Cyanotype

A cyanotype is a printing process that creates a blue image, best used to reproduce other images.  The key ingredient in this process is the use of iron instead of silver.  This process was discovered by Sir John Herschel in 1842 and was effectively the first, and long lived (nearly a century), means of photocopying.  The process is similar to others that had been created some years before.  This one was created accidentally due to an unreliable alchemist during Herschel's attempts at creating a direct photographic method in natural color.
During that time period blues as well as other vivid colors were very desired which instantly attracted attention to this new found method.  Herschel's impact on the world would not yet be known - for nearly a century this method was used for photocopying blue prints (hence the derivation of the word).

For more detailed information on Sir John Herschel and the discovery of Cyanotypes, please read:

Mike Ware - John Herschel's Cyanotype: Invention or Discovery?

It works through creating photosensitive ferric ferrocyanide ions through the use of ferric ammonium citrate and potassium ferricyanide.  The chart below shows how different reactants comes together and the results on the cyanotype process.  As iron has two states, Iron(III) and Iron(II) – which is noted with how many valance elections they have, there are different results.  Different colors are obtained with the difference between ferricyanide and ferrocyanide (which might look the same but one is spelled with an ‘i’ and the other an ‘o’.

Reactant	Ferricyanide Iron (III)	Ferrocyanide Iron(II)
Ferric Salts Iron(III)	Ferric ferricyanide Prussian yellow/brown Soluble, easily oxidizes and reduces via green (Prussian green) intermediates to Prussian blue	Ferric ferrocyanide Prussian Blue Highly insoluble, most stable product, to which all the others eventually revert
Ferrous Salts (II)	Ferric ferrocyanide Turnbull’s Blue (same as Prussian Blue)	Ferrous ferrocyanide Prussian white Insoluble and colorless, readily oxidized by air to Prussian blue.

To make the solution for cyanotypes you use the following to make two solutions, A and B. 

     Solution A: Distilled water at ~21 degrees Celsius 100 ml

                                 Ferric ammonium citrate (green) 25 g

     Solution B: Distilled water at 21 degrees Celsius 100 mil

                                 Potassium ferricyanide 10g

After making those solutions you then combine them together and have approximately an hour to work with the solutions.  By coating the print papers with one coat of the combined solution and allowing to dry you can prepare a page for taking an image. 

At first the paper will be yellow.  A negative is placed over top of the paper and pressed in a printing frame.  To make a digital negative, please see blog entry Making a Digital Negative.  Exposure time will vary 

depending on the strength of the sun.  If it is cloudy up to an hour might be required.  For my experimentation I remained outside for half an hour and still my image didn’t not come through as best as it could have.  On a good day, exposure can be only ten to fifteen minutes. 

Over the duration of the exposure the color of the darks will change from the applied yellow to a blue and slowly into an almost brownish blue.  When it has darkened into the darker brownish blue color the image should survive the next step.

It is important to understand that if the exposure is not long enough the image will not stick to the paper.  This is a different experience from previous experiments.  When fixing in previous experiments there is some fading or bleaching to the darks of the image.  Things that were very dark, near black were bleached into dark browns.  However the image remained on the page.  Failure to have the right exposure time for cyanotypes can lead to all out disappearing images, completely disheartening. 

To fix a cyanotype when using this method, all you have to do is run water over the image.  If the image was not exposed long enough most of the image will wash right down the drain with the water leaving only a little sections of the darkest blues.  However, if it is exposed for the right duration a blue image will remain.  Run under water for a few minutes and then allowed to dry.  Reactions with the air will further expose some of the image, though it doesn’t seem to be much.

There is another way to create a cyanotype that we did not perform because of the toxicity of the process.  It uses Ammonium Iron(III) Oxalate, Potassium Ferricyanide and Ammonium Dichromate.  Mixed together with 100 ml of distilled water and you have a solution that makes cyanotypes.  When made in closed quarters the toxic process can lead to death.  And as we don’t want anyone to die, I’ll only provide the ingredients and not the amounts.  Use the traditional method stated above to make nice Prussian Blue Cyanotypes. 

After a cyanotype is created the darks are represented in blues.  It is where the term blueprint came from because cyanotypes were used primarily to reproduce images such as architectural plans.  They had much less use in the art world.  However, to darken the colors and give it a nicer look, if you don’t want the blues, you can tone your image. 

Cyanotype Demonstration:

There is tea toning that involves using a dark tea (4-5 bags of black tea) bath and soaking your image until you are satisfied with the results.  The tannic acid in the tea will react with the iron salts and thus darken the tones to a navy blue or blue-black.  However, while the darks darken, the highlights or white areas will also darken a little, turning a bit brown with the color of the tea.  If droplets fall on picture or pool on the surface you can get water rings that will alter the image.  I rinse my image after tea toning and then held it up to hand dry a little to prevent further rings from developing.  [I had a ring developing but I caught before it had a change to fully dry.  I rinsed and re-soaked the image in the tea bath and then rinsed it again before drying.]

Another method of toning a cyanotype is Redevelopment toning.  To redevelop tone, you must first bleach the image in an ammonia or borax bath.  This will remove the blue.  Then exposing it to a tea bath, the tannic acid will react with the iron salts as they still remain on the image.  The image will redevelop with brown black color.  The process creates ferric tannates.  If you desire a red brown color, further soak the image in a bath of sodium carbonate. 

For more information regarding cyanotypes, I found this book segment to have a good amount of detail and instruction into the preparation of type 1 and type 2 cyanotypes

Historic photographic processes

 By Richard Farber

Another iron process is Van Dyke and uses silver.  For more information on the Van Dyke process, please see Van Dyke Blog Entry. 

In my experience, I enjoyed this process but it was very disappointing to see most of my image fade away with the first wash.  The sun really needs to be out and shining bright for a good image to stick.  I would like to try this again as making the two solutions and then combining them makes a really easy single application and then the fixing process is even easier by rinsing it.  However, if there isn’t any sun than there isn’t any point.  I don’t have enough patience to develop them for a full hour or however long it would take without any sun, unless I was doing something else in between that time.  This is a process that I consider doing with my son when he gets a little older.  (I tried salted prints with him, papers prepared in lab before taking them home, and he wasn’t really interested). 

