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Lighting with speedlight
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Dec 21, 2021 11:13:54   #
Dan' de Bourgogne
 
I’m confused ! The behaviour of light is not that simple.
The « rule » says, the bigger the light source (in relation to subject) , the softer the light impacts that subject. (cf. ombrelles, soft box, etc)
I imagine in turn, the more tiny the light source (in relation to subject), the harder the light should become…right ?

So I wanted to check what happens when lighting the same subject with the same speedlight firing at varying « decreasing » distances from subject (a black lether hand bag)…
1) 8D (=3,20 m) at P1/1,
2) then 4D (=1,60m) at P1/4,
3) then 2D (=0,80m) at P1/16,
4) and finally D (=0,40 m) at P1/64.
To compare apples with apples, I wanted to keep the subject with a constant exposure : camera settings remained constant…ISO 250 ; f/5.5 ; 1/320 sec…exposure was adjusted only via flash Power matching the distance flash/subject ; camera remained on tripod.
And I held the following reasoning (please correct if I am wrong) : The further the light (3,20 m vs 0,40m) the surface of the source becomes 8x8 times more little in relation to the subject. Therefore, this light source firing at 3,20m should create a hard light…in any case, the light is expected to be harder than if shot at 0,40m ! Therefore, the shadowy areas should become deeper.
Guess what ! The further the light, the more eligible become the shadowy areas ! See the pictures.
I got really surprised because I expected the « far » light to appear much harder : after all, if compared with the case of speedlight set at 0,40 m from subject, the relative size of the « far » speedlight looks like to be reduced 64 times in relation to subject.
My concern is : why does a speedlight set at distance create a light which appears softer than the light of the same source firing quite close ? I’m missing something…but what ? Do You have an idea ?

DSC 4244;SB-26 fired at P 1/1 dist. flash/front of Bag = 3,20 m
DSC 4244;SB-26 fired at P 1/1 dist. flash/front of...
(Download)

DSC 4245;SB-26 fired at P 1/4 dist. flash/front of Bag = 1,60 m
DSC 4245;SB-26 fired at P 1/4 dist. flash/front of...
(Download)

DSC 4246;SB-26 fired at P 1/16 dist. flash/front of Bag = 0,80 m
DSC 4246;SB-26 fired at P 1/16 dist. flash/front o...
(Download)

DSC 4247;SB-26 fired at P 1/64 dist. flash/front of Bag = 0,40 m
DSC 4247;SB-26 fired at P 1/64 dist. flash/front o...
(Download)

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Dec 21, 2021 11:43:06   #
BebuLamar
 
Where do you take the picture? Light may be bouncing off the side walls when you put the light far away.

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Dec 21, 2021 12:16:22   #
Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)
 
Dan' de Bourgogne wrote:
I’m confused ! The behaviour of light is not that simple.
The « rule » says, the bigger the light source (in relation to subject) , the softer the light impacts that subject. (cf. ombrelles, soft box, etc)
I imagine in turn, the more tiny the light source (in relation to subject), the harder the light should become…right ?

So I wanted to check what happens when lighting the same subject with the same speedlight firing at varying « decreasing » distances from subject (a black lether hand bag)…
1) 8D (=3,20 m) at P1/1,
2) then 4D (=1,60m) at P1/4,
3) then 2D (=0,80m) at P1/16,
4) and finally D (=0,40 m) at P1/64.
To compare apples with apples, I wanted to keep the subject with a constant exposure : camera settings remained constant…ISO 250 ; f/5.5 ; 1/320 sec…exposure was adjusted only via flash Power matching the distance flash/subject ; camera remained on tripod.
And I held the following reasoning (please correct if I am wrong) : The further the light (3,20 m vs 0,40m) the surface of the source becomes 8x8 times more little in relation to the subject. Therefore, this light source firing at 3,20m should create a hard light…in any case, the light is expected to be harder than if shot at 0,40m ! Therefore, the shadowy areas should become deeper.
Guess what ! The further the light, the more eligible become the shadowy areas ! See the pictures.
I got really surprised because I expected the « far » light to appear much harder : after all, if compared with the case of speedlight set at 0,40 m from subject, the relative size of the « far » speedlight looks like to be reduced 64 times in relation to subject.
My concern is : why does a speedlight set at distance create a light which appears softer than the light of the same source firing quite close ? I’m missing something…but what ? Do You have an idea ?
I’m confused ! The behaviour of light is not that ... (show quote)


There are two things at play here - the apparent size of the light relative to the distance - the sun is a huge light - the diameter is 865,000 miles - but at that distance it behaves like a point light source. Then there is the inverse square relationship of light intensity to the subject - at very close distances (3 ft) the amount the light decays over a 1 ft distance (front to back of a subject) is far greater than the amount of decay when the light is 10 ft away. If you are good at math you can calculate the difference, but in general photography it is usually enough to just understand the concept.

