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Showing posts with label negative. Show all posts
Showing posts with label negative. Show all posts

Wednesday 14 December 2011

Fixing negatives and papers


It is important to fix your negatives fully, this will ensure their longevity.

Fixing removes the last of any light-sensitive material from the negatives stabilising and securing the images so they can be viewed in day light. The temperature of the fix should be the same as the developer and stop bath, 20 degrees C.
Most fixers nowadays are rapid fixers supplied in liquid concentrate form and will complete the fixing process in about two to five minutes. (always check the instructions on the bottle) over fixing will start to bleach the negative. These fixers are usually suitable for film and paper. There is a chance in the case of warm tone papers that they may suffer from bleaching of their warmth with rapid fixers, it would therefore be better to use a more traditional fixer made up from a powder to ensure no loss of tone.



Tuesday 13 December 2011

Experience


There is no substitute for..................

In the initial stages of your quest to produce a good set of negatives with your first film, you are starved of knowledge and information and read everything you can lay your hands on. This is counter productive and becomes confusing as different people have their own method of arriving at the same result. Pick one practitioner with a simple method and stick with them, forsaking all others until you know what results will be obtained when you pull the film from the developing real.

The more straight forward the method the less things need to be checked when something go's wrong. What people do not tell you is that film processing is very forgiving and if you don't quite get the time right, the temperature is not spot on or you forget to invert the tank the right amount of times it will not make a vast difference to the final outcome. Possibly they will be slightly thiner or denser than normal but what is normal in your case? It is not until you have processed a number of films that you will truly know. Once you know what to exepect you can then personalise the method to get the negatives that suit your own taste.

Monday 12 December 2011

Timing development


You should always base your process time on the latest information available for your usual developer. Then be prepared to use these figures as a guide or starting point. You should check each set of negatives carefully, if they are starting to look dark/dense then you will need to adjust the process time by say twenty per cent. If they are looking thin/light then a slight increase in process time is needed. It is a good idea to stick to one make of developer and film until you understand what it is capable of. By doing so, you will be able to extract every detail from the negative that was originally captured. With experience comes knowledge.

Sunday 11 December 2011

Agitating the developing tank.


The main reason for inverting the developing tank is to make sure that the film gets equal treatment in the developer. One of the best ways of achieving this is to tumble the tank by turning it from end to end.

Why do we agitate the tank? The developer interacts with the emulsion of the film. It vigorously attacks the silver it come into contact with and becomes exhausted. By inverting the tank you refresh this action, producing evenly developed negatives. It is
important to get this right. To little agitation will allow by-products of the process to build up, leaving pale-toned streamers as they slide to the bottom of the tank. Likewise excessive inversions will produce currents in the developer, creating uneven development. Most process times allow for agitation.
Once the developer is added you should agitate the tank for the first thirty seconds but before you put the tank down give it a slight twist and tap it on a hard surface ( it is a good idea to lay a soft towel down so you do not damage the tank) so you dislodge any air bells/bubbles that may have attached themselves to the film. Then you need to agitate for ten seconds in every minute of the process time about four inversion per ten seconds or as the developer manufacturers instruction advise. For example PMK Pyro recommend one inversion every fifteen seconds. 
I have used this inversion method from the start of my developing career ( no pun intended) and has produced consistent results every time. Once you have found a method that works for you; you should stick to it.

Friday 9 December 2011

Farmers reducer.


This is a follow on from my last post on reduction.

Over developed or over exposed negatives may need to be reduced to make them a better printing prospect. This is achieved with chemicals that strip silver from the final image. Like developing, reducing a negative requires practice so you get an idea of how much to take away. It is best carried out in a place that is well ventilated with diffused light so you can see the process at work. It is a good idea to pre-soak the film it will allow you more control by slowing the process down. With experience you will get to know at what point to remove the negative. The chemicals do not stop working instantaneously. Because you can repeat this procedure it is better to reduce the negative in small steps so as not to over do it.

Reducers can be supplied ready mixed or you can mix your own. The formula that follows is a proportional reducer for overdeveloped negatives:

Stock Solution A

  • Potassium Ferricyanide 7.5 grams.
  • Water 1 litre.

Stock Solution B

  • Sodium thiosulphate (Hypo crystals) 200 grams.
  • Water 1 litre.

Notes: Ferricyanide has good keeping qualitys if kept out of strong sun light. Once you have mixed the chemicals you should use immediately. If you are using a stepped method of reduction do not contaminate solution A with Solution B as it will stop working. Working temperature of 20 degrees. You can place a dry negative in solution A but will need to watch the process carefully for between 1-4 minutes then transfer to solution B for about 5 minutes.

