Thursday 2 June 2011

Understanding Prints.

Or not as the case maybe. Walking around the V&A with Armano he was very interested in the type of cameras possibly used when the images were taken and how the prints were made. I also have a curiosity about this and also the apertures and shutter speeds used. We both acknowledged whilst this is only part of the photographical story it also helps students understand the effects that can be achieved using these technical aspects.

Armano made some interesting comments about why he thought some were film or large formats and how that could possibly translate into how the images were printed and what effects this would have on the size/quality of the prints. I don't really know much about that, did read some bits when I saw the Shadow Catchers exhibits but I don't think the technical jargon did much apart from go in one eye and out the other.... so thought I'd go off and dig about a bit...a few below thanks to the V&A Exploring Photography: Photographic Processes. There are more but possibly one's I shall never or rarely come across.

Albumen Print

The albumen print was invented in 1850 and was the most common type of print for the next 40 years. It produced a clearer image than its predecessor, the salted paper print. An albumen print was made by coating paper with a layer of egg white and salt to create a smooth surface. The paper was then coated with a layer of silver nitrate. The salt and silver nitrate combined to form light sensitive silver salts. This double coated paper could then be placed in contact with a negative and exposed to the sun to produce a print.

Makes sense egg albumen = albumen print!

Autochrome

Autochromes were the first really practicable colour photographs and were made by a process patented in 1904. An autochrome was a coloured, transparent image on glass, similar to a slide. The colour came from a layer of translucent granules of potato starch, each dyed red, blue or green to create a coloured mosaic on the glass plate. During exposure, light travelled through these granules to reach a light sensitive layer below; red granules would only allow red light to travel through, and so on. The light sensitive layer was thus selectively exposed by colour. When the autochrome was held up to the light, the coloured granules were viewed in combination with the black and white image behind to create a colour photograph.

C Type

A c-type print, such as Ektachrome, is a colour print in which the print material has at least three emulsion layers of light sensitive silver salts. Each layer is sensitised to a different primary colour - either red, blue or green - and so records different information about the colour make-up of the image. During printing, chemicals are added which form dyes of the appropriate colour in the emulsion layers. It is the most common type of colour photograph.

Carbon Print

Carbon printing was introduced from 1864. A sheet of paper was coated with a layer of light-sensitive gelatin which contained a permanent pigment (often carbon). It was then exposed to daylight under a negative. Carbon prints have a matt finish and can be produced in a variety of colours, ranging from rich sepia tones to cooler shades of grey and blue. Because of their resistance to fading they were much used in the 1870s and 1880s for book illustration and commercial editions of photographs .

Collodion Negative

A sheet of glass hand-coated with a thin film of collodion (guncotton dissolved in ether). This contains potassium iodide and is sensitised on location with silver nitrate. For maximum sensitivity, the plate had to be exposed while still wet and developed immediately. Introduced in 1851 by F. Scott Archer, the process gave a high resolution of detail. Dry collodion negatives, introduced later, were made by covering the collodion with a layer of albumen or gelatin.

Digital Image

Digital images are created using a gridded mosaic of light sensitive picture elements, called pixels, embedded on a computer chip. The pixels emit electrical signals in proportion to the amount of light they receive and these signals are converted to numbers and then stored electromagnetically - in a computer or on a disc, for example. Digital images can be manipulated and altered by computer and regenerated in many ways: on computer or television screens, on film, printed or projected. The technology for producing digital images is evolving rapidly with new possibilities constantly emerging.

Dye Destruction

Dye destruction prints are made using print material which has at least three emulsion layers, each one sensitised to a different primary colour - red, blue or green - and each one containing a dye related to that colour. During exposure to a colour transparency, each layer records different information about the colour make-up of the image. During printing, the dyes are destroyed or preserved to form a full colour image in which the three emulsion layers are perceived as one. Dye destruction prints are characterised by vibrant colour. The process used to be called Cibachrome: it is now known as Ilfochrome.

Dye Transfer Print

Dye transfer prints are prized for their rich colours and relative permanence. A dye transfer print is produced from three separate negatives made by photographing the original negative through red, green and blue filters. A mould is made from each of the three negatives which are transfered to a gelatin coated paper to produce a full colour image.

Interesting to note that the example image they give is William Eggleston's Tricycle, Memphis, 1969-71 as he is considered to have been such an influence on the use of colour photography. I wonder why they chose that particular image? Maybe as it is one of his best known.

Gelatin Silver Print

Gelatin silver prints are the most usual means of making black and white prints from negatives. They are papers coated with a layer of gelatin which contains light sensitive silver salts. They were developed in the 1870's and by 1895 had generally replaced albumen prints because they were more stable, did not turn yellow and were simpler to produce. Gelatin silver prints remain the standard black and white print type.

Here the examples are by so many artists I recognise including work David Goldblatt whose work I've just seen! Also now know that Robert Frank's images were printed on gelatin silver print.

Interesting video on youtube  YouTube - C-types vs. Giclee Prints at theprintspace which talks about digital C -Type printing.

Some of the images were also printed on cotton rag paper which I had never heard of so looked that up too...if you want to get technical

http://www.breathingcolor.com/support/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=61

But seems that its paper made of or with cotton fibres...http://en.wikipedia.org/wiki/Cotton_paper
they print money on cotton rag, well you learn something new everyday! And a nice advertising plug :oD Khadi Cotton Rag Paper


Having done that bit of research I still am not sure of all the technical stuff and what it means, but hope to look further because understanding the print helps you understand what equipment was used to produce the photograph.

Investigating further I found a website which I shall read in depth a bit later. It looks like it will be quite useful in helping me analyse images. Part of it covers materials and techniques which states  'The choice of materials and techniques applied in photography are intrinsic to the photographs that are produced. Recognizing these artifacts and understanding the creative process of an individual photographer deepens appreciation of the photograph.'

http://notesonphotographs.org/


references

Exploring Photography[n/d] Exploring Photography: Photographic Processes [online] V&A Website. Available from: http://www.vam.ac.uk/vastatic/microsites/photography/processes.php [Accessed 2 June 2011]

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