If you were to shoot a speelight through a diffusing material, like one of those combo reflector/diffuser screens and you place the speedlight far enough so that you illuminate a large part of that screen, the subject will see a much wider light, and shadows will be softer.

If you have a flashlight that has a focusable beam - you can test it for yourself.

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Dec 21, 2021 13:59:07   #
PHRubin Loc: Nashville TN USA
 
Dan' de Bourgogne wrote:
...The « rule » says, the bigger the light source (in relation to subject) , the softer the light impacts that subject. (cf. ombrelles, soft box, etc)...

The rule applies to the physical size of a source as (solid) angle of view as seen from subject.

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Dec 21, 2021 16:07:19   #
Dan' de Bourgogne
 
BebuLamar wrote:
Where do you take the picture? Light may be bouncing off the side walls when you put the light far away.


I shot this picture in the living room 18'x18'...8'1/3 high.(white walls+white ceiling+2 large doorwindows)
The flash was set on a stand; 90° from lens axis left side; zoom head directed perfectly horizontally to the front of the lether bag, exactly at half hight of it.
Despite the black bedsheet I hang as a backdrop (90°camera right side=exactly aligned with subject and flash), certainly a lot of light was boucing quite everywhere when the flash was set at 3,20 m.
You are right: there has been a lot of spill light which interacted with the flash burst! Thank You for Your comment.
Neverthe less I'm disappointed because I wanted to create an image with a nice gradient in the shadowy areas by making the apparent size of the speedlight much bigger than id seen from far away...Hélas, it did'nt work that way. To achieve the result I was after, I must use either a brelly or any kind of big diffuser...exactly what I wanted to avoid! Obviously, there is no other way to make the light softer. In fact, I was looking for a solution to get more "gradient" in shadowy areas without using a big diffuser with powerful light source. But it seems there is no way!

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Dec 21, 2021 16:30:38   #
E.L.. Shapiro Loc: Ottawa, Ontario Canada
 
Considering the small size and compact construction, the higher-quality speed lights are pretty amazing little gadgets. On the surface, the basic design, a SMALL liner flash tube, backed up by a rather highly-polished reflector made of chrome-plated metal or mirror mylar and only defused by a plastic lenticular-like material in a small housing, all seem to be antithetical to soft or even lighting. Nonetheless, they will provide enough volume of light for practical exposure and moderate ISO settings. Many of the little units will adequately cover a moderately wide-angle field and can be adjusted to long-throw lighting for moderate telephoto usage. Pretty decent performance if used correctly, however, when mounted on the camera and unmodified, there is just so much aesthetic quality and versatility we should expect from them. Basically, they provide a fairly harsh, flat light that will also suffer the effect of the inversse square law and yield a normally exposed subject with overexposed foregrounds and underexposed backgrounds.

So, photographing a black leather product with a Speedlight is not an ideal method. Nonetheless, if you look at the first shot which was made at a closer light to subject distance there is more detail in the metal ornament and the zipper. The theory is that the closer the light source to the subject, the softer the effect is proven the and the detail is diminished as the light is placed further away although the exposure may be constant. Since the leather material is somewhat polished and has some surface sheen, there is a hotspot which is a reflection of the flash, If the subject was a person's face, there would be a difference in the specular highlight and the transition for highly to show would be more gradual in cases where the light source was closer in.

As for exposure, unless you use a flash meter and make accurate incident light readings, it is hard to tell if exposure actually tracks proportionately by reducing and increasing flash power. There is another phenomenon that accompanies flash usage called "unseen secondary light". As you change the position of the flash unit as per distance, more or less light is bouncing from walls and ceilings will affect the actual exposure. Even if you are using a mono-light with a modelling lamp, this small but additional volume of light o lack thereof remains unseen by the photograher until the result is examined.

Even the broadest, largest, and soft light sources will become slight or significantly harder as they are moved further from the subject. This doe not mean that a 4' softbox or umbrella-equipped light is gonna become a spotlight at 30 feet away but there will be a difference in the transition from highlight to shadow and how much or little the light tends to wrap around the subject.

I am not sure exactly what want to determine without experiment/test. If it is a matter of lighting aesthetics, I suggest you do another test with a more dimensional or round object whereby you can see the gradations of light and shadow and compare the dimensionality. If you are only interested in coverage of the light or whether or not your Speedlight is tracking proportionally as power changes are made, you will need to apply more control over exposure readings via a meter and isolate the subject in an area with dark walls or a tent of black seamless paper to negat the effect extraneous bounced light.

