Interior shots using on-camera flash

[Manfred M]

Bruce ... I think you are wasting your time if you hope to adjust the background indoors by shutter speed when indoors.

Basic flash as when I started doing syncro-sunlight back in the late fifties has not really changed and in low ambient light [indoors] the shutter speed has little or no affect on background levels and only in daylight ambient levels does the shutter have any effect which brings us back to the old maxim that "the aperture controls the flash and the shutter the ambient light"

The one thing that has most certainly changed is the is the higher ISO capabilities of a modern camera. Of course, in the 1950's, camera lenses tended to have lower maximum apertures and unless you had an in-lens leaf shutter, flash synch speeds were painfully slow. My first SLRs had synch speeds of 1/60th and 1/90th sec, respectively. So while basic flash has not changed, the parameters we use flash under have.

I remember when I started serious shooting in the 1970's, ISO 400 was as fast as films got and even at that relatively paltry speed, I was more than capable of doing existing light work indoors. If you can capture an image with existing light, it can definitely add to your image, so there is no question that even moderate ISO settings and appropriate shutter speeds and aperture settings, indoor ambient light combined with flash can be part of the light capture process.

The simplest test to see the ambient light impact is to take a shot of the room at the ISO, aperture setting and shutter speed. Whatever you see on the camera's display will most definitely be in the shot as well.

[William W]

The Shutter Speed can definitely be used to control the Ambient Exposure of the Background when Flash being used to illuminate a Foreground Subject in an INTERIOR SCENE.

If that is what one wants to achieve, then it is certainly NOT a waste of time to harness the knowledge and the skills to do it.

In simple terms and generalizing: By increasing the Shutter Speed the Ambient Exposure will be reduced and the Background will thus be rendered darker.

This can be done with any camera which has a manual Shutter Speed control and the ability to trigger a Flash - but it is more easily achieved on some cameras than on others.

The OP is using a Nikon DSLR and a Dedicated Nikon Flash - the Canon System works very similarly.

***

Bruce,

Maybe this will be of some assistance in the PREPARATION for your experiment and it should serve as a background as to why I commented so definitively yet briefly, in Post #16.

In simply terms it will be easier to have a dark background and make a good shot of it if:

> there is a larger Subject to Background distance than Camera to Subject Distance, a 2:1 or larger ratio is a good beginning.

> you do not use HSS (because of the reasons listed above) especially loss of Flash Power and reduction of Maximum Flash Working Distance.

A typical example that I would use to beginner Wedding Photographers is the B&G First Dance - (typically)

The Camera is to be at about 12ft and the background crowd needs to be at about 25~30ft behind the B&G. Drag the Shutter at TWO stops under the Ambient Exposure and Flash as Key on the Subjects at FEC about minus 2/3 Stop.

As per Manfred’s responses there are many variables to consider.

Also, each Shooting Scenario will be different.

Manfred mainly commented upon the consideration of the MULTIPLE LIGHT SOURCES and the TYPE OF LIGHT from each source.

Also please refer to Post #7 where Paul mentioned using positive FEC. Note I am NOT arguing that would not give a good result – it would in SOME circumstances.

Here are some more variables that you might consider when you make your experiment, (not all of the variables but the main ones I have collected):

> the functionality of FEC in consideration of the amount of IMAGE SPACE the MAIN SUBJECT occupies within the scene

> the functionality of FEC / TTL in consideration of the COLOUR of the MAIN SUBJECT

> the functionality of FEC / TTL in consideration of the 'reflective value' of the MAIN SUBJECT or some object near the main Subject (e.g. an highly polished wooden lectern's fascia with the MAIN SUBJECT standing behind it - that can be a recipe for BIGtime underexposure)

> the aesthetic that YOU want - how much POP of the MAIN SUBJECT relative to how SUBDUED the BACKGROUND

> the Light Modification of the Flash (if any, i.e. bounce, diffuser, etc)

> Nikon Dedicated Flash Systems work slightly differently to Canon. Nikon is both smarter and more consistent in its nuances, in my opinion.

*

This is an illustration of what I described in Post #16. I think this would be a good STARTING POINT for your experiments. The examples have a few notes underneath each which might assist you defining the parameters for your experiment so you get the answers and the experience that you want.

