20D HITS THE FIELD !!!

"Prometheus" wrote in message
...
In article , Jonathan Wilson
writes
On Sat, 2 Oct 2004 11:23:24 +0100, "Len"
wrote:

saw the reference to 2nd. curtain synch. Could you please explain the
difference from 1st curtain?
I keep on seeing these terms mentioned but have never found an
explanation
for them.

It means the flash goes off just before the shutter closes, 1st
curtian means the flash is fired just after the shutter opens.

The problem with first curtian is that when there are moving objects
any motion blur is after the initial flash... so if you where shooting
say someone running from left to right they would be frozen by the
flash at the left side then you would see the blur/ghost image of
thier movement to the right... The movement trails/blur should be
behind the frozen person, so it ends up looking wrong.

If you cant picture the above visually, think of a comic book picture
of someone running (say road runner, beep beep, lol) where tbey put
the speed trails behind the person, with first curtain sync they would
have to draw the character with the speed trails in front of the
runner.

But first curtain flash must leave any speed trails behind the moving
subject; ask yourself, how can they be recorded before the shutter is
open.

The problem with first curtain sync is that if your subject *moves in
response* to the flash and there is enough ambient light to record that
movement (as is often the case) it is far better to have that movement
take place when the shutter closes rather than when it has just opened.

You are not corect here...
First curtain and second curtain have nothing to do with subject reactions.
It is entirely focussed around where ghosting of the moving subject appears.
With a moving subject, the there will usually be ghosting (this is the
transparent "ghost" of the moving subject which is created by a longer
exposure when the actually flash burst is shorter than the duration the
shutter is actually open). When the flash fires, it create a fully-lit
subject recording on the film or sensor.... -Since the shutter is open for
a short period of time either before or after the flash fully illuminates
the subject, you get this effect.

The ONLY thing 1st or 2nd shutter synch is for is for you to decide where
the ghosting effect appears. It will appear in FRONT of the movement in 1st
curtain, due to the fact that the flash fires immediately, followed by the
shutter remaining open for a split second AFTER the flash no longer
iluminates the subject. -This makes for a very unnatural looking "ghost"
because the motion lines appear in FRONT of the subject (since the camera
kept exposing after teh flash fired).

With second curtain synch, the camera is instructed to fire the flash at the
tail end of the exposure--in that split second right before the shutter
closes. This means that the first split second of exposure happens right
before the flash fires, which will create the ghosting effect appearing
BEHIND the flash-illuminated subject.

Picture a night shot of a moving car with its lights on.
1st curtain: You'll continue to expose the moving car for a moment AFTER
the flash has fired, meaning the trail accross your image created by the
lights will look weird because it extends out in front of the car (since the
car moves forward after the flash fired). The flash firing moment creates a
solid looking image, but the continued exposure still records what it
can...so you get the effect.

2nd curtain shot of the car:
Shutter opens...and records some movement.
Flash fires right before shutter closes, meaning the "solid looking" car
appears at the front, with the partially recorded light trail appearing
behind the car.

This is the WHOLE deal with 1st/2nd curtain synch.
Again... It has nothing to do with subject reaction times.

"Prometheus" wrote in message
...
In article , Jonathan Wilson
writes
On Sat, 2 Oct 2004 11:23:24 +0100, "Len"
wrote:

saw the reference to 2nd. curtain synch. Could you please explain the
difference from 1st curtain?
I keep on seeing these terms mentioned but have never found an
explanation
for them.

It means the flash goes off just before the shutter closes, 1st
curtian means the flash is fired just after the shutter opens.

The problem with first curtian is that when there are moving objects
any motion blur is after the initial flash... so if you where shooting
say someone running from left to right they would be frozen by the
flash at the left side then you would see the blur/ghost image of
thier movement to the right... The movement trails/blur should be
behind the frozen person, so it ends up looking wrong.

If you cant picture the above visually, think of a comic book picture
of someone running (say road runner, beep beep, lol) where tbey put
the speed trails behind the person, with first curtain sync they would
have to draw the character with the speed trails in front of the
runner.

