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02-13-2011, 02:28 PM   #1
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Rear Curtain Sync Off Camera

Sorry if this issue has been discussed to death, but I can't seem to find a truly workable answer anywhere in the forum. I have tried most of the ideas presented here but none of them work (well some sort of work, almost).

Equipment:
K7 camera in Manual mode
Pentax 55mm f/1.4 DA* SDM Lens
2 - AF360FGZ flashes


I want to fire both AF360's off camera. I want to set the flash output manually and independently. I don't want preflashes. I don't want wires. I want to shoot from at least 20 feet in front the model. I know, picky, picky picky.

I do model photography, often with fairly long Tv to expose the background, and I really would like to sync the flashes with the rear curtain. Why? Because once the model sees the flash, he/she transitions his/her pose. Unfortunately, the shutter is still open and there can be some ghosting. I could encase the model in clear rigid plastic, but they tend to complain.

The K7 gives me a choice of rear curtain sync OR wireless. The only mode for rear curtain is PTTL (or SB), complete with preflash. Rear curtain is absent from the menu when in X-sync with a PC cable. I can get rear curtain on one of the AF360s, but only when mounted on the hot shoe, with wireless mode switch set to Master, and power switch set to ON, which defaults to PTTL mode complete with preflash. Since I can't be in wireless mode AND rear curtain sync mode, Flash #2 can be set to do nothing (i.e. tiurned off), or in Slave 2 wireless mode which fires both on preflash & real-flash. The manual tells me that rear curtain sync using the pop-up flash and and external flash is supported, but it doesn't say it is supported wirelessly (I have found it to be not), and therefore not with the internal flash in controller mode. In other words if I want any rear curtain sync, I am stuck with some form of on camera flash.

I think the only solution may be a fully PTTL wired arrangement:
1 hot shoe adapter F on the camera - $40
2 hot shoe adapters F under AF360 number 1 - $80
1 hot shoe adapter F under AF360 number 2 - $40
1 F5PL cable 9.5 feet from camera to Flash #1 - $90
1 F5PL cable 9.5 feet from Flash #1 to Flash #2 - $90

I fear that I could spend $340 to do this, and still not get rear curtain sync on both off camera flashes. On top of that, I am still stuck with PTTL, preflashes, cables all over the place, and a maximum distance between all this stuff of 9.5 feet.

I have tried sync-links, radio triggers, sticking an old hotel room key card with a tiny hold punched into it in front of the internal flash ond so on and so on and so on.
I haven't tried the Metz solution suggested elsewhere in this forum, but that's another healthy investment, and I am not convinced that it really works either.

Sorry for the long form question. But please believe me, I have read every bit of Chinglish in the manuals of both camera and flash. I am using a supposedly compatable lens and suported exposure mode (Manual). I have tried plenty of ideas, but still can't seem to do what I want.

So, do I compromise my list of wants, spend the $340 and go with the wired solution (above)? If I do, will it really work?
Do I find some 14 year old hacker-genius to rewrite the K7 firmware?

02-13-2011, 08:04 PM - 2 Likes   #2
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Problem Solved!

No 14 year old hacker-genius needed. Just a bit of conversation with another 60 year old engineer. Elegant it's not, functional yes. It fires both of my AF360FGZ units and my studio monolights in trailing sync mode ONLY.

List of materials:
qty. 1- Sunpak DIGI-ADAPT flash adapter bracket with built in slave ($21.25 at Adorama).
qty. 2- Plastic hotel key cards.
qty. 1- Radio Frequency trigger transmitter.
qty. As many as you want - RF trigger receivers.

Procedure:
Cut a piece of key card exactly the width of your camera hot shoe. Fold one end so that it can slide into the hot shoe, and fold it again to conform to the shape of the back of the pop-up flash. Fold the other end so that it comes over the top of the pop-up. Rivet the entire second key card to the end of the first strip and fold it into an ell shape that keeps it as far in front of the flash as possible (to avoid melting), but can be held quite securely by the small edge on the top of the camera. The idea is to completely block the light from the front of the pop-up but allow it to exit from the side(s).

