Processes and Sensors

Cyanotype

Invented by Sir John Herschel in 1841, this simple process gives a continuous-tone image of Prussian Blue using a sensitising solution of Ammonium Ferric Citrate and Potassium Ferricyanide. These iron salts, when exposed to natural or artificial ultraviolet light, are reduced to their ferrous state, producing a high contrast blue image when oxidised. Oxidation is hastened by immersion in running water, which also washes away the unused iron salts.

Wet Plate Collodion

http://www.collodion.org

http://www.johnbrewerphotography.com/wetplate-collodion-workshops

https://www.keithcarterphotographs.com

Gum Bichromate process Gum bichromate is a 19th-century photographic printing process based on the light sensitivity of dichromates. It is capable of rendering painterly images from photographic negatives. Gum printing is traditionally a multi-layered printing process, but satisfactory results may be obtained from a single pass.

www. christopherjames-studio. com/build/materials/. /GumBichromateSm www.christopherjames-studio.com/build/materials/.../GumBichromateSm.pdf

Bromoil Process

www. nationalmediamuseum. org. uk/~/media/Files/ www.nationalmediamuseum.org.uk/~/media/Files/.../Photography/BromoilProcess.pdf

https://www.youtube.com/watch?v=5qIwhEiVWbQ

https://www.youtube.com/watch?v=ddzbnHQ1mJU

https://www.silverprint.co.uk/directory/alternative-photography/

Digital Sensors

A charge-coupled device (CCD) is a device for the movement of electrical charge, usually from within the device to an area where the charge can be manipulated, for example conversion into a digital value. This is achieved by "shifting" the signals between stages within the device one at a time

Used for a number of years in video and stills cameras, CCDs long offered superior image quality to CMOS sensors, with better dynamic range and noise control. To this day they are used in budget compacts, but their higher power consumption and more basic construction has meant that they have been largely replaced by CMOS alternatives. They are, however, still used in medium format backs where the benefits of CMOS technology are not as necessary

CMOS Sensors Complementary metal–oxide–semiconductor, abbreviated as CMOS /ˈsiːmɒs/, is a technology for constructing integrated circuits. CMOS technology is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits.

CMOS sensor Long seen as an inferior competitor to the CCD, CMOS sensors have progressed to match or better the CCD standard. With more functionality built on-chip than CCDs, CMOS sensors are able to work more efficiently and require less power to do so, and are better suited to high-speed capture. As such, they are required in cameras where burst shooting is key, such as Canon’s 1D series of DSLR cameras.

What is Dynamic Range? Dynamic range in photography describes the ratio between the maximum and minimum measurable light intensities (white and black, respectively). In the real world, one never encounters true white or black — only varying degrees of light source intensity and subject reflectivity. Therefore the concept of dynamic range becomes more complicated, and depends on whether you are describing a capture device (such as a camera or scanner), a display device (such as a print or computer display), or the subject itself.

Put simply A photographer can extend the range of shadow and highlight detail to introduce to an un-natural degree, giving extra visual impact in its minimal measure, but extreme contrast detail and colour in its maximum measure