But first curtain flash must leave any speed trails behind the moving
subject; ask yourself, how can they be recorded before the shutter is
open.

The problem with first curtain sync is that if your subject *moves in
response* to the flash and there is enough ambient light to record that
movement (as is often the case) it is far better to have that movement
take place when the shutter closes rather than when it has just opened.

You are not corect here...
First curtain and second curtain have nothing to do with subject reactions.
It is entirely focussed around where ghosting of the moving subject appears.
With a moving subject, the there will usually be ghosting (this is the
transparent "ghost" of the moving subject which is created by a longer
exposure when the actually flash burst is shorter than the duration the
shutter is actually open). When the flash fires, it create a fully-lit
subject recording on the film or sensor.... -Since the shutter is open for
a short period of time either before or after the flash fully illuminates
the subject, you get this effect.

The ONLY thing 1st or 2nd shutter synch is for is for you to decide where
the ghosting effect appears. It will appear in FRONT of the movement in 1st
curtain, due to the fact that the flash fires immediately, followed by the
shutter remaining open for a split second AFTER the flash no longer
iluminates the subject. -This makes for a very unnatural looking "ghost"
because the motion lines appear in FRONT of the subject (since the camera
kept exposing after teh flash fired).

With second curtain synch, the camera is instructed to fire the flash at the
tail end of the exposure--in that split second right before the shutter
closes. This means that the first split second of exposure happens right
before the flash fires, which will create the ghosting effect appearing
BEHIND the flash-illuminated subject.

Picture a night shot of a moving car with its lights on.
1st curtain: You'll continue to expose the moving car for a moment AFTER
the flash has fired, meaning the trail accross your image created by the
lights will look weird because it extends out in front of the car (since the
car moves forward after the flash fired). The flash firing moment creates a
solid looking image, but the continued exposure still records what it
can...so you get the effect.

2nd curtain shot of the car:
Shutter opens...and records some movement.
Flash fires right before shutter closes, meaning the "solid looking" car
appears at the front, with the partially recorded light trail appearing
behind the car.

This is the WHOLE deal with 1st/2nd curtain synch.
Again... It has nothing to do with subject reaction times.

The problem with first curtain sync is that if your subject *moves in
response* to the flash and there is enough ambient light to record that
movement (as is often the case) it is far better to have that movement
take place when the shutter closes rather than when it has just opened.

From: "Mark M"

You are not corect here...

Actually he is correct for the situation he describes.

First curtain and second curtain have nothing to do with subject reactions.
It is entirely focussed around where ghosting of the moving subject appears.

Well, you're wrong ... while shooting shore birds at close range in Alaska not
too long ago I was using fill-flash with a moderately long ambient shutter
speed. The birds would often flinch or even run off when the flash popped
before they got used to it ... with first curtain sync this meant a blur as the
bird moved in reaction to the flash. With second curtain sync the shutter was
about to close before the flash went off so there was no blur. That's why I
always set the CF to 2nd curtain sync when shooting wildlife (this was a new
camera and I had forgotten to change it but since it was digital I could see
the problems that night when I reviewed images and made the CF change.

With a moving subject, the there will usually be ghosting (this is the
transparent "ghost" of the moving subject which is created by a longer
exposure when the actually flash burst is shorter than the duration the
shutter is actually open). When the flash fires, it create a fully-lit
subject recording on the film or sensor.... -Since the shutter is open for
a short period of time either before or after the flash fully illuminates
the subject, you get this effect.

What you say makes sense for a moving object, but what the first poster
described was something sitting still that reacts to the flash ("*moves in
response* to the flash and there is enough ambient light to record that
movement").

The ONLY thing 1st or 2nd shutter synch is for is for you to decide where
the ghosting effect appears.

You're not taking into account other situations, like the one described above,
where there is NO ghosting if you use 2nd curtain sync because the subject
isn't moving until the flash startles it.

Bill

The problem with first curtain sync is that if your subject *moves in
response* to the flash and there is enough ambient light to record that
movement (as is often the case) it is far better to have that movement
take place when the shutter closes rather than when it has just opened.

