Backscatter myths

[Guest]

I have read here again that 'using the edge of the strobes' avoids back scatter

That is indeed not true. What that does is to create areas that are not lit in the frame so only part of it is lit and the rest is dark

I wrote on uwpmag about it time ago https://www.uwpmag.com/?p=uwp-back-issues&issue=129 this is an example of inward lighting which is for close up work the benefit is that there is nothing behind the subjects and much less at the sides

Pointing the strobes outwards accomplishes no purpose whatsoever other than wasting power

Now as some people know backscatter cannot be avoided. If there are particles in the water your camera will see them

Example of an ambient light image with strobes off the images are nothing special just to show the purpose as I was testing the sony 14mm GM

 

 

Plenty of particles going however the strobes were off the camera can simply see the particles

 

Just few seconds later the same shot a bit close using strobes position is regular pointing forward behind the dome so that the 14mm lens cannot see the flash

 

As you can clearly see the amount of particles is unchanged the strobes increase the contrast on the wreck and the image actually looks better

 

 

 

Back in the days of compacts camera had in built flash this will create an issue with anything you were shooting unless it was bang on in front of the lens so here starts the strobe not pointing to the subject. However if your strobe is at an angle you can indeed point the strobe to the subject even directly the particles will reflect back to the strobe not into the lens

So the strobe does not have to be aligned with the lens but that does not mean you can't point it at subject. Crossed strobes do exactly that

 

Clearly certain techniques like cross strobes do not work at all if there are particles in the water however a strobe pointing outwards simply creates dark areas in the top and bottom of the center of the frame, it does not avoid beaming particles on the side of the subject.

Inward lighting is one good technique for edge lighting but as the light does not go behind the subject is more effective than pointing the strobes out as that fires up the sides of the frame

[turandot]

Very good thoughts about backscatter with underwater strobe lights. Thank you @Interceptor121

[fruehaufsteher2]

Lit backscatter will be more prominent seen in your picture than if it is not lit by the strobe. Either use a beamformer or point outwards - at the price that you are lighting up much water and fish that can not be seen in the picture.

 

In some instances it can be useful to open the aperture as far as possible so the backscatter between you and the object is more blurred and less disturbing in the final image. 

[turandot]

Many times "the magic" of backscatter is called Photoshop or Lightroom. Most of the photos we see on social media have gone through LS or PS 😁

[ChrisH]

Just to make sure: for the second picture you had the strobes on either side of the housing, pointing forward, not inward, right? How far away were the strobes from the housing?

[Guest]

57 minutes ago, fruehaufsteher2 said:

Lit backscatter will be more prominent seen in your picture than if it is not lit by the strobe. Either use a beamformer or point outwards - at the price that you are lighting up much water and fish that can not be seen in the picture.

 

In some instances it can be useful to open the aperture as far as possible so the backscatter between you and the object is more blurred and less disturbing in the final image. 

Nope

As demonstrated in this example it makes absolutely no difference

 

Pointing the strobes outwards does only one thing bring the light away from the centre on the sides where normally there is nothing interesting and creates nice dark areas in the centre on top and bottom of the frame

 

read the post again and examine the images one without and one with strobes

 

The idea of opening the aperture is not going to work as due to dome port optics with subject in the distance a lot is in focus everywhere. A flat port is something that will work better as long as the particles do not become bokeh balls

[Guest]

16 minutes ago, ChrisH said:

Just to make sure: for the second picture you had the strobes on either side of the housing, pointing forward, not inward, right? How far away were the strobes from the housing?

two 8+12 segments fully extended to the sides strobes behind the dome pointing straight ahead

 

Either way the fact that you see the particles with ambient light shows that when there is a lot of stuff in the water your less will see it full stop

[ChrisH]

Just now, Interceptor121 said:

two 8+12 segments fully extended to the sides strobes behind the dome pointing straight ahead

 

Either way the fact that you see the particles with ambient light shows that when there is a lot of stuff in the water your less will see it full stop

Yes of course the are always particles in the water and there is no way to avoid them completely. But you can reduce the amount of backscatter (= particles that are lit up by the strobe and reflecting the light back to the camera) with strobe placement and using the edge of the strobe light. 

 

As you have done here. You used the edge of the strobe light to light up the subject. That is what is meant by "using the edge of the strobe light": you did point the strobes forward und put them on arms aside of the housing. So only the edges of the strobe light hit the subject.

That is in all its essence what is meant with "using the edges of the strobe"...

