Freezing a dancer jumping with flash and flash duration advice

[teigas]

Really cool. The one with the toothpick.

So what you are saying is that in my first try i did not have enough light on the subject in the start? She is to dark? That is why she looks transparent..

Lets say i have a black backroung and the person moves along the background perhaps to the left.
Then i set a flash at the end of the trail agains the person wich thens goes of in the end of the exposure. Will i then need to add more light that is not flash light in the start when the person that perhaps drags some fabric in the air behind her starts moving and also along the trail / path she is moving?

[Loose Canon]

So what you are saying is that in my first try i did not have enough light on the subject in the start? She is to dark? That is why she looks transparent..

Lets say i have a black backroung and the person moves along the background perhaps to the left.
Then i set a flash at the end of the trail agains the person wich thens goes of in the end of the exposure. Will i then need to add more light that is not flash light in the start when the person that perhaps drags some fabric in the air behind her starts moving and also along the trail / path she is moving?

What I am saying Teigas is that your flash wasn’t bright enough at the end and that’s why she appears partially transparent (too dark) in the “frozen” part. She wasn’t exposed enough by the flash because your flash wasn’t bright enough to expose her properly.

The amount (brightness) of ambient light will determine the brightness of the motion trail. The more ambient, the brighter and more exposed the motion trail. The more exposed the motion trail, the less transparent the motion trail will appear. It should still be somewhat transparent, but will appear brighter with more ambient lighting it.

The flash will determine the exposure of the “freeze”. You have to have enough flash hitting the dancer to fully expose her to keep her from looking transparent when the flash fires and she is being “frozen”.

Rear curtain flash is where you are dealing with the two exposures (a nod to George). Ambient and flash.

Hope this makes sense Teigas. I have the feeling you are "getting it"!

[george013]

Rear curtain flash is where you are dealing with the two exposures (a nod to George). Ambient and flash.

Hope this makes sense Teigas. I have the feeling you are "getting it"!

It's still a flash exposure within a ambient light exposure. With the second curtain you only changed the time of the flash exposure from the beginning to the end of the ambient light exposure.

In that picture of mine there is no second curtain used. Wouldn't be necessary for this. What amazed me is that you can look through the top of the body while her shoes are clear.

The other reason I’m not getting this is because in a studio setting, or for freezing motion with flash, which this thread is about, ambient light must not play a role in the exposure so must be taken out of the equation to the point that it doesn’t. Manfred and Bill have addressed this and Teigas has demonstrated with his black frames that he too, understands this.

There is ambient light. That why it's important to take the picture when there is a minimum of movement in the image on the sensor. Read Bill/Williams post.

What is rpt?

George

[Manfred M]

So what you are saying is that in my first try i did not have enough light on the subject in the start? She is to dark? That is why she looks transparent.

Yes. All three shots you posted today are significantly underexposed.



Larger aperture, higher ISO or more light. I'd go for the more light myself, As for where you might place the Einstein with octa, start with the classical 45/45 position. Pointing down at the subject at 45 degrees and at an angle of 45 degrees towards your subject. Adjust as required.

[Loose Canon]

There is ambient light. That why it's important to take the picture when there is a minimum of movement in the image on the sensor. Read Bill/Williams post.

We are obviously talking about two different things. Because if you expose the shot such that ambient light does not play a role in the exposure, which is what I said and you quoted, there is no ambient light in the exposure.

[teigas]

What is rpt?

George[/QUOTE]

It is a nikon function where the flash fires several blink and you set how many it is going to fire in one picture over a certain time. If you see the hand picture i attached its several flashes from the flash so the arms are frozen at different places. All that is one picture, the picture where i move is also experimenting with RPT

[teigas]

Thank you GrumpyDiver I will try to add more light in the next test.. And thank you for the tip on light placement. On the other matter with the jump and freeze.

[george013]

@ Loos Canon
Two different approaches. There is ambient light. The question is how to deal with it to get a desired result.

@ Teigas,
I already found it. I know it as stroboscopic flash.

George

[Loose Canon]

Okay George! Works for me! I'd probably say the same approach with two different ways of saying the same thing!

[William W]

In the following comments I am referring to the original question of freezing a dancer with Flash in a studio, gym or similar:

. . . There is ambient light. That why it's important to take the picture when there is a minimum of movement in the image on the sensor. Read Bill/Williams post. . . .

There has been a misunderstanding because that is not what I wrote nor what I meant to imply.

