Rear/Second Curtain Sync

The Phototron · Oct 17, 2007

Okay, I have some potentially stupid questions.

First, is rear curtain sync possible if the camera (Rebel XT) has this custom function? Or is it only possible if the flash (Vivitar 285HV) also has it?

That is my situation, and so far I don't think it's possible to do rear curtain sync with vivitar 285HV on my Rebel XT. I read the manual, but it's not telling much.

So here's the follow up questions:
Is rear curtain sync only possible with Canon flashes on my rebel xt?

Also is it possible with strobes like dyna-lite, and calumet's travelite?

Big Mike · Oct 17, 2007

Good question :scratch:

Big Mike · Oct 17, 2007

From the 'EOS Flash Bible'

This depends very much on the camera and flash unit that you’re using. Early on, Canon put control for this feature on the flash unit. Later they switched to putting control for this feature on the camera body. So whether you have second-curtain sync available to you depends on a complicated set of permutations.

Many mid to high end Canon flash units, listed below, have a button or switch which lets you enable second curtain sync. It’s usually marked with a triple triangle ( >>> ) symbol or the word SYNC. For instance, on the 430EZ and 540EZ you press the + and - buttons together simultaneously to turn on second-curtain sync. When you do so a triple triangle symbol appears in the LCD. On the 300EZ and 300TL there’s a small slide switch - left is first-curtain sync and right is second-curtain.

Most midrange and professional EOS bodies from the A2(E)/5 onwards have a custom function that lets you specify whether you want first or second curtain flash. The exception is the original Elan/100, which had a custom function that can only control the internal flash and not external flash units. In the case of a camera with a custom function and an external flash unit which has a second curtain switch then you use the physical switch on the flash to control the function.

Low-end EOS cameras, such as the 1000 series or Rebel series, do not have any custom functions and so cannot control second curtain sync options directly. So to take advantage of second curtain sync on such cameras you must have an external flash which has externally-available controls to operate it.

Second-curtain sync cannot be used with any EOS camera in a PIC (icon) mode - you have to be set in P, Av, Tv or M modes. And you can’t set second-curtain sync in stroboscopic mode or FP mode, since that wouldn’t make any sense. Finally, second-curtain sync requires a dedicated Speedlite flash unit - it isn’t supported on flash units connected via a PC socket (see PC connector section below).

The Phototron · Oct 17, 2007

Thanks VERY MUCH Mike, though it doesn't comfort me very much that I have to get another Flash just for rear curtain sync. :/

Big Mike · Oct 17, 2007

Ya, that's too bad...I would think it would be easy to just make the flash fire are the end of the exposure.

You could probably try a few tests, just o confirm this. Set a shutter speed of a second or more and set the camera to 2nd curtain, then put your Vivitar on and shoot away.

The Phototron · Oct 17, 2007

Big Mike said:
Ya, that's too bad...I would think it would be easy to just make the flash fire are the end of the exposure.

You could probably try a few tests, just o confirm this. Set a shutter speed of a second or more and set the camera to 2nd curtain, then put your Vivitar on and shoot away.

Yeah I did test it, I was just so desperate that it didn't work, so I came here to confirm it.

But you are right, it shouldn't be too hard to activate it manually in the end of a long exposure with the test button.

Edit: It's actually almost impossible! Panning and firing the flash manually at the same time.

Big Mike · Oct 17, 2007

Oh, I guess you could try that.

I was thinking that is shouldn't be too hard for Canon Engineers to make it fire at the end of an exposure...it's just an electrical signal to fire the flash.

Although, thinking about it. If it's an off-brand flash, the camera wouldn't exactly know how long the flash burst is going to be...it would be hard to time it at the end of the exposure.

The Phototron · Oct 17, 2007

That makes more sense, although it makes me sound like an idiot.

Garbz · Oct 17, 2007

More importantly how would this work with TTL metering? The flash needs to metre first and then expose significantly later. I'm sure it all sounds easy if you have the datasheet infront of you. Would suck if you didn't.

Maybe canon also simply withhold this information from competitors to increase sales of it's own speedlights.

Big Mike · Oct 18, 2007

More importantly how would this work with TTL metering? The flash needs to metre first and then expose significantly later. I'm sure it all sounds easy if you have the datasheet infront of you. Would suck if you didn't.

You can still use TTL metering and 2nd curtain sync (with a Canon flash). The pre flash fires before the exposure as usual...but then the actual flash doesn't fire until the end of the exposure....so the longer your exposure, the longer the delay. This can be troublesome when shooting people because they might move or blink after the first flash. Of course, if the scene changed between the metering and the flash...the exposure may not be accurate.