PREFACE:

1. All shots are JPEG SOOC , just downsized in Photoshop and whatever sharpening it does.

2. The ‘interior’ was purposely ‘complex’ both by way of mixed lighting and also light and dark objects included in it.

3. Kit: EOS 20D; EF 35 to 135 F/4~5.6; 580 EX

4. Shooting: Camera in M Mode; Lens set at 35mm; Flash in E-TTL Mode, FEC is active and set at - ⅔Stop (minus two thirds of a Stop), the Flash Head aimed directly at the Subject without any Light Modifiers, the Flash Zoom is set at 50mm (i.e. the ‘correct setting’ for a 35mm lens used on an APS-C camera)

5. Distance from Subject to extent of Background (blue wall) is 20ft

6. For this part of the ‘experiment’, the ONLY parameter which is changed is the Camera to Subject Distance (and of course the lens’s focusing on the Subject),

*

Frame 01

This is the Ambient BACKGROUND of our scene and it is shot in AVAILABLE LIGHT ONLY at the ‘correct exposure for the background': F/4 @ 1/10s @ ISO1600



As mentioned, both the multiple lighting and also the diversity of the the objects present a ‘complex scene’, that we want to ‘darken as our background’.

*

Frame 02



This is the Subject set at 20 ft from the rear of the room.

The camera set about 10ft from the Subject and the exposure is F/4 @ 1/40s @ ISO1600, i.e. Two Stops underexposed for the Ambient.

This is about 2:1 Distance Ratio that I suggested for the beginning of your experiment.

Note that, because the Subject occupies a relative small area of the foreground frame the Flash is effective across a wide range of the foreground and (I believe that) the FEC took into account the WHITE sofas either side of the main Subject and the AMBIENT ILLUMINATION on them and also the floor.

The Flash is definitively UNDERexpsoed in this shot – and for this scenario FEC set to positive, would certainly be the recipe. However, if the subject were bigger and occupied more of the foreground, but we still had 2:1 Distance Ratio, then we might require 0 (zero) FEC.

For your experiment I suggest that you make several shots at each SHOOTING DISTANCE varying the FEC. Doing this will create a Subset of images within your main experiment, to learn about the amount of FEC required considering the FRAMING and SIZE of the MAIN SUBJECT within the whole of the SCENE.

Reiterating that the COLOUR (and also the ‘reflective value’) of the MAIN SUBJECT that you use, will affect the computation of the Flash/Camera TTL metering. For example a WHITE Main Subject will usually require a different FEC to a BLACK Main Subject. Goofy is dressed in an IKEA bag to represent ‘an average person dressed averagely’.

In this frame, there is noticeable Background darkening – so the ‘experiment’ is ‘working’.

Note the table lamp at camera right which is about half way into the background, and the chair and cushion on it at camera left at the background wall are both effectively 'darkened'.

*

Frame 03



This is the Subject set at 20 ft from the rear of the room.

The camera set at 6ft from the Subject and the exposure is F/4 @ 1/40s @ ISO1600, i.e. Two Stops underexposed for the Ambient.

This is a Distance Ratio of about 3:1

In this frame, there is the same noticeable Background darkening – so the ‘experiment’ is still ‘working’.

Note the table lamp at camera right which is about half way into the background, and the chair and cushion on it at camera left at the background wall.

Also note that the FEC, (still set at minus two thirds of a Stop), seems to be ‘working better’. Goofy is still tad underexposed, but he is looking a lot better than in Frame 02.

*

Frame 04



This is the Subject set at 20 ft from the rear of the room.

The camera set at about 4ft from the Subject and the exposure is F/4 @ 1/40s @ ISO1600, i.e. Two Stops underexposed for the Ambient.

This is a Distance Ratio of about 5:1

In this frame, there is the same noticeable Background darkening – so the ‘experiment’ is still ‘working’.

The table lamp at camera right is out of shot, but the chair and cushion on it at camera left at the background wall are not.

Also note that the FEC, still set at minus two thirds of a Stop, seems to be ‘working perfectly’. Goofy is looking a lot better than in Frame 03. In fact for MY aesthetic, Goofy and the Background are perfectly exposed for the amount of POP / Lighting Ratio that I would want for that type of shot.

The ugly flash shadow from the direct Flash is another issue, but I was not making an experiment for that issue.

***

Epilogue:



Here is a picture of the rig that I used to make the images above - no real thought to the selection, I just grabbed a DSLR with a card in it, plonked on something that would work as a Standard Lens and put a Dedicated Hot Shoe Flash on top. This rig then, as I understand it, would satisfy the criteria for your experiment.

