Rear curtain sync trouble with background curtain light

[teigas]

Hello i asked a little her before about rear curtain sync around a year ago. I am going to try it again. But i like to test it on myself before i get somebody better looking standing there. I understand the concept, i need some kind of constant light to give light to my trail. Then the flash at the ends freeze me.
The problem is the backround in the location i have been allowed to shoot in. Its a stage curtain and it has lines that i also get in the picture.

So I am wondering if sombody has any advice to how to avoid so much light on the background, so i might not get the curtain trails in my trail of light.

The setup is a Nikon D800 - 24-70 on a tripod. I have an einstein with a softbox that freezes me. For the trail i have a foto constant light in a softbox refloctor. I tried lightining it so it just hit my back straight from the right. But i got a better trail if i used the constant light towards the backrground, but then the curtain stripes are shown.

So any suggestion? Try to get further away from the background? With the constant light? Or move it more in from the right and try to put somthing black on the egde of it to block it in the start ? Like a small black wall or somthing?

Hope sombody have som advice, because i really want to avoid the curtain structure.

I did only had help pressing the shutter for 15 min, so have to get back and experiment some more another day, so would be nice with suggestions to try out.

Her is the first orginal attempt


her is a small edit


Her is another straight from cam (took of my pants to check with bare legs against the background:


Her is a fast edit:


Her is the light setup:


Will it be better to try to change the constant light more in the direction of the red?


Cell phone photo of the location: I am on the stage the piano is not there everyday:


Her is one I shot last year, but the structure is there (same light setup that i showed almost at least same directions)

[Dave Humphries]

Hi Lars,

Here is another straight from cam (took off my pants to check with bare legs against the background)

I admire your dedication to test the concept

The problem is the background in the location i have been allowed to shoot in. Its a stage curtain and it has lines that I also get in the picture.

So I am wondering if somebody has any advice to how to avoid so much light on the background, so i might not get the curtain trails in my trail of light.

The setup is a Nikon D800 - 24-70 on a tripod. I have an einstein with a softbox that freezes me. For the trail i have a foto constant light in a softbox reflector. I tried lightening it so it just hit my back straight from the right. But i got a better trail if i used the constant light towards the background, but then the curtain stripes are shown.

So any suggestion? Try to get further away from the background? With the constant light? Or move it more in from the right and try to put something black on the edge of it to block it in the start ? Like a small black wall or something?

Hope somebody have some advice, because i really want to avoid the curtain structure.

Technically, your best bet would be to get the constant light as close as possible to the subject (I am assuming the subject to curtain distance will remain the same).

As a consequence, because of the ratio of the distances and the fact that the increased amount of light falling on the subject will allow you to reduce exposure overall and hence effectively dim that falling on the curtain, will help achieve what you want. This is fabled "the inverse square law" at work.

Moving the constant light to the right obviously causes more problems than it solves. Whether you can raise it and angle it down a bit and flag it to hit the curtain less, may also help, perhaps even use more than one; to ensure better coverage. Angling down will unfortunately put less lights on your subject's legs though.

Hope that helps, Dave

[Mike Buckley]

Have you opened the stage's curtains to determine if the resulting background would work better for you?

I could be wrong but it appears that your photo includes the stage's rear curtain, which is a lighter color than the other curtains. Try using one of the dark curtains, though they may be too close to your continuous light source.

Also consider creating your own background perhaps made of black fabric that is stretched flat. Alternatively, buy large sheets of the stuff installed underneath "floating" wood floors (because it's extremely lightweight). Paint the sheets flat black and lean them against the curtain or rear wall.

[bje07]

And what about a grid on your softbox to avoid dispersion of light?

[Manfred M]

I agree with Dave's thoughts - the issue is primarily that your continuous light source is not just lighting the subject, but enough is falling on the background to have it show up in the image. I assume you are already shooting as far from the curtains as possible?

Getting the continuous light source closer to the subject will have the inverse square law work in your favour, as the light drop off will be more extreme and with a bit of luck the drop off will be enough for it to not show up. Mike's idea of putting up your own background would work too, but that would be both time consuming and costly given the area you would need to do this for.

What is behind the curtains? If there is some considerable space there, you might wish to open them up to see how much of your continuous light actually hits that area. Depending on what is back there, it might help or if it is light reflective colour, it could make things worse.

[William W]

. . . rear curtain sync . . . I understand the concept, i need some kind of constant light to give light to my trail. Then the flash at the ends freeze me.
The problem is the backround in the location i have been allowed to shoot in. Its a stage curtain and it has lines that i also get in the picture . . . advice to how to avoid so much light on the background, so i might not get the curtain trails in my trail of light.

