Light Science & Magic

I have had this book for a few months now and have dipped into it now and again. I intend to read it alongside the "Artificial Light" section of the course. It was recommended because it facilitates understanding of light, by explaining physics in ways that are easy to understand. Lighting effects come in and out of fashion, and new equipment is coming out all the time, but the laws of physics don't change. Therefore I figure that by studying this book in depth, I will save money over time on seductive lighting equipment (always looking to save money!).

Unbelievably, I got an A grade in A' level physics less than 20 years ago. I think I must have left my brain on a bench in Amsterdam because it's like starting from scratch.

The book contains experiments & projects, and I will upload some of the results onto this post.

Update 20 June 2010

Well I've ploughed through chapters 1-4 of this book, and it has been a challenging but stimulating learning process. I enjoy science, although I find the application into practical photography quite a big leap. The first 3 chapters are about principles and chapter 4 is the first practical application into surfaces. I thought it would be useful to summarise some of the key learning points gained so far.

There are 3 important principles of light which predict how it will behave:

1. The effective size of the light source is the single most important decision in lighting a photograph
2. Three types of reflection are possible from any surface. They determine why any surface looks the way it does and are diffuse reflection/ direction reflection and glare.
3. Some of those reflections occur only if light strikes the surface from within a limited family of angles.

There are 3 attributes when describing the light - brightness, colour & contrast. Colour is classified by the Kelvin temperature scale (and is what I have been looking at in projects 51 - 53). A high contrast light source is also known as a hard light and occurs when its rays all strike the subject from nearly the same angle. Shadows are sharp & clearly defined. Therefore a low contrast, soft light is when light strikes from many different angles i.e. diffused light. For a single light source, the size of that source is the primary factor influencing its contrast.

Photographic lighting is the interaction between the light itself, the subject & the viewer.

A subject can do 3 things to the light that strikes it:

1. Transmit it (e.g. glass). This can be direct transmission or diffuse transmission of translucent subjects.
   
2. Absorb it (e.g. black velvet). Most subjects only partially absorb & selective absorbtion determines colour.
   
3. Reflect it. This is the most relevant to photographers and can be diffuse reflection, direct reflection or glare (polarised reflection).

Diffuse reflections are the same brightness regardless of the angle from which they are viewed, and examples are white card, light blue tissue paper etc.

• NOT AFFECTED BY ANGLE OF LIGHT
• NOT AFFECTED BY CONTRAST OF LIGHT SOURCE
• ARE AFFECTED BY DISTANCE FROM THE LIGHT (inverse square law - see project 55)

Direct reflections are a mirror image of the light source that produces them.

• THE ANGLE OF INCIDENCE EQUALS THE ANGLE OF REFLECTION
• THE REFLECTION IS AS BRIGHT AS THE LIGHT SOURCE ITSELF, HOWEVER THE SIZE OF THE REFLECTION IS DETERMINED BY THE DISTANCE FROM THE LIGHT

Direct reflections are used to determine the family of angles for a surface, and this determines where we should place our lights. A light placed outside of the family of angles will not produce direct reflection.

Polarised reflections are similar to direct reflection in that the angle of incidence equals the angle of reflection but a polarised reflection is always substantially dimmer than a photograph of the light source itself. Glossy subjects produce a greater amount of polarised reflections, and they are more visible with black or transparent subjects because they produce weaker diffuse reflection so it's easier to see the direct reflections.

Some points as to whether a reflection is polarised or direct reflection;

• If a subject is made of a material that conducts electricity, its reflection is likely to be unpolarised;
• Therefore electrical insulators such as plastic, glass & ceramics are more likely to produce polarised reflection
• If the surface looks like a mirror, it is likely to be simple direct reflection.
• The conclusive test is the appearance of the subject through a polarising filter.

Placing a polarising filter over a light source and turn a direct reflection into a polarised reflection. As the open sky is a polarised light source, this can mean that sunlit metals etc. actually produce polarised reflections.

I found the section on polarised light & reflections the hardest bit of the book to get my head around, but it is pretty key. From now on, I will simply upload any of my results from any experiments that I do as I work my way through the book (e.g. photographing certain surfaces, texture etc.)

