Tagged: High

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.

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).

23rd July 2015 – Road Trip to Weston-Super-Mare

Off to Weston we went, aka “Super-Mud”, last meeting and though the skies were lowering the turnout was pretty good and a good time was had by everyone I talked to. What more can you ask for? Well it was Weston Bike Night, organised by the Royal British Legion Riders Branch, and runs every Thursday from May to September. So I hopped on my motorbike and made my quid (£1) donation to the RBL to park on the Marine Parade Lawn and wandered round with my camera, before meeting up with the rest of the club on the beach by the Grand Pier. They had, it turned out, been taking pictures of a convict making his way up the beach, with the express purpose of compositing them into a single photo in post production (Photoshop, Gimp). If you look back through this year’s competition galleries you will get the idea of who and what sort of thing. The sun also made a show right at the end of the day and we were presented with a salmon pink sunset against the grey of the clouds as a finale. Not too shabby.

 

It is often said, not least by me, that in photography, painting with light, the light is everything. So far so obvious. What we are really saying is that the contrast in any given light situation is everything, as the same subject in different lighting gets a different reaction from its viewer. We are not just talking of low light here, where we have options within the exposure triangle, and in the way the camera works in other ways, but, when the weather is as it was on Weston’s beach and the contrast is low, the temptation is to save it for another day, but we can be missing opportunities. Contrast is what determines how “flat” the light in your image looks. Possibly, most logically, we can see this in monochrome images, but it most definitely applies to colour ones too.

 

Essentially, contrast comes in two flavours. Thinking of the black and white image and we can imagine the more obvious of these expressed as a tonal range, which we have touched on before. The tonal range is that between (theoretical) absolute black to (theoretical) absolute white which we would affect in post production editing programmes through levels and curves. The second flavour is colour contrast which is about the predominance of a colour in relation to the colours around it.

 

When we are producing black and white photographs we are really talking producing images constructed of the shades of grey (no tittering at the back). Soft images record little range in those shades, it is all middle and very little of the absolute ends, whereas hard looks stark because we have a band of hard blacks and a band of hard whites and very little in the middle. This is not the same as low key (mostly darker shades of grey surrounded by blacks) and high key images (mostly lighter shades of grey surrounded by whites). The emotional tone that low key images give out tends towards the sombre whereas high keys have a lighter mood, but tonal contrast isn’t just limited to black and white.

 

Colour, as we have explored before, tends to overwhelm tone when provoking emotion in a viewer, but good tone is a major element in the construction of a colour image too. Because there is more variation in colour, more information to play with, then the possible outcomes are multiplied accordingly. Broadly the more saturated a colour is in relation to the others in the image and relative to its position on the colour wheel. The degree of saturation is also important to colour contrast and that can be affected by exposure (try bracketing a couple of shots by two thirds of a shot and look at them in comparison, warmth, feel/mood can be subtly or not so subtly effected.

 

Meanwhile, back on the beach at Super-Mud, we are faced with some impressive cloudscapes that are throttling the contrast out of our seascapes, aided and abetted by a distant haze shrouding the South Wales coast. Looking on the (not too) bright side we are not trying to photograph either a black cat in a coal hole or a polar bear in the Arctic). Those both represent zero contrast situations. Give up go home, assuming you survive contact with said cat and/or polar bear. As we are in neither we can do something about our rather dull scene (other than retreat to the pub). All the rules of composition still apply but we are not bereft of options. The exposure triangle was mentioned above and in pushing two of the elements in that, aperture and shutter speed, we could just make a keeper.

 

Exposure Value Compensation it’s called and it’s that button that allows you to adjust the average that your meter is measuring up or down, usually by up to two or three stops, depending upon what camera you are using. It does not matter whether you are in Shutter or Aperture Priority or shooting in manual (though this is a bit of overkill bearing in mind you already have control of aperture, shutter and ISO in manual mode, but it is possible to employ as another way of under or over exposing from the average). First meter as normal then apply +0.3 ev on the scale. Try again up to a stop, or in the extreme, up to 2 stops or more, basically adding dark. In manual you will possibly be moving in half stop intervals depending on the age of the lens, but most modern ones seem to move in thirds. The same basics apply. Shoot in RAW for the best post production options. What you will do here is affect the colour contrast. Yes the whole image will look progressively darker, but that is not necessarily a bad thing. On the Mini group trip to Weston, where there was a vivid orange sunset, this actually strengthened the composition by allowing the sky and certain reflections to be the focal points against an increasing rich, dark background. Essentially for this technique you are looking to set the narrowest practicable aperture matched with the highest shutter speed you can get a workable image in the light conditions.

 

Try it next week when we visit Portishead Marina. Dock Gates, 7 pm. See you there.

4th June 2015 – On High Dynamic Range Imaging and Marmite questions.

HDR Imaging. What does it mean to you? Horrible Disastrous Rubbish? Highly Desirable Representation? Something in between? Our much welcome and returning speaker, David Southwell ARPS would admit that there is a lot of the former around but if done properly, High Dynamic Range images are an important tool in the photographers tool box. Most of his ARPS panel consisted of them taken in the demanding situation of the interior of Bristol Cathedral. Thoughts were certainly provoked and the discussion afterwards was more animated than usual which would suggest that this is a bit of a Marmite question, “Love, it hate it, you can’t ignore it” as per the advertising slogan. We will return to this later, for Marmite questions have a hidden truth within them.