One answer is to ensure that the Exposure of the Constant Light on the Subject is far greater than the Exposure of the Constant Light on the Background. (aka the Lighting Ratio of the Subject to the Background Curtain). A suggested starting point to test would be to get an Exposure Difference of 4 Stops, but experience tells me that I think you’ll need closer to 6 Stops to get rid of those curtain folds.

The (constant) light falls off according to the Inverse Square Law. In simple terms to get a big Exposure difference, you’ll need to get the Subject close to the light and the Background Curtain as far away from it as possible.

So the Lighting Set would be: Dancer Extreme Stage Front; Constant Light as close as possible to Dancer. Use the farthest Background Stage Curtain.

One immediate issue with that Lighting Set is the problem of keeping the Constant Light even across the path of the dancer, obviously as the Constant Light is moved closer to the Dancer the distance of travel of the dancer will be limited because if the Dancer travels too far you run the risk of the Constant Light falling off enough on the Dancer to render an uneven exposure.

This link has an introduction to The Inverse Square Law as it applies to some Photography Scenarios and has pictorials which I think you will find useful.


*

Setting the Constant Light at an angle is an idea to try, that will increase the distance of the Constant Light to the Background, but it will also increase the range of distances of the Constant Light to the Subject – at one end of the Dancer’s travel the Constant Light will be closer to the dancer than at the other end – and this might render an appreciable exposure difference.

***

Another option is to use a flat and also matt black backdrop: this could be either painted board of stretched material/canvas, but it is essential that matt black paint is used. Obviously even with using a flat (physically flat) matt (no gloss) black (painted) background, you would strive to achieve as much Light Fall off on the Background as possible

WW

[William W]

Much of my response is repetition, sorry, but I was composing my response over my breakfast and others responded during that time, although along the same ideas, there are a couple of detailed suggestions, so I will leave it.

[William W]

And what about a grid on your softbox to avoid dispersion of light?

I'd consider doing that as good practice and for safety: but if you look closely at the sample images the folds on the curtains seem to be at a constant density/exposure across the background curtain: if the noticeable exposure of the Curtain Folds was caused by an appreciable bleed from the Soft Box Flash to the Background Curtain, we'd expect that the Curtain Folds at Camera Right would be less noticeable.

WW

[teigas]

Hi Lars,



I admire your dedication to test the concept



Technically, your best bet would be to get the constant light as close as possible to the subject (I am assuming the subject to curtain distance will remain the same).

As a consequence, because of the ratio of the distances and the fact that the increased amount of light falling on the subject will allow you to reduce exposure overall and hence effectively dim that falling on the curtain, will help achieve what you want. This is fabled "the inverse square law" at work.

Moving the constant light to the right obviously causes more problems than it solves. Whether you can raise it and angle it down a bit and flag it to hit the curtain less, may also help, perhaps even use more than one; to ensure better coverage. Angling down will unfortunately put less lights on your subject's legs though.

Hope that helps, Dave

Thank you, will try a little more tomorrow afternoon if I am able to (depens if nothing is happing there or not). Wil try out some of your advice.

[teigas]

Have you opened the stage's curtains to determine if the resulting background would work better for you?

I could be wrong but it appears that your photo includes the stage's rear curtain, which is a lighter color than the other curtains. Try using one of the dark curtains, though they may be too close to your continuous light source.

Also consider creating your own background perhaps made of black fabric that is stretched flat. Alternatively, buy large sheets of the stuff installed underneath "floating" wood floors (because it's extremely lightweight). Paint the sheets flat black and lean them against the curtain or rear wall.

Behind the back curtain there is a movie screen because its a cinema also. The front curtain is old and is orange :P The other in the middle are not curtains just som small parts , cant be closed.

I think making my own background in this case would be to big a project, but understand the idea.

[teigas]

Thank you for the reply. Behind the back curtain it a movie theather screen so dont think that will help, since its also white. I can also try the other tips her by moving as far away as i can get from the rear curtain.

[teigas]

One answer is to ensure that the Exposure of the Constant Light on the Subject is far greater than the Exposure of the Constant Light on the Background. (aka the Lighting Ratio of the Subject to the Background Curtain). A suggested starting point to test would be to get an Exposure Difference of 4 Stops, but experience tells me that I think you’ll need closer to 6 Stops to get rid of those curtain folds.

