تويت
التصوير الفوتوغرافي الحديث
تطوير السلبية ..
الفيلم المكشوف ..
DEVELOPING THE NEGATIVE
Developing a roll of film is really a simple process . All you need to do is to follow instructions carefully and understand them as you go along . We will try to tell you not only how to develop your film , but also why each step is taken so that you won't be following instructions blindly . In that way , if you happen to use a different type of film , or a different style of developing tank , you will be able to modify these instructions intelligently and still get perfect results . The important thing is to understand what you are doing before you proceed .
We will start at first with the simplest methods , using as little material and equipment as possible . Later on , as you learn more about developing , you can undertake more difficult processing and mix your own formulas .
THE EXPOSED FILM
Before you start developing your film , it would be a good idea to stop a moment or two and see just what a film is made of , and why it needs development . We have already discussed this , but a brief review will give you a clearer understanding of what you are doing so that you can do a much better job of developing your film .
A photographic film consists of a sheet of plastic ( usually cellulose nitrate or cellulose acetate ) , one side of which has been coated with a thin layer of hard gelatin containing many microscopically small particles of silver bromide . When you made your exposure , you allowed your camera lens to project an image onto this film . The light , that was projected on the film , started a very interesting series of chemical reactions , producing a latent or invisible image in the film emulsion .
The exposed film with its latent image looks just like any other film . The latent image is so microscopically fine that it is completely invisible , but if the film is placed in a developing solution , the silver bromide of the emulsion breaks down around this latent image to form a visible image of silver metal . This image is then fixed or made permanent in a fixing solution that dissolves away the unexposed silver bromide . After fixing , the film is washed free of chemicals and hung up to dry .
Fig . 1 All that is necessary for developing a roll of film .
At this point , the film is called a negative , since the light values are reversed . Where the subject was light , it reflected a large amount of light into the camera so that a lot of silver was deposited ; where the subject was dark , it reflected very little light into the camera , and so at that point in the image very little silver was deposited . The negative , of course , is not a correct picture because the light values are reversed , but it can be used to make a print in which the light values are again reversed to make them correct . This process of printing will be covered in later assignments .
تطوير السلبية ..
الفيلم المكشوف ..
DEVELOPING THE NEGATIVE
Developing a roll of film is really a simple process . All you need to do is to follow instructions carefully and understand them as you go along . We will try to tell you not only how to develop your film , but also why each step is taken so that you won't be following instructions blindly . In that way , if you happen to use a different type of film , or a different style of developing tank , you will be able to modify these instructions intelligently and still get perfect results . The important thing is to understand what you are doing before you proceed .
We will start at first with the simplest methods , using as little material and equipment as possible . Later on , as you learn more about developing , you can undertake more difficult processing and mix your own formulas .
THE EXPOSED FILM
Before you start developing your film , it would be a good idea to stop a moment or two and see just what a film is made of , and why it needs development . We have already discussed this , but a brief review will give you a clearer understanding of what you are doing so that you can do a much better job of developing your film .
A photographic film consists of a sheet of plastic ( usually cellulose nitrate or cellulose acetate ) , one side of which has been coated with a thin layer of hard gelatin containing many microscopically small particles of silver bromide . When you made your exposure , you allowed your camera lens to project an image onto this film . The light , that was projected on the film , started a very interesting series of chemical reactions , producing a latent or invisible image in the film emulsion .
The exposed film with its latent image looks just like any other film . The latent image is so microscopically fine that it is completely invisible , but if the film is placed in a developing solution , the silver bromide of the emulsion breaks down around this latent image to form a visible image of silver metal . This image is then fixed or made permanent in a fixing solution that dissolves away the unexposed silver bromide . After fixing , the film is washed free of chemicals and hung up to dry .
Fig . 1 All that is necessary for developing a roll of film .
At this point , the film is called a negative , since the light values are reversed . Where the subject was light , it reflected a large amount of light into the camera so that a lot of silver was deposited ; where the subject was dark , it reflected very little light into the camera , and so at that point in the image very little silver was deposited . The negative , of course , is not a correct picture because the light values are reversed , but it can be used to make a print in which the light values are again reversed to make them correct . This process of printing will be covered in later assignments .
تعليق