Overall, I really like the blue tones, though albumens brownish tones are very nice as well, and I’m quite a fan of the Van Dyke clarity (please see other blog entries for further information on these processes).  If I did this again I would probably try the redevelopment toning just to see how it comes out.  

albumen

Introduction:

Albumen in the whites of eggs is why this printing process is often called an Albumen Print.  The albumen binds the salt added to the page in application.  This can be done ahead of time to create a nicely coated, glossy surface.  Because it could be done in advance and last indefinitely, this became one of the first commercially available paper for doing prints. 

The invention of the albumen printing out process is credited to Louis Desire Blanquart-Evrard, however a letter from someone not known by anything more than H.L. had used egg whites and water in printing in 1839.  He experimented with Niepce’s albumen on glass which created a negative. 

The creation of the albumen printing out process came around the same times as the collodion process for glass negatives.  It was if they were meant for each other as a negative placed over the sensitized paper would provide a positive on the paper.

The salted egg whites process became popular because of its nice positive images.  The ability to create the papers so they could last allowed them to be produced commercially by many companies from American and European countries.  Dyes for the papers were introduced as well to give a tint to the final paper and used primarily for portraits, however as dyes fade with exposure to light it is hard to tell which papers had once been dyed nowadays. 

Albumen printing papers dominated the photography industry from the invention of the collodion glass plate process by Fredrick Scott Archer.  Even when the negative process turned from wet plates to dry, the albumen printing papers had already established itself.  It remained popular for forty years until emulsion-type gelatin and collodion printing-out papers captured the market.

Process:

To make an albumen print, you must first coat the paper with albumen and to do that you must make the albumen mixture. 

Take fresh eggs (one large egg makes about one ounce of albumen) and separate it from its yolk.  It is important to only use the egg whites without any hint of yolk or stringy-ness that can also appear.  It is also suggested that you separate each egg over a separate bowl, as one would in cooking, to avoid contaminating the entire batch with a bad egg.  Once the egg whites are separated, chlorides need to be added and this mostly salt (sodium chloride) or ammonium chloride.  There should be about 2.5% chloride composition to the egg whites. 

The chlorides are the most important thing in the photosensitivity of the paper.  The chlorides bond with the silver making a photosensitive compound which darkens when exposed to light. Forgetting or not putting enough chlorides in the mixture will weaken you’re photos.  Dissolve the chlorides in the minimum amount of water and add to egg whites.    

Next, beat the eggs into a froth.  We combined our eggs in a bowl and then shook it until it was frothy.  This breaks down some aspects of the eggs and further denaturing will take place as it sits and ages a few days (suggested a week) – do so in a refrigerator so the eggs don’t go bad.  This is necessary before application to the paper.  After it has had a few days to age it needs to be strained to remove the bubbles.  You can do this with muslin or cheese cloth.  Bubbles transferred to the paper on which the print will be made will create distortions and flaking so it is important that there are no bubbles in the mixture. 

Once the mixtures is strained, removing the bubbles, place the albumen in a flat bottom dish, preferably one that can handle the size of the paper to be coated.  Remember to avoid bubbles at all costs.  There should be about 2/3 depth to the albumen solution.

The paper to be used for printing should be coated on one side.  It is messy when there is albumen on both sides of the paper so be sure to keep in on one side.  Making a sort of boat by bending up the edges you can float the surface of the paper in the egg whites without getting any on the back.  It is important to cover the entire page smoothly.  Float the papers for about a minute. 

Once it is coated, take it from the albumen and hang it to dry.  A hotter room temp. will allow the papers to dry faster and glossier.

A second coat can be applied but isn’t necessary.  It will only allow for a glossier surface on which the print is fixed to. When drying the second coat, be sure to turn it and hang it from the other end that was originally used so that the coat is smooth.  Multiple coats will alter the depth of the image and their brilliance, but it will also affect the toning and fixing process as it will be more difficult to fix with the thicker coats. 

 In order to do a second coat, float the single coated albumen sheet in a 70% isopropyl alcohol mixture and then dry.  To prevent the chlorides from leaching from the paper it is important to put in the percentage of chlorides that was in the albumen so 2.5%.  The alcohol will harden the albumen surface so that another albumen coat can be applied.  Repeat the albumen applying method for the first coat of albumen.  Hang dry. 

There are other ways of hardening the albumen, but the alcohol method was the one we used in our experiment.  You can also hold the paper over a continuous stream of steam.  The heat will cook the surface of the paper and thus harden it. 

It is important to understand that while the double coat will make a thinner negative work better, it is also going to be more brittle and less flexible and a single coat.  So care needs to be taken with these images. 

If you don’t use all of your albumen mixture it can be saved for a few weeks.  You’ll be able to tell when it goes bad by the way it smells, color and sedimentation.

Once the albumen layer is prepared a silver concentration can be applied to the surface.  The silver nitrate solution is the same solution used in previous experimentation, see salted paper experiment.  The preferred solution concentration is 12%.  Allow solution to dry in dark area as the silver chloride formed with the addition of the silver nitrate is photosensitive.  In previous techniques, the application of silver was through a floating process as well, but we simply brush the silver solution across the page which prevents the possibility of air bubbles and lack of silver in some places. 

It can be noted that in the past, the 19^th century when albumen prints were all the rage, that ammonia fuming took place.  A dish of ammonia would be placed in a box in which the sensitized pages were hung and left for five to ten minutes.  This process was to supposed to increase the sensitivity and the brilliance of the prints, and while it does increase these features, it is not required to get a good print. This primarily took place in the United States, not Europe. 

A negative, either digital (see Making Digital Negatives blog entry) or traditionally collodion glass negative is then placed over the albumen paper and exposed to the sun or UV light source.  The UV light will darken the silver in the exposed places.  It is best to use the sensitized papers as soon as possible.