The (constant) light falls off according to the Inverse Square Law. In simple terms to get a big Exposure difference, you’ll need to get the Subject close to the light and the Background Curtain as far away from it as possible.

So the Lighting Set would be: Dancer Extreme Stage Front; Constant Light as close as possible to Dancer. Use the farthest Background Stage Curtain.

One immediate issue with that Lighting Set is the problem of keeping the Constant Light even across the path of the dancer, obviously as the Constant Light is moved closer to the Dancer the distance of travel of the dancer will be limited because if the Dancer travels too far you run the risk of the Constant Light falling off enough on the Dancer to render an uneven exposure.

This link has an introduction to The Inverse Square Law as it applies to some Photography Scenarios and has pictorials which I think you will find useful.


*

Setting the Constant Light at an angle is an idea to try, that will increase the distance of the Constant Light to the Background, but it will also increase the range of distances of the Constant Light to the Subject – at one end of the Dancer’s travel the Constant Light will be closer to the dancer than at the other end – and this might render an appreciable exposure difference.

***

Another option is to use a flat and also matt black backdrop: this could be either painted board of stretched material/canvas, but it is essential that matt black paint is used. Obviously even with using a flat (physically flat) matt (no gloss) black (painted) background, you would strive to achieve as much Light Fall off on the Background as possible

WW

Thanks for the input i will test some more tomorrow night if nothing is happeing there.

So the best case would be to have the dancer almost at the front end of the scene and then perhaps have the camera in one of the seat rows, or at the very end of the sceene, and the same with the constant light, but at the camera point so i dont get the light stand on the picture itself?

Since i only had 10 min to test today (because the guy who was going to help me press the button had somthing come up) i think i was around parlell to the piano, so i have some wiggle room further back, but there comes a point where i have to choose to get the camera in to the seats or have it on the stage.

Would it be a solution if i get the light really close to try to use two constant i have that to even out the trail?

Your quote her:
"Setting the Constant Light at an angle is an idea to try, that will increase the distance of the Constant Light to the Background, but it will also increase the range of distances of the Constant Light to the Subject – at one end of the Dancer’s travel the Constant Light will be closer to the dancer than at the other end – and this might render an appreciable exposure difference."

If i place one light from the right and one from the left coming in at an angel would that perhaps work or just mess it up?

I also seen this video https://www.youtube.com/watch?v=LpDqh90NsKM but then again he has a perfect black background, but he lights from behind with the constant, but not really a long exsposure either. So the trail is not so long.

Thank you for the replies.

[teigas]

I agree with Dave's thoughts - the issue is primarily that your continuous light source is not just lighting the subject, but enough is falling on the background to have it show up in the image. I assume you are already shooting as far from the curtains as possible?

Getting the continuous light source closer to the subject will have the inverse square law work in your favour, as the light drop off will be more extreme and with a bit of luck the drop off will be enough for it to not show up. Mike's idea of putting up your own background would work too, but that would be both time consuming and costly given the area you would need to do this for.

What is behind the curtains? If there is some considerable space there, you might wish to open them up to see how much of your continuous light actually hits that area. Depending on what is back there, it might help or if it is light reflective colour, it could make things worse.

Thanks for the input, behind the back black curtain there is a movie screen white since its also my local movie theather.

Today i only had 15 min, because the guy who helped me had somthing come up, and self timer and rear currtain sync did not work sadly.

I think i was paralel to the piano today when i tried, but the camera was not so far from stage end. But i guess I have some wiggle room with moving everything backwards a little. Thank you for taking the time to reply.

[William W]

. . . So the best case would be to have the dancer almost at the front end of the scene and then perhaps have the camera in one of the seat rows, or at the very end of the sceene, and the same with the constant light, but at the camera point so i dont get the light stand on the picture itself?
Would it be a solution if i get the light really close to try to use two constant i have that to even out the trail?
If i place one light from the right and one from the left coming in at an angel would that perhaps work or just mess it up?

SUGGESTED LIGHTING, DANCER and CAMERA PLACEMENTS:

1. Get the dancer as close to the front of the stage as possible.

2a. Get the Constant Light as close to the dancer as possible.

2b. I suggest that you try one light first. I think it best to always try to keep the BEGINNING of any lighting set a simple as possible – and that usually means using as FEW lights as possible and see f that works: if it doesn't, then try two Constant Lights.

3. Place the camera so that you do not get any of the lights in the shot.

Here is a rough pictorial guide:



The YELLOW ARROW is the Einstein.

