Tagged: ISO

11th October 2018 – Arthur Kingdon

Arthur Kingdon was our guest speaker and a very well received evening of his (mainly) underwater pictures. Our own Julie Kaye introduced us to this genre last year. Arthur took us around some of the worlds hotspots for underwater photography and took us back a few years too.

The equipment needs to keep a diver live aside, the hostile environment, and days when a diver cannot see their hand in front of their face, aside, pretty much most sorts of cameras can be used given a functioning housing. This is an equipment heavy branch of photography.

But all that equipment does, plus a heap of research and local knowledge, is get us to the photo opportunity. Then the photography begins. Less light to no light depending on depth, colour shifts also dependent on depth and things with big teeth and a bad attitude looming in the dark.

So among the other environmental factors and the need to master shooting close up using wide angle lenses (fish eye lenses are not uncommon but that is not where they got there tag from), there is also a need to shoot at high ISO’s. And high ISO’s mean noise in the image. So, something common to us all.

Our personal attitude to noise is the key to its perception and thereafter our attitude to an image that contains it. Noise in digital photography is caused by the action of electricity passing threw circuitry where it encounters impurities and as a result generates signals that are not part of the designed outcomes. It is just part of the physics of electrical circuits.

When we increase the ISO we boost the signal. When we boost the signal we boost the noise in that signal. At low ISO’s, that is around the base ISO that the sensor was designed for, usually 100, there is so little noise that we cannot or do not perceive it. Double the ISO to 200 and we double the amount of noise in the image. This maybe equally undetectable but eventually it does become obvious.

There are two sorts of noise we can detect in our images. Luminance, which manifest as little points of light and which we are likely to be far more tolerant of because their visual impact is less, and chromatic or colour noise, which can be hideous over fairly limited levels.

Luminance noise, as the name suggests, comes about under restricted light conditions. It can be caused by bumping up the signal via the ISO or through long exposures. Its source is the sensor heating up as it does its complex job very rapidly using very small channels which create resistance and therefore heat. It produces “Hot pixels”, little squares of white, which are usually quite easily dealt with in post.

Chromatic noise manifests itself as tiny worms of colour, especially in very dark or very light areas in an image. It comes across as tonal aberrations in an image. It can be lessened in post production through noise reduction software, but it comes at the price of a certain smudging of the image.

Whereas it is true that the newest sensors are a lot, lot better at handling noise than they were even five years ago it is still a by-product of boosting the signal and causing heating of the circuitry. It is also true that the situation of the photograph is also important to our perception of noise in an image from a sensor of pretty much any size or age.

Getting the focus spot on is probably the greatest distractor from noise that there is, especially when we fill the frame with it. It is also the easiest of the solutions to our perception of noise in any given image to enact. It doesn’t alter the amount of noise in a frame but it does fool our senses about the amount of it.

A correctly exposed image will draw less of our attention to high ISO image noise than an underexposed one – though there is lesser noise obvious in an overexposed exposed one.

So a frame filling, sharply focused, correctly exposed image will go a long way to positively influencing our perception of any photograph, a high grain one just as much lower, though, again, none actually reduce the physical amount of noise but does diminish our perception of it.

JPEG is also, because of the nature of its algorithms, not a good option for shooting in, especially when you further process it. Shooting in RAW is a better option if any post processing is going to be involved. The reason being JPEG applies noise reduction, giving that loss of fine detail we alluded to above, RAW comes with everything left in. That means we can apply noise reduction manually as we see fit. With JPEG we have to take what we are given.

 

101 Corner

Light is everything in photography, but to make a photograph we have to do something with it. Basically we have a frame, what the viewfinder shows us, and we move around or move what is in the frame around to make an image that shows us something interesting.

Arranging things in the frame, however we do it, is called composition. Composition is the second most important thing in photography after light. Every photograph ever taken, or ever will be taken, combine these two things. Consciously using these two things is the absolute basis of making better pictures and they have evolved over centuries.

Although they are usually referred to as “The Rules of Composition” that is not helpful, as rules imply something that is absolute. They are better thought of as the Tools of Composition. We select the appropriate tools to make a photograph, just as we would select a hammer not a screwdriver to drive a nail into a plank of wood.