After exposure the paper needs to be fixed.  Without fixing the image will darken until the image is gone. 

The colors formed will be a rich purple to dark brown.  Fixing the image is the same for a silver process (see Salted Paper entry for fixing methods). 

The exposed pages can also be toned, though we did not tone our images.  A gold or platinum toning bath can take place.  Black tones were achieved with gold toning, but wasn’t very popular in the 19^th century.  More information on albumen can be found here and is where most information was taken for this blog. 

  

My experience: 

When doing this lab we didn’t quite know what we were doing and ran into many difficulties.  From cracking the eggs and getting shells in it and even bursting some of the yolks to not fully understanding the hardening process on the day of the lab.  Some of the difficulties we encountered in particular was bubbling of the albumen which then left foamy parts on the images.  The images could not print on those foamy parts and tended to flake off once dried (after exposure, fixing, etc.).  It is very important that there are no bubbles on the papers. 

Also, the second coat came with some difficulty.  We did not understand the use of the alcohol and thought that the second coat was to be applied and then the alcohol bath.  So for the second coat on two of our papers was done without alcohol.  We did not apply alcohol after as we had caught our mistake.  The remained of the coats were done in the correct manner and left to dry. 

We did not use a hair dryer to dry our pages at first as we thought air drying was better.  But as time became restricting we broke out the hair dryer and used it.  It may have made it so that our second coats, the ones that did not have the alcohol to harden them, actually come out right as the direct heat would have had a similar effect to the steaming process.  In any case, though we had issues, the second coats did come out glossier. 

We went into this lab without a full understanding of what we were supposed to do and that was wrong.  It was a little more complicated and we were very busy than with other labs beforehand.  While we were also coating albumen sheets, we made up gelatin and arrowroot coatings for other papers.  We had four papers for each person and five people in our group so that we were rushed on time.  We did not even do our printing on this day, but instead only prepared our pages, the albumen being prepared during class time a few days prior. 

More time, full understanding, and better organization would have made this process easier.  The images we created were not the best as most albumen prints had issues with bubbles.  However, they did have a nice clarity, depth, and detail as well as gloss which salted paper did not have.  I also enjoyed the nice tones of purplish browns that came with the process.  It was my favorite over the gelatin and the arrowroot. 

More information:

This video provides a nice animated step by step guide to the albumen printing procedure, though the writing is in a different language there are English subtitles along the bottom, but there isn’t much as far as that in the first place. 

For some more information on glass albumen photography and the chemistry behind it presented from a 19^th century manual see: Orr's Circle of the Sciences: Practical chemistry By William Somerville Orr

Photographic news from the time period can be seen here: The Photographic news: a weekly record of the progress of photography, Volume 10

According to another book of the 19^th century, it has information on photographic processes, some of which has never been printed before (at the time), which can be viewed here if one wished to a comparison of then and now:  Humphrey's journal of the daguerreotype and photographic arts and ..., Volume 13

If you’d like to see a video of an albumen print from a collodion glass negative: '

For some brief information on the collodion process a video and wiki:

Overall, the albumen process makes nice photos but the steps to preparing the papers is a bit messy.  I’d much prefer having to purchase premade albumen sheets instead of making them with icky egg and shaking till frothy and then application and drying… it really doesn’t smell that pleasant (not that it stinks, I just don’t like egg smell, or anything raw really).  Of course that is probably just a personal opinion. 

It’d be interesting to attempt a glass albumen negative as another student did in class.  If I experimented in albumen again I would be sure to eliminate bubbles from the mixture as it was really disappointing to see them scar my image.  A second trial would be better than the first purely because I now fully understand what I’m doing with the process. Trial and error is how the scientists did it, so I guess it’s good enough for me too ;) 

van dyke brown process

Introduction:

The Van Dyke photographic process is named for the color of the print as it so matches a brown oil paint that was named for a Flemish oil painter.  An image is created on a photosensitive paper through the similar methods named before, a negative over sensitive paper in a printing frame. 

The iron-silver process was invented by Sir John Herschel and dubbed the Argentotype in 1842.  From then on there are many derivatives of his invention like the Van dyek, Kallitype, sepiaprint and Brownprint.  The Van Dyke process was developed off of John Herschel’s Kallitype in 1899 by W J Nichol.

Further information and references: 

       Lloyd Goodman - Alternative Photographic Process
       Mike Ware - The Argyrotype Process
       Alternative Photography - Vandyke Notes

Some 19^th century reading for interesting reference:
       The British Journal of Photography By Henry Greenwood

       The photographic news, Volumes 1-2 edited by Sir William Crookes, George Wharton Simpson

For a very nice video:

[begins with its own process for making a digital negative]  This is a different process, where solution is applied to a paper with printed toning and then exposed under a negative.  This would be interesting to try.   Though it might seem a bit difficult to ensure that the negative aligns with the image. 

Process and my experiences:

The process to make a Van Dyke print is to coat a page with a photosensitive solution, in this case an iron and silver mixture. 

To make a Van Dyke solution you make three solutions and combine them together. 

Part A:

-                33 mL Distilled water

-                9 grams ammonium ferric citrate green

-               18 grams ammonium ferric citrate brown

Part B:

-                33 mL Distilled water

-                1.5 grams Tartaric Acid

Part C:

-                 33 mL Distilled water

-                 3.8 grams silver nitrate.

Add part B to part A and then add part C while slowly stirring.  Store solution in a dark area within a tightly lidded glass bottle and age for a week.  Solution keeps stable activity for years after ripening period.

To coat the page, you just brush the solution on to the page though paper or organic fabric can be dipped into the solution (I would imagine this to be a messier process).  Hang the page to dry or, in our situation, we tape our pages down and then use a hair dryer on low to air dry them.  By taping them down there is less curling of the wet page.  Only one coat of this solution is necessary though it is probably better to do it thicker than thinner.