From: "Mark M"

You are not corect here...

Actually he is correct for the situation he describes.

First curtain and second curtain have nothing to do with subject reactions.
It is entirely focussed around where ghosting of the moving subject appears.

Well, you're wrong ... while shooting shore birds at close range in Alaska not
too long ago I was using fill-flash with a moderately long ambient shutter
speed. The birds would often flinch or even run off when the flash popped
before they got used to it ... with first curtain sync this meant a blur as the
bird moved in reaction to the flash. With second curtain sync the shutter was
about to close before the flash went off so there was no blur. That's why I
always set the CF to 2nd curtain sync when shooting wildlife (this was a new
camera and I had forgotten to change it but since it was digital I could see
the problems that night when I reviewed images and made the CF change.

With a moving subject, the there will usually be ghosting (this is the
transparent "ghost" of the moving subject which is created by a longer
exposure when the actually flash burst is shorter than the duration the
shutter is actually open). When the flash fires, it create a fully-lit
subject recording on the film or sensor.... -Since the shutter is open for
a short period of time either before or after the flash fully illuminates
the subject, you get this effect.

What you say makes sense for a moving object, but what the first poster
described was something sitting still that reacts to the flash ("*moves in
response* to the flash and there is enough ambient light to record that
movement").

The ONLY thing 1st or 2nd shutter synch is for is for you to decide where
the ghosting effect appears.

You're not taking into account other situations, like the one described above,
where there is NO ghosting if you use 2nd curtain sync because the subject
isn't moving until the flash startles it.

Bill

"Bill Hilton" wrote in message
...
The problem with first curtain sync is that if your subject *moves in
response* to the flash and there is enough ambient light to record that
movement (as is often the case) it is far better to have that movement
take place when the shutter closes rather than when it has just opened.

From: "Mark M"

You are not corect here...

Actually he is correct for the situation he describes.

First curtain and second curtain have nothing to do with subject
reactions.
It is entirely focussed around where ghosting of the moving subject
appears.

Well, you're wrong ... while shooting shore birds at close range in Alaska
not
too long ago I was using fill-flash with a moderately long ambient shutter
speed. The birds would often flinch or even run off when the flash popped
before they got used to it ... with first curtain sync this meant a blur
as the
bird moved in reaction to the flash. With second curtain sync the shutter
was
about to close before the flash went off so there was no blur. That's why
I
always set the CF to 2nd curtain sync when shooting wildlife (this was a
new
camera and I had forgotten to change it but since it was digital I could
see
the problems that night when I reviewed images and made the CF change.

With a moving subject, the there will usually be ghosting (this is the
transparent "ghost" of the moving subject which is created by a longer
exposure when the actually flash burst is shorter than the duration the
shutter is actually open). When the flash fires, it create a fully-lit
subject recording on the film or sensor.... -Since the shutter is open
for
a short period of time either before or after the flash fully illuminates
the subject, you get this effect.

What you say makes sense for a moving object, but what the first poster
described was something sitting still that reacts to the flash ("*moves in
response* to the flash and there is enough ambient light to record that
movement").

The ONLY thing 1st or 2nd shutter synch is for is for you to decide where
the ghosting effect appears.

You're not taking into account other situations, like the one described
above,
where there is NO ghosting if you use 2nd curtain sync because the subject
isn't moving until the flash startles it.

Ya.
OK.
The question was in the context of Bret's football game pictures, so I
answered within that context. I can certainly agree with the animal
situation.
I had not thought of that.
I do think the real intent behind 1st vs. 2nd is in controlling ghosting
effects, but certainly it would have other effects such as you describe.

"Bill Hilton" wrote in message
...
The problem with first curtain sync is that if your subject *moves in
response* to the flash and there is enough ambient light to record that
movement (as is often the case) it is far better to have that movement
take place when the shutter closes rather than when it has just opened.

From: "Mark M"

You are not corect here...

Actually he is correct for the situation he describes.

First curtain and second curtain have nothing to do with subject
reactions.
It is entirely focussed around where ghosting of the moving subject
appears.