However after I made the images I noticed a couple of points: one is totally irrelevant but the other is relevant to this thread

a) Ignore the CPL on the front of the lens. The lens was used by a Student and she forgot to take the CPL off the lens when returning it to me. The CPL does not hamper this experiment.

b) Please see my 580 Flash Head - see the note which is sticky-taped to it. That is a register of the GUIDE NUMBER for each Zoom Point of the 580 Flash Head.

In a shooting scenario where I do not trust the FEC / E-TTL functionality and/or I do not trust my manual over-riding of it, I will go Manual Flash and with Manual Camera.

In the absence of a Flash Meter (or the time to use it) I will use the Guide Numbers and Flash to Subject Distance and work manually with mental arithmetic. Not often used now, because the FEC and E-TTL are very smart and in a studio or other controlled environment I would usually use a Flash Meter - but it is still useful to know how to do it ALL manually, that's my opinion.

WW

All Images ©AJ Group Pty Ltd Aust 1996~2015, WMW 1965~1996

[William W]

. . . I think you are wasting your time if you hope to adjust the background indoors by shutter speed when indoors. . . in low ambient light [indoors] the shutter speed has little or no affect on background levels and only in daylight ambient levels does the shutter have any effect which brings us back to the old maxim that "the aperture controls the flash and the shutter the ambient light. . .

With due respect to you John,

Those statements are: incorrect.

WW

[jcuknz]

John, the faster SS did darken considerably the light coming from the window. In fact it makes it appear there is a solid wall behind the subject as opposed to a window. IMHO this leads credence that to the effect that increasing the SS will (as shown by your example) darken (underexpose) the ambient light in the background. This is the effect I want to achieve.
Thank you very much.

Bruce

Sorry Bruce but it only happened because the shutter speed was controlling relatively bright ambient light.
Remember my comment about if the light is several stops darker than the exposure then the shutter will have little or no effect on the results. The first frame illustrates how bright the window was even at 1/1000 f/8 even though the model is dark

My illustration below is how I did it a few years ago to show what can be done with a single light and reflectors.
I used the on-board as a trigger to set off the remote flash. If your flash has a built in trigger then you would not need the little box thing [ optical trigger about US$20 B&H New York ] they came in two kinds one which is shown has a socket to plug in the sync cord from the older type of flash, the other fits on the base of the flash and works the modern flash as a camera would.

The easiest way to get a dark background is to stop light falling on it so I organised a simple snoot thing to direct the light where I wanted it which was on the subject and nowhere else with the result that a light blue background became black.

The on-board had a piece of card taped to it loosely so enough light escaped to trigger the remote. There is a possible problem here that some cameras emit a pre-flash for focusing or exposure [ this is not 'red-eye' flash ] and this sets the flash off so it has no power left for when the camera tries to take the photo. Reducing the on-board's power with the shield reduces the likelihood of that happening.



I must have had a reflector of some kind [ I had white board and silver foil ] probably the white board which shows on the neck. In another shot I held a reflector up above the model to simulate a 'hair light' which separates the hair from the background ... and with another rig I cut a hole in the side of the snoot to let some light escape to light the background ... but you don't want that I gather

I am convinced that the way to use light is to control it rather let it flood everywhere ... say no more as it is a hobby horse of mine

Answer to my double post illustrating shutter speed in the dark ... the one on the left is the insert at 1/1000 over the base 1/50 frame.

[jcuknz]

With due respect to you John,

Those statements are: incorrect.

WW

If you care to explain why there would be some point to your post ... I know that in this modern age of 'helpful' gear fouling up the basics of syncro-sunlight ... but I worked it out all out probably before you started in this game ... without blogs and things spreading mis-information. It is a simple balance of natural and artificial light .... when there is natural light then the shutter has some effect, when it is effectively absent the shutter plays no part except I could have added for the benefit of nit-pickers slow sync or dragging the shutter whatever it is called.

I am trying to help Bruce solve his problem rather than score points off others. I really cannot see how your long post on this page helps Bruce in his stated aim to achieve a dark background indoors.

[jcuknz]

Manfred .. I am afraid when I started 'fast film' was 100ASA/ISO and the plates I used in the studio were Ilford Special Rapid at 25 ASA/ISO ... I remember May and Baker bringing out Promicrol which raised FP3 to the fantastic speed of 800 ASA without the usual blurring of grain in other forced development.
This rather scruffy copy off a print is one of the few memories I have of that experiment... I am sure these days I could do as good at 100 ISO ... but I thought it great at the time, 1952.



