Voyage autour d'un appareil photo - Prisma 1942 favori envoyer

Travel around a camera - Prisma 1942

LivreIn the manner of “camera for the useless”, the “Travel around a camera” makes it possible to the children of 1942 to learn the bas of the functioning of a camera. The expansion of the digital photography is far from send back this work to the oubliette. Quite to the contrary, the young people of today who know/ their first photographic with a digital camera want sometimes to know the silver photography. It is for them that I reproduce here some extracts of this little book.
Under rather childish forms, the exposed concepts are it very clearly.
There hare even adults who should read this page.




It is a very small travel which we offer to you to make accompanied by Finette and of Taquinet, but a travel full of wonders.

Like they, well certainly, you often wondered how the beautiful photographs which illustrate your books and your preferred newspaper could come out of a small mysteriously closed box, and how this round eye, out of glass, which is on one of its sides, was able to see as well as us.

As with his little friends, Professor Fémur will teach it to you, and you will be soon able to make, you also, of beautiful photographic pictures

When you will be proud of your results, you will send to our Competition your more beautiful photographs, and your pleasure will be great to have done them without any help.

Undoubtedly, us oblige you not to make yourself development and printing, but that it must be well you who decided subject of these pictures, and the way of making them, thus you will increase your chances with our Competition.

You know well besides that only the work which one makes oneself is the means of learning quickly, and which knows if one day, when you become brilliant, you will not have the idea to make of photography your job, a job full with of pleasure.



After months of researches, Professor Fémur, Member of the Academy of Imprecise Sciences, come to see his efforts crowned of success.
Ten small red balls rest in a round box],… ten pills of Microtrapufilominate, which must make it possible to reduce the size of any living being.
- Quickly let us announce the good news to my old colleague Professor Transitoire, said the scientist.


GuidaIn the corridor, it meets Finette and Taquinet which it made come to the town of Capucine-sur-Brindille for the holidays.
- Do you come out my uncle? said Taquinet, you had however promised us to make us visit your Laboratory…
- I’m going to my friend Transitoire. I will be soon back. Enter and wait for me well wisely. Especially do not touch with nothing!

And the uncle Fémur moves away with bouncy.
Finette and Taquinet push the door of the Laboratory and enter in the room encumbered of small bottles and odd apparatuses.
- One often does not do the housework here, notices Finette. Look at the big cobweb, Taquinet! I will clean a little, my uncle will be pleased.
- Does not become aware you of that, the uncle well recommended to touch with nothing. Perhaps he makes use of dust to make his experiments! Ran-Pan come here!

GuidaThe dog of the two children which slipped into the laboratory and already on the trail of a mouse, gives up any chase to obey its young master.
While her sister examines with curiosity a glass balloon filled up of a green liquid where an old hat and a bone of lamb leg macerate, Taquinet approaches of the table of experiments and finds the round box leaved about by the uncle Fémur.

It calls Finette.
- The uncle left candies, come on, it will be a real treat!
- Don’t touch, the uncle would not be happy!
- It will not scold us because we will have eaten some candies… I am sure, moreover, that it held them for us. They are cough lozenges, thus take one! That will cure your cold!
Finette which is greedy lets try and accepts a small red ball. Taquinet which crunches already the biggest of the box gives one to Ran-Pan..
And immediately the disaster produced. In one second the children and the dog see their size decreasing so quickly that the surrounding objects take gigantic proportions.
A mouse big as a horse come out of its hole…
Ran-Pan, who has an uneasy conscience about the rodent, runs away while barking. Taquinet which does not understand what happen, pull her sister in a wild race.


GuidaMeanwhile, Professor Fémur who did not find Professor Transitoire at home, get back to his house.
He goes into the laboratory, sees the round box on the ground and the scattered pills and guesses  what is happened.
- Unfortunate children! They swallowed pills! There remain nothing any more but seven about them!
It gives a hint for to tear off the hair, of despair, but its hand meets only its bald head.


- Finette! Taquinet! … where are you? Shout it with a voice which makes vibrate the test-tubes.
Nobody answers and due… The two children who still run, heard this enormous voice which growl like the thunder.

Guida- The uncle is back! … Let us hide quickly! murmur Taquinet.
They arrive in a corner of the room where all kinds of heteroclite objects unwanted, of which an old black rectangular box, a camera.
- No time to loose, let us enter into this box! Ran-Pan, that courage does not embarrass, already took refuge inside.

The uncle Fémur who walks carefully, by fear of crushing the children, believed to hear a light sound in the far end of the laboratory, something like a trotting of mouse.


