RF-602 and Nissin Di866 Shutterspeed Flash Sync

I'm still miffed???

I'm having a location shoot this weekend. I really want to use my Nissin Di866 in my softbox but I'm unable to get 250th second (200th second is the fastest flash sync I'm able to get).

Now,, with my 430EXII and 430EX I'm able to get 250th second shutterspeed flash sync with both my 50D/20D and RF-602.

It has nothing to do with flash duration because I tested all three flashes from full power manual to 1/32nd power.

Freshly recharged Eneloops in both the RF-602 receivers and flashes. Flashes mounted directly onto the receiver hotshoe.

This occurs on all my three RF-602 receivers. What's going on?

Doesn't surprise me, sync speed is a prime example of the varying mileage between setups.

The more important question I would ask myself is "does it matter?"

Have you turn off flash sync on the camera, I have heard this about the 602, I read some where in here about it. I think itwas Skip that did some testing. I did get my 20D upto 320 with a slight black line at the bottom, shutter, at 400 it was halfway up.
What are you shooting?

ukcyberboy wrote in post #12687415
Have you turn off flash sync on the camera, I have heard this about the 602, I read some where in here about it. I think itwas Skip that did some testing. I did get my 20D upto 320 with a slight black line at the bottom, shutter, at 400 it was halfway up.
What are you shooting?

Read my original post. It expains it all

Maybe not, but a flash sync of 250th second would be better in brighter conditions than 200th second..

yogestee wrote in post #12686139
I'm still miffed???

I'm having a location shoot this weekend. I really want to use my Nissin Di866 in my softbox but I'm unable to get 250th second (200th second is the fastest flash sync I'm able to get).

Now,, with my 430EXII and 430EX I'm able to get 250th second shutterspeed flash sync with both my 50D/20D and RF-602.

It has nothing to do with flash duration because I tested all three flashes from full power manual to 1/32nd power.

Freshly recharged Eneloops in both the RF-602 receivers and flashes. Flashes mounted directly onto the receiver hotshoe.

This occurs on all my three RF-602 receivers. What's going on?

Basically, it's propagation delay in the electronics of the triggers.

archer1960 wrote in post #12688478
Basically, it's propagation delay in the electronics of the triggers.

This could be the case. But that doesn't explain why I can still get 250th second out of my 430EX Speedlites.

archer1960 wrote in post #12688478
Basically, it's propagation delay in the electronics of the triggers.

Sounds more like delay in the electronics of the Nissin flash if the same triggers can work at 1/250 with both versions of the 430ex flashes. Not saying that it is but the delay of the triggers should be the same no matter what flash is attached.

dedsen wrote in post #12688506
Sounds more like delay in the electronics of the Nissin flash if the same triggers can work at 1/250 with both versions of the 430ex flashes. Not saying that it is but the delay of the triggers should be the same no matter what flash is attached.

All electronics will have some propagation delay, both the triggers and the flash. Apparently the 430's delay is enough less than the Nissin's, that the added delay of the triggers puts the Nissin over the line.

dedsen wrote in post #12688506
Sounds more like delay in the electronics of the Nissin flash if the same triggers can work at 1/250 with both versions of the 430ex flashes. Not saying that it is but the delay of the triggers should be the same no matter what flash is attached.

Dale,, I double checked my Di866 with my ST-E2 today,, 250th second no problems..

I'm thinking this.. Combination of the two..

This post shows how I compared the sync speed of two flash units at the same time:
https://photography-on-the.net …hp?p=4640256&po​stcount=27

I was testing triggering methods, not flash units, but the same approach could work for you if you really want to prove (or disprove) something about your flash unit.

I'm not familiar with the Di866 but if there a way to fire it with an optical slave, that will take away the potential variable of your RF-based triggering system.

^^^

Thanks Curtis for the info.

Bit of a guess, but it could be how the Nissin picks up the trigger signal. With Canon E-TTL, there are numerous trigger signals going out through different contacts, including two for normal flash (plus HSS, second curtain etc).

If you have a pair of identical triggers and two guns on two receivers, on different channels, and you fit one to the hot shoe and the other into the PC socket via cable, if you have a moving subject you will get a double flash image. If you then connect the hot-shoe trigger via an adapter so it can only pick up the centre pin, the double image disappears. The difference is about 1ms, which in terms of shutter travel is rough equal to dropping from 1/250sec to 1/200sec. I assume it's some kind of compensation for the delay introduced when there are multiple pre-flashes going out ahead of the main flash.

To put that another way, if you fit the RF-602 into the hot shoe, you will get a certain x-sync speed, but if you plug it into the PC socket or directly to the centre pin only, you need to drop the shutter speed 1/3rd of a stop. Maybe the Nissin is only picking up from the centre pin when used in manual?

I believe the difference in sync speed is due to the Nissin Di866's ability to respond to the trigger signal from the RF602. In technical terms the input of the Nissin Di866 presents a load to the output of the RF602. The load presented by the flash could easily require the RF602 to work a little harder to get the voltage up to the point that the flash fires. The other possibility could be the rise time of the signal out of the RF602. The RF602's signal could have ringing on it that the Nissin does not see, until things stabilize. Someone with a Oscilloscope could verify what the signal out of the RF602 looks like.

Hope this helps,

110yd

To confirm if my theory above is correct, plug the RF-602 transmitter into the PC socket via cable and compare the Canon/Nissin sync speeds then. I suspect they will both be the same, at 1/200sec.

Thanks Hoppy and 110yd

Not having 250th second with the Di866 isn't a huge concern but it would be nice.. I have a few options. I'll use the 430EX so 250th second is assured..

The shutter shadow when using the Di866 is only slight, so if I really need 250th second I can always shoot a bit loose then crop into the image.

Once again,, thanks guys