Rear curtain sync

B

Bigfatmole

Senior Member
Hi guys please help. I trying to use the flash on and off with rear curtain sync. All the you tube videos I've watched only show the flash fire at the end of the exposure which is how I expected it to work. However on my D610 & my D5100 the flash fires at the start and at the end of the exposure . I'm under the understanding with rear sync the flash should only fire at the end of the exposure, am I doing something wrong ??? Is there a setting apart from putting flash on rear sync which needs to be set ? Or should it fire at start and at the end. If there is a setting that needs changing please can you direct me to where it is..many thanks in advance :)
 
W

WayneF

Senior Member
You are OK, that is how things work. Assuming you are using TTL mode, the early flash is the TTL preflash, maybe 100 milliseconds before the shutter opens. It is there for front curtain sync too, we just cannot distinguisht it separately then. But with rear curtain and a longer shutter duration, we see it separated by the shutter duration. It is fully normal, and preflash is required for TTL.

You could eliminate TTL preflash by using Manual flash mode.
 
Last edited:
B

Bigfatmole

Senior Member
Yah Thankyou Wayne , so if I was to put flash on manual would it do away with the pre flash and be more how I expected it to work ? I'll have to go n try it :)
 
G

Geoffc

Senior Member
Bigfatmole said:
Hi guys please help. I trying to use the flash on and off with rear curtain sync. All the you tube videos I've watched only show the flash fire at the end of the exposure which is how I expected it to work. However on my D610 & my D5100 the flash fires at the start and at the end of the exposure . I'm under the understanding with rear sync the flash should only fire at the end of the exposure, am I doing something wrong ??? Is there a setting apart from putting flash on rear sync which needs to be set ? Or should it fire at start and at the end. If there is a setting that needs changing please can you direct me to where it is..many thanks in advance :)
Click to expand...

It's the TTL pre-flash? If you put the flash to manual it only fires once. Just tried on my D800.
 
B

Bigfatmole

Senior Member
Cheers guys, I've been and tried it on TTL and manual and yep on manual it's how I wanted it to be .. So simple to fix but was driving me mad lol.
have a merry Xmas guys and Thankyou again :)
 
W

WayneF

Senior Member
Bigfatmole said:
Yah Thankyou Wayne , so if I was to put flash on manual would it do away with the pre flash and be more how I expected it to work ? I'll have to go n try it :)
Click to expand...

Yes. I don't know how you are using it, but for many outside scenes at night where we are seeking rear curtain blur trails, manual flash mode might be more appropriate anyway.
 
Top