Tagged: ETTR

November 15th 2018 – Shooting with Models

A practical in three parts using local models Ashley Claire, Steph Kiddle and Paul Walker, who were brilliant (as usual) and four lighting stations (the fourth being occupied by a mannequin’s head) run by club members, Richard Clayton, Steve Dyer, Gerry Painter and Myk Garton.

Again, I am glad to report, there was much discussion and sharing of knowledge and practice between members and it just underlines the wide range of experience there is in the club and a shared willingness to develop as photographers together.

Using lights/flash/combination thereof we can, as was amply illustrated, create a wide range of lighting effects. All are about the light, of course and when we say light we also mean shadow. In fact without at least a hint of shadow we aren’t going to have an image. There has to be a minimum of contrast.

There are two sorts of contrast, colour and tonal. Colour contrast (a.k.a. luminance or luminance contrast) is the difference in the colour and brightness of the object and other objects within the same field of view (or frame). Tonal contrast is created when light tones and dark tones lie alongside each other.

This weeks blog is going to concentrate on tonal contrast, easiest when referring to monochrome, more specifically black and white (there are other colour combinations, for example cyanotypes). Luckily there was a station using Film Noir as its inspiration, run by Richard.

Although the noir refers to the darkness at the heart of the story line, hard contrast lighting was, in turn, at the heart of its cinema photography especially in its mood setting scenes.

Although this can be accessed using natural light, by far the best technique is to choose the background first and then place the subject in it. That applies to nearly all photographs, one way or another, but, given the inflexibility of natural daylight at any given time, it is a pretty sound rule of thumb.

And keep it simple.

But we were talking about studio (at least indoor) photography, being by far the easiest for the amateur photographer to control. It is quite straight forward but takes application to master. Like any other skill it needs to be practised.

The nature of our cameras’ sensors is that, at least at the current time, they can “see” a lesser range of dark to light than can our eyes. This means that certain decisions have to be made and introduces us to a rule of thumb known as “Exposing to the right” or ETTR. It applies to monochrome and full colour. It’s also a strategy known as “Protecting the highlights”.

The right referred to is the right hand of an exposure histogram. Most CSC/DSLR cameras produce one of these for each shot. The right hand side plots the brightest part of the picture. If not accounted for – if the end of the graph shows a big spike – then areas of our image will be burnt out – just white with no detail.

Generally we try and avoid this by exposing for these highlights. Shadows also hold a lot of detail and it is easier to get this back into the final image than detail in the highlights. We want to try and avoid a spike (the spike is evidence of something called “Clipping”) to the left too, where everything is too dark to see detail, but, normally, shadows are more forgiving.

The reason that black and white is a good way to do this is that it takes the distractions of colour out of our equation. The results are a little more obvious and black and white has an aesthetic all of its own, particularly boosting the effect of shape and line.

Metering in general tends to be something that first timers, in particular, can find a little difficult. Yes we can buy flash meters, but they are not cheap. They do make things go a little quicker. However, good old fashioned practice will soon determine what is right using test shots.

The guide number for our flash gun is the how far that unit will project light at theoretical f1.0. This will be a GN xx and is usually printed on the unit or it can be found in the handbook. It is calculated thus: Distance x Aperture = Guide Number. So my Amazon Basics flash unit has a GN of 33 (Meters) on full power. So if I want to use an aperture of f8 my optimum distance to set the flash is 4.125 meters (13 feet 6 inches) calculated GN/Aperture=Distance or 33/8=4.125.

In reality I would probably set the unit to ¼ power and put the flash between 3 and 4 foot way. It would be a start because ambient light will play a part and whether the flash gun is the soul light source (rare for me) or balancing out ambient light. Again practice is the key and this is one instance where chimping is a desirable technique. Trial and error is a good teacher.

Thus far thus technical. But, and when shooting models it is a big one, by far the most important thing it is talking to not at or down to our model. If they are experienced they probably know a lot more about this process than we do.

101 Corner

Lighting the Portrait – by Richard Clayton.

How many lights does it take to successfully light a portrait, two, three, five? In reality, it only takes one light to make a successful portrait – and the best way to start, is to learn with one light. Look at the shadows it creates, lighting a portrait is as much about shadows as it is about highlights.

Add a modifier and see how that affects the quality of the light.

So what light should we use? The answer is any light will do, from a desk lamp all the way to an expensive pro level strobe, but don’t forget that abundance of free light that comes through a window.

Whatever light source we use, we can modify it in much the same way.  A soft box for a strobe or some heavy net curtain for a window. Why not a soft box for a window? Well, one of the jobs of a soft box is to make a small light source bigger, with a window, we already have a large light, we just might want to diffuse it a little.

If outside, and wanting to use the free light in the sky, AKA the Sun, our best bet is to find some open shade, this will act like a large soft box in the fact that the light will be softer and less contrasty, we won’t get uneven highlights and shadows on the skin.

There are many options for a single light source that will make a great portrait. Mastering one light, gives us more confidence to add another. Recreate this video, it doesn’t matter what light source, and black and white is as good as colour.

10th November 2016 – Ann Cook and Carnivals

Anne Cook made a welcome return to Reflex with another illuminating talk that was, let’s face it, fun.  We can’t always locate the terms guest speaker and fun in the same sentence and whether we learn anything apart from the hardness of chairs that children are subjected to in modern day education (chairs, damn it, the cold hard floor was what we  got, etc etc) is not necessarily a topic we need to travel to club to speculate on.  The feedback from members was particularly effusive which is always a good sign.