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Dec 21, 2021 17:32:13   #
Dan' de Bourgogne
 
Hello Gene51! I'm happy You took time for this post. Once again You opend my brain...OK...relative size++++ inverse square law.! I just forgot the last one.
I'm angry to have spent the time to write this post ...because I'm absolutely aware of the effect of the inverse square law...I knew that lighting a part from subject from 3,20m would not produce a really noticible difference than lighting
another part of the same subject from 3,60m. At least, the exposure difference would never comme near like 2 stops!
Sorry to have forgot this "beginner rule"...I don't understand anymore why I wanted to make the relative size bigger just in setting the light source closer...In fact, relative size has to be understood when set at a given distance; I forgot this last point! Mea culpa.
That is where skilled professional people like You are shining: in 10 secondes You know what, why and how to...which takes hours by other guys like me! Thank You Gene...you are a great technician

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Dec 21, 2021 17:42:18   #
Dan' de Bourgogne
 
PHRubin wrote:
The rule applies to the physical size of a source as (solid) angle of view as seen from subject.


Oh yes...I apologize...I wanted to explore what happens if only the relative size gets bigger (or smaller). But I forgot one thing: the distance should remain the same . What makes me furious is I'm aware of the inverse square law!
Don't ask me why I wanted to play with distance to alter the relative size...because perhaps I thought it could be an easyer way compared to set up a brelly or soft box?
In any case, thank You PHrubin to take time for me!

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Dec 21, 2021 18:08:42   #
E.L.. Shapiro Loc: Ottawa, Ontario Canada
 
If you want to do product or still life work, you may want to consider a simple light setup. One light, a softbox and a reflector. See the setup in the attached image. It works well with a cloth, leather, metal,s and many other materials and surfaces.

If you don't have a monolight or do not intend to get one, you could use your Speedlight and improvise a model lamp.





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Dec 21, 2021 18:16:57   #
Dan' de Bourgogne
 
E.L.. Shapiro wrote:
Considering the small size and compact construction, the higher-quality speed lights are pretty amazing little gadgets. On the surface, the basic design, a SMALL liner flash tube, backed up by a rather highly-polished reflector made of chrome-plated metal or mirror mylar and only defused by a plastic lenticular-like material in a small housing, all seem to be antithetical to soft or even lighting. Nonetheless, they will provide enough volume of light for practical exposure and moderate ISO settings. Many of the little units will adequately cover a moderately wide-angle field and can be adjusted to long-throw lighting for moderate telephoto usage. Pretty decent performance if used correctly, however, when mounted on the camera and unmodified, there is just so much aesthetic quality and versatility we should expect from them. Basically, they provide a fairly harsh, flat light that will also suffer the effect of the inversse square law and yield a normally exposed subject with overexposed foregrounds and underexposed backgrounds.

So, photographing a black leather product with a Speedlight is not an ideal method. Nonetheless, if you look at the first shot which was made at a closer light to subject distance there is more detail in the metal ornament and the zipper. The theory is that the closer the light source to the subject, the softer the effect is proven the and the detail is diminished as the light is placed further away although the exposure may be constant. Since the leather material is somewhat polished and has some surface sheen, there is a hotspot which is a reflection of the flash, If the subject was a person's face, there would be a difference in the specular highlight and the transition for highly to show would be more gradual in cases where the light source was closer in.

As for exposure, unless you use a flash meter and make accurate incident light readings, it is hard to tell if exposure actually tracks proportionately by reducing and increasing flash power. There is another phenomenon that accompanies flash usage called "unseen secondary light". As you change the position of the flash unit as per distance, more or less light is bouncing from walls and ceilings will affect the actual exposure. Even if you are using a mono-light with a modelling lamp, this small but additional volume of light o lack thereof remains unseen by the photograher until the result is examined.

Even the broadest, largest, and soft light sources will become slight or significantly harder as they are moved further from the subject. This doe not mean that a 4' softbox or umbrella-equipped light is gonna become a spotlight at 30 feet away but there will be a difference in the transition from highlight to shadow and how much or little the light tends to wrap around the subject.

I am not sure exactly what want to determine without experiment/test. If it is a matter of lighting aesthetics, I suggest you do another test with a more dimensional or round object whereby you can see the gradations of light and shadow and compare the dimensionality. If you are only interested in coverage of the light or whether or not your Speedlight is tracking proportionally as power changes are made, you will need to apply more control over exposure readings via a meter and isolate the subject in an area with dark walls or a tent of black seamless paper to negat the effect extraneous bounced light.
Considering the small size and compact constructio... (show quote)


Thank You Mr. Shapiro! this is again a very nice, extensive, precise and very well explained comment. Meanwhile I understood where I made a mistake in this "journey" dedicated to see by myself what happens if one wanted to change the relative size of a light source (making it either bigger or smaller); I apologize but I just forgot that changing the distance not only did vary the relative size but also introduced the effects of the"inverse square law". I just forgot the thing every beginner knows! That's why I'm angry...don't ask me what I was thinking of. I wanted to "explore" a way to make a light source just a bit bigger (without setting it in an ombrelle or in a softbox) and see what happens with the produced shadows on the subject. I wanted to take a photo of a basket ball but I did'nt find it, so I took a lether bag! The aim was only "educational"
In any case, thank you for your help and all those tips ans comments.