The RED ARROW is the Constant Light.

The BLUE line represents that you want to get the LARGEST distance possible between the DANCER and the BACKGROUND.

The GREEN line represents that you want to get the SHORTEST distance possible between the CONSTANT LIGHT and the DANCER.

Good luck with the test shoot

WW

[William W]

Additional thought -

I have assumed that you were using a Constant Light on a Stand - a light that you supplied yourself.

If you can use the Lighting Rig in the Theatre, then I suggest that you investigate the TWO lights circled in YELLOW.

These two lights appear to be:

1. Broad Lights

2. Set equidistant from STAGE CENTRE.

I have no idea of the power rating, but they appear reasonably chunky so I expect that they're 1K or maybe 1.25K. It is a bit difficult to estimate how far IN FRONT OF the stage that rig sits, but if it is about 5~10 metres in front of the stage, then, if those two lights are angled down on the Dancer, there would be not much (effective) lighting spill onto to the Backdrop Curtain.

Additionally, you should be able to lower that rig: as you make different rig heights you will get different lighting angles on the dancer and a different fall off on the backdrop. Using those two lights means that you can place your camera directly under them and you will have no lighting stands to worry about.



WW

[teigas]

SUGGESTED LIGHTING, DANCER and CAMERA PLACEMENTS:

1. Get the dancer as close to the front of the stage as possible.

2a. Get the Constant Light as close to the dancer as possible.

2b. I suggest that you try one light first. I think it best to always try to keep the BEGINNING of any lighting set a simple as possible – and that usually means using as FEW lights as possible and see f that works: if it doesn't, then try two Constant Lights.

3. Place the camera so that you do not get any of the lights in the shot.

Here is a rough pictorial guide:



The YELLOW ARROW is the Einstein.

The RED ARROW is the Constant Light.

The BLUE line represents that you want to get the LARGEST distance possible between the DANCER and the BACKGROUND.

The GREEN line represents that you want to get the SHORTEST distance possible between the CONSTANT LIGHT and the DANCER.

Good luck with the test shoot

WW

Thank you , will try it tonight If i am able to borrow the theather again looks like its going to work out.. So will try your suggestion. The stage lights are a little different i think, so not sure if i am allowed to use them, the rig that is furthetest back with stage light is usally not that rigged i think. It was a concert there last night so i think thats why. Again thank you for the advice.

[george013]

Thank you , will try it tonight If i am able to borrow the theather again looks like its going to work out.. So will try your suggestion. The stage lights are a little different i think, so not sure if i am allowed to use them, the rig that is furthetest back with stage light is usally not that rigged i think. It was a concert there last night so i think thats why. Again thank you for the advice.

Can't you put your own light in a higher position? It looks the curtain are only visible due to the constant light.

A wonderful project.

George

[teigas]

Can't you put your own light in a higher position? It looks the curtain are only visible due to the constant light.

A wonderful project.

George

Will also try that today. So thanks again for all the input.

[Manfred M]

Can't you put your own light in a higher position? It looks the curtain are only visible due to the constant light.

A wonderful project.

George

Putting the light higher (without moving it closer to the subject) is just going to increase the amount of light spilling on the background, unless the light is flagged (i.e. something put in front of it to eliminate the light spill). That's going to take a huge flag, so I'm not sure how practical that will be.

Getting the light closer to the subject (and taking advantage of the inverse square law that will determine the level of light drop off) and / or getting the subject as far away from the curtain as possible are really the most practical approaches.

[William W]

Can't you put your own light in a higher position? It looks the curtain are only visible due to the constant light. . .

That's not a good idea and there are several reasons why and those reasons are not just limited to the problem of the Exposure of the Backdrop Curtain.

Ideally to achieve the maximum fall off and the least bleed of the Constant Light onto the Backdrop, the Constant Light needs to be at the same Elevation as the Dancer: that is specifically why I made this suggestion if you choose to use the Theatre's Lighting Rig -

Additionally, you should be able to lower that rig: as you make different rig heights you will get different lighting angles on the dancer and a different fall off on the backdrop. Using those two lights means that you can place your camera directly under them and you will have no lighting stands to worry about.

As Dave originally stated it is all about the Ratio of the Distances - Light the Dancer : Light to Background; and as Manfred reiterated this is the simplest approach.

Not withstanding those facts, the artistic value of the Light Trail has to be considered, from the outset your examples (Lars's examples) have been of a Lighting Trail made by a the dancers being FRONT LIT with a Constant Light, (i.e. not Top Lit).

WW