 

Ann showed, amongst many other fine examples some images taken at carnival, which is particularly apposite to this time of year as we are coming to the end of the Somerset season. The last one on the Somerset circuit is at Wells this coming Friday (18th November 19:00 get there early). Having attended the Burnham-On-Sea round this year I can definitely affirm that it is something well worth making the time and effort, if you can get there.

 

So we are going to look at taking photo’s of street processions at night. The most obvious thing is that we are talking of photographing very high contrast scenes, that are moving, admittedly slowly, that  can look distinctly two dimensional as brilliant point of light swim through a sea of black, which generally require high ISO’s to get reasonable shutter speeds and some interesting metering challenges.

 

There will be the large floats, some a part of a two three or four articulated trailers, but there will also be smaller floats, hand carts and individuals decked out in lights, there will be groups and there will be all sorts of other wheeled and ambulatory traffic. Variety is not short at these affairs and the lights are the main attraction.

 

The basic answers to these conundrums is to crop tight, centre weight or spot meter and expose to the right.

 

Cropping tight means we are likely to even out the overall exposure in a reasonable amount of the frames we capture. We will still get areas of high contrast and some of them will still have totally blown out areas of white and areas of inky blackness, but there are a significant number where we can limit the dynamic range some. This can put more emphasis on the mid-tones but whether  that is a good or a bad thing is a matter of taste and of colour.

 

Metering these days is a lot smarter than it was five years ago. Leaving our camera on matrix / evaluative (basically our cameras approximation of the whole frame)  isn’t necessarily a disaster, modern algorithms are pretty good at drawing conclusions that prove to be reasonably “accurate” (they are accurate but that has to be measured against our expectations) but  we are talking an average balanced somewhere between the highest and the lowest value.  Most cameras have the opportunity to switch between two other modes that increasingly ignore larger parts of the scene.

 

This gives us more  information about a smaller part of the scene that we have judged to be more important. How do we know that? Well we’ve pointed our camera at it and taken notice of what effect this has had on our suggested exposure triangle settings. This is either  because the scales in our view finder for shutter/aperture or under or over exposure are indicating a problem or the scene in our EVF is too dark or too light. What the camera has done is taken all the zones programmed into it and set these against where we are focused to give the reading a final weighting. There are other considerations but these change form manufacturer to manufacturer and can incur consideration such as colour, highlights and so on – Nikon use a comparison data base of shots of similar light/shade characteristics. This is common to Evaluative and centre weighted modes.

 

More so than fancy names for “Taking-the-whole-frame-into-consideration”, centre weighted does what it says on the tin. It takes the information in the centre of the frame into account either severely downgrading or completely ignoring the information on the outside of the frame.  It doesn’t, by and large take notice of the focal point, instead just giving it a general, centre balanced reading. By restricting the area taken into consideration, prominence is given to the area more likely to include the crux of the image.  Good when the boarders contain light that is in strong contrast to the main subject and might otherwise have undue influence on the final decision.

 

Spot takes the central are only, around 2% of the frame, around the focus point. Everything else is ignored. Photographing wildlife or Super-moons (or just the plain old ordinary moon which in the carnival context is a lot more apposite) benefit from this. Taking the moon in particular, the difference is a blown out image using the evaluative or centre weighted options because the light reflected from the moon is many, many times stronger than that which might be bouncing around the rest of the atmosphere. The argument in the wildlife example stems from a similar situation, say in the question of a bird in flight where it will be darker than the sky it is set in, or for the variations between fur and the cover it is in or breaking from.  A characters face in comparative dark to the lights of a float with, potentially, tens of light bulbs throwing a shadow, yields a similar situation. Our meter might read the scene but in ways only remotely related to the way we see it.

 

Exposing to the right in itself gives no clear clue as to what exactly it is we are talking about. It relates to the histogram (posh name for graph) that we find somewhere in our camera’s menus and which we can turn on so that it appears in our camera’s live view and or view finder (depending on make and model). Pretty much every camera has the facility including some, but certainly not all, compacts and is also referred to as ETTR, even in polite company. The way the histogram is set out the shadows are on the left and the highlights are to the right. We don’t want spikes at the extremes of the scale because that tells us we are producing images that are heavily under or over exposed. Fine, but only to a degree, if we are shooting high key or low key portraits or similar.

 

What we want, in an ideal world is for there to be a fairly even shaped curve in between the two extremes of the histogram. That gives us an image that is evenly exposed. Of course this depends on the lighting of the scene and in extremes we know that shadows are more recoverable than burnt out highlights (if it is truly burnt out there is no useable information there to recover). Therefore we expose deliberately for the highlights in the picture and recover the shadows in post using whatever editing programme we have access to.

 

Of course it is a matter of personal preference, some people are dead set against the idea of ETTR, personally I find it useful, especially when someone else is controlling the lighting. In the studio we have more options and it entirely depends upon the sort of image we want to craft. The argument evolves around the number of tones on show in the image. If we are shooting a 12 bit RAW image we have 4096 tones available across the range. Each f-stop in our range (remember our meters render an average for the scene) accounts for twice as many tones as the previous one as our f-number increases. The brightest part of the range in the image accounts for half of the available tones, the next stop about half of that again and so on. The whole calculation takes place within the dynamic range of the camera sensor and that again is dependent upon make and model.

 

What happens is that by exposing to the right stretches out the details to the left and the more that happens the less smooth the transition between the dark tones, and we risk compromising the quality of the picture. That is why we need to look at taking pictures of the carnival floats in the context of the other two considerations we talked about above because the more we operate towards the centre of the cameras dynamic abilities the more leeway we have to accommodate the extremes of light and dark.

 

Go and enjoy.

 

N E X T   M E E T I N G

Kev Spiers and Rich Price on their return to Iceland.