[Guest]

7 minutes ago, ChrisH said:

Yes of course the are always particles in the water and there is no way to avoid them completely. But you can reduce the amount of backscatter (= particles that are lit up by the strobe and reflecting the light back to the camera) with strobe placement and using the edge of the strobe light. 

 

As you have done here. You used the edge of the strobe light to light up the subject. That is what is meant by "using the edge of the strobe light": you did point the strobes forward und put them on arms aside of the housing. So only the edges of the strobe light hit the subject.

That is in all its essence what is meant with "using the edges of the strobe"...

 

Not at all you are hitting the strobes with both lights combined and as your arm are quite close compared to the subject you are indeed going head on as the two strobes beam combine.

The lens is overall narrower than the strobes so there is part of the frame that is hit by the centre and par only by one

Moving the strobe outwards generates an ellypse projection which ends up with dark areas

 

Little scheme as a memory aid. While you can try to slightly angle out the strobes this in general creates more issues than opportunities as it increase the dark area in the centre

 

   

[ChrisH]

You are hitting the subject with the edges of both lights. The center of the strobe does not point at the subject. There is nothing more in the "myth" of using the edges of the strobe: you light the subject with exactly the edges of both strobes (as you have done!).

 

Using the edged of the strobe does not (!) mean that you angle the strobes out.

 

If you would not want the use the edges of the strobe, you have to attach them directly to your housing without the strobe arms. But if you put them on strobe arms and get them away from the housing, you are using the "edges of the strobe light" for lighting up the subject.

 

If you have a dark spot in the middle of the picture you just put the strobes to far away from the housing. Pull them back in al litte bit and you have the subject light up well without too much backscatter.

 

That is really all there is about it. No complicated "myth" or something.

[ChrisH]

nullSee the attached image. It is all there is to this topic.

 

And yes, in this picture there would be a dark spot in the middle of the subject (a common mistake in wide-angle shots). But the beam of the strobes is wider as shown in the picture here. It is just for demonstration purpose of the concept of "using the edges of the light".

 

And again: using the edges of the strobe light is exactly what you have done! It does not mean to angle the strobes outwards or hitting the subject with just one strobe without overlapping the light of the two strobes! You will almost always hit the subject with the light from the two strobes. It has nothing to do with "using the edges of the strobe light".

[Guest]

Just now, ChrisH said:

nullSee the attached image. It is all there is to this topic.

 

And yes, in this picture there would be a dark spot in the middle of the subject (a common mistake in wide-angle shots). But the beam of the strobes is wider as shown in the picture here. It is just for demonstration purpose of the concept of "using the edges of the light".

 

And again: using the edges of the strobe light is exactly what you have done! It does not mean to angle the strobes outwards or hitting the subject with just one strobe without overlapping the light of the two strobes! You will almost always hit the subject with the light from the two strobes. It has nothing to do with "using the edges of the strobe light".

your beam angle from here is very narrow like 60 degrees it is more 90

When you increase distance the strobes become light sources edges or centre matters very little and the beam combine I have measured that on a pool wall at various distances the most power is in the centre

As your arms are actually really short 80 cm extension at best anything further away than 80 cm will be hit by the centre not the edges at distance in fact the concept of edge and centre blurs a lot

I do not call this edge lighting it is just flat wide angle lighting with no special technique

 

[ChrisH]

I am afraid to say I think you are just overcomplicating the things here. 
 

For standard wide angle lighting you just don‘t point (!) the strobes at the subject (angle them inwards). You just leave them pointed forward and increase or reduce the distance of the strobe from the housing until you have an eaven light on the subject and backscatter is reduced a lot. 
 

That is all. And that is what is ment by „using the edges of the strobe light“. Just a simple term to state: do not point the strobe directly at the subject!

 

It does not say or mean that you are not hitting the subject with two strobes overlapping or what you maybe feel ist the center of the beam. 
 

Its just: dont point the strobe directly at the subject. Nothing more. 

[Guest]

8 minutes ago, ChrisH said:

I am afraid to say I think you are just overcomplicating the things here. 
 

For standard wide angle lighting you just don‘t point (!) the strobes at the subject (angle them inwards). You just leave them pointed forward and increase or reduce the distance of the strobe from the housing until you have an eaven light on the subject and backscatter is reduced a lot. 
 

That is all. And that is what is ment by „using the edges of the strobe light“. Just a simple term to state: do not point the strobe directly at the subject!

 

It does not say or mean that you are not hitting the subject with two strobes overlapping or what you maybe feel ist the center of the beam. 
 

Its just: dont point the strobe directly at the subject. Nothing more. 