When applying the solution you have to be careful of the solution ‘setting up’ on the page.  It is important to work fast and light, quickly brushing on the solution and not rubbing it into the page.  The surface will be glossy as it is wet but will become more matte as it sets up.  You must not run over it with the brush after that point.  You must also be careful of streaking the surface or the image will not come out as well as it can.  So when applying, try to get a decent amount of solution on the brush and move over the page coating it as smoothly as possible as fast as possible. 

Once the page is dry, put it in a printing frame with a digital negative.  We used the digital negatives that we already created in the albumen and cyanotype experiments.  It was suggest to use the albumen ones as they would have the better contrasts.  I decided to do two tests one with each and see if I could see a difference.  There didn’t seems to be much of a difference, but the day was cloudy, as usual and that may have contributed to it. 

The exposure time is 20 to more minutes under artificial UV florescent lights; 10 to 15 minutes in direct sunlight, and approximately 30 minutes with photo floodlights.  Cloth needs approximately 50% more exposure time.  On a cloudy day, we stayed outside for about 15 minutes, I believe.  We were looking for a nice darker color and it turned out to be relatively orange.

After exposing, we washed the image and put it through a bath as follows:

The fixing process for Van Dyke has five baths and goes fairly quick, which is nice.  The first bath is water with a little citric acid.  A pinch of citric acid is all that it needs as the bath should be a neutral to mildly acidic pH.  The image should remain in the bath for about five minutes.

The next bath is one of fresh running water for a minute or two. 

From the running water, move the image to into the first of two hypo baths.  Each bath is made with 3% hypo and the image should soak in it for one minute each. 

Then finally, the image should be rinsed for forty minutes in running water. 

When fixing, the first bath will fade the image and it may be a bit startling, particularly if the last experiment done was a cyanotype where you may have experienced a vanishing image from poor exposure.  However, you will see a darkening of the image when put in the hypo solution.  The resulting image is nice and dark. 

As the image dries the print will darken. 

References: Formula and process.  A very thorough article on the Van Dyke process and the toning that can be performed with it: Van Dyke: an alternative printing process by Pete Caluori.

I liked this process a lot.  The resulting color and clarity of the image was something that I desired.  It was easy to apply, though we did not have to make the solution as it was made previously which might take away some of the fun of the process.  However, the image was only outside for 12 minutes and had a decent print.  The fixing process was also nice to see as the image faded in it’s orangy color and then darkened into a nice tone, almost as if it was kidding around by pretending to be fleeting only to come back stronger than the original look.  I would very much like to attempt this on fabric and see what comes out as well as the video’s suggestion, a printed out tonal picture and then the image printed on top.  The resulting image was quite beautiful.  

making a digital negative

In Cyanotype and Albumen printing we used digital negatives.  We also used a digital negative for Van Dyke prints but as it was the last experiment we performed we did not create new images and simply reused the ones already created.

Now a digital negative is a negative that was printed out on a transparency.  To create the negative we first picked an image that we wanted to use.  For me, and I’m not exactly sure what other programs are capable of making this digital negative, but Adobe Photoshop was the program used.  The following steps will take place within the Photoshop program however, the concepts can probably be applied to another program if you have one. 

Upload your image into Photoshop.  To do this, I saved my image to my computer and then opened it up through Photoshop’s open file link.  However, you can probably create ‘new’ and then copy paste the image into the new window. 

Now, I’ll note right now that I don’t really know much about technology and what I’m actually doing, this is just a reiteration of the instructions provided to us by our professor. 

Okay, so once you have your image open you have to tweak it.  [Most of these things you must do will be found under the Image tab].  So find the contrast/brightness, and alter the contrast and the brightness until you get the image you desire.  The image will come out clearer if you increase the contrast as the tonal ranges vary (longer).  The brightness can also be upped if you so desire.

Next, set your image mode to 16 bits… I have no idea what that really means but its something you have to do.

The next step is to upload a curve.  The curve will alter image and make it is the best for the process.  There are different curves for each process.  For instance there is one for albumen, cyanotype and Van Dyke, however we only used the albumen and the cyanotype curves thus making only two types of negatives.  You can download these curves by either buying packs or finding them on the internet.  Our curves were provided through our professor.  Go to Image, adjust, curves and it will bring up a window.  If you are using a newer edition of Photoshop there is a little box next to the drop down menu of the new window that will allow you to load the downloaded curve.  The image will be altered by the new information contained in the curve. 

The next step is to make it a negative which requires inverting the image, a gray scale image.  You then have to convert it into RGB, flatten if it asks, and convert back to 8 bits if you have to do it manually. 

Now a new layer must be applied.  The new layer will have no background and thus be clear.  We will in a sense dye or paint the layer in an image as the color filter will allow for better pictures.  Set the layer mode to screen. 

For a salt and albumen a density range of 2.5 or otherwise known as R:25 G:50 B:0 is preferred.  Just input the numbers into the color picker, which is the little box that holds a color in the tools to the side.  This will make a green tone. 

For cyanotype we want a hue of 15 and lightness of 30 or R:70 G:19 B:0.  This will make a red tone.

 You must then use the paint bucket to coat the layer.  The image will then change tint to the color you imputed and the image can printed out on transparency.  If, when you use the fill, your image is no longer seen and you only have color it is because you did not change it to a screen.  Undo the action and change the layer mode to screen and then fill.

Once you’ve printed the image out on a transparency you have your digital negative.  Other processes negatives like Van Dyke can be made this manner by simply finding the right curves and the correct color screens.

It is important that you use and save your photo at the highest quality to improve the result from your negative.  Also, use the best print out method you can find.  Office Max will print a transparency better than your computer, if your computer can print transparencies.  The quality of the image and thus the printed negative will greatly affect the outcome of your final print so use the best.  Office Max prints transparencies for around $1.50. 

camera obscura and lucida

**Warning: This blog is currently suffering from formatting issues and is not as pretty as it could be.  Please disregard as best as possible.  

