Tutorial Second Curtain Flash Synchronisation.

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Second Curtain Flash Synchronisation. - Second Curtain Flash Synchronisation.

Second (or 'Back') Curtain Flash Sychronisation. What's that all about then? It's not as difficult or complicated as it sounds.

Our DSLR cameras (or SLR film cameras for that matter) are fitted with focal plane shutters sitting just in front of the sensor. Focal plane shutters consist of two metal blinds which travel upwards across the sensor. Earlier cameras had cloth blinds and the blinds travelled horizontally, but nowadays pretty well all shutters on modern cameras use metal blinds and...
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Plain English at its best Thanks for explaining it to us
Bob
 
Resurrected from the grave this thread..:D

You are correct though Bob, Our CT is a fountain of knowledge..(y)
 
ignore
 
dod said:
There is one thing though, if you're using a Canon 580/430 (don't know about others) with 2nd curtain and ETTL(II) you get a preflash as well to calculate exposure. This will record on the image. I think to avoid it you need to go fully manual. If I could find the manual I would read it :(
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Wont that pre flash be before the shutter opens though Doddy. ;)
 
CT said:
Wont that pre flash be before the shutter opens though Doddy. ;)
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Found it, you're right, I'm an idiot :nuts:
 
Brilliant way of explaining 2nd curtain sync. If manuals explained procedures in a similar way, we would all reduce the learning curve. I did not understand this subject when I read about it in the manual, so therefore never used it. I will now. Thanks Cedric (y)
 
Ive always kept in on second curtain because of that reason but recently read something about that making more people blink when used with ETTL flash as they are further apart?
 
I always thought there was only one shutter, now this explains a lot of things. I learn something new every day.

Superb, clear description many thanks CT.

Regards,

JB
 
Id noticed it flashes twice, i was going to start a thread about it untill this one poped up!! lol...

Right, so Manual is the way to go.. i couldnt see the point of second sync if it fired on the first aswell!! :shrug:
 
Janice said:
Ive always kept in on second curtain because of that reason but recently read something about that making more people blink when used with ETTL flash as they are further apart?
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I wouldn't use 2nd curtain sync routinely anyway, Janet - just for those occasions when it's merited with a moving subject. That first flash as I'm sure you know, is just a pre-exposure metering flash. With 1st curtain sync the effect is almost like one continuous flash from the point of view of your subjects.

With 2nd curtain sync the two flashes being further apart, could well cause blinking in your subjects but I wouldn't use that mode for portraits or wedding groups anyway. (for example)
 
krazy_horse said:
I always thought there was only one shutter, now this explains a lot of things. I learn something new every day.
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Well there IS only one shutter, it just has two blinds and two methods of synchronizing with a flashgun :)
 
fraggle101 said:
Id noticed it flashes twice, i was going to start a thread about it untill this one poped up!! lol...

Right, so Manual is the way to go.. i couldnt see the point of second sync if it fired on the first aswell!! :shrug:
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That first flash is just a pre flash which occurs fractionally before the shutter opens and which is used to determine the correct amount of flash for the actual exposure, so it has no effect on exposure at all.

If you don't believe it until you've proved it (a bit like me)...

Set the camera on a tripod in a room with very subdued light so you get an exposure time of several seconds. Manually focus on something in the room.

Set 2nd curtain sync.

Fire the shutter and immediately after that pre flash, move the camera slightly, and let the actual flash fire before the shutter closes.

When you look at the image you'll find no ghost images from the first flash, which there would be if it occurred while the shutter was open.
 
CT said:
I wouldn't use 2nd curtain sync routinely anyway, Janet - just for those occasions when it's merited with a moving subject. That first flash as I'm sure you know, is just a pre-exposure metering flash. With 1st curtain sync the effect is almost like one continuous flash from the point of view of your subjects.

With 2nd curtain sync the two flashes being further apart, could well cause blinking in your subjects but I wouldn't use that mode for portraits or wedding groups anyway. (for example)
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Ah right. Thats where I mightve gone wrong with my wedding shots where I had a lot of blinkers.

Will change to first unless needed (y)
 
Thx CT, i'll have a go at that.. not that i dont believe you!! just in the name of science.. lol.. its a good excersise and helps to reinforce and Underpin knowlage.. (Que David Brent..)

Iv learnt something today.. (y)
 
That's probably the most easy to understand description and usage of SCS that I've ever read....cheers CT

Bob
 
Excellent choice of photos to illustrate the point.

Thanks!

Cathy
 
Many thanks for a great plain english explanation, all begins to make sense now.
 
Wow, I now feel sane again!! I just bought the book by J. Dennis Thomas 'Speedlite System - Digital Field Guide' and was only this morning reading the section on 2nd curtain sync. I read that section at least 3 times and still couldn't fully understand it's uses.:bang:

Thank you very much for your excellent explanation and particularly the photo examples. You should write a book:geek:
 
LOL. Thanks. Glad it's helped. I don't take credit for the pics though, I borrowed those from elsewhere.

It's just worth pointing out that these examples were obviously taken with an unnecessarily long shutter speed to emphasis the light trails.
 
Well written and explained CT, I know it's an old thread, but I missed it. (Thanks Skipper)
 
I've been playing with my 50D tonight and found this setting and was wondering what the difference was. Low and behold TP has the answer! Thanks for the great tutorial
 
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