Potassium ferricyanide is a poison. Avoid contact with your skin and do not breathe the fumes.

Checking development times?


How do you know that the negatives you are looking at are correctly developed and not under or over exposed. The only way to be sure is to do a test. What follows is a method to help you achieve this:
   Choose a subject like a view or still life to take a series of photographs.
   First you will need to determine what the correct exposure should be.
   Then set the camera settings to two stops under and take the picture.
   Follow this by setting it to one stop under and take another picture.
   Now enter the correct exposure settings and press the shutter.
   Next, one stop over and two stops over respectively.
   Once you have done this wind the film on two frames and repeat the procedure, once done do the same again with a two frame separation so you now have three test strips.
Once back in the darkroom cut the film into three strips. Give the first section of film half the recommended development time the second set twice the time and the third group the suggested process time. Then compare the combined results of exposure and development and you will be able to clearly see which was developed correctly. It's worth the cost of a film to know that your films have been correctly developed.

Friday 2 December 2011

Single shot developers.


One shot developers do what they say on the box! They are for single use and have a quality advantage over reusable ones, also removing the worries about usability. I know this may sound wasteful in these times of rising prices, but what cost do you apply for peace of mind when developing those precious negatives.


The advantages:

  1. Fresh developer each time.
  2. Ensures constant quality.
  3. Consistant developing times.
  4. No need to use replenisher.

In most cases these days most developers can be used as single shot, in the case of PMK Pyro and RO9 it is the only way.

What does developer do?


The function of the developer is to bring out the latent image held in the emulsion. This is achieved by a chemical reaction, acting on the silver, producing dark areas where it is light and bright areas where there is shadow. The negative is reversed later with the print. The two most important things to keep at the front of your mind are: the development time and the temperature. It is these two factors that ensure the ultimate image quality you later produce in the print. Too short a development time will produce too thin a negative, like wise too long a process time will make the negative too dence, leading to very short and very long print times.

Wednesday 23 November 2011

Types of Enlarger Negative carriers


There are two main types of negative carrier, with and without glass. There are arguments for and against each type. Lets be honest there are three types, the adjustable.

Glass-less carriers avoid the Newton rings effect (a post for a later date) but also have the disadvantage of allowing the negative to buckle when they warm up, this is more pronounced with 6x6 negatives. To minimize this you should be very careful when focusing and use a smaller aperture to increase the sharpness across the negative.

Another disadvantage of a glass carrier is dust; to be honest it is not the big deal that everyone makes it out to be. It is just a case of being methodical in your approach. The main advantage of glass carriers is that they keep the negative flat. Another plus is that you can experiment with unusual effects by using various materials such as flower petals, salt crystals and soap suds etc in the carrier.


There are adjustable carriers also, which are very handy as they allow you to mask out badly illuminated edges without having to increase the magnification, or you can adjust them to include the rebate of the negative.

Enlarger


An enlarger consists of:

Enlarger for 35mmm negs
only. with out multigrade
head. Condenser type.

A baseboard on which enlargements are made; a column, which serves as a slide for the support arm, that holds the enlarging head, which consists of the lamp housing that contains the bulb; a single or double condenser; negative carrier, a place to fix the lens; a means of focusing and lastly a red filter that swings in front of the lens.

The lamp contained in the light housing is of the opal type and has a power output of 75, 100 or 150 watts. The pearlescents of the bulb with the help of a condenser distributes the light evenly across the negative. The lens focuses and projects the negative image on to the baseboard or rather an easel with paper on it. The higher the enlarging head is from the baseboard the closer the lens is to the negative the greater the magnification. The closer the head is to the baseboard the greater the distance the negative is from the lens the smaller the magnification of the picture. The typical focal length of lens for 35mm negative is 50mm and for a medium format (6x6) is about 75mm.
A multi format Enlarger with multi grade head.
Diffuser type.

The negative is clamped in the carrier which incorporates a mask that is the same size or format as the film and then placed in the light box. It is not a good idea to cut the negatives into single frames, it is better to leave them in strips to make it easier to line the frame up with the mask in the carrier, this also means you are less likely to scratched them.


Focusing is usually done manually, although there are enlargers available with automatic focus, these are usually more expensive.

Saturday 19 November 2011

Fox Talbot a short history to his discovery


William Henry Fox Talbot born 1800 died 1877.

Fox Talbot was considered a polymath some of his interests and qualifications included Philosophy, Mathematics, Physics, Egyptology, Philology, Syrian, Chaldean cuneiform text and photography. Fox Talbot carried out his experiments at the family home which was Laycock Abbey Wiltshire.

Fox Talbot's sketch of Lake Como
using camera obscura.
 