Room Camera Obscura: 

http://www.mexicanpictures.com/headingeast/2007/04/camera-obscura-1.html

Introduction:

Camera obscura is derived from latin to mean darkened room. The earliest mention of a device similar to a camera obscura was made by the Chinese philosopher Mo-Ti (5^th Century BC). He inverted an image into a darkened room through a pinhole. Aristotle was said to understand the optical illusion of the camera obscura as he viewed the crescent shape of a partially eclipsed sun projected on the ground through the holes of a sieve and the gaps between leaves of a plane tree. In 1490, Leonardo Da Vinci gave descriptions of camera obscuras in his notebooks.

The first camera obscuras were darkened rooms, like Dutch Scientist Reinerus Gemma-Frisius used to view a solar eclipse in 1544.

Lucida in use:http://en.wikipedia.org/wiki/File:Cameralucida01.jpg 

The images were improved with the addition of a convex lens on the aperture in the 16^th century. The later addition of a mirror to reflect the image onto a viewing surface. A camera lucida is the term used when the image is reflected down onto a viewing surface. Giovanni Battista Della Porta suggested in his book Magiae Naturalis published in 1558, that these be used for drawing assistance. 

room camera obscura illustration

Riva Degli Schiavoin, Venice, Canaletto, 1740
Painted with the use of a camera obscura.
Grand Tour Gentlemen would purchase these type paintings because it looked like how it looked when they saw them, alive and with the right perspective. 

Johannes Kepler Tent obscrua:

http://www.acmi.net.au/AIC/CAMERA_OBSCURA.html

The term "camera obscura" was first used by German astronomer Johannes Kepler in the early 17^th century. He used a portable camera for surveying in Upper Austria. In the 17^th and 18^th centuries, artists used portable camera obscuras to assist in their drawing or realistic scenes. Such artists include Jan Vermeer, Canaletto, Guardi, and Paul Sandby. By the beginning of the 19^th century, the camera obscura could be used with photosensitive paper with little to no alteration in design. 

Room camera obsuras were popular in the 19^th century as well, used as for education and entertainment. With the addition of a lens, the images could become bigger and crisper. They were placed in parks with beautiful scenery, along beaches, and other places of interest.

Postcard: Famous Camera Obscura Santa Monica, Calif. c.1900
http://www.acmi.net.au/AIC/CAMERA_OBSCURA.html

Some camera obscuras can be seen here: http://brightbytes.com/cosite/portable.html

Some camera obscuras found in US parks can be seen here: http://brightbytes.com/cosite/portable.html

This information was summarized from: http://brightbytes.com/cosite/what.html

Additional Links –

Timeline of the History of Photography: http://www.historiccamera.com/history1/photo_history300.html

[click two page advances to find information on camera obsucra]

Timeline of Historic Cameras:

http://www.historiccamera.com/historiccameras/historiccameras.html

Video:

What is a camera obscura and how does it work: http://www.youtube.com/watch?v=tmAPtrpdoZw

Book: http://books.google.com/books?id=00gWAAAAYAAJ&printsec=frontcover&dq=Camera+obscura&hl=en&ei=EfarTdShNITl0gGjlYH6CA&sa=X&oi=book_result&ct=result&resnum=3&ved=0CDQQ6AEwAg#v=onepage&q&f=false
 
Process:

camera obscura with mirror: 

http://www.acmi.net.au/AIC/CAMERA_OBSCURA.html

http://wikis.lib.ncsu.edu/index.php/GD_342/Glossary

The process to make a camera obscura with a lens is to determine the focal length of the lens first. The focal length will determine the size of the box in which the image will be projected. With a longer focal length, the screen on which the image is projected must be farther away. With a shorter focal length, the screen must be closer. So once deciding what the focal length is, the distance where the image must project will be known. From there, you can decide to use either a mirror, or just a screen. Using a mirror: the mirror must be placed at a 45 degree angle in order to project the image up 90 degrees, on to the top of the box where the screen would be placed. Should a simple screen be used, the screen must only be placed at the end of the focal length but the image will be upside down. 
Traditionally, the boxes were made of wood and a piece of grounded glass would be placed wherever the screen is required. The grounded glass captures the image. Sliding camera obscuras can be used, and this is where the lens can move farther away from the screen in order to focus, like zooming on current cameras.

A camera obscura can be made out of anything. From paint cans to tins, Pringles cans, cardboard boxes (ex. Cereal boxes, Pop Tart boxes, etc), anything can be used. The goal is merely to provide a dark space in which to view a screen on which an image is projected from through a lens or pin hole. Pin holes will provide an image, but when using a lens, the image will be clearer. Plans for camera obscuras can be adjusted in whatever fashion in order to achieve this goal.

How they work:

When light hits an object, it reflects the image, like a seeing your reflection on the surface of a pond. When the light rays, when narrowed by a hole or a lens, will focus the light and rays flip, thus flipping the image. A lens will focus the image more than a pinhole by bending the light.  The screen or back of a room, catches the image, upside down. If the image moves closer or farther away from the hole, the image within the camera obscura will adjust and grow fuzzy as it cannot focus. These pictures help demonstrate how light travels and creates the image.

Example of light bending with contact of a lens, the grass being a lens, then the direction/trajectory of the shopping cart being the light.  When the rays of light contact the lens, they bend and alter which can lead to distortions in the actual image, a fishbowl effect.  

http://science.howstuffworks.com/mirage1.htm

http://en.wikipedia.org/wiki/Lens_(optics): a good site for a quick review of how lenses work with plenty of pictures showing light traveling through various types of lenses.

http://rctc-photo-1.blogspot.com/2011/01/web-work-2.html

 
My Camera Obscura Project:


For my camera obscura we used a lens to focus the image. When using a lens it is necessary to measure the focal point of the lens. I used a magnifying glass I bought at a hardware store for a few dollars, even though we were given a plastic magnifying glass for class. I decided to use my own image as it was clearer. The plastic magnifying glass we were given did not have a smooth surface and thus distorted the image. The glass magnifying glass was clearer, however, it will alter the focal length, making it different from others in class that used the given magnifying glass.

