Tagged: Sensors

20th September 2018 – Commanding Light and Equipment

Lighting options, from basic budget and food photography after break, special thanks to the ever inventive Ian Coombs for the artistic food plates, and to Myk Garton and Richard Clayton among others for their light tutorials.

The most important thing in photography is light and the best camera for the job is the one you have got on you. Two propositions that in themselves are their own truths. That said the cameras that we have offer us varying degrees of flexibility. Beyond developing us by making us think of the things that we do automatically more deliberately, an effect that quickly wears off, new/new to us equipment is just another way of getting the job done, maybe a little easier.

These days we are as likely, in fact, more than likely, to move from a camera phone to a more traditional form factor – something we think of more as a traditional camera – as a means of getting “better” photographs. Form factor is the physical size and shape of a piece of equipment. These days we think of cameras as being, mostly, hand holdable items. Certainly, when coming from a hand-holdable device like a camera phone, we look to how the camera handles, where the buttons are, weight and heft, balance.

Different formats have different aspect ratios, basically the ratio of the width of the sensor to the height. The 16:9 of our camera phones fits the the aspect ratio of our TV’s. Mirrorless and DSLT APS-C crop sensors are usually 3:2. DSLR’s (and SLR’s) 4:3. That effects how we frame – one isn’t necessarily better than another – because those are the dimensions we are given to work with. Those frames are given and we tend to adapt accordingly. It becomes more evident when we move between formats, such as cropping a 3:2 to a 4:3 competition format, especially for prints.

The sensor size is usually the single biggest factor in overall quality. Not necessarily the number of (fantasies of camera company marketing departments, by and large) but the size and number and layout of the pixels. A phone sensor is approximately 5mm x 3.5mm, a full frame camera 34mm x 24mm. Compacts, Bridge Camera’s, Micro Four Thirds, APS-C come in between. Bigger is generally better.

More complex is the arrangement of knobs, switches and dials, which at best will be software options, more likely not options at all, on a phone. Full manual is a lot easier concept to mount on a larger form factor.

On the flip side pure convenience, connectedness with programmes and channels that enable sharing of pictures, and, not least, portability are on the camera phones side. These days people rarely travel beyond the front door without their phone and therefore a camera. The biggest downside remains those lower quality images, which look fine on a phone screen, probably the most frequently employed method of display.

Although what we see as a “proper” camera these days is subject to change, the fact remains tha the best camera you have is the one you have got, but there is no escaping the fact that cameras still take pictures but photographers make photographs. Make a poor photograph and it will not be improved one iota by how much money was spent and how sophisticated the means of capturing it were. It will remain poor.

101 Corner

Last week we put forward the proposition that light is everything in photography. It is. This, sooner rather than later, leads the photographer to the question of “Settings”. Indeed the more time we spend on the internet the more it would appear that settings are the most important thing in photography. They are not. Light is. This obsession as Mike Browne points out, is nonsense on stilts. Settings do not lead to the picture. The scene, what we are taking the picture of, leads to the settings. The light is what nature or the photographer, makes it (natural/artificial light). Light is everything in photography.

The principles set out using a portrait setup are applicable to everything else. A good way to think about using light is that we are manipulating the direction of light and from that the direction of shadow. The same effects can be replicated using a torch or reading light, LED or other strip light, a flash or a specifically designed lighting rig. A piece of grease proof paper makes a great diffuser. Black card or material makes a good flag. Aluminium foil makes a good reflector. The important thing is to practice. As with last weeks video a simple set up is best. To remove the effect of colour use black and white. Try replicating this short video on your own table top.

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).