At one stage I used a Leica with a 1/20 sync speed and with other Leicas of the time sync was obtained by the rotation of the speed dial which had a brass chip braised to it which made contact with a shoe fitting in the accessory slot.... one day my boss came into the darkroom saying his flash didn't work ... I saw that he had fitted the shoe in back to front .. at the time I thought silly old man ... but I suspect he was having me on as he was a pretty clued up guy. Probably discovered his error in the field and then came home to test me.

Further to #25 the point about faster emulsions/sensors is the meaning of "effective level of ambient light" which changes with the speed of the sensor ... so I am afraid Bill is jumping to unfounded conclusions by not reading and comprehending properly ... easy done on the web.

[William W]

I know that in this modern age of 'helpful' gear fouling up the basics of syncro-sunlight ... but I worked it out all out probably before you started in this game ... without blogs and things spreading mis-information.

Those occur as personal comments and implications toward another member. It occurs to me that those type of comments out of character for you, John.

***

I am trying to help Bruce solve his problem rather than score points off others. . . I really cannot see how your long post on this page helps Bruce in his stated aim to achieve a dark background indoors.

So do I - want to assist Bruce.

If it occurs to you that I want “to score points off you”: then you are incorrect in that assumption. So we can put an end that topic of conversation, right here - and right now.

***

If you care to explain why there would be some point to your post . . . [in low ambient light [indoors] the shutter speed has little or no affect on background levels] . . . when there is natural light then the shutter has some effect, when it is effectively absent the shutter plays no part I really cannot see how your long post on this page helps Bruce in his stated aim to achieve a dark background indoors.

Post #22 is the explanation.

Noted that you do not understand that Post #22 as an explanation.

Here is an explanation of it in another way.

1. F/4 at 1/10s @ ISO 1600, is “low ambient light [indoors]”.

That exposure indicates SCENE at about EV = 4

EV = 4 is what I, and I expect most Photographers, would term “a low level ambient indoor scene”.

*

2. The Scene is lit by a lot of artificial light (not that it matters anyway). The hard and very bright pedestal lamp reflecting off the ceiling creates most of the illumination for the Chair at the rear camera left and the piano stool the hard shadows underneath both are indicatives. Note the exposure of these shadows in the examples in Post #22. The Lamp-shade of the Lamp situated at Camera Right is illuminated by the ‘artificial’ light-globe inside the Lamp. Note the exposure of the Lamp-shade in the examples in Post #22.

Certainly the scene has a small amount of light coming in from outside through the curtains. It was raining outside – there is definition in the sheer curtain at the exposure F/4 @ 1/10s @ ISO1600 which is an indicative of how dark was the exterior of the house from the “natural light”.

*

FRAME 01 used the AMBIENT exposure: F/4 @ 1/10s @ ISO1600

FRAMES 02; 03 and 04 used the AMBIENT exposure F/4 @ 1/40 @ ISO1600

In other words, for FRAMES 02; 03 and 04, the SHUTTER SPEED was INCREASED.

It seems apparent to me that when comparing/contrasting Frame 01 to Frames 02; 03 and 04, it is quite obvious that the Background in Frames 02; 03 and 04 are DARKER, than in Frame 01.

This fact of the "background being darker", is noted by several comparing/contrasting several OBJECTS that are contained in the background, including but not limited to:

> the TABLE LAMP at camera right
> the CHAIR and CUSHION on the chair, at camera left.
> the reflection of the TABLE LAMP in the glass of the framed tapestry on the background wall
> the white in the OIL PAINTING, camera left on the background wall
> the SHADOW of the chair at camera left

*

Defining The Background:

Note that the TABLE LAMP is about 10ft behind the MAIN SUBJECT

Note that the wall, chair and framed tapestry is about 20ft behind the MAIN SUBJECT

***

John, if that does not better explain how changing the Shutter Speed made the background darker in that 'low level interior scene', then perhaps the following six images and the accompanying text will allow for a better understanding of it.

Also, irrespective of me sincerely wanting to provide a comprehensive answer to your direct question asking for an explanation, the additional topics raised suggesting a lack of experience and a purposeful spreading of misinformation were NOT well received and so the readership might judge for themselves, what is, exactly what on those two particular matters, i.e. :

> but I worked it out all out probably before you started in this game (op cit)
> without blogs and things spreading mis-information (op cit).