To measure the focal length, the glass was held up near a wall with a window behind it. The image of the window will appear on the wall. Moving the lens forward or back from the wall until the image is clear is the proper focal length. I then measured the distance of the lens from the wall to discover the focal length. The focal length was quite small, about 65mm. Others in class had focal lengths of up to six inches.

lens taped in toilet paper roll

The next step I did was to make a tube to hold the lens. Cutting the toilet paper roll down one side, lengthwise from opening to opening, I adjusted to opening to around the lens and then taped it around lens. It is important to know how far the tube open is behind the lens as it plays into the focal length. The tube was too long and I cut it down to shorten it. I then put the tube against the box that would be the camera obscura, and traced the circle to cut out. Once cut out, the circle allowed the tube to be inserted into the box. Tape around the end of the tube ensured a nice fit. 

Disassembled Camera obscura.  Lens detached from box.  Box opened to show screen inside and hole for viewing.

In the space of the square, I used various different screens to see which worked best, from a coffee filter; to a translucent, gray, plastic binder divider; to a tissue held between two pieces of plastic; and then finally wax paper. Wax paper worked best. I wasn't really experimenting with different types of screen for the sake of experimentation, but because the suggested wax paper was not available at the time of construction of my camera. Still, the results are this:

Coffee filter was too dark. An image could be seen but it wasn't very clear. It was hard to tell if the focal length needed adjustment or if the screen needed to be thinner, clearer.

The greyed plastic binder was too clear. The circle of light was too bright and bleached out most of the image in the center of the screen. However, on the outskirts of the image, I could make out a faint, ghostly translucent image. This was too clear. I attempted three sheets of plastic to increase the density, but the image remained too clear for each. I decided to try finding something to place between two sheets of plastic and decided on two ply tissue, but separating the ply to make just one.

With the tissue in between, the image could be seen, but it still wasn't as clear as I would later see with wax paper. However, after adjusting the screen and the tube a little for maximum clarity, it made a clear image. Once wax paper was made available, I replaced the tissue and the plastic with wax paper. The image was clearest in this method. After finding the clearest screen, I adjusted the tube, pushing it in and out to see if the image could become clearer. I managed to make a very clear image.



The short focal length made it necessary for the camera obscura to be very close to the image you actually wanted to see, about two feet or so from the front of the tube. The image is upside down, because of the way the light comes in through the lens and then flips as the rays of light that hold the image cross and project an upside down image on the screen. A mirror could have been used to project the upside down image onto the top of the camera obscura, where the screen would then be placed. This would right the image orientation. However, I decided not to use a mirror, though I thought it interesting to try.

Upper right corner shows image through camera obsura (flipped for clarity, would be upside down)  Distance required for clear image shown in left picture.  

My courses link I found helpful in this project (probably only accessible by RIT students enrolled in the class): https://mycourses.rit.edu/d2l/lms/content/viewer/main_frame.d2l?ou=334489&tId=1750709

  

Additional Information:

A great link that tells a lot on camera obsuras and more: http://www.acmi.net.au/AIC/CAMERA_OBSCURA.html


Whole rooms can be turned into camera obscuras, such as your bedroom. By applying the proper lens or hole in a shade that blackens the room, in the morning when the sun comes up and light shines on the outside, the image of outside will be inverted into the room for as long as it remains dark. Opening the shade will obviously make it too bright to show the image that would be projected on the wall.

To do this yourself with more specifics follow this link: http://www.funsci.com/fun3_en/sky/sky.htm

BBC: A camera obscura room: http://www.youtube.com/watch?v=RuJ_Jd6Qgyo Great Video! We should totally do this in a classroom J



Summary:

Camera obscuras and lucidas alter light into images by concentrating them onto a surface. Making camera obscuras in parks must have been truly entertaining in the day - to spy on someone and not being seen. To make a large room size camera obscura seems like the greatest experiment. It would seem that a portable camera obscura works best with a wax paper screen. It would have been nice to be able to see things farther away within the camera obscura but the lens picked did not allow for that. If this project was to be redone, it would be best to evaluate several lenses to pick the right one for a clearer, farther picture.

19th Century Cartoon
depicting Camera Obscura
http://www.acmi.net.au/AIC/CAMERA_OBSCURA.html

 

salted paper and photogenic drawing

**Warning: this blog is currently suffering from formatting issues and is not nearly as pretty as it could be.  Please disregard it as best as possible.

Salted Paper Print: 

http://www.nga.gov/podcasts/fullscreen/0803arttalk02.shtm

Introduction:

A photogenic drawing is an image applied to paper by the use of contact on a photosensitive surface. It is primarily a sort of silhouette, though the density of the object applied can alter the outcome, for example a leaf pressed against photosensitive paper and exposed to sunlight can let some UV rays through the thinner portions of the leaves but not the veins as they are denser allowing the veins to show up within the leaf image as an end result when typically, or in theory, should everything have the same density and no other light rays get through all the images would be simple silhouettes.

The way in which the light hits the paper is also important. The darkest exposure will be through direct sunlight, but as light bounces off of items, sunlight that has hit an object can affect the outcome of the image as well, leading to lighter or even darker spaces (should more light be directed to one area) on the final image for an object that isn't pressed completely flat to the paper. It is important to be aware of how light can bend because should you use glass plates over your objects to hold down them down during exposure and must make due with, say, multiple sheets or the corner of glass might cut across the paper in some manner, while you might think that since it is clear it will do nothing, you will find that a line can develop since the light will enter through the glass and bend at the corner, thus altering the density of light in that area and leaving a visible line. 
The images are warm in tone because they use sunlight to develop called printing out.  Because the sun develops the image and not chemicals in a dark space, the warmth is evident in the photos.  When the image is fixed with hypo, the image is lighter because the silver is removed.  But when the image is fixed with salt, the silver is not removed and no bleaching occurs.  This keeps the picture dark, and can potentially lead to further darkening if exposed to sun as the salt doesn't guarantee the silver from not reacting and further darkening

floating paper in salt solution

Salted paper is a photosensitive paper in which salt is applied to a page and then silver nitrate is brushed over top of that (with drying in between). The dry salt reacts with the silver applied in the top coat (two coats worked best in experimentation – see blog post: photogenic drawing for data on best concentrations, coats and paper for experimentation) and produces silver chloride which is a photosensitive compound insoluble in water. When exposed to light, particularly sunlight, though results can be achieved with very little sunlight and thick cloud cover - the exposure is will longer, the silver will darken and anything blocking light from the paper will leave an image. However, without fixing, the image will not last as once the object is removed the light will activate and darken the remaining silver compound on the page until the entire thing is dark and no more image exists. To prevent the further reaction of sunlight and silver, the image can be fixed onto the page through two methods. Soaking the images in salt saturated solutions will apply more salt to the page and while it does not effectively remove the reactant silver it will make it harder for the silver to react through the excess salt.

