Maximum Flash Sync Speed with 645DF+110mmLS+Profoto Air

[Transposure]

Gents,
I have a question concerning flash sync speeds.

My understanding is that flash sync speeds up to 1/1600s are possible with the 645DF + Schneider 110mm LS + Profoto Air.

My testing has shown less. Tests show syncing up to a maximum shutter speed of ONLY 1/800s.

Test Setup:

Mamiya 645DF
Schneider 110mm LS lens
Leaf Aptus II 7
Profoto Air Transceiver in 645DF hotshoe
Profoto Air Transceiver plugged in sync port of Profoto Pro-B2 pack

As soon as the shutter speed is set 1/3 stop faster than 1/800s, a black frame results.

The million dollar question.....
Why can't flash be synced up to 1/1600s AS ADVERTISED?

Is this functionality only limited to use with the vertical grip? That would seem odd to me.

Anyone??

 

[Guy Mancuso]

Very simple if your flash duration is not fast enough it simply will not get in fast enough to record. Bottom line at full power most flash units do not have a fast enough flash duration. Need to cut power as that will make the flash duration faster in time to sync with the shutter. Also most wireless remotes won't work that high but the Profoto Air remote does as I have done this . The issue is short enough flash duration, cut power and try it again.

Second part of this is the Aptus 7 as it may have a cut off of 1/800. I know the Phase backs have this ability to go to 1/1600. I think Leaf is at 1/800 and my bet this is the real issue but the above is very true as well you need fast duration speeds

 

[kdphotography]

I believe the Aptus II series can flash sync up to 1/1600. I had no problems doing 1/1600 with P65+ and IQ180 with LS lenses and wireless---no need for the vertical grip. My guess is perhaps the heads being used are the limiting factor for flash duration... Cutting power should help.

ken

 

[dougpeterson]

Aptus ii backs support 1/1600th.

The Air transmitter has to be set to "fast" mode which eats up battery a bit faster but allows faster sync. Can you confirm this is the issue?

If not you should also check your back and body firmware are up to date.

Also if I recall correctly there was a very small number of Aptus-ii units shipped before full fast sync speed support was enabled. I can't recall personally ever coming across such an Aptus ii. If you have one of those units you should speak with your dealer to get yours upgraded to the full compatibility. Though I suspect it is simply the "fast" vs "normal" mode on the transmitter or the firmware.

One quick test is to shoot with a sync cable direct to the back.

 

[Transposure]

Hi Guy, Hi Ken,
Thanks for your replies.
I looked at the system again and realized that the DF switches to focal plane shutter above 1/800s. Up to 1/800s, the "LS" logo appears in the top screen. Above 1/800s, the "FP" logo appears on the top screen.

That would seemingly explain it. However, it is certainly discouraging. The 110mm LS are touted as being able to sync up to 1/1600s.

So, I checked the Custom Functions. Custom Function 18 is associated with Leaf vs. Focal Plane shutter priorities. It was set to "Automatic Switching" (0). I switched Custom Function 18 to "Only Lens Shutter" and then the 645DF cannot be moved above 1/800s.

Guy,
Incidentally, I lowered the power on the Pro-B2 to about 1/3 power. One third power on my Profoto 8A represents its fastest duration (1/12,000s). The Profoto Pro-B2's are rated at 1/7400s and presumably this occurs at its respsective 1/3 power setting.

Personally, I do not think that it is the Pro-B2. Its specified duration ranges from its slowest 1/2200s up to its fastest 1/7400s.

Since Ken had success with the Profoto Air system, it seems to point to either the 645DF or the Aptus II.

Any further thoughts considering the foregoing?

 

[dougpeterson]

Ken and guy: the reason I don't suspect the cause is simply insufficient flash duration is the abrupt nature of the falloff. Normally if the flash duration is not sufficient then 1/3rd of a stop faster than 1/800 should not immediately result in a black frame but rather an underexposed frame (since some of the flash curve is being missed).

 

[dougpeterson]

Body firmware version (seen under custom function 99)?

 

[Transposure]

Hi Doug,
Thanks for your input as well.
Hmmm, fast mode on the Profoto Air transmitter?
That is a new one for me. But I am all ears.

The back is actually a DM33, which I understand is the same as the Aptus II 7. Following is from the "About" page:
Firmware Version is 5.041
Interface Version is 3.0.5
LS Support: Normal

So, how does one change to the "Fast" mode on the Profoto Air transceivers?

Thanks!
Ken

 

[Transposure]

CF98: Lens Firmware 1.1
CF99: Body Firmware 1.25

 

[kdphotography]

Ken,

Latch onto Doug while you've got his attention.

ken

p.s. It shouldn't be a problem leaving the DF on "autoswitching" or "LS only"

 

[yaya]

If the serial number of your back is lower than LI301000 then it doesn't have the hardware required for 1/1,600. Which seems to be the case as the "About" screen says LS Support "Normal" rather than "Extended"

You can get the back upgraded if you need the extra speed

Hope this helps

Yair

 

[Transposure]

Yair to the rescue!

My SN is lower than that, and the "Normal" vs. "Extended" seems to tell the story. Thanks Yair!

 

[Guy Mancuso]

I had to send my old P40 to Denmark for the hardware change to get extended.