*

When making the sample images for Bruce, there were shot SIX FRAMES for each of the THREE sequences of the DIFFERENT CAMERA POSITIONS made.

Initially I did not want to reveal all these images, because I wanted Bruce to explore the many facets of his experiment and realize and understand the many relationships between the Flash Exposure and the Ambient Exposure. But an additional five images should not disrupt Bruce's endeavour that much, if at all.


The following are the six frames that I made with the camera situated 4ft from the MAIN SUBJECT. The Flash is set at minus ⅔Stop FEC and the only variable between each shot is the SHUTTER SPEED used. These are all, as before, JPEG SOOC

From Top Left, moving across and then to the next line of two, the exposures are:
F/4 @ 1/5s @ ISO1600
F/4 @ 1/10s @ ISO1600 (exposed as per the sample ‘FRAME 01’ in Post#22)
F/4 @ 1/20s @ ISO1600
F/4 @ 1/40s @ ISO1600 (the sample ‘FRAME 04’ used in Post#22)
F/4 @ 1/80s @ ISO1600
F/4 @ 1/160s @ ISO1600

If it is not obvious by interrogating these six images and the data provided with them, that the CHANGE OF SHUTTER SPEED is indeed controlling the Background Exposure and ‘darkening the background’ (which is the aim that Bruce wants to achieve), then I am at a loss as to how better to compose an explanation.



WW

All Images ©AJ Group Pty Ltd Aust 1996~2015, WMW 1965~1996

[pnodrog]

Above Bill has nicely demonstrated the the saying referred to by Jcuknz that "the aperture controls the flash and the shutter the ambient light".... So long as nothing else including ISO is changed this will hold true for all levels of ambient light (even night scenes with slow sync) If the ambient lighting totally overpowers the flash intensity lighting the subject it may not be easily observable.

However the original question asked was about the effect of adjusting shutter speed using high speed sync at which point increasing the shutter speed reduces the exposure from both the ambient and flash illumination.

So the basic answer to the original question is NO.

All the high speed flash sync is doing is enabling the use of a flash in situations where the ambient light is such that at the selected ISO and aperture the shutter speed for correct exposure will be faster then the highest FP sync of the camera. In this mode the shutter speed will be effecting the exposure from the flash and ambient light in unison.

[jcuknz]

I guess the problem with this thread is that two people could be and probably are mis-assuming what Bruce intends to do in the future and have assumed different targets. In a hyperthetical way I would suggest [L.Paul] that there comes a point when the shutter speed is quicker than the flash [ without personal experience ] if flash has a duration of 1/1500 and the shutter is increased past that then the shutter speed will affect both the flash and ambient light. But I think Bruce suggested 1/50 and 1/1000 so I went with those and choose a situation where ambient light was almost non-existent, just a street light coming through the window.

[pnodrog]

John I find one of the most difficult things to do on this forum is to not be misunderstood while still being as brief as possible. If I am too brief I find there is an enormous danger of being either confusing or misinterpreted often both...

[pnodrog]

I have finally found an article that illustrates clearly the effect of shutter speed on exposure when using HSS flash.

http://neilvn.com/tangents/high-speed-flash-sync/

[William W]

. . . the original question asked was about the effect of adjusting shutter speed using high speed sync at which point increasing the shutter speed reduces the exposure from both the ambient and flash illumination. So the basic answer to the original question is NO. . . .

I agree, one simple and generalized answer to Bruce's Opening Post is to state that Shutter Speed affects both the Ambient Exposure and the Flash Exposure when HSS is activated.

Perhaps more importantly in the context of the OUTCOME that Bruce detailed in his Opening Post, (i.e. he wants to get a dark background indoors using Shutter Speed changes), I think it is it is good to mention, again, that if Bruce activates HSS, it will certainly NOT be a very easy method for him to get the results that he wants. (Though, for the archival record of the thread, it is relevant to mention that it possible to achieve, to some extent, in some shooting scenarios.)

*

I thought that the conversation had progressed to a point beyond ‘answering the original question about using HSS’. There are many early posts providing many reasons why HSS would NOT easily work for Bruce to attain his goal.

Note Bruce answers in Post#14 to the effect that he doesn't mind what the shutter speed is, so long as he gets the desired darkened background.

Note that in Post #16, there is (another) specific warning to Bruce NOT to use HSS.

In any case, it seems quite obvious that Post #22, which was provided as a guideline for the OP’s experiment, is specifically NOT about using HSS. I think that it is reasonable to conclude that any responses to Post#22, would have assumed that also.