David did an excellent job of explaining the technical origins of HDR, essentially boosting the fixed capabilities of digital images to catch a range of 6 – 6.5 EV at best (depends on the sensor construction and other factors), or about one half that of the human eye (10-14). Using software and exposures of the same scene metered between exposure for shadow detail to exposure for highlight detail and the range in between (see here for a much more detailed explanation and on how to go about creating a more natural version of the effect) a single image is produced capturing the entire range of luminosity values in the scene. There is a more technical and vastly more expensive way to create HDR using oversampled binary image sensors. Here is what Wikipedia has to say about that and for the rest of us, rest assured they will be coming to high end mobile phones in the near future.

Some DSLR’s, CSC’s, Mobile Phones have an HDR facility built in, but this will almost certainly work with JPEG’s which have a more limited dynamic range than versions of RAW or Tiff. Handled carefully they can be effective, but as always there is the question of how much control is needed, required or is desired by the photographer. The camera processor and choice of jpeg format mean that certain assumptions have been made at the coding stage you do not have an input to. David left us in no doubt that, whereas process can be automated, shoot in RAW (preferably 16 bit, but 8 bit has got him some spectacular results). Your standard 8 bit image (as used in JEPGs and a lot of cameras shooting RAW) gives you 16.8 million colours (more than you can see) and 16 bit 281 trillion (far, far, far more than you can see). 16 bit gives you far more subtlety to play with, whereas 8 bit tends towards grouping colours into bands rather than representing them as subtle variations of colours. In a not particularly accurate but certainly useful way of looking at it we can say the difference is in the ability to reproduce shades, though the human optical processing system does vary from individual to individual. David asserts that 16 bit is the future and for those interested in HDR and, eventually, all photography, so now is a good time to start working in it as far as you can.

But why bother if all we want is the picture that represents a decent looking image of the widest possible range? Well now this is the tricky bit and where its detractors get dismissive of the technique. Before we touch on that, and we can only really touch on it here for reasons of time, space and the need to preserve a semblance of sanity, we need to deal with that problematic idea that you can only make art through fine motor skills. We have treated with this before (27/11/14) so I am not going to go into it again, but part of the attraction of HDR is to make the photograph look more like a painting. OK this is a gross simplification, a minority point in a minority interest, but that does not undermine its validity. Photography’s inferiority complex has existed since print 1 frame 1 in the history of photography. Both are trying to make that emotional connection with the viewer. If that is absent it doesn’t matter how good the draughtsmanship, the image does not work.

David made the point that it is, despite his determined advocacy of the technique, only ONE tool in the box, a very important point. We all have our favourite tools. He gave an estimate of about 3% of his own photography – and this coming from a man who needs 16 TB storage space in his computer system and a high end spec to match in terms of graphics and processors, memory and monitors. To give you an idea, that’s about 640,000 25mb raw images, if my maths is right, so 20,000 ish frames to make up his HDR section when full – with David spending up to 8 hours getting it right on each one! Slightly more involved than Justin Quinnell’s equipment needs, for sure, but they are two ways of making an artefact, two different ways of making a connection. The other 97% isn’t and that is the point. There is no technique that suits all horses on all courses but the more techniques a photographer can master the more complete that photographer will be. Not in pseudo competition with fine art, but in terms of their own personal development and capabilities. HDR has a role to play in getting emotion into an image, certainly it gets a reaction like no other photographic technique I have come across. That’s the art of photography.

OK let’s not tot up the cost of the sort of system David is talking about, he is a very experienced photographer with deep roots in computing. Looked at that from that perspective it just puts the technique out of the range of most of our pockets in the club. HDR can be done on a laptop using programmes that aren’t Photoshop. David reckons that layers and blending, cloning and careful metering are the basics and they can be practiced in any number of ways. Indeed Photoshop isn’t fully 16 bit yet and the vast majority of monitors out there cannot handle 16 bit data and the ones that do will cost you about the equivalent of the average UK wage. Start in 8 bit and make your way up. Practice, practice, practice the basics. Be critical, seek criticism, put the feedback into your practice. The same points were made by the last speaker.

So let’s come back to the Marmite question again. “Love it, hate it, you can’t ignore it”. That is simply not true. Looked at logically the vast majority of the British public remain in denial that Marmite is a big issue facing the United Kingdom. It’s a clever ruse to sell a strong tasting edible (or inedible depending on your view) spread. If a Marmite insurrection has sprung up then it has passed me by. HDR certainly provokes strong opinions, but in ten years time it may be a capability so ubiquitous in photographic equipment that we give it no thought, in exactly the same way as most people do with most Marmite questions. Depth of field may be going the same way, where the out of focus becomes a filter you apply. The technology has been around for a while, only now it’s electronic. Those that do tend to feel strongly about this sort of thing, feel very strongly indeed, how do you like Marmite?

N E X T  M E E T I N G

Your Picture Your Way – Architecture & Artistry. Bring an image or two on these themes and give us some insights on the who the what, the why, the where, the when and the how!

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

Monday June 15th – peaking between 00:30 and 02:00 The Milky Way.