Power pack recommendations for faster flash sync speeds?

[Paul_Kluber]

Hello:

One of the things that made me frown when switching from Hasselblad film to the Kodak digital slr/n was the slow flash sync speeds available when using Speedotron power packs. After noticing recent shootings of clean backgrounds still showing second curtain travel shadows at even 1/90 sec with the Blackline power packs at most settings, I was wondering if anyone has a recommendation for true 1/125 sync clean frames using power packs to at least 2400 w/s?


Maybe it is time to retire some of my Speedo's for something better.

Thanks,

Paul

[LarryLetzer]

We use Photogenics for flash in our studio with the 14NX and have had no problem getting our hi-key images well, hi key. Flash recycle is quite fast as I have not tried to make an image and was slowed by the lack of flash power.

On location we use the Quantum turbo power pack and we have not been slowed with those either. Granted, neither of these gives us 2400 WS, but I do not need that much power. Here is a photo of my hi key area with about 600 WS.

[Straus]

Are you sure it's the packs and not the camera? We use the Pro/n and I get the same thing as you with the 2nd curtain darkening one edge at 125th, 90 seems ok though. Using Speedo as well but I don't think a shorter flash duration will solve the issue. Here might be a test. Shoot off a few frames at your full 2400w/s @ 125th, then turn down the pack to 400w/s @ 125th (adjusting your exposure of course). The flash duration is WAY faster at the 400w/s and if your still getting the curtain shadow I'd assume it's the camera. The only reason to blame the Speede packs is if there's some very odd slow response time to actually trigger the pack itself which I doubt.

[Paul_Kluber]

Hello:

Thank you both for your responses. I took the time yesterday to run some tests with a Broncolor meter that also measures flash speed. Depending on the power settings of all the flashes used, the firing speed was 1/45 up to 1/125. The average being around 1/60 for the power range I use when shooting. As I recall, for Speedotron which is all I've ever owned, it takes time for the signal to travel down the sync cord or remote transmitter. Then it takes time for the capacitors to dump the power and shoot it down the cable to the flash head. Finally, it takes time for the flash to fire, rise through its cool to normal color temperatures and expose the picture.

It used to be that other flash units, like Broncolor, managed to shorten the whole process somehow. Also, I'm told that units without any head cables, like the Force 10 from Speedotron, have higher sync speeds even at maximum power similiar to Speedotron settings.

I have 12-4803 units that worked fine with my Hasselblad but now with going digital and Kodak slr/n almost two years ago...well you know the story. I am starting to get tired of applying a slight exposure gradient to frames where the problem is most apparent. On days where I don't want to bother, I just turn the sync speed down until the frame is clear of shadows.

Do either of you know anyone using the SLR/n with power ranging from 1000ws up to 4800 ws that gets higher flash sync speeds of 1/125th?

Thank you

[Chris_Lynch]

Flash duration is dependent on a number of issues: Power output setting on the pack, cable length, physical length of the flashtube etc. You may be experiencing dissimilar flash durations from packs set to different power levels. It seems based on your description of what you are doing that this might be the only variable in the setup. The more power going to the head, the longer the flash duration, the longer your shutter needs to be open to "see" the main part of the flash. Working at slower shutter speeds insures that you are exposing the scene with the maximmum amount of light being output by the head at the higher settings. I once shot a copy setup and when using 2 different packs there was a noticeable difference in exposure across the field of view due to differences in flash duration from the w different sources. This was not something a flash meter could pick up on. The SLRn is a good camera in the right situations and deplorable in the wrong situations. Whatever the case, I don't have a workaround except for you to take note of the power settings you are using various packs at and see what the results are.

Then again, you could buy something else but that will not be an inexpensive proposition if you are using all 12 of those packs you currently own. ( I think you wrote 12? )

Best of luck,

Chris