There are many such tools, some get used more often than others, some in combination. We will revisit this several times, but at the moment get your camera out for 20 minutes every day over the next week and use these three tools: “Thirds”, “Frame within a frame” and “Leading lines” to make half a dozen images a day. It can be in doors or out, with your phone or another sort of camera, the important thing is to go looking for these opportunities, or making them.

8th February 2018 – The Rest of the Way Around the Dial

POSTER

We did Programme as a camera setting back last November, when an alarming number of members were convinced that Elephants were a European phenomena (you had to be there), possibly confusing them (the pachiderms) with Mammoths, possibly from remembering seeing them at the zoo. This meeting it was the turn of the rest of the dial and no such confusion reigned thanks to the scholarly efforts of Chris Harvey, Gerry Painter, Steve Hallam, Eddie House and Simon Caplan. Between them they had manipulation of the exposure triangle well and truly nailed.

 

And if we nail the exposure triangle we have the control of light within our grasp. The other thing we need to have control of is what is acceptably sharp in the picture, a function of lens aperture and shutter speed moderated by the selected ISO setting. With these two things nailed in under ten minutes we are a photographer! Our position in the Point and Shoot Pantheon is but a matter of time!

 

Ah but …. these are the mechanical issues of image capture. Often photographers are as interested in the settings a frame was taken at as the content and whereas they are the key mechanical elements in capturing the image we are viewing they are actually a long, long way down the list of priorities in making a good, bad or outstanding one.

 

Unless our job is making, marketing and or selling cameras for a living.

 

The reasons are thus: to plagiarise  that image you have to be in the same place, at the same angle, in the same light, focused in the same manner, with the same connection to the same elements within the frame, and using the same size sensor. Even then all you have done is copy. The only thing worth copying is the look and that can be as much about post processing as image capture these days. The valid reason for copying a look is to learn about photography by applying it to other opportunities. The camera settings represent one choice from a multiplicity of options to arrive at the same amount of light captured.

 

Let’s put it this way: ISO 100, F8, at 1/125th second gathers as much light as ISO 400, F11, at 1/250th of a second, gathers as much light as ISO 1600, F4, at 1/8000th of a second gathers as much light as ISO 200, F32 at 1/15th second. What alters is the depth of field and the relative degree of that in these examples would depend on sensor/film size. This other variable is why we refer to crop factors compared to the old film size “full frame” 35mm standard (so that those of us set in our ways can get a handle on the perspective generated by a given focal length) and perspective is relative, he wrote with entirely deliberate ambiguity.

 

As we have been plugging the last few weeks rather heavily – and in every blog published for the club, regardless of author –  the issue of absolute prime importance is composition. Yes we have to get the mechanicals “right” for the image we have visualised but that will not arrest the attention of our viewer nearly as much as the arrangement of the elements in the frame. The legendary crime/street photographer Weegee, coined the phrase “F8 and be there” when asked what was the secret to success in his photography. Weege used a Speed Graphic 4 x 5 inch camera and a flash bulb for illumination. The point is, know our equipment and how it gets us the results we visualised. To be fare some people ascribe the quote to Robert Kappa but the point remains the same. Being there means we get the chance to get the picture the f stop is only of relevance If you have the camera with you.

 

Now, we can argue what being there actually implies. and the list would probably be quite lengthy. Most photography to do lists seem to end up that way. Some people even write books about it. Reading photography books is a very good idea, but putting the ideas we draw from them to use is even more productive. Knowing what camera settings other people use can be informative, knowing the performance limitations of our own camera gives us the confidence to experiment. In fact, it could be argued, there are two sorts of photographers who are happy about using Auto/Programme settings. Those who are just starting out and those who are confident enough in their use of the camera to know what it is going to do and when and under what conditions we might have to over ride or compensate. And that leaves us to concentrate on visualisation and composition, which is where the art is coming from.

 

Most photographers, however, set their cameras to  aperture priority and leave them there to control the depth of field. Which is fine. So is shutter priority to control blur. So is manual to control everything, though as a permanent setting does rather slow things down – which can be the point. Auto/Programme is fine. Find one that works for you and use the others to play to their strengths.

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.

13th October 2016 – Keeping it Fun.

Last evening the event was about making photography fun. Thank you to our speaker Margaret Collis. Fun, who could be against that? Well debates on Puritan Philosophy and outlook aside, fun is, generally, in the words of Sellar and Yateman “A good thing” (1066 and All That: A Memorable History of England, comprising all the parts you can remember, including 103 Good Things, 5 Bad Kings and 2 Genuine Dates). Fun with a camera, well what else?