The other method of fixing an image, a better method and more popular, is the use of hypo. Hypo is sodium thiosulfate. It works by removing undeveloped silver chloride crystals from the paper and thus preventing the image from darkening into obscurity. However, it will lighten or bleach the images greatly and a lengthy exposure time is suggested in order to retain a darker image after the hypo bath regardless with how quickly the image may darken once exposed to the sun.

Historical Background –

Talbot's Camera Obscura Replica 1820 (2)

Photogenic drawings were developed by William Henry Fox Talbot, a gentleman scientist. He announced the results of his experiments in 1839. The images created are silhouettes or negatives and his solution to fix the images consisted of the above mentioned salt bath. John Herschel picked up Talbot's experiments and discovered the fixing method of hypo.  Talbot used camera obscuras to create tiny images. Further information on Talbot and Herschel can found:












Talbot: http://www.rleggat.com/photohistory/history/talbot.htm

Herschel: http://www-groups.dcs.st-and.ac.uk/~history/Biographies/Herschel.html


 
Process:

The basic procedure for creating salted paper is to immerse or coat a page of good quality paper on which an image is desired, and then dry it. After a coat of silver will be applied though historical documents change the approximate concentration of salt and silver solutions, and some other specifics as the people of the 18^th century were experimenting with finding the best methods, as we did in a previous lab [see photogenic drawing experiment for details]. See 'Our Experiment' below for the process we utilized.

Salted paper and photogenic drawing were one of the first real ways of capturing images in a relatively short period of (exposure) time. It became a rather popular method with its simplicity in creation opposed to the Daguerreotype that used a relatively complicated method with harsh chemicals [ more information (a quick introduction) on Daguerreotypes can be found: http://en.wikipedia.org/wiki/Daguerreotype]. Several publications of the 19^th century deal with the photographic process of salted paper and the application to make photosensitive papers for images, as well as hypo fixing methods. One such publication is:

http://books.google.com/books?id=j2USAAAAYAAJ&pg=PA139&dq=salted+paper+photogenic+drawing&hl=en&ei=_KmrTdueIeGG0QHb_b35CA&sa=X&oi=book_result&ct=result&resnum=2&ved=0CEYQ6AEwAQ#v=onepage&q=salted%20paper%20photogenic%20drawing&f=false

It mentions soaking the paper in a salt solution and then pressing it with a wooden press to keep it flat and smooth. The objective is to keep the paper on which the image will be printed clean and pretty to look at. This is different than what was suggested for our lab procedure where the surface of the paper was brushed with salt solution. We had also taped it to the surface in an attempt to keep it from bubbling up aggressively and then curling during drying. The bubbled paper texture still occurs with the wetting of the paper, but is not as severe as if it was left untapped.

Another publication, Light: An examination of all the phenomena connected … by Robert Hunt, mentioned a manner in which the sensitivity of the paper can be maximized if a paper was made, salted and silver applied, and then kept for several weeks. Through the reapplication of silver to the surface "it becomes sensible to Light, even more than it was at first." http://books.google.com/books?id=GqoaAAAAYAAJ&printsec=frontcover&dq=Light:+An+examination+by+Hunt&hl=en&ei=SrOrTemAMMWtgQedg9jzBQ&sa=X&oi=book_result&ct=result&resnum=1&ved=0CEAQ6AEwAA#v=onepage&q&f=false


Our Experiment:

Silver to be applied to papers

Drying between coats

For the purposes of our lab, our group used salt and silver solutions of 2% and 12%, respectively, with two coats of silver and no additional salt coat in between. The paper was dried between each coat. First, salt was applied with a pipette and then spread over the paper with a sponge brush. A hair dryer was used to dry in between coats on a low setting. A coat of silver was applied as smoothly as possible, else poor sensitivity will develop on the page leading to poor images or a ghosting effect. After using a hair dryer once more to dry the paper, another coat of silver was applied to the page. The page will be covered with a silver compound that is insoluble to water called silver chloride. Crystals of this compound bond on the surface of the paper. The density of these crystal formations are affected by the concentration of silver and salt in each area. If the salt or silver is not applied smoothly over the surface of the paper, then ill effects can occur. The dual coats of silver tend to limit the possibility of a poor image.

We did not experiment in alternating salt coats as mentioned in the above reading though it may be interesting to try in the future.

It is important that once the paper is sensitized with silver that the light exposure is limited until the actual exposure is desired. The paper will steadily darken in limited light so it is best to exposed the papers as desired as soon as possible, particularly when a dark room is ill equipped as a darkroom (i.e. light sneaking in around the edges of blinds as in our classroom).

For the sake of our experimentation, we desired to test the effect of colored filters on the image. Three filters were cut from cellophane in the colors: yellow, red, and blue. It was our belief that the colored filters will affect the overall image. In order to test the effect of no filter on the page and for a little artistic expression, we cut stars into the centers of the cellophane and then applied them, with tape over three individual squares of sensitized paper. The stars cut out of the center, however, were not flattened to the surface of the paper and created difficulties later in the exposure. Glass should have been applied to the surface to keep the corners within the star from sticking up and thus letting light slip underneath the filter.