Attach the DIGI-ADAPT to the camera.
Mount the radio transmitter onto the DIGI-ADAPT hot shoe.
Turn on the K7 and set the flash mode to trailing sync.
Turn on the DIGI-ADAPT and select mode 3 (First Flash Delay). This mode keeps the DIGI-ADAPT in sleep mode until it is awakened by the PTTL preflash from the internal pop-up. The real flash from the internal pop-up triggers the DIGI-ADAPT.
Turn on the RF trigger transmitter and receivers.
Release the shutter and just like some Rube Goldberg contraption all of this fires the RF trigger transmitter and ultimately the AF360s and the monolights.

A bit of light from both fires of the pop-up does fall on the subject. It's not a problem at my shooting distances, but it might be troublesome in a different situation. In that case, build more of a box around the pop-up, but leave enought of an opening on the side next to the DIGI-ADAPT so that its optical sensor "sees" both the pre-flash and real flash. You also don't want the pop-up to overheat.

This works fine on my K7. The DIGI-ADAPT has 5 sync modes, and mode 3 was the only one that worked for me. It might work for other cameras too, maybe even Canons, perhaps by using one of the other DIGI-ADAPT modes.
02-13-2011, 11:48 PM   #3
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Nice job. I wonder if the K5 has the same flash limitations as the K7. It would seem that having a "manual" flash mode (camera just sends trigger to hotshoe) with rear curtain would be pretty easy, but I guess not.
02-14-2011, 01:20 AM   #4
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Thanks so much,
I was looking and still looking for this info so badly for years, until now.

This post should be in the DIY or strobist tutorial or equipment or camera function workaround (or thousands of other threads I have been through).

Thank you a million times...

02-14-2011, 07:26 AM   #5
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QuoteOriginally posted by sewebster Quote
Nice job. I wonder if the K5 has the same flash limitations as the K7. It would seem that having a "manual" flash mode (camera just sends trigger to hotshoe) with rear curtain would be pretty easy, but I guess not.
I think (and a guess - that's all it is) the camera needs to know when to signal the center post on the hotshoe before the event happens. Maybe in the old days, the mechanical action of the shutter closing could be easily sensed, and the center post made live. However today all of this is done electronically and rather than simply powering the center post, the camera passes some communication signals on a secondary contact.

Notwithstanding the foregoing, I still think manual should be manual and the camera should not think for me all the time. This is a complicated way to out think the camera's computer brain.
02-14-2011, 10:51 AM   #6
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QuoteOriginally posted by sandilands Quote
I think (and a guess - that's all it is) the camera needs to know when to signal the center post on the hotshoe before the event happens. Maybe in the old days, the mechanical action of the shutter closing could be easily sensed, and the center post made live. However today all of this is done electronically and rather than simply powering the center post, the camera passes some communication signals on a secondary contact.

Notwithstanding the foregoing, I still think manual should be manual and the camera should not think for me all the time. This is a complicated way to out think the camera's computer brain.
I only have a manual flash, and the only contact it has on the bottom is the center one. When you push the shutter (other than in bulb mode) the camera knows how long the exposure will be, so you'd think it could just send the pulse to the center contact after that much time. But you couldn't just hack together some cheasy circuit to do it... the timing is important, so maybe for whatever reason they haven't done it, and only the pttl flashes have the circuitry to get it right.

I'm sure that if they wanted it to work they could design it though. It's not that big of a deal, but it would be nice.
02-14-2011, 02:18 PM   #7
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QuoteOriginally posted by sewebster Quote
the timing is important, so maybe for whatever reason they haven't done it, and only the pttl flashes have the circuitry to get it right.
Pentax may save this function for the K1 or FF body. It should be an easy task to programming the firmware to do this. It should be easy to add a fine tuning function similar to the lens adjustment for second curtain based on the duration of the shutter speed.

Something like this:
start--------------^---stop, may be with default duration
start----------------^-stop, duration fine tuning, either sooner or later

I think the latest pocket wizard does have this fine tuning.

So the logic is possible to put it in a flash unit. It should not be difficult to put in a digital body. I use to write programs for micro processor, I know. And how can pentax sell overpriced flash units when they build in a such function in the body? I m the first going out to buy a dumb manual unit - I m already did ;-)

and I m happy now...

