There’s a rumor going around that the Sony a7RII’s max synch speed (which is spec’d by Sony as 1/250 second) is reduced if the electronic first-curtain shutter (EFCS) is turned on.
That didn’t sit right with me. Testing seemed called for.
I mounted a Zony 55 on an a7RII and aimed the camera at a white wall in manual exposure mode and the aperture set to f/11 so that I’d get a fairly sharp image of the shutter blade. I connected the hot shoe directly (all copper, no IR or radio synch) to a Paul Buff Einstein and set the flash for a full 640 watt-second dump. I made exposures at 1/320, 1/250, and 1/200 second with EFCS on and off.
Here’s what I got:
![EFCS off -- 1/320](http://blog.kasson.com/wp-content/uploads/2015/10/DSC5715.jpg)
Operating at just above the specified synch speed allows us to see how much margin there is in both modes. The EFCS case is slightly better.
![EFCS on -- 1/250](http://blog.kasson.com/wp-content/uploads/2015/10/DSC5713.jpg)
![EFCS off -- 1/250](http://blog.kasson.com/wp-content/uploads/2015/10/DSC5716.jpg)
Looking at the specified synch speed pictures, it looks like Sony is being a little optimistic when they suggest 1/250 second as the top synch speed. Or is it the flash?
Everything is hunky-dory at 1/200 second, though.
No problem with EFCS affecting synch speed, but what’s with the flash not synching at 1/250 second? For the answer, look here.
did you try with native Sony TTL flashes mounted on A7R2 hotshoe ? because there you have a clean X-Sync @ 1/250, even @ f22… so it seems may be something is not right with your A7R2 -> copper -> Paul Buff 3rd party flash…
I don’t own a Sony flash.
> I don’t own a Sony flash.
well, I as noted in a different comment, even non Sony flash and even fired remotely through a pair of dumb radio triggers (but good quality – Cactus V5) seems can do claimed 1/250 x-sync on Sony A7 w/o that visible blade shade as in your example with Paul Buff strobe hard wired to camera…
I think it may be a power/risetime issue. I’ll do further testing.
The problem turned out to be the flash rise time at high power settings. When I reduced the power, both cameras did OK at their rated maximum synch speeds, both with EFCS on and off.
http://blog.kasson.com/?p=12012
Thanks for commenting.
Jim
on a unrelated topic about zebra showing close to real raw clipping and UniWB:
those who dislike green tint (UniWB), might supplant
WB = UniWB
Creative Style = Neutral (contrast -3, saturation -3, …)
Zebra = 100+
with picture profile like this (no claim that it is the best set of parameters though) :
Gamma = Cine3 (reason : allows ISO below 800 unlike SLog, I tried Cine2 – but Cine3 works better for me)
Knee = Auto
Saturation = -32 (removes green tint with Setting Effect = ON – but then you deal with greyscale image)
Color Mode = S-Gamut
Color Phase = 0
Color Depth = 0s
and (not exactly related to clipping) :
Black Gamma = Wide/+7 (reason : darker areas in fame = brighter)
Black Level = +15 (reason : darker areas in fame = brighter)
I’m afraid I’m guilty of passing on that rumour; just saw your post on DPR and checked and found I was mistaken: now I see I needn’t have bothered as you have done it for us!
I wonder if the original source simply saw that there was a little shading at full sync speed which went away when it was reduced, and attributed it to EFCS without turning off EFCS to check?