1st and 2nd Curtain Flash

I am wanting to use a long exposure with one flash flashing at the beginning of the shot and the other at the end. Is this possible. I am using flashes with 603c transceivers on my 5Dmk3. Here’s a shot I took that will give you all an idea of what I want to accomplish. My shot cannot be a composite and must be all one shot. thanks

I've no personal experience of these - but - it should be possible with the 'delay timer' function on Cactus V6s
http://www.cactus-image.com/v6.html
http://www.cactus-image.com …0User%20Manual%​20(EN).pdf
section: 14.2
Your 5DIII would be setup to deliver first curtain sync - the camera's pc out port should propagate that (or you could interpose a Pixel TF321 under the V6 TXr) - then your 603s to network the first flash. (I'm not sure of the exact pass-through properties of your 603 TXrs.)(Also, I'm not sure whether or not your 603 in Tx function would need one of these under it:
http://flashzebra.com/​products/0273/index.sh​tml
)
Then a V6 in the camera's hot-shoe (or above a TF 321) set to the ms delay required to give a faux SCS signal just before the second curtain starts to close, should work as an SCS network source.

Alternatively, go V6 throughout and just use the delay on those Receivers contributing the faux SCS flash.

That's where I would start, I think!

I had to get creative with the equipment I have. I used my Yongnuo 603c’s, set custom flash settings on camera to 2nd curtain. I set the flashes to ETTL. This makes the flashes flash at the beginning and end of the shot. (I’m not sure why). I then setup my camera and worked on my timing as this is a self portrait. Anyway, I pretty much got the shot I wanted.

WillMeades wrote in post #17960387
I had to get creative with the equipment I have. I used my Yongnuo 603c’s, set custom flash settings on camera to 2nd curtain. I set the flashes to ETTL. This makes the flashes flash at the beginning and end of the shot. (I’m not sure why). I then setup my camera and worked on my timing as this is a self portrait. Anyway, I pretty much got the shot I wanted.

Hosted photo: posted by WillMeades in
./showthread.php?p=179​60387&i=i145176584
forum: Flash and Studio Lighting

The first flash is the TTL metering preflash. Even though Rear Curtain sync is useable in TTL with some systems, you have to bear in mind that the flash metering and the actual flash exposure are at both ends of the shutter duration spectrum. Your distance from subject to flash could change in that time, depending on how long the shutter is open, which could change the flash exposure of the subject.

Interesting that that setup works.

" .. that the flash metering and the actual flash exposure are at both ends of the shutter duration spectrum .. " Under ETTL normally that is not the case, but here, interposing the simple M only 603s has brought the pre-flash (first flash) to be later than normal ETTL pre-flashes, such that it is included within the capture.

agv8or wrote in post #17960407
The first flash is the TTL metering preflash. Even though Rear Curtain sync is useable in TTL with some systems, you have to bear in mind that the flash metering and the actual flash exposure are at both ends of the shutter duration spectrum. Your distance from subject to flash could change in that time, depending on how long the shutter is open, which could change the flash exposure of the subject.

That makes sense to me now! When I set the flashes to manual I would only get the 2nd curtain flash, but I needed a flash of some sort at the beginning of the shot. So in the end this worked for me. thanks for the explanation.

OceanRipple* wrote in post #17960415
Interesting that that setup works.

" .. that the flash metering and the actual flash exposure are at both ends of the shutter duration spectrum .. " Under ETTL normally that is not the case, but here, interposing the simple M only 603s has brought the pre-flash (first flash) to be later than normal ETTL pre-flashes, such that it is included within the capture.

I had my camera setup in M and 2nd curtain. I set the flashes to ETTL. When I set the flashes to match the camera I would only get one flash (2nd curtain). But I needed the flash at both ends of the shot. Sometimes I just stumble upon something that seems to work for me.

Every other month our camera club has a print competition. This time the theme is “long exposure”. So I could not use composites which would have made this shot very easy. I figure that most prints will be water, nighttime traffic, etc. So I wanted to do something a little different. We have to name our prints, so I thought I would name this one “Inner Conflict”. Thanks for the feedback.

If you want a blurred streak between the two exposures in ETTL then you need to add a resoanble strong second constant light source. If use a tungsten light then the streak will a different color and you have set light balance to flash/5500K if the camera does this on itself.
The shown example has only one flash and the second light souce and does not have to be a second curtain flash if you use bulb exposure.

mmmfotografie wrote in post #17960431
If you want a blurred streak between the two exposures in ETTL then you need to add a resoanble strong second constant light source. If use a tungsten light then the streak will a different color and you have set light balance to flash/5500K if the camera does this on itself.

I experimented with this as well but wanted a cleaner look. So I used very dim ambient light to minimize any streaks. Then I had to move very fast between 1st and 2nd positions. It took about 10 shots to get what I wanted. Hopefully it will confuse the judges a bit.

Try using the Multi-flash function on your speedlite.
Set it for to the widest gap between flashes.
I set a Godox TT850 to 1Hz and 2 flashes. Set the shutter to 1 second. Got a flash at the beginning and the end of the exposure.

With a black background it should work just about exactly as you want.

WillMeades wrote in post #17960432
I experimented with this as well but wanted a cleaner look. So I used very dim ambient light to minimize any streaks. Then I had to move very fast between 1st and 2nd positions. It took about 10 shots to get what I wanted. Hopefully it will confuse the judges a bit.

If I am not wrong if you use Bulb exposure you will have enough time to move. Use a remote trigger and you will get the metring flash and if you press the second time you will get the second and real flash.

I can be wrong and I have never experimented with these kinds of ways to light.

mmmfotografie wrote in post #17960638
If I am not wrong if you use Bulb exposure you will have enough time to move. Use a remote trigger and you will get the metring flash and if you press the second time you will get the second and real flash.

I can be wrong and I have never experimented with these kinds of ways to light.

You are correct. But I set my shutter speed based on how much ambient light I wanted (or did not want) in the photo. It was easier for me to adjust my own speed in turning.
thanks