02-16-2011, 01:08 PM   #8
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QuoteOriginally posted by hoanpham Quote
And how can pentax sell overpriced flash units when they build in a such function in the body? I m the first going out to buy a dumb manual unit - I m already did ;-)

and I m happy now...
+1

AND because the functionality in camera gets overridden by an AFxxx on camera, AND because Pentax wireless is not for anyone the least bit serious, AND because the AF series flash manuals haven't been rewritten since *ist, AND Pentax has invested $0 in flash technology, AND since the private brand companies only expend enough effort to make their units kind of work with Pentax ...... Yeah dumb manual flash with oddball workarounds is what we are stuck with. My AF360s were a serious waste of money.
04-13-2012, 02:35 PM   #9
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I'm looking to do exactly this as well. But this "Sunpak DIGI-ADAPT flash adapter bracket with built in slave" is discontinued. Would anyone happen to be able to suggest an alternative?

Thank you very much
04-15-2012, 09:16 AM   #10
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QuoteOriginally posted by sandilands Quote
Problem Solved!.
I think I tracked the description of your setup. But could you post a photo of it, in particular you manufactured part?
04-17-2012, 06:10 AM   #11
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Well this shows I know nothing about shooting video. Pretty sloppy, but hopefully it gets the idea across.
04-17-2012, 06:43 AM   #12
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This may be a similar device ... Sunpak Digital Slave Unit with Preflash Cancellation DSU01
04-17-2012, 08:20 AM   #13
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Hello Sandlands,

Thank you for that. I found this thing and ordered it last week, it's a unit that you can train to ignore pre flashes, much the same way that your setup was described. It arrived at work today and I get to try it after work when I'm home, hope the bloody thing works!

Firefly Electronics - Information
04-17-2012, 08:51 AM   #14
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QuoteOriginally posted by sandilands Quote
+1

AND because the functionality in camera gets overridden by an AFxxx on camera, AND because Pentax wireless is not for anyone the least bit serious, AND because the AF series flash manuals haven't been rewritten since *ist, AND Pentax has invested $0 in flash technology, AND since the private brand companies only expend enough effort to make their units kind of work with Pentax ...... Yeah dumb manual flash with oddball workarounds is what we are stuck with. My AF360s were a serious waste of money.
+1

Try being in my shoes

Bought a 360 to do reverse lens macros last year. Discovered that it falls asleeeeeeeeeeeep after 60s.

Bought 2 540s to solve this issue (2 so I can balance light better). Discovered that these give me ghosting so need to use trailing sync.

Discovered that only PTTL can do trailing sync with my Pentax flashes. But PTTL on Pentax with M42 doesn't let me use manual power settings like the 1/64 that I typically use. And using M42 means PTTL only outputs trailing at 100%, so can't even complete one stack (typically a few 100 shots merged).

Think I've solved the manual power settings on my 540s by using this slave trigger to trigger the 540s (set on manual 1/64) from a 360 mounted. But the 360 mounted still only triggers at 100%, so it looks like I need to buy a Metz 58 which allegedly CAN do trailing sync in manual power mode.

So at the end of the day, 1 metz 58 triggering 3 crap yonguo flashes with my slave would give me a better solution than using 540s and a 360. Serious waste of money indeed.
04-18-2012, 06:02 AM   #15
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I hear your pain Nass. I bought two of the crap YN560ii flashes a year ago. $45 each. I use them almost exclusively now instead of my expensive Pentax 360s. On a shoot last week, I needed a third strobe so I pulled a 360 out of the bag. Now the YN560s do go to sleep after about 5 minutes, but they wake up with a hit on the trigger. The 360s don't just doze, they "Van Winkle", not to be reawkened until I flip the switch.

The YN560s are a bit lower power, but they sport 7 steps from 1/1 to 1/64 and you can also (undocumented feature) make them breakdown each level into 7 sub levels. So you can get 1/16 + 4/7 if you want. They have two optical slave modes. S1 is conventional and will fire twice when using the pop up on the camera (ugh!), but they also have an S2 mode - ignore preflash - ingenious! They're cheap, lightweight, a bit flimsy, and don't take kindly to a fall onto the studio floor, but they also work. AND if you don't mind using your pop up as master (light will hit the subject) the YNs in S2 mode can ignore the preflash and fire in rear curtain sync if the camera is so set. But as you say, the only power setting for the pop up or a 360/540 on the hot shoe is 100%. The YNs unfortunately don't work particularly well with the side flash out of my hotel card rig.

I like the sounds of that Firefly unit. Post your results!
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