Our objects: filters, wood cut flower, false flowers, etc

Four other photogenic drawings were made using items brought from home. Potpourri, false flowers (not plastic but sort of thick, structured fabric), and a flower wood cut out used as objects for our drawings. These were primarily done for fun, in my opinion, and the results were quite pleasing and exciting. Glass was used over top the objects to prevent them from blowing away. Four sheets of glass were placed over top, creating the above mentioned lines after the fact.

On two large cutting boards, we taped three papers for the filter test and then four papers on the other for our drawings. Salt and silver were then applied to the papers. Tape on all four sides of our squares kept the bubbling to a minimum. Once dry, we applied our above mentioned objects and filters to the papers and planned for exposure. Glass was only used on the object images, not the filter images.

Filtered Experiment Exposure

Objects exposed to sun with glass over top

Still attached to their boards, we took the images out into the sun. It was a sunny day, though a bit of wind blew around campus. The images began to change and darken within thirty seconds of exposure. For the sake of a dark image that would not bleach out as badly when put through the hypo baths, we exposed our images for three minutes. When going out with the star filters, the way the sun came down affected the images as we turned them from when we went down the steps when first going outside to when we put them in their final resting place for the duration of the exposure time. Therefore, light snuck underneath the filters on two sides, altering the way the stars came out over all (though admittedly they were not the best star cut outs, just something done quickly).

The objects images developed as quickly as the filters. These two boards were taken out a different times, though one followed shortly after the other. A breeze got underneath the glass and moved an petal of potpourri from one image to another close by. The result was interesting as the place where it had been turned a bit ghostly, while the final resting place didn't darken as darkly as the rest of the image background, giving a sort of ghostly look, but hardly noticeable unless you were looking for it. It was particularly bleached out after the hypo bath, further making it less noticeable.


 
Observations/Experience:

The images came out quite dark, even after the fixing bath. The overall result was exciting to see everything working so quickly – our first experiments with contact printing being anthotypes is quite slow and not nearly as exciting for college students of the 21^st century. The dark backgrounds and the lighter object images were negatives. The false flowers were not completely opaque to the sun's rays and thus darkened a decent amount underneath the objects. It left a gray image underneath. The result had some depth to the images I didn't expect.

Object Images after exposure, before hypo bath

The woodcut flower had some depth to it as well. The way the sun hit the corners of the object shadowed some of the space within and thus limited the exposure to the sun's rays, making it not as dark. It looked more like the flat cut out than I expected, as I had just expected the overall flat image without depth.

blue filter after exposure

red filter after exposure

yellow filter after exposure

The filters were interesting to see and I had little idea on what the overall result might be. The blue turned out to make the darkest image, turning so dark that the star was not visible at all after the exposure (before the hypo bath). Yellow and Red filters had similar results, leaving faded, not very dark images. 

red filter photo after hypo

yellow filter photo after hypo

blue filter photo after hypo

The hypo bath lightened the pictures a lot. At first, we thought the images were lost, but with the hypo bath (this was the first time we used hypo for fixing) the solution bleached the images, revealing the stars on the filter experiments as well as making the false flower images to be more visible.
In our excitement with our lab and actually creating images that were quite clear, we used the rest of our lab time to make more papers and exposed them, though some of us took some home to attempt images with camera obscura. There are no results of these additional experimentation, but it is something quite fun to do. Time constraints, however, limit the number of tests or fooling around that we could do. It is only a two hour class.

Before Hypo Bath.  See depth along bottom edge.

It is important to remember that silver cannot be put down the drain in clean up. So any silver nitrate experimentation performed should be kept in containers and exposed of properly. This includes the silver concentrations, and hypo solutions that remove silver to keep from over exposing. The water used for rinsing the images is not something that has to be kept as the silver chloride is insoluble and will not wash away down the drain.

After Hypo Fixing

The hypo bath was arranged as four stations. Three minutes spent on each bath was necessary. The papers are immersed in a water rinse, then a hypo bath and then another hypo bath, ending in another water rinse. An hour of rinsing is required to remove any excess hypo from the images. This was performed at home as there was no more time in class. Keeping the images damp, we took them home to perform the final rinse. The hypo solution was a ten percent concentration made up by the instructor and the student assistant as the class went about their lab, making photosensitive papers and then exposing them.

Additional Information on Salted Paper and Photogenic Drawings can be found:

On Processes: http://www.alternativephotography.com/wp/processes/saltprints/a-dash-of-salt

On Processes: http://unblinkingeye.com/Articles/Salt/salt.html

Images in the Library of Congress: http://www.loc.gov/pictures/related/?fi=format&q=Salted%20paper%20prints--1850-1860.

Some History: http://albumen.conservation-us.org/library/monographs/reilly/chap3.html

Modern Day Salted Paper Artist: http://www.artlimited.net/image/en/278520

Summary:

Making salted paper is easy and relatively quick to do, allowing for easy fun. The silver is something to be careful with, however, as it can burn your skin. When working with silver nitrate, it is important to wear a lab coat to protect your clothes and skin, to wear gloves to protect your hands, and to wear goggles to protect your eyes. Not doing so is sort of foolish and not really something that is so hard to do that is avoided. It is best to only make the paper to be used to avoid any unwanted exposure beforehand in our situation, as the room we work in is not the darkest of rooms. Playing around with different types of translucent objects, perhaps color glass, and some objects that are thinner or thicker in density would be fun to do should there be more time. Should the opportunity to play around with process arise again, it would be interesting to experiment with digital negatives and creating what would be considered a photograph of these days, actual images of rooms, or something with a camera obscura, of even portraits in some manner. The color glass would be a particular interesting activity as it would bring into effect the filter papers that we experimented with. Different colors lead to different effects on the light filtering through to the paper and provides an interesting result.  A collage of glass and other objects might be something interesting, as well as the removal of objects and replacement with a new object to further play with the ghosting effect.


 
Image References:

1 - http://www.precinemahistory.net/images/talbot_oval.gif

2 - http://www.ssplprints.com/lowres/43/main/19/98554.jpg