D750's flash output.

[DAVID MANZE]

Hi guys,

I've been trying to link a couple of extension flash guns together using the camera's built in flash to trigger. The problem is one of the camera's pre-flashes which trigger the extension flashguns but don't synchronise with the shutter, the net result is you see the ext. flash through the viewfinder and get dark shots.

I have a optical trigger that I purchased when I shot Pentax which has switch for "red eye setting" with rotary control adjustable to ignore the pre-flashes and only triggers from the main one......unfortunately it doesn't seem to function....more dark frames.

I've by passed optical coupling from the camera and have dug out a cable and hot-shoe adapter which at least works. I've also ordered a radio controlled trigger and four slaves from China, so a wait of a few weeks!

However, it leaves me with the question, how many pre-flashes are there and is there no mode that just uses the main exposure flash without any pre-flashes at all?

I rarely use flash so thanks in advance!

--
Dave's clichés

 

[Rabbson78]

You didn't mention the make of flash guns you are using but in general setting the flash guns to iTTL and the camera to commander mode (all on same channel) will get correct exposures. If you want to manually control the power output of the flash guns then set them to slave mode S2, they will then ignore any pre-flashes.

Incidentally I had a set of cheap Chinese radio triggers and eventually threw them away - simply to unreliable.

 

[BirgerH]

Hi guys,

I've been trying to link a couple of extension flash guns together using the camera's built in flash to trigger. The problem is one of the camera's pre-flashes which trigger the extension flashguns but don't synchronise with the shutter, the net result is you see the ext. flash through the viewfinder and get dark shots.

Hi David.

That's strange. The preflashes should be immediately before or simultaneously as the shutter opens - and after the mirror is going up - you should not be able to see the flashes in the viewfinder.

To me it sounds as your flashgun is not set for iTTL or not compatible to Nikon CLS (AWL) - and reacts on the first pre-flash instead of the triggering final flash. Still - you should not be able to see it in the viewfinder.

I have a optical trigger that I purchased when I shot Pentax which has switch for "red eye setting" with rotary control adjustable to ignore the pre-flashes and only triggers from the main one......unfortunately it doesn't seem to function....more dark frames.

Yes - if it's made for Pentax - it will not be compatible to Nikon CLS (AWL) - but maybe work in manual.

I've by passed optical coupling from the camera and have dug out a cable and hot-shoe adapter which at least works. I've also ordered a radio controlled trigger and four slaves from China, so a wait of a few weeks!

However, it leaves me with the question, how many pre-flashes are there and is there no mode that just uses the main exposure flash without any pre-flashes at all?

I don't know how many pre-flashes, there are - but enough to set two or three individual groups with different metering instructions. The slaves are sending pre-flashes as well, which the camera uses for the metering. It's all done inside, I would estimate 1/500 - 1/10000 of a second.

If you don't want pre-flashes, you have to set up everything as manual. Then the master flash (commander) will just trigger the slaves.

I rarely use flash so thanks in advance!

 

[Flashlight]

If you set the built-in flash and external flashes to manual it should work, without iTTL of course.

 

[jl_smith]

What Flashlight said -- set your onboard to manual. That said, I've also used Commander mode with the 750 and my optical slaves have no problem firing, so I don't know if it uses a pre-flash or not in that mode (using Yongnuo 560-IIIs for optical slaves).

Also, check your flash -- if they're firing from a pre-flash, you might be able to set the flash itself to wait on the second flash from the controlling flash, not the first flash. I can do this with my Yongnuos, but I've never had to.

 

[j_photo]

Set flash to Manuel, so that there are no preflashes on the camera fkash. Or, set slaves to S2 mode which should cause the slaves to ignore the preflashes.

 

[DAVID MANZE]

Thanks for the replies guys!.......

I have a bunch of old and not so old flashguns which just have the early auto functions but no TTL capabilities......but for testing I use manual mode.

Ok I've found the flash manual mode E3 in the menu........it was set to TTL, I've now changed it to M or CMD (command) .....

.......and all is good!

Thanks again!!!

--
Dave's clichés