The cat Ratif which follows it jump up towards the camera where Finette, Taquinet and Ran-Pan were enclosed.
- Here thus where hide our disobeying, said the uncle Fémur while leaning.
- Come out, wretches, that I pull you the ears!
Only Ran-Pan answers him of a small barking, but of a tone so plaintive that the old scientist can prevent himself from smiling in his venerable beard.
- Let us go, the punishment is rather strong, Let us return to them first form.
It will take in a cupboard a small tube of green pills and returns towards the camera.

GuidaBut it stops perplexed.

- How to make them swallow these pills of Tricosavonite which neutralize the effect of the Microtrapufilominate? he says by pulling on his  moustache. They should not have the mouth larger than a hole of needle. Best is to put me at their size.
By care, it makes come out Ratif, because it does not want ending its days in the stomach of a cat.
Then, when it is reassured on this point, it swallows a red pill.
The effect is immediate. He sees the camera suddenly taking the proportions of a coach of railroads. He takes some steps and bangs with great knocks the wall.

- Open the door my children! … Open, it is me your uncle! Taquinet is not proud…
- Do you believe that we can open? He says to her sister.
- If you want that the uncle forgives us, do not make it waiting, answers Finette.
Ran-Pan prefers anything to say and will be done very small in a corner.

The back side of the camera opens slowly and Professor Fémur makes his entry in the dark housing. The children jump to him to the neck and are soon forgiven. Ran-Pan even is entitled to a caress of the old man.
Then the uncle takes a small mysterious look suddenly.
- Do you know where we are here? Ask it.
- In a box, Taquinet answers, perhaps in a shoe box, we did not have time to look at well, we were so hurry to hide us!
- If I did say to you, starts again the uncle that we are in a camera, you would be well astonished, doesn’t?

Finette and Taquinet open large eyes. In a camera! … They would never have suspected it, not believing only of one box which appears empty to them, it can coming out so much wonders. Their astonishment is transformed into curiosity.
And then Professor Fémur sees a splendid opportunity to give a lesson to his little friends.
- Thus let us benefit from this adventure, he says, to study photography together.
We are here in what is called the darkroom. Taquinet, opens a little that we see more clearly. Perfect, thank you!”
The scientist gets out a piece of chalk of his pocket and starts to draw on the black inner side of the camera.
Here a hermetically closed box, which we will transform into camera.


GuidaGuidaIf I bore a small hole on the front face of this box, the luminous rays will penetrate inside. I put  in front of this opening a small character… Immediately its reversed image will be projected on the bottom of the box]. Our camera is finished. Quite primitive, I admit it and not very luminous… It would be necessary to pose a long time to obtain an acceptable photograph. Moreover, the image would not be very definite.


- But if you bore a larger hole, your camera would be more luminous, said Taquinet which the subject interests.
- If I bored a larger hole, the light which would penetrate in this box would be stronger of course, so strong even as the darkroom would not be whole black any more! The image obtained, if I even obtained one from them, would be terribly deformed. No, there is another solution which consists in putting in front of the small hole a convergent lens, a magnifying glass, if you prefer, as your magnifying glass for postage stamps. This lens put in front of the darkroom takes the name of lens and gives a quite definite image when it is placed at a distance which varies with the distance of what one wants to photograph. It is said whereas the image is “focused”.

- Yes, but how to keep this image? … That you think of it, Taquinet, asks the uncle.
Taquinet scrapes his head, but the answer does not come.
- Well, to keep this image, the uncle carries on, it will be enough for me to put on the bottom a plate covered with a material sensitive with the light and called photographic plate. I will obtain, after treatment of this plate, a reproduction of the image…
- A photograph, said Taquinet.

Guida- Exactly! … the uncle answers.

Moreover, for understanding this explanation well, nothing is better than a good demonstration. Do not move! …

The uncle comes out the camera and, after having opened the shutter (about which we will speak further), places himself at some distance from the lens.
The children who are remained inside the box see not without surprised taking shape on the bottom the image of the uncle Fémur, who, the upside down, making their a funny face. Ran-Pan, which does not understand anything with all this magic, considers it careful to keep away.

The scientist calls the children then. They join their uncle, curious about what it again will teach them.
- I explained you presently that the light penetrates by the lens, start the uncle Fémur, and comes to strike the bottom of the darkroom by forming the image of the subject.
But the photographic plate that I placed at the bottom of this darkroom is very sensitive and this light should be determined. It is the shutter which takes care of this operation. It is said whereas the shutter make the pose or the instantaneous.


