Rear Curtain Sync w/ 5D

Started Feb 21, 2012 | Discussions thread
Henrik Herranen
Senior MemberPosts: 1,653Gear list
Like?
Re: Won't solve the problem at hand
In reply to kb2zuz, Feb 23, 2012

kb2zuz wrote:

The 580EX-II does have an auto-trysistor mode, but I am uncertain if Canon lets you use 2nd curtain sync with it (it may by just figuring the longest duration that may be needed or it may not because it cannot be certain of the duration as the duration is stopped during exposure).

I tried this with the same 5D2 + 580EX II combination as earlier in this thread using an exposure time of 1/2s. Couldn't do it. The flash refused to go into 2nd curtain sync mode in the auto-tyristor / external metering mode.

I cannot completely understand the reason for this behaviour. I understand that the camera cannot know exactly how long the flash will be lit because the flash does the decisions. However, the camera must know that flash duration cannot be more than the time the shutter is completely open when maximum sync speed (1/200 s) is used. So why cannot the camera open the shutter, wait for a while, then tell the flash to light up e.g. 2 ms before starting to close the 2nd curtain (replace 2 ms with whatever the longest flash time of the 580EX II is)? This way I could still have almost perfect 2nd curtain sync with long exposure times (long being e.g. 1/10s).

Kind regards,

  • Henrik

-- hide signature --

And if a million more agree there ain't no great society

 Henrik Herranen's gear list:Henrik Herranen's gear list
Canon PowerShot S90 Canon EOS 5D Mark II Canon EF 135mm f/2.0L USM Canon EF 100mm f/2.8 Macro USM Canon Extender EF 1.4x II +5 more
Reply   Reply with quote   Complain
Post (hide subjects)Posted by
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark post MMy threads
Color scheme? Blue / Yellow