You can point them inwards actually when you want to reduce the light on the edges and make the subject standout this has nothing to do with backscatter 

backscatter is there and doesn’t go away dont get obsessed and just shoot

[RomiK]

18 minutes ago, ChrisH said:

I am afraid to say I think you are just overcomplicating the things here. 
 

For standard wide angle lighting you just don‘t point (!) the strobes at the subject (angle them inwards). You just leave them pointed forward and increase or reduce the distance of the strobe from the housing until you have an eaven light on the subject and backscatter is reduced a lot. 
 

That is all. And that is what is ment by „using the edges of the strobe light“. Just a simple term to state: do not point the strobe directly at the subject!

 

It does not say or mean that you are not hitting the subject with two strobes overlapping or what you maybe feel ist the center of the beam. 
 

Its just: dont point the strobe directly at the subject. Nothing more. 

No worries @ChrisH, off course you are right and contrary to the original post you can actually explain it. OP doesn’t understand the term ‘lit by the edges’ the same as 99% of photographers refer to this technique and that’s alright, everybody has their own vocabulary. He shot the image with flash using just that ‘lit by the edges’ technique he just doesn’t know it. Peace ✌️ 

[Guest]

This is a pool wall image with the strobes in the same position at a few meters

The hot spots are the strobes which are very  much in the middle of the frame

 

 

Edge lighting is another myth it seems

[ChrisH]

4 minutes ago, Interceptor121 said:

This is a pool wall image with the strobes in the same position at a few meters

The hot spots are the strobes which are very  much in the middle of the frame

 

 

Edge lighting is another myth it seems

A few meter is much too far in underwater photography. 
 

But anyway: no, it is not a myth! 🤷🏻‍♂️ It is just not understood what the „myth“ actually means. That does‘t mean it is a „myth“ and is wrong!

 

I am afraid I don’t know how to explain it other than I have already done. The picture clearly proves that you - sorry- just don‘t understand what is ment with the „myth“ and your wrong assumption of the myth leeds you to the impression that the „myth“ is wrong.

Using the edge of the strobe light does not mean what you think it means. If your assumption of the myth would be right then of course the „myth“ would be wrong! 
 

But nothing what you are trying to prove is meant by the „myth“. 🤷🏻‍♂️

[Guest]

4 minutes ago, ChrisH said:

A few meter is much too far in underwater photography. 
 

But anyway: no, it is not a myth! 🤷🏻‍♂️ It is just not understood what the „myth“ actually means. That does‘t mean it is a „myth“ and is wrong!

 

I am afraid I don’t know how to explain it other than I have already done. The picture clearly proves that you - sorry- just don‘t understand what is ment with the „myth“ and your wrong assumption of the myth leeds you to the impression that the „myth“ is wrong.

Using the edge of the strobe light does not mean what you think it means. If your assumption of the myth would be right then of course the „myth“ would be wrong! 
 

But nothing what you are trying to prove is meant by the „myth“. 🤷🏻‍♂️

 
Of course big wide angles scenes are shot 2-3 meters away and if your strobes have enough power the images come out just fine 

The 1.5 meters limit is another myth 

3 meters away the strobe will have lost 3 stops you shoot at full power gb22 you are at f/8 increase iso two stops back to f/16

not a problem as long as your strobes have power 

a lot of what you repeat is at least 15 years old misconception 

go out and try some fish schools

[ChrisH]

I have done enough fish schools, don‘t worry. I have also no problems with backscatter 😉
 

And no, wide angle big scenes are not (!)  shot at 3 meter distance. 
 

It is simly not true and I don‘t know who told you such things?

 

And I am afraid you will „demyth“ the 1,5m „myth“ again based on a wrong assumption what it is all about, as you have done with the „edge of the strobe light myth“, that is only a myth if you not understand what is meant by it. 🤷🏻‍♂️

 

Anyway, as I have stated before I just don‘t know how to explain it other that I have done. 

So we have to agree to disagree. 

[Guest]

6 minutes ago, ChrisH said:

I have done enough fish schools, don‘t worry. I have also no problems with backscatter 😉
 

And no, wide angle big scenes are not (!)  shot at 3 meter distance. 
 

It is simly not true and I don‘t know who told you such things?

 

And I am afraid you will „demyth“ the 1,5m „myth“ again based on a wrong assumption what it is all about, as you have done with the „edge of the strobe light myth“, that is only a myth if you not understand what is meant by it. 🤷🏻‍♂️

 

Anyway, as I have stated before I just don‘t know how to explain it other that I have done. 

So we have to agree to disagree. 

