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08-03-2013, 12:54 PM   #1
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Is there a way to sync over 1/125?

Has anyone figured out a way to "trick" a 645D to fire a studio strobe over 1/125th without using a LS lens? I own the 75mm LS but I need something wider and I don't mind losing a little bit of my frame if I shoot at 1/200th or higher since the files are so large.


Bob Croslin

08-05-2013, 05:45 AM   #2
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Well I don't know anything about the 645D but I was playing around yesterday with the Tak 6X7 90LS and the AF360fgz.
Part of that was using the AF360 in slave 2 mode (optical trigger page 47) off camera in bounce mode, with a small AF160 flash on the lens. That worked consistently even when the 2 flashes are not in line of sight.

I see in the AF360 manual page 60 that AF360 supports High Speed Sync on the 645D (You would have to select the 645D as on page 17)

So perhaps you could run an AF360 on the 645D , and its initial pulse can optically trigger the slave flash unit/s. Then you can run shutter up to some speed where the curtain becomes visible. ( I recently tested an Olympus M43 and its shutter is fully open up to 400th or so, even thogh its flash sync is 180th)
You might also be able to do something similar with the HSS wireless mode of the AF360.
08-05-2013, 05:49 AM   #3
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Unfortunately this won't work for the work I do. I'm trying to sync at a high shutter speed to capture action and I'm typically doing this in bright sunshine. Optical slaves don't typically work well in bright light.

I'm wondering if there's a way to hack the firmware to add a 1/250th to the X-sync setting.
08-05-2013, 05:59 AM   #4
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See page 46 of the AF360 manual, the HSS is available on the radio channels too.

By the comment in your op, why can't you use a smaller camera which fires flash at high shutter speeds like the Oly M43?

08-05-2013, 06:06 AM   #5
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QuoteOriginally posted by bcroslin Quote
Unfortunately this won't work for the work I do
Oh Yes it might ( I don't know your conditions)
I just took the AF360 outside and oriented it to face direct (a little hazy) sunlight, the little AF160 will trigger it at 3 metre distance up to about 30 degrees off axis of its red sensor area.
08-05-2013, 07:20 AM   #6
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Wombat - I've been doing this a long time and I've been down that road with optical triggers and they might work but not consistently. I'm shooting in situations with athletes where I get 20 min's to make an image for a magazine or a commercial client. The stakes are very high and unfortunately optical has let me down too many times. I simply need a trigger like my Pocketwizard MiniTT1 for my Canon that essentially tells the camera it's a flash capable of HSS and then it overrides the camera's non-HSS flash sync.
08-05-2013, 08:16 AM   #7
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Sound like you need a pro digital back with a leaf shutter for that.
The focal plane dslrs seem to be limited to around 250th ( eg the D800 etc)
08-07-2013, 11:35 AM   #8
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I really would be curious what photo you need it for.....

For leave shutter ther is only the option of LS75 and LS135 (or LS90 and LS165 via 67>645-Adapter).... nothing wide and all these are limited to 1/500 ..... nothing faster for Pentax MF.

HSS consumes a huge amount of the power - at 1/2000 there is nothing left :-(

Depanding of the photographic task it might be an option to use B-Mode and a dark environment -----Transfers the speed of the shot below 1/10.000 (That would be the same with 1/125 in a dark environment. Typically it is enough to have 2-3 stops lower ambient light than flash light.

10-24-2013, 12:06 AM   #9
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i have a 75,mm f 2.8 "ls" lens, i belive there is a 135mm " ls" lens also. with eirther lens you use a flash with a pc cord. mount the flash on a bracket and plug it into the lens. the lens must be mnually cocked and ait as hi as 1\500 sec. ls stands for leaf shutter. sometimes these lenses can be had at KEH.

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