Well, you're wrong ... while shooting shore birds at close range in Alaska
not
too long ago I was using fill-flash with a moderately long ambient shutter
speed. The birds would often flinch or even run off when the flash popped
before they got used to it ... with first curtain sync this meant a blur
as the
bird moved in reaction to the flash. With second curtain sync the shutter
was
about to close before the flash went off so there was no blur. That's why
I
always set the CF to 2nd curtain sync when shooting wildlife (this was a
new
camera and I had forgotten to change it but since it was digital I could
see
the problems that night when I reviewed images and made the CF change.

With a moving subject, the there will usually be ghosting (this is the
transparent "ghost" of the moving subject which is created by a longer
exposure when the actually flash burst is shorter than the duration the
shutter is actually open). When the flash fires, it create a fully-lit
subject recording on the film or sensor.... -Since the shutter is open
for
a short period of time either before or after the flash fully illuminates
the subject, you get this effect.

What you say makes sense for a moving object, but what the first poster
described was something sitting still that reacts to the flash ("*moves in
response* to the flash and there is enough ambient light to record that
movement").

The ONLY thing 1st or 2nd shutter synch is for is for you to decide where
the ghosting effect appears.

You're not taking into account other situations, like the one described
above,
where there is NO ghosting if you use 2nd curtain sync because the subject
isn't moving until the flash startles it.

Ya.
OK.
The question was in the context of Bret's football game pictures, so I
answered within that context. I can certainly agree with the animal
situation.
I had not thought of that.
I do think the real intent behind 1st vs. 2nd is in controlling ghosting
effects, but certainly it would have other effects such as you describe.

Prometheus wrote:


With first curtain you fire the flash as soon as the first half of the
focal plain shutter is open and might get blurring of your subject due

Front sync: the flash fires as soon as the first curtain is COMPLETELY open (not
first half of the FP shutter).

to them reacting to the flash during the ambient light exposure before
the second curtain closes, with second the flash fires just as the
second curtain states to cover the film/sensor and so response occur
after the shutter has closed.

Rear sync: flash fires just BEFORE 2nd curtain begins to close (about 2
milliseconds before the curtain begins to cover the frame).


--
"There is no such thing as inaccuracy in a photograph.
All photographs are accurate. None of them is the truth."
-Richard Avedon
-- rec.photo.equipment.35mm user resource:
-- http://www.aliasimages.com/rpe35mmur.htm
-- e-meil: there's no such thing as a FreeLunch.--

In article , Alan Browne
writes
Prometheus wrote:

With first curtain you fire the flash as soon as the first half of
the focal plain shutter is open and might get blurring of your
subject due

Front sync: the flash fires as soon as the first curtain is COMPLETELY
open (not first half of the FP shutter).

If I had meant partially open I would have said so. There are TWO
curtains in an FP shutter assembly, one is half of two.

I should have identified what the second is doing, for flash it must be
open until the first is open (it need not close until sometime
afterwards of course); but we should understand this much about flash
photography.

to them reacting to the flash during the ambient light exposure
before the second curtain closes, with second the flash fires just as
the second curtain states to cover the film/sensor and so response
occur after the shutter has closed.

Rear sync: flash fires just BEFORE 2nd curtain begins to close (about 2
milliseconds before the curtain begins to cover the frame).

Apart from the typo (should have been 'starts' not 'states') that is
essentially what I typed.
--
Ian G8ILZ

Guys OK!

Thanks for the info. I can now see why you would want 2nd curtain synch. I'm
just a bit afraid to ask why anyone would then want 1st curtain as well!
Ducks for cover.............

Regards

Len

"Len" wrote in
:

Thanks for the info. I can now see why you would want 2nd curtain
synch. I'm just a bit afraid to ask why anyone would then want 1st
curtain as well! Ducks for cover.............

I assume that first curtain can be used for ...

1. those birdies that react on the shutter sound.
they will be somewhere else when the 2nd curtain
synced flash flashes.

2. it feels better when the flash gets of when you
push the button.


/Roland