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Dec 21, 2021 18:46:55   #
Dan' de Bourgogne
 
E.L.. Shapiro wrote:
If you want to do product or still life work, you may want to consider a simple light setup. One light, a softbox and a reflector. See the setup in the attached image. It works well with a cloth, leather, metal,s and many other materials and surfaces.

If you don't have a monolight or do not intend to get one, you could use your Speedlight and improvise a model lamp.


Yes, this suggestion to take a product shot is a very good idea.
Tomorrow I will try to produce a photograph of this lether bag I took today. Of course this will be done following Your recommandation...nevertheless, I don't intend to paint my living room in black! We will see what can be done. Thank You for the idea! My wife is always proud when I take her stuff to make it a provisory "photo subject"!

Reply
 
 
Dec 21, 2021 21:39:30   #
E.L.. Shapiro Loc: Ottawa, Ontario Canada
 
Dan' de Bourgogne wrote:
Yes, this suggestion to take a product shot is a very good idea.
Tomorrow I will try to produce a photograph of this leather bag I took today. Of course, this will be done following Your recommendation...nevertheless, I don't intend to paint my living room in black! We will see what can be done. Thank You for the idea! My wife is always proud when I take her stuff to make it a provisory "photo subject"!
img src="https://static.uglyhedgehog.com/images/s... (show quote)


I have painted many walls BLACK over the years and much to the chagrin of several landlords and my lovely wife. In each case, it required several coats of paint and an illuminizer to correct the damage.

Don't be "angry" about forgetting about certain techniques. Goos photograhy is at least 50% problem-solving. So when you solve a problem, be happy!

Reply
Dec 22, 2021 06:03:37   #
billnikon Loc: Pennsylvania/Ohio/Florida/Maui/Oregon/Vermont
 
Dan' de Bourgogne wrote:
I’m confused ! The behaviour of light is not that simple.
The « rule » says, the bigger the light source (in relation to subject) , the softer the light impacts that subject. (cf. ombrelles, soft box, etc)
I imagine in turn, the more tiny the light source (in relation to subject), the harder the light should become…right ?

So I wanted to check what happens when lighting the same subject with the same speedlight firing at varying « decreasing » distances from subject (a black lether hand bag)…
1) 8D (=3,20 m) at P1/1,
2) then 4D (=1,60m) at P1/4,
3) then 2D (=0,80m) at P1/16,
4) and finally D (=0,40 m) at P1/64.
To compare apples with apples, I wanted to keep the subject with a constant exposure : camera settings remained constant…ISO 250 ; f/5.5 ; 1/320 sec…exposure was adjusted only via flash Power matching the distance flash/subject ; camera remained on tripod.
And I held the following reasoning (please correct if I am wrong) : The further the light (3,20 m vs 0,40m) the surface of the source becomes 8x8 times more little in relation to the subject. Therefore, this light source firing at 3,20m should create a hard light…in any case, the light is expected to be harder than if shot at 0,40m ! Therefore, the shadowy areas should become deeper.
Guess what ! The further the light, the more eligible become the shadowy areas ! See the pictures.
I got really surprised because I expected the « far » light to appear much harder : after all, if compared with the case of speedlight set at 0,40 m from subject, the relative size of the « far » speedlight looks like to be reduced 64 times in relation to subject.
My concern is : why does a speedlight set at distance create a light which appears softer than the light of the same source firing quite close ? I’m missing something…but what ? Do You have an idea ?
I’m confused ! The behaviour of light is not that ... (show quote)


I strongly suggest you use a subject that you will actually be taking images of, like people, rather than a purse.
The flash will react differently on a face.

Reply
Dec 22, 2021 08:55:36   #
sueyeisert Loc: New Jersey
 
An excellent book on lighting with a flash is by Neil Van Neikerk. Look him up,on Amazon. He also has a website with lots of information about lighting.

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Dec 22, 2021 10:22:12   #
Dan' de Bourgogne
 
E.L.. Shapiro wrote:
I have painted many walls BLACK over the years and much to the chagrin of several landlords and my lovely wife. In each case, it required several coats of paint and an illuminizer to correct the damage.

Don't be "angry" about forgetting about certain techniques. Goos photograhy is at least 50% problem-solving. So when you solve a problem, be happy!


Bonjour monsieur Shapiro! I took today the photo You suggested me yesterday! Now I'm trying to transfer it from my SD card into the PC. For unknown reason,I have now a trouble: my PC does'nt identify the new storage device (my SD card) I want to upload. So I have first to solve this issue...

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