For clarity:

There usually is ambient light; though in some circumstances there may not be, for example one can photograph an exploding balloon in a blackened room by setting the camera's shutter to 'B' (Bulb) and fire the Flash manually a the time of the explosion; in this shooting scenario there is no Ambient Light

BUT (this bit is important) - Even if there is ambient light in the scene, when we want to freeze the motion using Flash the aim is to ensure that the ambient light does NOT make a meaningful exposure on the film or sensor.

Therefore, the ambient light in the scene should have nothing to do with the Photographer wanting to capture the dancer at the time of minimum movement because the Photographer should have the Ambient Light suitably UNDEREXPOSED so that there is no evidence of the Ambient Exposure in the image.

***

IF we are using Flash to arrest the Subject Movement, then, two main reasons for wanting to capture the Dancer at the point of minimum movement are:

1. Artistic Value - at the peak of the leap is when a Dancer is 'floating' see reference to the backdrop image of Li Cunxin in the previous Post #31.

2. Because mostly always the Subject will be moving in DIFFERNT directions and at DIFFERNT speeds.

Whilst the Photographer might have a Flash 'speed' (duration) suitably fast enough to arrest the main speed and direction of the Subject Movement that Flash 'speed' (duration) might not arrest other movements of the Subject.

An example - the Dancer's Torso and Head might appear frozen as they move in a direction at 45 degrees toward the camera and at a speed of 15kph: but the Dancer’s arms and hands might display a of movement blur if those arms are moving up and down, (which is transverse movement 90 degrees to the Camera) at a speed of 20kph.

***

In a BASIC summary to freeze a dancer leaping using Flash:

1. Usuallyalways when we use Flash there are two sources of light to consider: the AMBIENT LIGHT and the FLASH LIGHT

2. If we want to use the FLASH LIGHT to arrest (freeze) Subject Motion then we must ensure that the Ambient Light does NOT make a ‘meaningful exposure’ on the Subject.

3. The Ambient Light 'not making a meaning exposure’ means - that we either need to:

a) have the Ambient Light UNDEREXPOSED enough so that it does not appear as an exposure on the film or the sensor

OR

b) have the Ambient Exposure TIME at about the same ‘speed’ as the Flash ‘speed’ (duration) necessary to arrest (freeze) the Subject's Motion.


WW

[george013]

There has been a misunderstanding because that is not what I wrote nor what I meant to imply.

IF we are using Flash to arrest the Subject Movement, then, two main reasons for wanting to capture the Dancer at the point of minimum movement are:

1. Artistic Value - at the peak of the leap is when a Dancer is 'floating' see reference to the backdrop image of Li Cunxin in the previous Post #31.

2. Because mostly always the Subject will be moving in DIFFERNT directions and at DIFFERNT speeds.

Whilst the Photographer might have a Flash 'speed' (duration) suitably fast enough to arrest the main speed and direction of the Subject Movement that Flash 'speed' (duration) might not arrest other movements of the Subject.

An example - the Dancer's Torso and Head might appear frozen as they move in a direction at 45 degrees toward the camera and at a speed of 15kph: but the Dancer’s arms and hands might display a of movement blur if those arms are moving up and down, (which is transverse movement 90 degrees to the Camera) at a speed of 20kph.

***

I don't see any misunderstanding.

George

[William W]

George refers to my Post #31 and this commentary addresses that response:

Well said.

Thank you and thank you to others to who have commented.

***

A flash photo always exist out of 2 exposures: 1 with existing light and within that 1 with flash light. It's the same you say.

No. I did not write that, but I understand how my comments could be misunderstood to think that I implied that.

I am not arguing just for the sake of arguing: I am making this point crystal clear, because precision with the use of and the meaning of words is critically important for the OP to grasp and understand the concept of how to use Flash to freeze Subject Motion.

What George has written is correct for MOSTLY all flash photographs – but not correct for ALL Flash Photographs. Please refer to my example of the bursting balloon in Post #50 above.

As an example - whilst moderately difficult to set up, a (proficient) Dancer could make a leap on a blacken stage where there was no Ambient Light and the Flash could be triggered manually at shout by the Dancer.

BUT - most importantly, as I re-iterate again: if we are using Flash to freeze the dancer in a leap, what we want to do is make the Ambient Exposure irrelevant.

To do this we need to make the Ambient Exposure a great amount UNDERexposed relative to the Flash Exposure

*

May I add 1 more consideration. The background A dark background may eliminate the motion blur due to the existing light part more than a bright background. I think.

I have thought about this point for quite a while. I take the word ‘background’ to mean a backdrop, or background objects from which the Ambient Light would be REFLECTED.

NOT that the 'background' is a SOURCE of Ambient Light.

I am quite confident that the answer is: usually no.

As a generalization a dark background will not assist any more or any less to eliminate the motion blur due to the existing light part more than a bright background.