 

Sometimes, some people make me wonder if the fascination with the craft squeezes the fun element out of it. Margaret pointed out that some people do seem to let competitions dictate their style and habits, which is a shame because that is also limiting of the ability to develop and learn in new directions. For the amateur fun forms a big part, there are plenty of other, less expensive hobbies out there after all. But even the best hobbies have their ups and downs, few though have the capacity for variation that photography offers. So, this week the blog is going to be dedicated to making pictures work. Basically we are limited by our own imagination, one of those useless truisms because if we can’t imagine it in the first place we are unlikely to do it ….

 

So let’s assume we are feeling lazy or for some other, less fortunate reason, we are housebound, where to start? There are plenty of things around the house. A favourite is to use toys or miniature figures to play with scale around common household goods, even foods. Then there are water droplets, frozen flowers, oil on and in water, the list goes on. You don’t need to sail the world to get your photographs, though that does sound like a great idea. Peering over the duvet or over the crater of a volcano the successful picture has variations around a common technical theme, the exposure triangle, but however well the technicalities are executed, all successful pictures prompt an emotional response.  Avoid the technically proficient, artistically deficient. The key to that emotional response is to make a story out of the elements: a simple, bold, cleanly framed, single element which in the balance of everything in it, we call a narrative.

 

Narrative, is about events linked by common elements, a thread, a story. We are familiar with the idea of spoken or written narrative, of those told in films and on TV. Making the one frame narrative is actually more familiar to ourselves than we may think. In thinking it we can think it too difficult, but actually it is quite natural to us. We contrive these all the time because, it seems we are hard wired to make stories of things in order to make sense of them. We become photographers when we stop taking image of things and start making images about things.

 

There are two situations this covers, the individual photograph always and photographs in series, from a collage (which can be very difficult to get right) to a sequence around a common theme, which we will label a project. I stress the point about the individual photograph because even if it is being part of a wider story (the Kingswood Salver is an excellent case in point), it has to stand in relation to the others on its own technical and aesthetic merits. The technical we have talked about and talk about all the time, not least because it is generally easy to agree about. The aesthetic, what we consider beauty in relation to a person or object, is both what we are talking about and a subject all of its own. A philosophical one, a scientific one, a personal one, too big for this little blog, beauty is a context of a combination of qualities, including shape, colour, or form, that pleases the imaginative senses of an individual, especially the sight. Look at these photographs culled from Friday’s Guardian (14 October 2016) newspaper website, pick your favourite and decide what you like about its shapes, colours and forms.

 

So can we use a bit of logic from what we have said about the connectivity at the centre of our photographic narrative? Well a couple of points I think. Firstly it is made, on purpose by framing and lighting and positioning. It is a product of selection. It is made by context. Secondly, and derived from this, it is deliberate.

 

Now it is beginning to sound very complex and a little off-putting. It is actually a question of looking, actively looking, pictorially, at what is around you. Now we make images for more than one reason. It can be a quick note, a documentary record, a statement, a creative impulse, a memory, and so on and so forth. Our guides to looking are the rules of composition, they help us find those connections that we alluded to above. This is as much about learning to see in the picture format as anything else. That is the key to starting, being deliberate, we referred to this last week and before when we talked about opportunities falling to the prepared. Serendipity. That can be aided by putting in another step before we press the shutter and that is to ask ourselves why this picture appeals.

 

Essentially, then we are going to end up with a mixture of pictures (point, click and chimp) and images (see, compose and capture) and that is OK. In fact we can see the differences between them and that can help with our own development. But it should not be a trial, it is about moving and direction and seeing and taking those pictures for the same reasons as always. Because it is fun.

29th October 2015 – Light Trails & Light Painting

Apologies for the non showing of the last round of the ROC but I am having technical difficulties which are proving rather entrenched. There are also lasting problems with posting to the club’s Facebook Page via the blog. Ah well, such is life. Last meeting was all about light painting and our thanks go to Myk Garton and Tony Cullen [EDIT not Cooney as originally published] for their efforts and Megan Gearing for being the model once again. Definitely a fun night.