Although it was clear to me that Post #22 (and #27) were show how best to get the results that the OP wanted and were certainly NOT in any way about using HSS, if that was not clear to all, then I am sorry for that lack of clarity.

WW

[William W]

I guess the problem with this thread is that two people could be and probably are mis-assuming what Bruce intends to do in the future and have assumed different targets.

If there is a problem with this thread, I don't think that problem is any lack of clarity about Bruce's stated intentions.

It occurs to me that it is quite clear what Bruce intends to do in the future - he intends to achieve his goal of darkening the background.

It also occurs to me that Bruce stated his 'target' quite clearly and was to use the easiest and most efficient method to achieve his goal of 'darkening the background'.

Reference Post #14:

. . . it does not matter to me what shutter speed I use as long as I can obtain the desired effect; i.e. darkening the background.

If 1/60 will get me there or 1/8000 it does not matter. HSS is an option that I have; however if I do not need it to hopefully get my effect so be it

Bruce

WW

[William W]

. . . the original question asked was about the effect of adjusting shutter speed using high speed sync at which point increasing the shutter speed reduces the exposure from both the ambient and flash illumination.
So the basic answer to the original question is NO.
All the high speed flash sync is doing is enabling the use of a flash in situations where the ambient light is such that at the selected ISO and aperture the shutter speed for correct exposure will be faster then the highest FP sync of the camera. In this mode the shutter speed will be effecting the exposure from the flash and ambient light in unison.

And –

I agree, one simple and generalized answer to Bruce's Opening Post is to state that Shutter Speed affects both the Ambient Exposure and the Flash Exposure when HSS is activated. . . .

Perhaps more importantly in the context of the OUTCOME that Bruce detailed in his Opening Post, (i.e. he wants to get a dark background indoors using Shutter Speed changes), I think it is it is good to mention, again, that if Bruce activates HSS, it will certainly NOT be a very easy method for him to get the results that he wants. (Though, for the archival record of the thread, it is relevant to mention that it possible to achieve, to some extent, in some shooting scenarios.)

L.Paul et al,

As an explanation an example test and a sample use of why my response was carefully written:

1. Explanation

We all should know that any Flash has an EFFECTIVE RANGE. Beyond that range any area of the image (the Background) will NOT have any Flash Exposure at all. This applies whether we are using HSS or not. It is simple maths - the flash's light 'falls off over distance'

The pictures from cameras set on full auto at a night-time football game which are used to take pictures of the playing field from the stands are indicative of the flash simply making zero affect on the exposure of the players.

When the Camera and the Flash are NOT in HSS, then any Shutter Speed change directly affects the AMBIENT Exposure.

However, it is erroneous to use the functionality of HSS as a premise to make the conclusion or to imply that when the Camera and Flash ARE in HSS - any change in Shutter Speed will NEVER affect the EXPOSURE of the Background (the resultant darkness or lightness of the background).

In a shooting scenario when:
1. the camera and Flash are HSS
2. where the BACKGROUND is beyond the Maximum Flash Working Distance
3. where the BACKGROUND AMBIENT ILLUMINATION is (bright) enough to be recorded on the image

THEN – any change of the Shutter Speed, WILL have an affect the Exposure of the Background (the lightness or darkness of the background)

***

Working Exercise

Important to note so that there is absolute clarity of purpose for this illustration:

> this exercise is to show results of a Camera and Flash set to HSS when using shutter speeds faster than x-Sync and the main point is to show that a change in Shutter Speed can have an effect on the lightness and darkness of the background of an interior scene which is illuminated only by artificial lights. The scene is below and the images were made at about 0100hrs and with all heavy drapes closed, here:



> the Camera, Lens and Flash rig, aperture, scene are the same as previously, but ISO selected for the exercise is ISO200 and as before all images are JPEG, SOOC

> the X Flash sync of an EOS 20D is 1/250s

*

These are the results:

Working from top left and then to the right and then the next line, the exposures are:

F/4 @ 1/50 @ ISO 200
F/4 @ 1/100 @ ISO200
F/4 @ 1/200 @ ISO 200
F/4 @ 1/400 @ ISO 200 (HSS Activated)
F/4 @ 1/800 @ ISO 200 (HSS Activated)
F/4 @ 1/1600 @ ISO200 (HSS Activated)



As expected, and in concert with the results of first exercise posted here, the first three frames show a darkening of the background as the Shutter Speed increases.

