canon rumors FORUM

Gear Talk => EOS Bodies - For Stills => Topic started by: Forceflow on May 04, 2013, 04:14:58 PM

Title: 7D and rear curtain flash :(
Post by: Forceflow on May 04, 2013, 04:14:58 PM
Why will my 7D not do a rear curtain flash with non-Canon devices? I just purchased the pixel soldier remote trigger set only to find out that Canon wont let me do a second curtain flash. There is no reason not to allow rear curtain. All the camera has to do is to send the flash signal and that is it :(

Any ideas what is behind this or even better a fix for this?
Title: Re: 7D and rear curtain flash :(
Post by: neuroanatomist on May 04, 2013, 05:20:37 PM
The only workaround I'm aware of is to use 3rd party RF triggers (PocketWizard, Phottix Odin).
Title: Re: 7D and rear curtain flash :(
Post by: Forceflow on May 05, 2013, 04:25:41 AM
But how does that work? As soon as I connect the RF trigger I can no longer select to activate the flash on the second curtain. Only solution I found is to work with the internal flash and mount an optic slave to it, then connect the RF transmitter to the optical slave. Then you have to make sure that the whole thing is covered so no light from the internal flash actually gets on the subject you want to photograph. I have not yet tried this but I ordered a cheap optical slave to see if it will work. But this is an extremely cumbersome design and in my opinion absolutely unnecessary.
I mean why can't the camera simply send the flash signal? Even if you are working with Canon only flashes it renders off camera second curtain flash completely unusable. (As soon as I activate remote triggering the second curtain option is greyed out) I really can't understand the reasoning from Canon behind this.
Title: Re: 7D and rear curtain flash :(
Post by: neuroanatomist on May 05, 2013, 06:49:58 AM
With PW/Odin, you enable second curtain sync as a setting on the trigger, not with the camera menu.
Title: Re: 7D and rear curtain flash :(
Post by: Marsu42 on May 05, 2013, 07:14:21 AM
The only workaround I'm aware of is to use 3rd party RF triggers (PocketWizard, Phottix Odin).

The very good and extremely reasonably priced Yongnuo radio triggers also do remote 2nd curtain sync, though with some constraints imposed by the old Canon ettl2 protocol - but it does work, so that would/will be my personal choice (until Canon comes up with a ettl3 protocol with remote zoom and 2nd curtain sync...)
Title: Re: 7D and rear curtain flash :(
Post by: Forceflow on May 05, 2013, 02:28:15 PM
The very good and extremely reasonably priced Yongnuo radio triggers also do remote 2nd curtain sync, though with some constraints imposed by the old Canon ettl2 protocol - but it does work, so that would/will be my personal choice (until Canon comes up with a ettl3 protocol with remote zoom and 2nd curtain sync...)

Can you elaborate on the constraints and compatibility with manual flashes? I read some info about it but it was unclear how and if the Yongnuo can do second curtain remote triggering. From what I was able to gather you need to have a Canon flash connected to the Yongnuo trigger in order to be able to do 2nd curtain settings. (Because they have to be set in the camera, else how can you do second curtain bulb mode)
Title: Re: 7D and rear curtain flash :(
Post by: Marsu42 on May 05, 2013, 03:40:44 PM
Can you elaborate on the constraints and compatibility with manual flashes? I read some info about it but it was unclear how and if the Yongnuo can do second curtain remote triggering. From what I was able to gather you need to have a Canon flash connected to the Yongnuo trigger in order to be able to do 2nd curtain settings. (Because they have to be set in the camera, else how can you do second curtain bulb mode)

Afaik the Yongnuo 580ex2 clone looks different, but emulates the Canon flash so that there should be no difference to a "real" Canon model. As for 2nd curtain sync this is really hard to figure out (I haven't bought the triggers yet), all I can do is quote a review I found: http://flashhavoc.com/yn622c_review/ (http://flashhavoc.com/yn622c_review/)

Quote
Second Curtain Sync works with the off camera flashes, but not with the wireless menu function enabled. So you no longer have remote control of more than one group. But that is still much better than no second curtain sync at all off camera (like Canons RF system).
Title: Re: 7D and rear curtain flash :(
Post by: spturtle on May 05, 2013, 04:38:58 PM
Why will my 7D not do a rear curtain flash with non-Canon devices? I just purchased the pixel soldier remote trigger set only to find out that Canon wont let me do a second curtain flash. There is no reason not to allow rear curtain. All the camera has to do is to send the flash signal and that is it :(

Only Pixel's "King" triggers support E-TTL which is required for 2nd curtain sync. For those you would just need to set "Wireless Func." to "Disable" in the flash functions menu on the camera, same as with yongnuo YN622C. But the pixel soldier is not a "TTL" trigger so AFAIK it can't support 2nd curtain sync.
Title: Re: 7D and rear curtain flash :(
Post by: Forceflow on May 06, 2013, 02:00:36 AM
Only Pixel's "King" triggers support E-TTL which is required for 2nd curtain sync. For those you would just need to set "Wireless Func." to "Disable" in the flash functions menu on the camera, same as with yongnuo YN622C. But the pixel soldier is not a "TTL" trigger so AFAIK it can't support 2nd curtain sync.