 

Essentially light painting takes advantage of the camera’s ability to take long exposures, it’s relatively limited dynamic range, a dark background and some bright lights either as illumination on a subject or as a subject themselves. It is not an expensive thing to set up and you can get some striking results relatively easily. Equipment is a tripod or place to secure your camera preferably capable of being set to fully manual (Bulb) and, optionally, a remote shutter release, a light source and some darkness. You have a variety of options what you do with the light, depending upon what the source is, from outlining everyday objects with light using a single LED all the way up to multiple exposure big item, multiple flash set ups, cityscapes and landscapes. It is one of those things that really does apply to pretty much any subject.

 

Light Painting is all about the what copious amounts of dark do to light, colour and contrast when exposed on a digital processor or film. Given the amount of trial and error it really does play to the cost advantages of digital and even then there are time savings to be had through simple things like turning off your camera’s long exposure noise reduction until the final shot, (which will halve the exposure processing time) or working out exposure with the 6 stop rule. This is based on a fairly simple piece of mathematics and lies within the exposure triangle. If you set your camera’s ISO to 6400 whilst you get the shot composed and exposure sorted, then, using the metering in seconds recorded in the test shots, reset to ISO 100 and expose in minutes, e.g. a 10 second ISO 6400 shot is a 10 minutes at ISO 100, a 4 second exposure at 6400 is a 4 minute exposure at 100 ISO etc. ISO 100 is six stops slower than ISO 6400, hence the name, and it works for the identical aperture setting.

 

I would turn the long exposure noise control back on when all the groundwork has been done (and leave it on as default) because it works to a quite significant advantage in the quality of the final image. That said different sensors have different sensitivities and you may well get 5 or 10 second exposures without significant noise intrusion, and that is best at low ISO’s, though I don’t know of any digital sensors to match The Kono! Donau’s film speed of ISO 6 (marketed as ideal for light painters) from Lomo (though at £27 for three rolls I am in no hurry to find out). It’s a relatively simple thing to check out where your camera starts to produce intrusive noise using test exposures at minimum ISO and worth knowing for your camera. I have seen the figure of a 30db Signal to Noise Ratio as being “acceptable” to “professionals” – frankly I have no idea, though DXO measure these sort of things. What is acceptable is subjective and individual. Go and find out for your camera.

 

Of course photography is Greek for painting with light, but, as defined above light painting makes more of the dark. Light painting scenes have, by design, higher contrast than will be found in most photographs and will also, most likely, require some post production to fix light leaks or darken weakly lit areas. The fact that we are dealing with opposite ends of the histogram actually helps as getting rid of distracting background detail can often be achieved with a simple adjustment of the contrast slider. Yes that is a broad generalisation because every frame is different, but with the single frame light painting the reduced colour palette and high contrast actually don’t often require much fiddling around.

 

Not that some people are content to leave it at that. The techniques can usefully be extended from drawing with a light against a very dark background, through illuminating an object or objects via a single light source, to full blown composites of hundreds of frames of sometimes very large objects. All can come under the light painting banner, and can, I suspect be labelled on a scale from interesting to obsessive, depending on where you stand (and what equipment you have access to), but there is another relatively cheap and easy-with-the-right-techniques that you can access. Light trails. In a lot of ways we have already talked about this earlier in this post, when we talked about single lights, but you have many options in making those. And don’t forget star trails, vehicle lights, trains, boats and planes – it doesn’t have to be you in charge of the lights, though that helps in organising the outcomes. Light painting is a fine way of capturing some vibrant images, give it a try.

 

 

N e x t  M e e t i n g

Returning our visit earlier in the season we welcome Hanham Photographic Society.

13th & 20th August 2015. On Poor Light and ISO

Two away days to cover as last weeks scheduled blog got displaced. Hopefully back on track now. An unexpected opportunity to tour a Tannery courtesy of member Nick Hale replaced our scheduled Millennium Square trip the week before last and a trip to Blaise Hamlet last week both threw up some tricky light conditions, namely the lack of it and flat light with low contrast. The Thomas Ware & Sons Tannery was formed 175 years ago. The process and buildings are fantastic material and I look forward to seeing members images after the summer’s road trips. Thanks Nick, that was a fascinating evening and all the members were suitably impressed, I thought. Blaise Hamlet was built to house the workers who serviced the John Nash designed main house of the Blaise Castle Estate when they retired. John Harford bought the estate land in 1795 for £13,000 (a bargain £1.2m in today’s coin, using the Retail Price Index, but the average wage in 1795 was circa £20 per anum, in 2014 £25,000 – Source EH.Net ) The castle itself was a folly built as part of the evolving grand design of the estate.