However, the salient point is that the background area at and around the TABLE LAMP continues to become darker as the Shutter Speed is increase through 1/400s; 1/800s and 1/1600s

The reason for this is that the Table Lamp is located in an area of the background which is beyond the Maximum Working Distance of the Flash - BUT - it is illuminated brightly enough by the ambient light to be recorded as a visible portion of the image .


***

Practical use – just one example

Let’s assume we are in a Ballroom or Reception Room and at one end there is an array of huge chandeliers.

At the other end we have a Subject and we want to make a tight Torso Portrait, ALSO with the chandeliers in the background and with those chandeliers being Out of Focus. The OoF will be easy to achieve, because the room is long, but let’s say we also want a Very Shallow DoF to emphasize the Subject’s eyes, so we want to use F/1.4 (or similar).

When we want to make this shot, the room is at is full ambient lighting power. We make a Light Meter Reading on the Subject and note: F/1.4 @ 1/200 @ ISO100 is correct for skin tones. And we want to use Flash to subdue/enhance/fill that Ambient Lighting on the Subject.

Our X-Flash Sync is 1/250s

Looking down the room we foresee a problem. We make Light Meter Reading of the end of the room where all the chandeliers are located and we are worried. To be sure of that meter reading take an out of focus test shot of the chandeliers and we note that if we use F/1.4 @ 1/200 @ ISO100 we will have way WAY too much ‘specular dazzle’ in the background and that will spoil the ambiance of the image that we want to make. So we now need a method to subdue that Background and reduce the Ambient Exposure of it – i.e. a method to make the background darker.

We do not want to close the aperture too much, because we want to maintain a very shallow DoF.

We cannot go to a lower ISO, because we at the floor ISO.

We now have an impatient Subject – we have an idea - but our ND Filter Pack is in the camera bag locked in the Manger’s Office, because, as we are all human and even after only being in the game for long enough to make more than 1500 weddings and events we still make the inevitable ‘assumption’ – we thought that wouldn’t need to use the ND Filters at night, at the reception – so we packed them up after we did the Beach Portraits.

The Subject is getting extremely irritated with this extended 7 second pause in the proceedings.

One method to make that shot is to switch to HSS and use a shutter speed FAST ENOUGH to make the AMBIENT EXPOSURE of the BACKGROUND subdued enough (dark enough) for our goal.

This technique is actually the reverse of ‘dragging the shutter’ and I have seen it used by a few W&P Photographers whom I know. I have used this technique and it works. If you don’t take my word for it, try it and do a test for yourself like the exercise above; whilst only a rudimentary experiment for illustration it does provide an insight as to how it is possible to use the Shutter Speed to control the exposure the Background when the camera is in HSS and how the technique can be an elegant and simple solution to the example problem of that Tight Torso Portrait, especially when working under the pressure of time.

But it seems this technique is not often mentioned on many websites, forums, blogs and things.

Oh well maybe it is a technique that you read about first, here at CiC.

WW
All Images ©AJ Group Pty Ltd Aust 1996~2015, WMW 1965~1996

[pnodrog]

Interesting, you have introduced another variable. Provided the subject remains within the guide range of the flash in HSS at the selected shutter speed it obviously works. I'll concede it may even be useful if you do not want to stop down as you could to achieve a similar result without using HSS. I will need to up my flash power to make it practical for the photography I do.


What distance was the subject away from the camera?

Has been an interesting thread... Thanks Bill

[William W]

Interesting. What distance was the subject away from the camera and did the flash output increase during the test? I assume it did.

Hi L.Paul,

The Subjects were at about the 4~5ft distance. (Experience tells me the Subjects could be up to 8~10ft with one 580, direct flash, in that shooting scenario – maybe I could squeeze 12ft, if I were to choose to correct the exposure/levels in post-production - but I am a life time member of the JPEG SOOC fan-club).

The distance from Subject to Lamp was 10ft (as per the other experiment).

Yes, the "flash output" must have "increased" as the Shutter Speed shortens through HSS Shutter Speeds. That is just maths to allow a consistent (Flash) exposure on the two Subjects, with a shorter shutter speed time, for each exposure.

The consistent Flash Exposure on the two Subjects, is easily noted throughout the set of all six frames.