*

Rationale:

Let’s assume that the Ambient Light (your words ‘existing light’) which is falling on the Subject will require a shutter speed of 1/xth seconds to freeze the Subject Motion.

Any light which is REFLECTED from any background be it either a bright coloured or a dark coloured background and which subsequently illuminates the Subject from a different angle, will still require a shutter speed of 1/xth seconds (or slower) to freeze the Subject Motion.

*

However: there might be the unusual circumstance where a light coloured background could reflect some of the Ambient Light on the Subject at a different angle to the main ambient light

This reflected light could illuminate an area on the Subject which otherwise would have been in shadow from the main source of the Ambient Light and that area of the Subject might exhibit Motion Blur as a result.

I have done a reasonable amount of theatre work, and I have never noticed this phenomenon, but yes I certainly agree that it could happen. Indeed it might have happened to me and I simply did not attributed the reason of the Motion Blur, correctly.

So thank you, George for pointing that out to me.

WW

[William W]

I don't see any misunderstanding

Hi George,

I don't wish to have a long side conversation, but for clarity, you wrote this and this the point which I am addressing:

"There is ambient light. That why it's important to take the picture when there is a minimum of movement in the image on the sensor. Read Bill/Williams post. . ."

What you have written above means:

'the REASON for taking the picture at the time of least movement is BECUASE there is Ambient Light. Read Williams post because he thinks that too' (key words are in caps)

Firstly I did not write nor did I mean to imply that.

Secondly, if we want to freeze the Subject by using Flash then to do the best job possible the fact that there is Ambient Light in the scene has absolutely nothing to do with us wanting to capture the shot at the moment of least movement. . . because if we want to freeze the subject using flash - we want to make the Ambient Light absolutely irrelevant to the exposure.

If you do not consider that you have misunderstood what I wrote then that's fine: but I consider it most important for the OP to understand this critical point of eliminating the Ambient Exposure from having any meaningful effect on the Final Image.

WW

[William W]

Originally Posted by george013
“A flash photo always exist out of 2 exposures: 1 with existing light and within that 1 with flash light.”

. . . The other reason I’m not getting this is because in a studio setting, or for freezing motion with flash, which this thread is about, ambient light must not play a role in the exposure so must be taken out of the equation to the point that it doesn’t. Manfred and Bill have addressed this . . .

Correct, Terry.

I trust my last few comments have addressed this point adequately.

WW

[Loose Canon]

Correct, Terry.

I trust my last few comments have addressed this point adequately.

Well thanks Bill!

To be honest I thought this point was addressed adequately in Teigas’ past thread, by myself, Manfred, you, and addressed adequately in your previous posts in this thread. Addressed by Manfred and myself in more than one way in this thread, and again stressed by you in your last few comments.

With as many times as it has been reiterated on dealing with motion, ambient and flash, I would be at a loss as to how to further explain it. Whether or not it is accepted is beyond my scope.

I also think Teigas is getting the point and that’s what matters. It’s his thread and his inquiry. What is left is to get to the task of putting this information to work and start shooting. I’m betting he will get some good results at least partially due to some of the information being put out here.

[William W]

. . . I also think Teigas is getting the point and that’s what matters. It’s his thread and his inquiry.

Yes. I concur.

That's the main reason why I persisted in re-wording the same message, several times.

*

What is left is to get to the task of putting this information to work and [for Teigas to] start shooting

Yes. I concur.

WW

[george013]

William and others,

I've rereading this thread again. In post 32 I reacted on Williams post describing things in a swimming pool, a place where light is out of your control. I forgot the fact that Teigas is doing it in a studio/place where he can control the light.
Sorry.

George

[teigas]

I got to test a little today.. We did some shots where she jumped.. But she had fallen on hear moped the day before, so she coul not do what we inteded.. But got a few , i messed a litle up the t1 on one of them hate working under limited time and she had limited time, my head boils ;P and i forget things.. Will post some of those these weekend. I also tried 2 curtain that worked better than last time.. But she should had another shorts.. And to criticies myself i just put to lights on the floor for ambient in the start, and they spilled back on the back curtain.. Not sure where i should put them to avoid this, more middlevel perhaps..
This one i am posting her is actually a dobbel exspousre in my nikon d800.. Toook the first on and then changed the settings and shot one more fram that the camera added on of. Not sure if it worked but nice to test out stuff.. Atleast a better result than the one i posted earlyer.. So improvment :P

[William W]

. . .Atleast a better result than the one i posted earlyer.. So improvment

It is improvement on the previous shots: especially the Exposure is much improved. Keep practicing and keep trying new ideas.

WW

[teigas]

Thank you William