Well i will take the picture and you wont

unfortunately big schools dont fit at 1.5 meters and fish get scared

i have not seen any schools on your website I do plenty

it is not possible to achieve perfection but certain dogmas are very limiting and have no reasons to exist or there wont be any other picture that is not just close up

funny enough lots of people THINK they are close but actually arent hence I do my tests in the pool so I measure 

a good gn 32 strobe will work fine with big fish schools with an iso of 400-500 and aperture as small as f/11 and exposure speed in a normal range

no need for red tape you as close as you need for framing and use strobe power to shoot when you are far without boundaries full frame camera recover lots of shadow really no longer an issue

besides I was doing the same with the GH5

most times on boats even in workshops what stops people taking shots of large scenes are diving skills and lack of trust in the equipment 

[ChrisH]

20 minutes ago, Interceptor121 said:

Well i will take the picture and you wont

unfortunately big schools dont fit at 1.5 meters and fish get scared

i have not seen any schools on your website I do plenty

it is not possible to achieve perfection but certain dogmas are very limiting and have no reasons to exist or there wont be any other picture that is not just close up

funny enough lots of people THINK they are close but actually arent hence I do my tests in the pool so I measure 

a good gn 32 strobe will work fine with big fish schools with an iso of 400-500 and aperture as small as f/11 and exposure speed in a normal range

no need for red tape you as close as you need for framing and use strobe power to shoot when you are far without boundaries full frame camera recover lots of shadow really no longer an issue

besides I was doing the same with the GH5

most times on boats even in workshops what stops people taking shots of large scenes are diving skills and lack of trust in the equipment 

There is no reason to take every picture that is „possible“. It is about getting good pictures. 

 

It has nothing to with the actual topic, but I don‘t show all pictures on my website.

But I went through my archive just for you and found a really old picture I took some years ago with not so good lighting and an ugly sun in the background but shot with a fisheye (!) and at close distance. I didn‘t know back then that it can‘t be done and just did it… but I was told now here that it is not possible. So now I know that it is impossible to aproach schools of fish close enough for even a fisheye shot and won’t do it again 🤷🏻‍♂️

[Guest]

35 minutes ago, ChrisH said:

There is no reason to take every picture that is „possible“. It is about getting good pictures. 

 

It has nothing to with the actual topic, but I don‘t show all pictures on my website.

But I went through my archive just for you and found a really old picture I took some years ago with not so good lighting and an ugly sun in the background but shot with a fisheye (!) and at close distance. I didn‘t know back then that it can‘t be done and just did it… but I was told now here that it is not possible. So now I know that it is impossible to aproach schools of fish close enough for even a fisheye shot and won’t do it again 🤷🏻‍♂️

This is at best a hundred snappers far from being a school but you didnt know that you dont face snappers head on unless you are several meters clear

it takes a certain understanding of fish behaviour to understand how to approach schooling fish and it depends species to species 

again there is no rule to say what you should do based on strobes distance it depends on the fish

i dont break fish school in fact I know exactly how to shape them hence the fish shape and other ball shape

unfortunately 90% of divers and photographers swim right through it ruining the composition or stand in the way like you did 

Edited May 30 by Interceptor121

[ChrisH]

9 minutes ago, Interceptor121 said:

This is at best a hundred snappers far from being a school but you didnt know that you dont face snappers head on unless you are several meters clear

it takes a certain understanding of fish behaviour to understand how to approach schooling fish and it depends species to species 

again there is no rule to say what you should do based on strobes distance it depends on the fish

i dont break fish school in fact I know exactly how to shape them hence the fish shape and other ball shape

unfortunately 90% of divers and photographers swim right through it ruining the composition or stand in the way like you did 

Yeah well I did see that one coming, it had to be 😅

 

Well I wish you all the best with your future pictures!  
I am sure they sell well and are constant winners in all contests because well, nobody else has a clue what they are doing or what they are doing is actually all wrong!
 

Have a nice evening!

[Guest]

3 minutes ago, ChrisH said:

Yeah well I did see that one coming, it had to be 😅

 

Well I wish you all the best with your future pictures!  
I am sure they sell well and are constant winners in all contests because well, nobody else has a clue what they are doing or what they are doing is actually all wrong!
 

Have a nice evening!

It is not about winning

the snappers in your image are turning away from you because you ambush them and by doing that you broke the school 

people get so obsessed about taking their photos that no longer have any time to understand what fish does

Pretty much 90% of divers and photographers are like you if thats a consolation 

[fruehaufsteher2]

If you, Interceptor, just could reduce using the word „you“ and reduce blaming or insulting others, your posts would be much more helpful and a win for this forum