The idea of photography came to Fox Talbot while he was on a family holiday at lake Como Italy. He was using a camera obscura and Lucida to aid his fruitless attempts to sketch the lake ( Pictured right is a sketch drawn by Fox Talbot of lake Como using a camera obscura in October 1833) He put these devices to one side and thought back to a procedure he had used with a camera obscura that put an object on to a piece of paper attached to the back plate; this image did not last long it disappeared like a ghost in to the night. It was at this time that he thought it would be nice to fix the image permanently to the paper.

Fox Talbot started looking in earnest for a way to fix an image to paper in 1834; he would first have to find a paper that could be submerged in a solution of salt and silver nitrate without it disintegrating. The result of combining these two chemicals would make silver nitrate a light-sensitive salt that was not affected by the moisture in the paper. He now had a paper that could be used for photogenic drawing. The first pictures he produced were of leaves and lace. He placed these on a sheet of light-sensitive paper and put a sheet of glass over them, then left them out in the sun.


Fox Talbot used many different types of camera to produce his pictures. There we a couple of cameras or boxes that only measured two or three inches which Fox Talbot left around the grounds of Laycock Abby in different places with light-sensitive paper in for about an hour at a time. They were nick named mouse traps by the family. His early cameras would use telescope or microscope lenses.

This is the picture of the famous Oriel window in the south gallery of Laycock Abby. It is the earliest surviving paper negative dated 1835. when originally taken you could count the two hundred tiny pieces of glass that made up the window with the help of a lens. This is a replica of the camera he used to take the Oriel window shot.

By chance in 1840 Fox Talbot discovered when re-sensitizing some paper that the image had appeared; this became known as the latent image. Before this time he was having trouble with the sensitivity of the papers. Although he had been able to fix the images by using a strong salt solution of potassium iodine of hypo to stop the images fading. This new discovery was a major break through that meant exposures could be achieved in one to three minutes instead of half hour or more. The year after Fox Talbot discovered how to make his photogenic drawing process more sensitive to light by adding Gallic acid to the process. He also found that a further treatment of Gallic acid and silver nitrate would bring the latent image out. It was time he changed the name of the process to Calotype (from the Greek "Kalos" meaning beautiful) the Calotype was a negative/positive process introduced in 1841. Strictly speaking Calotype should have referred to the Positive part of the process.



The advantages of the calotypes were unlimited prints from one negative, retouching could be done to the negative or print, the paper print was easier to see and could be handled with out damage and had warmer tones.


Some of the draw back of this process were that prints tended to fade; fibers in the paper reduced the quality of the print, making the focus soft but some people found this an advantage. Materials were less sensitive to light needing longer exposure.



For more information:

Friday 11 November 2011

Dry side of the darkroom.


Typical layout for dry side of darkroom
This is the area where you will have your enlarger set up. The table will need to be large enough to allow for timer, puffer (like a rocket air) and magnifying glass. There will also need to be space for you to lay out your negatives, printing paper, scissors and or guillotine/rotary trimmer and holding back and burning in tools. It is a good idea if this area also has cupboards and draws for keeping your paper and equipment in.

Saturday 5 November 2011

Developing tanks.


There are a number of well-known makes to choose from. The most popular and widely used is the Patterson system. Another and maybe not so well known is the German maker Kaiser no lesser a system. So what are the differences? When buying a universal developing tank, if cost is one of your main considerations the Kaiser system wins hands down as being very good value for money. So much so its worth considering if you are thinking of buying a Paterson second-hand.

Both systems have good and bad points to consider. Starting at the top in both cases I have found no matter how well the cap has been put in place it leaks slightly when inverting the whole tank. It can be a messy annoyance when using PMK Pyro as it stains whatever it drips on too. Yes I know that each system comes with an agitator but the Paterson one is difficult to use because it is so thin, unlike Kaisers which has a top to it you can grip and when turned also moves the spiral up and down in the solution as well. Each company uses a different way to fix their lids. Paterson's idea is a twist and click method which I prefer but can be miss aligned if you are not careful. The Kaiser tank has a screw top which I have managed to cross thread each time.

The Kaisers spiral design is the main reason that I have one of their developing tanks. I'm having trouble with kinking the film when loading 120 format onto Paterson spirals and have used lots of different ideas to overcome it. The main difference with the Kaiser reel is that it has two large feed in wings where you load the film which makes loading a lot easier and faster with no kinking. Because of the trouble I've been having with the Kaiser screw top tank I now use a Paterson tank with the Kaiser reel, it is a little loose on the centre tube but the C clip stops it moving up and down when inverting. So for now I have the best of both worlds.