slave
Smith-Victor PG250S Wireless mini slave

I also bought a Pentax RC waterproof.

I was intending to use the on-board K-30 flash as a master to set off the slaves, until I realised there's a "preflash" before the shutters are open, which effectively makes the slave fire off whilst I presume(?) the camera sets its own internal exposure setting? Thus making the picture darker whenever the slave flash is used. I have the camera set to Manual and Manual focus, and I've got the D FA 100 WR Macro on at the moment.

From what I've read around here, there's no way to turn off this preflash, so that it only fires once the shutter is open. Is this correct? The way I've been getting around it so far, is to set it to 3 sec remote mode, hide the flash sensor, press remote, uncover slave sensor, bam!

Is my only other option to get a wireless setup and chuck these slaves on wireless slaves, with a wireless master on the camera hot-shoe?
Actually, there are several possible workarounds. The easiest is to mount a small conventional flash (non-ttl) and use that as the master. Depending on the lens, you can block electronics (use the physical aperture to set an aperture rather than employing the A setting). The on-board flash will not pre-flash, but will discharge at full power which is not ideal - especially for macro work.

Jim Johnson on this forum swears by the Seagull SYK-5 smart optical slave which has a dial to allow for the pre-flash - at about $12 each that's an economical solution.

I have a Canon-version of the Metz 58-AF1 that seems to work quite well in servo mode with Pentax - you have to test it so it can "learn" the timing of your master flash, but from there you have many manual output settings available down as far as 1/64th I believe. I'm sure any of the Metz flashes that provide a servo setting would work well.

07-19-2013, 05:51 PM   #9
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It worked! Chucked the smaller of the slaves onto the hot shoe mount to act as a master, and one of the larger ones off to the side, screwed into my little Velbon tripod. The camera set the flash off only once, and it was whilst the shutter was open, resulting in a delectable photo of the pollen on the dying bunch of flowers I gave my girlfriend.
07-19-2013, 05:59 PM   #10
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Next question -

I want to use flashes with shutter speeds faster than 1/180. Can I do this with radio controlled flashes?

If this is impossible, how does one capture still images of insect wings mid-flight, without blur? Do you just have to have good lighting to start with?
07-20-2013, 12:08 AM   #11
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QuoteOriginally posted by timbo Quote
Next question -

I want to use flashes with shutter speeds faster than 1/180. Can I do this with radio controlled flashes?

If this is impossible, how does one capture still images of insect wings mid-flight, without blur? Do you just have to have good lighting to start with?
I don't think radio control will get you fast shutter speeds, not that I've got any radio triggers, but I couldn't with optical trigger methods.

I can't say I've ever tried such an insect shot, but I would say you either need lots of light/high ISO to get fast shutter speeds or perhaps a flash with HSS. High Speed Sync basically keeps firing the flash at a low enough power that it can be repeatedly fired to give a constant light for a period (i.e. the shutter time). This means you can use any shutter speed but you lose range and it won't stop action, for that you need a fast shutter speed. I think you may have to do a bit of HSS googling to see if anyone has used HSS for insect wing shots.
07-20-2013, 12:20 AM   #12
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QuoteOriginally posted by timbo Quote
I want to use flashes with shutter speeds faster than 1/180. Can I do this with radio controlled flashes?
No.

That's not the fault of the triggers but Pentax cameras stop triggering the hot-shoe and sync-port once the shutter speed exceeds the sync-speed.

You can stop motion with either HSS (requires dedicated flashes) or by reducing the ambient light so much that the only significant contribution comes from the flash. Smaller flash powers yield shorter flash durations.
07-20-2013, 12:27 AM   #13
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Thanks for the help guys. Here are some pictures I took once I learnt how to use the slaves effectively.





07-20-2013, 02:25 AM   #14
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HSS is not made to stop motion because the flash duration is just as long as the exposure.
What you want is mostly flash light inside the photo, flash duration is often around 1/4000 to 1/2000 if not firing at full power.
The lower the power settings the faster the flash duration = better stopping power.
07-20-2013, 05:48 AM   #15
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QuoteOriginally posted by Anvh Quote
HSS is not made to stop motion because the flash duration is just as long as the exposure.
HSS allows you to use flash at high shutter speeds.

If you use a shutter speed of 1/2000 with HSS, you are going to stop motion.

QuoteOriginally posted by Anvh Quote
The lower the power settings the faster the flash duration = better stopping power.
That's what I wrote before, but this only works if you can get the ambient light down to a level were it doesn't contribute at 1/180 anymore.
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