 

The sun was hidden by a uniform blanket of rain-threatening cloud for both events, which was a pity, as the plentiful sky lights and doorways held the promise of some photogenic lighting in the tannery and the warm coloured stone of the main house and the intertwining of nature and construction to be found at the Blaise cottages (cue debate on the use of buildings to reinforce social order) offer a lot of subtleties that contrasting light brings to the fore. So, if photography is about light, and it is all about light physically, what do we do in the absence or limitation of it? The obvious answer to this is to provide our own, but this is not always feasible, so this week we are going to look at shooting in low light situations, what can and what cannot be reasonably achieved and the costs of doing so in terms of quality. We shall be looking more closely at ISO, the more mysterious member of the Exposure Triangle.

 

The options on camera are, basically, open the aperture, select a lower shutter speed, or select a higher ISO. The other useful option is to use additional, artificial lighting, either constant light or flash/strobe. A tripod can help with longer exposures. The two other options that spring to mind are focus on details rather than panoramas or switch to black and white, but these are variations, though very useful ones (yes photography is about details and exclusion but we are talking about large buildings here remember and in general at the moment, not in particular). Then there is the pack-up-go-home option and its local variant, pack-up-go-home-come-back-another-day. But where’s the challenge in that and where the learning opportunities? Are you a photographer or a Sherpa?

 

ISO stands for the International Standards Organisation, doesn’t just apply to cameras, it does exactly what it says on the tin, publish standards for a huge variety of items, systems and products. One of them covered film “speed” or the way that film reacted to light, more specifically, the sensitivity of the crystals in the emulsion applied to the transparent film base react to light. The most widely used standard was the American Standards Association (ASA now known as ANSI, the American National Standards Institute) and that was eventually adopted by the ISO (DIN or the Deutsches Institut für Normung e.V. was used by Agfa among others and had a different numbering system) ISO was carried over to digital processors by the manufacturers, the familiar making sense when introducing a new way of doing something.

 

Of the three parts of the exposure triangle ISO is the one that acts directly on the sensor. The other two parts, aperture and shutter speed work by throttling the amount of light before it reaches the sensor. ISO directly plugs into the sensor to alter its sensitivity to the amount of light reaching it with its own particular characteristics. With aperture it is depth of field and with shutter speed it is motion blur. ISO can boost it. It can also cut it to a point. There is a constant where the sensor will provide the best quality image, usually around 100 ISO and a group of ISO numbers where very little difference is made by the sensor manipulating the light received, but gradually, as with faster film emulsions, there comes a point where the image will begin to noticeably deteriorate with the incursion of noise. Noise is a product of the signal moving around the sensor, and is a function of all electrical circuits. How much signal (desired data) there is and how much poor data there is in relation to it. As poor light produces more poor data (noise), and the chip amplifies that data to produce the image, the quality starts to deteriorate as artefacts generated by the process become more apparent. All sensors will have a certain amount of noise present at any ISO, it’s part of the mechanics of the sensor. The amount of noise as a proportion of the overall signal determines the reproductive quality of the image. When the light is good and the ISO is set at or close to the speed of the chip then the signal is strong and the noise is low but gradually this inverts the more boost is applied. When you amplify the signal you amplify the noise in the circuit, when the signal to noise ratio is good this doesn’t matter much, but noise will increase as you boost the signal and it will be an increasing amount of what is going on. Hence, well, noise at high ISO’s.

 

On the part of the photographer getting to know your cameras useable limitations – and it is a judgement thing rather than a given absolute – we have to judge how much noise we are prepared to put up with in an image. There are ways of limiting its effects in post production, also in camera with some models, but the pay-off is a softening of the image. Also do not forget the idea of an optimal viewing distance, as a rule of thumb 1.5 – 2 times the length of the diagonal of the viewing area (works for tv’s too) AND the minimum pixels per inch – calculated by dividing 3438 by the viewing distance). So that is pretty much it, without getting over my head in technical details. ISO and noise.

 

Tonight – Millennium Square. Meet under the big shiny ball at 19:00 hours (7 PM).