Mhm... will this work even if I do not have an E-TTL flash? If so it might be a solution. Still pretty annoying but better than nothing I guess. (Still do not understand why Canon does not offer a manual second curtain, after all they have to do this for bulb mode anyways...)

Thanks a lot for the insights folks!
Title: Re: 7D and rear curtain flash :(
Post by: bycostello on May 06, 2013, 05:11:48 AM
canon and rear curtain have issues...
Title: Re: 7D and rear curtain flash :(
Post by: Forceflow on May 14, 2013, 12:31:21 PM
Man... I really hate Canon's flash implementation. So I played around a bit with an optical slave unit the pop-up flash to trigger the remote flashes. In theory this works, but it's a bit hit and miss. Really not reliable enough to take to a shoot. (Even though I don't do any professional shoots I still want to be able to rely on my equipment)
So I went ahead and purchased two Yongnou 622-C and lo-and-behold once I attach them to my 7D I can actually select 2nd curtain! I thought I was finally set until I realized that this again only works if you use eTTL compatible flashes :(
My plan was to attach my Pixel Soldier on top of the YN to trigger all the flashes. But if I do that it's 1st curtain yet again. (Even though the camera let's me actually set it to 2nd curtain) Then I attach my Sigma 610DG to the remote unit of the YN and it does indeed go of on the 2nd. I try to connect my YN flash to the second unit and it goes off on the 1st curtain again.
Only upside so far I see is that with the YN I can actually remote control my Sigma eTTL flashes, which didn't work before. That means I can use my ring flash and 610DG in high-speed-synch and have the 610 remote triggered. That is pretty cool and the reason why I'll stick to the YN. In addition to that I can still use the optical slave and attach it to the PS and have it remotely trigger the two YN flashes I have. (Though then again it'll be a bit hit and miss, though better than the pop-up flash solution)

All in all really not nice and highly annoying :( (Especially considering how much money I threw at this problem by now)
Title: Re: 7D and rear curtain flash :(
Post by: wickidwombat on May 15, 2013, 01:24:27 AM
But how does that work? As soon as I connect the RF trigger I can no longer select to activate the flash on the second curtain. Only solution I found is to work with the internal flash and mount an optic slave to it, then connect the RF transmitter to the optical slave. Then you have to make sure that the whole thing is covered so no light from the internal flash actually gets on the subject you want to photograph. I have not yet tried this but I ordered a cheap optical slave to see if it will work. But this is an extremely cumbersome design and in my opinion absolutely unnecessary.
I mean why can't the camera simply send the flash signal? Even if you are working with Canon only flashes it renders off camera second curtain flash completely unusable. (As soon as I activate remote triggering the second curtain option is greyed out) I really can't understand the reasoning from Canon behind this.

the odins have a screen on the controller so you active all functions from this instead of the camera ie HSS and second curtain as well as group powers and ratios
Title: Re: 7D and rear curtain flash :(
Post by: AvTvM on May 15, 2013, 04:08:46 AM
Canon's wireless flash protocol sucks big time.

This is the only culprit for all the difficulties you and all other Canon users are experiencing if they wish to use 2nd curtain sync over wireless. A few newer items of Third Party gear - al of them listed in this thread - do offer workarounds - but all of them are both limited in functionality and ergonomically cumbersome. 

Even when they introduced their new, expensive as hell Speedlite 600EX-RT and ST-E3 trigger with radio wireless technology, Canon refused to implement an improved version of its wireless [ETTL] flash protocol, that would allow a straightforward workflow and direct control over all relevant flash parameters - including 2nd curtain sync and power zoom of flash reflector - directly on the Camera's LCD panel and flash menu. 

Nikon CLS allows all of this -  of course including wireless 2nd curtain sync together with iTTL - for more than 2 decades by now. It also does not stuff the totally stupid concept of "flash ratios" - "A:B" - down its users throats.

This is one of the reasons why I am refusing to invest any more money in my Canon gear. Until they got this sorted out. Or until I finally make the switch to Nikon and send Canon to hell. 
Title: Re: 7D and rear curtain flash :(
Post by: Marsu42 on May 15, 2013, 04:39:02 AM
Even when they introduced their new, expensive as hell Speedlite 600EX-RT and ST-E3 trigger with radio wireless technology, Canon refused to implement an improved version of its wireless [ETTL] flash protocol, that would allow a straightforward workflow and direct control over all relevant flash parameters - including 2nd curtain sync and power zoom of flash reflector - directly on the Camera's LCD panel and flash menu.