Project 61: Making the Best Use of Built-in Flash

The objective of this project was to practice using my flash against a wide variety of subjects, as well as indoors and outdoors. My key learning outcome from this was to work out how to vary the power output of the flash - it was one of those Eureka moments where you wish you had known earlier as it would have saved so many overexposed disasters. I attach here some of my results, as well as some success stories with flash from my archives. One of the many advantages of digital photography is the speeding up of the learning process - metadata allows you to look back at earlier photos and see exactly what you did (flash on/off etc.). My photo of the butterfly was simply taken with pop up flash on the camera - "professional" cameras don't even have pop up flash, and yet there are some occasions when it is handy just to have it there - the butterfly was a classic example. If I'd gone inside to retrieve my flashgun, the butterfly would have gone when I came back or moved into a lesser position. The flash was useful for lighting the butterfly and blowing out the detail on the background (a whitewashed wall).

One other learning tip I've heard, but not yet had a chance to try, is the use of an orange "gel" over the top of the flash when taking photos as sunset. I have used my flashgun in those situations and found that the mismatch between the daylight balance of the flash against the warm evening light looks false. I hope to put that into practice next week if we get some nice sunsets and will upload the results if successful. UPDATE - SUCCESS!! My final picture for assignment 4.


I am fortunate in that I rarely experience "red eye" in my photographs. I am always slightly surprised at how many people don't correct red eye for framed pictures/photobooks when it can even be corrected in default & free software nowadays. Perhaps they are so used to seeing it in snapshots that it doesn't occur to them that there is another way! Perhaps I am becoming a photographic snob - I quite often find myself mentally correcting other people's photographs.

Low ceilings vs high ceilings - why is that high ceilings are so sought after in all those property programmes and in magazines? Yes they might be a period feature but they make rooms so much harder to heat (I still shiver when I think of my cold damp Victorian student bedroom) and give a cold atmosphere rather than a cosy, homely low ceiling (think of a cosy timber beamed cottage). They are so much harder to paint and de-cobweb. But most of all, low ceilings prevent light fall off when used for bouncing flash indoors - allowing shots to be captured indoors where they might otherwise be missed or cursed with harsh direct flash. I'd have low ceilings any day, and would include them in my wish list for a property (if I was thinking of moving house, which I'm not, because I am blessed with aforementioned low ceilings).

The final thing I want to say about flash is that it remains my only photographic "light". After completing the "Artificial light" section of the course, I have been severely tempted to invest in x, y and z lighting equipment. It is frustrating when reading photography lighting books that they always seem to have another bit of photographic lighting equipment in the "menu". Examples include strip lights, massive softboxes, portable softboxes (still very expensive), diffusers with built in handles, plexiglass backgrounds etc. etc. Scott Kelby's book was particularly disappointing as his first volume seemed to say that you could do a lot just using a shower curtain against a window. His next 2 books then seem to have a new bit of equipment on every page. If you want to photograph a pineapple you need this bit of lighting equipment, if you want to photograph a bottle you need this, if you want to photograph a child you need that. Another expert then bangs on about a different bit of equipment for the same thing. It all gets so confusing that I feel like not bothering - apart from the expense I would also need to build an extension to store it all. I have also come to the conclusion that my continuous tungsten light is useless because it's too hot to do anything with. I can't afford a master speedlite for my Canon and can therefore only have 1 off camera flash. So my kit of photographic lighting consists simply of a flashgun, torch & reflector! I guess I need to master those 3 to get the best out of them.

Project 60: Shiny Surfaces

The object of this exercise was to practice photographing a shiny surface. I also read the chapter on photographing metal in "Light Science & Magic" alongside the course notes.

I understand the principle that the environment will be reflected in the surface, and therefore the key to photographing a shiny surface is to alter the environment that is reflected i.e. it is an exercise in reflection management. The most difficult part of this project was not the theory but the practical of getting the environment right - problems I encountered included greaseproof paper that was too narrow for the task, tissue paper that was too floppy, tripod legs getting in the way, trying to focus the lens with the tracing paper attached, trying to stop a shower curtain falling off my head etc. etc. It sounds so easy in the notes, but wasn't that always the case on Blue Peter as well? What also became apparent is that moving the camera was part of reflection management, not to mention composition management, but that wasn't easy once you'd attached a cone of tracing paper.