***

Probably it is worth mentioning a few points in a different form of words:

A Shutter Speed increase during HSS means the Flash Power has to increase. That Flash Power increase does NOT constitute an increase in the Maximum Flash Working Distance. In simple terms the "Flash Power Increase" is "all sucked up getting the same amount of flash out there in a shorter period of time". In fact as the Shutter Speed of HSS is made shorter, the Maximum Flash Working Distance DECREASES.

The overriding premise, whether we are working in HSS or non HSS is - ALL Flash must have a Maximum Flash Working Distance (MFWD) beyond which the Flash is simply NOT effective on the image. (*1).

In any situation where the BACKGROUND of the scene is BEYOND that MFWD and also the BACKGROUND is BRIGHT ENOUGH to be recorded by the film or sensor, then a SHUTTER SPEED variation will effect a change on the exposure of that BACKGROUND.

I think that because HSS is so often used in an attempt to ‘manage very bright light’ and mostly always used outdoors and more often than not with far too few Speedlites to do the job of providing adequate Flash as Fill for the Subject that all these particular issues are very widely discussed.

However, the scenario of DARKENING the background while using the HSS Flash as KEY, is very rarely canvassed, except as I mentioned by (probably) only a few W&P Photographers, and if discussed on the www it probably is amongst themselves on dedicated pro forums, or personally within pro associations and the like. (I know those two points as fact, because I have been involved in such conversations and also Master Classes on Flash use). It's not a typical subject for most Wedding & Portrait Pros anyway, so it is a rare topic of conversation, on any account.

It's probably worthwhile adding I have found only those quite experienced pros, especially those experienced at using flash quickly and under the pressure of time when shooting on location are the folk who are really aware of this oddment Flash Technique and the (rare, but often useful) applications and uses of it.

WW

Footnote *1 – Beyond the MFWD, the flash might still have ‘an effect on the image’ in so far as it might constitute a ‘catch-light’.

[William W]

Addendum:
L.Paul, you edited your post after I had initially responded to it – I’ll make what I consider important additions here -

Interesting, you have introduced another variable. Provided the subject remains within the guide range of the flash in HSS at the selected shutter speed it obviously works.

No. I didn’t ‘introduce’ another variable. The Maximum Flash Working Distance has always been a fact. I mentioned that as fact earlier on in this thread. That’s not nitpicking - I know what you mean, just pointing I didn’t ‘introduce’ MFWD as a new variable – it was always there, whether it is recognized and accounted for in conversations and blogs and commentary and when out shooting, is another matter and that point is important, because there are so many photographers who consistently make inadequate consideration, or no consideration of the MFWD.

*

. . .I'll concede it may even be useful if you do not want to stop down as you could to achieve a similar result without using HSS. I will need to up my flash power to make it practical for the photography I do. Has been an interesting thread... Thanks Bill

Yes. One can achieve similar results by NOT using HSS. I think that comment is very important for two reasons:

1. to reinforce (again) that for the GOAL Bruce wants to achieve – then NOT using HSS would be a much easier option for him.

2. the word ‘similar’ is important – one can’t get the SAME result. I have found the usefulness in the technique is mainly for very shallow DoF work.


You are most welcome and thank you for the kind comment.

WW

[pnodrog]

Thanks Bill - you were too quick in starting your answer. As I slowly comprehended your amazing experiment I edited my above reply while you were busy typing..

We have done it again. No you did not introduce another variable - it was just one I was overlooking which of course you can only do once the guide number is maxed out.

[William W]

. . . I . . . comprehended . . .

Good. I am very happy. Thanks for confirming that you - 'get it'.

[Manfred M]

Bill - your post #34 sums it all quite nicely and elegantly. To paraphrase what you have written

1. The key contributor to light drop-off from a speedlight is the inverse square law. The farther you are from the flash source, the darker things will get; and that is related to the square of the distance.

2. Any other continuous light sources can also contribute light to the scene, but as they tend to be relatively weak when compared to the amount of light output by the speedlight. While ISO and aperture will still impact how much light is contributed by the ambient light sources, the shutter speed will have the largest impact.

In fact you can see the effect of their contribution by taking a shot of the scene without any flash, using the same aperture and shutter speed that you are and any impact that you see will also be present in the flash image.

3. Once you get into HSS, your image is effectively being illuminated by two continuous light sources; the pulsed light from the flash and the ambient light. Here the impact on the image will be 100% controlled by the classical combination of ISO, shutter speed and aperture. In most instances the contribution of the ambient light will be negligible because of the difference in intensity of the two light sources. The inverse square law still holds for the light output from the flash.