29th January 2015 – On Landscapes

Member Adrian Cooke took us through some of his favourite landscape pictures last meeting and his presentation was well received by the members. We are now regularly fielding 40+ at each meeting and that has something, a lot, actually, to do with the programme. In the words of Butler and Yeats, “A good thing”. Active members mean a healthy club.

 

Adrian shoots a lot of landscape photography, he has a lot of it on his door step, nonetheless the fact that he showed us a wide variation of images of the same landscapes just goes to prove that no two images are ever the same, even when the subject is identical (Maybe). Adrian showed some scanned slide film images among the purely digital images and the colours were quite different in comparison. Now there are a whole lot of technical issues in scanning slides to digital, and the image sensor may not have the same dynamic range as the (negative) film, and just how much information you can get on film as opposed to a modern sensor, the way that each respective medium records light, standardisation of results, and a swathe of other pros and cons  constantly rumble around like a number of other technical questions that seem to get in the way of people making pictures. None of those, and all of them, are my point. It is refreshing to sit back and rediscover some of the features that many people now can’t appreciate because they have never been exposed to the processes nor the outcomes. Sometimes I suspect that the memory of those images is superior to their physical reality. One day I will go for a rummage in the attic to find out. These technicalities were hurdles and barriers to entry, the number of photographs taken was exponentially smaller, but the role of mastery has not changed.  Just the size, number and relative cost of the spanners it takes to make even a poor image.

 

Not that Adrian’s images suffered in the quality category, familiarity and technique were in evidence aplenty. Perhaps the most consistent point to come across was the importance of the focal point. There are a number of ways to promote the (usually single) focal point. With landscapes it is generally held that greater depth of field is desirable but, nonetheless the question still remains what is the focal point and where in the frame am I going to put it. Yep we are back to the  thirdsfifthssevenths and  “Golden ratio” , so I will move on.  The f-stop isn’t the only way of highlighting the focal point. Careful use of, or observation of, contrast and shapes will also do it, as, of course making it the largest thing in the picture (OK, obvious, but worth mentioning). It also helps with not providing too many points for the eye to rest on, and thereby confusing things, and that is less likely to happen if there are fewer places to fill them with.

 

The eyes journey around the image is important. The photographer creates that journey and the elements within it make up the story. As was stated at the judging of the last round of the ROC, for a photograph to really make an impact it really should be telling one story and one story only.  As Adrian implied, these images don’t just happen they are created. Another feature of Adrian’s photographs were the role that lines play in the journey we make around each image through the use of horizontal, vertical, diagonal and converging lines in making patterns to give impressions of depth and scale or leading to the focal point.

 

Timing is also important. Adrian related how he tended to shoot towards sunset, though there were a good few early mornings represented in his presentation.  This is the period of the “Golden Hour“, where the light has a different quality to that of the rest of the day and for which The Photographers Ephemaris is a great tool. Almost by implication this brings in the idea of longer exposures, which have effects of their own, pretty much demand the use of a tripod, for lower ISO settings tend to give better results with less noise but increase the problems surrounding camera shake. Almost counter intuitively this allows for the capture in motion, especially of water and clouds. Adrian discussed using ND filters to cut down the light and ND grads to help even out the exposure (back to dynamic range again – the range of lighting that a sensor or film can represent. Of course it helps when you don’t confuse your Infra Red Filter for your big stopper ND filter as I did on Sunday (apologies to Dan Ellis who I leant it to) but then there is something there about labelling things. Or in this case not loosing your filters. Maybe I should take note.  Also Dan discussed the use of a polarising filter (and when to use one) and certainly this can have a quite dramatic effect on skies and cut down on reflections when the light comes in from the side. And of course not just limited to landscape.

Adrian’s presentation provided a thoughtful and thought provoking refresher on landscape photography, and the club thanks him for his time and effort. Next meeting we have a speaker, who will talk about editing and take us through the process using some pictures from the club. Marko Nurminem has worked at the “Very high end” in editing images, including for previous speaker Damien Lovegrove. See the link RCC EVENTS Feb_05_15 Marko Nurminen_No_Images for more information.

 

A N N O U N C E M E N T S

A reminder from Dan Ellis about the Ask The Club session. Get your questions in by 12th February, either via FB or the forms you can get from the table where the register is kept on club nights.