I don't understand that either - it'd had been the perfect opportunity to use ettl-3 over rt and ettl-2 fallback for optical.

They did some changes though with the very good group mode - I'd really like to now why they did nothing for 2nd curtain or zoom over wireless, did they run into tech problems, didn't they have enough r&d resources, don't they care or is the new 660rt just around the corner?
Title: Re: 7D and rear curtain flash :(
Post by: Forceflow on May 15, 2013, 01:17:45 PM
Pixel soldier triggers don't support rear curtain, hss, etc. Your trigger needs to support it, and so does your flash.

You'd need Pixel Kings, YongNuo 622c, or similar triggers that have that capability.  If you're on a budget, I suggest the YN622c trigger set. It's cheaper and you get more bang for your buck than the kings, and with the right flash, supports menu setting flash changes.

Keep your pixel soldiers though, in case you want to remote trigger your camera/flash chain (i.e. Your pixel soldier plugs into only the shutter release port, tells the camera to fire remotely, which fires the YN622 or pixel king or whatever trigger in the hotshoe, which sets off your flash(es).

Thing is with the YN-622C second curtain only works if you have an eTTL flash connected to it and not a dumb manual flash. (At least not for me) Which again is fairly stupid. I mean for a multi-flash setup I really don't need intelligent eTTL flashes at all. A 'dumb' manual unit is much easier to work with anyways, but of course then I can't do second curtain again :(
Title: Re: 7D and rear curtain flash :(
Post by: Forceflow on May 16, 2013, 01:19:42 AM
Well, the flash must support second or rear curtain sync too, or it isn't there to use.

And that is the thing I really don't understand. What great magic must the flash know in order to be able to rear-synch? I mean the camera sends the signal to fire the flash before the shutter closes and that's all the flash needs to do. This is especially true for bulb mode since in that case Canon cannot even do it's famed 'I'll send the shutter speed setting to the flash' since the camera doesn't know the shutter length anyway. So it should just send a dumb 'fire now' command.
I have done the combining of flashes that you described but that is pretty much useless for me. I need all my flashes to fire on the rear curtain and not have some of them fire on first curtain and some on the rear curtain. (Well, I guess I could see one or two applications were this would be a fun thing to do, but not for the majority of my pictures)
This is turning out to be much more annoying and certainly a lot more expensive than I thought it would :(
Title: Re: 7D and rear curtain flash :(
Post by: Marsu42 on May 16, 2013, 04:59:38 AM
I mean the camera sends the signal to fire the flash before the shutter closes and that's all the flash needs to do.

In ettl mode, the flash sends the command signals with the low-power pre-flash before the shutter *opens* - it probably tells the slave flashes "wait this time, then fire with this strength". The pre-flash isn't only for flash power calculation, that's why you need to have a pre-flash in optical mode even if all flashes are set to manual - and the new rt mode seems to be a 1:1 copy but with radio transmission.

But it is indeed a bit mysterious why slave flashes would need a dedicated "2nd curtain sync" capability for this, probably their fw doesn't allow them to wait for a longer time than 1st curtain sync (mere speculation)
Title: Re: 7D and rear curtain flash :(
Post by: Forceflow on May 16, 2013, 05:14:49 AM
I mean the camera sends the signal to fire the flash before the shutter closes and that's all the flash needs to do.

In ettl mode, the flash sends the command signals with the low-power pre-flash before the shutter *opens* - it probably tells the slave flashes "wait this time, then fire with this strength". The pre-flash isn't only for flash power calculation, that's why you need to have a pre-flash in optical mode even if all flashes are set to manual - and the new rt mode seems to be a 1:1 copy but with radio transmission.

But it is indeed a bit mysterious why slave flashes would need a dedicated "2nd curtain sync" capability for this, probably their fw doesn't allow them to wait for a longer time than 1st curtain sync (mere speculation)

In non-bulb mode this is true, but in bulb mode it's not. (Since the camera cannot know for how long I will press the shutter) Hence the camera must send a simple 'fire now' command.
Title: Re: 7D and rear curtain flash :(
Post by: Marsu42 on May 16, 2013, 05:19:19 AM
In non-bulb mode this is true, but in bulb mode it's not. (Since the camera cannot know for how long I will press the shutter) Hence the camera must send a simple 'fire now' command.

Ok, very valid point, the only idea I have about that is that it sends the flash power setting via pre-flash, and then the actual fire signal via dumb flash trigger (slaves fire when the main flash fires). Probably this two-stage version only works for long bulb and not for short x-sync, so it cannot be used for 2nd curtain remote...
Title: Re: 7D and rear curtain flash :(
Post by: bycostello on May 16, 2013, 05:49:58 AM
big failing on canon the 2nd curtain issues