Anyway, here's 2 examples of how not to photograph a shiny surface (note the reflection of the 3 ceiling lights and my camera in the face of the 2nd watch):



























And here's some results using various backgrounds (light vs dark), set ups etc. My favourite was the shot of my watch (bought for myself exclusively with Tesco tokens) at the end, where the low key lighting works well. I found the live view function of my camera to be extremely useful when arranging the light for this shot, which was provided by a torch. I have found powerful torchlight to be a most useful artificial light, being so flexible and easy to move around, not to mention inexpensive. Used in conjunction with live view, it is an excellent way to learn lighting set ups.

Project 59: Concentrating Light

This is a technique I plan to make more use of, and will perhaps incorporate it in my assignment on artificial light.

As a first go, I used my flashgun and a long rolled up tube of black card to form a very long "snoot". I chose a slightly unimaginative subject of my son tucked up in bed, a sight very special to me but probably not to anyone else. The contrast was a bit strong for this image, but it created something a bit different to a snap of my son asleep. I would like to try this effect in daylight, where the extra focused beam draws attention to something without looking too much like a torch light.

Project 58: Contrast & Shadow Fill

This project was looking at contrast & shadow fill, using indoor lighting to manipulate the end result. This was a project I was keen to try, as I tend to pull the shutters down when photographers talk about using reflectors. I tend to use the "hit & miss" method of lighting, rather than actual planned manipulation. However, as with all the artificial light projects, I am keen to learn, and chose a subject where even a small difference in contrast would be apparent.

I found the difference between all the examples quite striking. The best shadow fill was achieved by the smooth shiny side of the foil, and the most pleasing shadow fill was achieved with the gold reflector as the extra warming of the light worked well with this subject. I realised after completing the project that an extra reflector to bounce some light onto the eye would have made the image much more satisfying.

The bare flash image also highlighted how this subject did not suit such stark contrast. However, a perusal though any photography book will demonstrate how strong contrast often creates the greatest drama. I have already commented in another post on how William Eggleston used strong contrast in a lot of his shots.

I have included a few of my images taken recently which I feel are stronger because of the strong contrast light. This is either through shape enhancement, shadow play or by making portraits more evocative.

Project 57: The Lighting Angle

I used my husband as a subject for this project, as I have been keen to try a bit of formal portraiture using lights, albeit a flashgun rather than glamorous studio lights. I used my Canon Speedlite 430 EX, reflected off a silver umbrella, as this gave the most diffused light in the previous project. However the weakness of the light became apparent as I started to more away from the side. The light was too weak to spill around the side of his face. One I had completed the project, I realised that I should have been adjusting the exposures as I moved the light round, however the results clearly demonstrate the principles & key learning points.

The most obvious result was that backlighting emphasised shape. In this particular image, this added nothing, and looked a bit strange. This would be more relevant for something with a strong shape, and possible slightly transparent as well, such as a glass ornament or bottle (see project 24). The image lit directly above and behind was the more acceptable one with backlighting. I have seen an example of using backlighting with flash to emphasise the shape of a child jumping and I plan to give this a try when I have time and will upload the results. In that particular example, the "action" of the child compensates for the lack of detail in the subject.

The second result was that front lighting (either at level or above) gave the flattest image, with little sense of form. The one lit with the light pointing down was particularly unappealing. However there is an argument that the lack of shadows could be flattering, and this is probably a good light to use for a passport photograph!

Finally, the side lit ones gave the greatest illustration of form and 3 dimensional shape, and I think the one lit from the side pointing down probably has the edge in terms of highlighting form.

I was quite impressed with the effect of lighting directly overhead. It created interesting shadows, which are not really flattering for a human face (nose shadows etc.) but could be capitalised in a subject of a certain shape.

So which is my favourite from the set? Obviously the side lit image (2nd image), partly because of the lighting, and partly because of the expression on my husband's face (watching World Cup highlights while modelling). This emphasises the point again that the subject is generally the most important thing, lighting secondary.