Pose, when it opens during a rather long time.
Instantaneous, when it lets pass the light only one fraction of a second.
- As when I open largely the door of the farmyard to make come out all hens or that I only half-open to make come out  that which one will eat for the lunch, said Taquinet.
Interested Ran-Pan raises the ear.
- Let us speak now about the diaphragm, starts again the uncle.
- The diaphragm, stops Finette, it is a skin which one has in the chest.
- Stupid animal, that has nothing to do with the photography, stops Taquinet.


- No, the diaphragm is a device which regulates the entry of the luminous rays in the camera. Small, when the sun is bright, it must be largely open when the light becomes less bright, as the knob of the radio which you turn in a direction or in the other according to whether you want to hear the orchestra of Radio-Bricole in all its width or the talk of Professor Diguedon like a murmur.
Taquinet extremely well understood the explanations of the old uncle.
- You speak presently about the sensitive plate, which did you call thus? Ask it.



- The plate or the sensitive film are made of a support, glass for the plate, celluloid for the film, on which one cast a layer of sensitive material with the ligh called emulsion. The emulsion is composed of a layer of gelatine in which microscopic silver bromide grains are drowned which will be impressed by the light.

GuidaIn certain films the emulsion is double, i.e. it include a sensitive higher layer and a lower layer of less sensitivity which the preceding one which allows a very great margin of exposure and thus cures the errors that one could make. Lastly, a dorsal layer prevents film from bending after development and thanks to its special coloring the role “of anti-halation”.
- The anti-what? Askes Taquinet. -
- The anti-halation, explains the uncle, i.e. this layer prevents the formation of the halation, which does not have anything to see, believe me, with “hello” of the telephone! One calls “halation” of the awkward reflections which are formed on the image when the light comes to strike the lens too highly.
Professor Fémur gets a magnifying glass out of his pocket and makes examine with the children the thickness of a piece of sensitive film.
They distinguish clearly the sensitive layer, with silver bromide grains, the support, and the dorsal anti-halation layer.
- Now that we have made knowledge with the camera, said the uncle Fémur, we will study the manner of us of being useful about it. For that, let us make a walk in the countryside, we will have the easiness to treat it all the difficulties which can arise to a beginner photographer.
- Then, we will find again our normal size, my uncle, asks Taquinet.
- Later, later, the uncle answers.

“For understanding well my explanations, it is necessary that you remain in this camera and, moreover, I do not want wasting my pills of Tricosavonite unnecessarily.
The Professor find again his normal size, seizes Finette and Taquinet and slips them into the pocket of its waistcoat, then the camera under the arm, it comes out of the laboratory. Ran-Pan, which remained in the box thinks with bitterness that photographers beginners or not are impossible people.

The uncle Fémur, after going through the garden, arrives in a meadow where feeds a fatty cow, the beautiful Beurrette. He stops close to a wood bench placed there and put down the camera there. Then, it comes out Finette and Taquinet of its pocket where the two children were neighbourly with a watch which made a noise of power hammer.

It places their on the bench and there sit down itself.
- Here’s the ideal place to explain the depth of field he says by opening the box of Microtrapulo-filominate.
Time to swallow a pill and it joined the children.
- Oh! Uncle, what a air volume displacement when you change size, declares Finette.
Ran-Pan left its forced refuge. He regrets it immediately when he sees to come towards him an enormous snail which bet with a friend to go round the pasture in one year and thus does not have time to lose.

The uncle and the children are again in the camera. On the inner side of the bottom Beurrette appears which rolls big eyes


If the image of the cow and a area extending ahead and behind the animal are perfectly sharp, on the other hand, beyond this limit, sharpness is less perfect. As Finette and Taquinet are astonished some, the Professor explains to them that focusing  is made exactly on the ruminant.
- The area of sharpness which extends ahead and behind subject, said the uncle, is called depth of field.
To increase this area of in-depth sharpness, it is necessary to reduce the aperture, if, however, lighting is favourable.
The diaphragm has, indeed, two functions to provide.
The first function (about which we already spoke) is to modify the luminosity of the lens.
The second function, which interests us at the moment, is to modify the depth of field.
With the diaphragm largely opened, the area of sharpness will be very limited but will increase in-depth, as we close the diaphragm.
The uncle leaves the camera and operates the diaphragm. Finette and Taquinet, which examine with attention the bottom of the box see the front and the back plane of the image to increase its sharpness… and this image becomes sounding…
Beurrette, outgoing of its nonchalant torpor has just made a moo which makes vibrate the walls of the darkroom. The Professor Fémur, Finette, Taquinet and Ran-Pan, after having swallowed each one a pill of Tricosavonite find again their normal size.
They carry on their walk in the countryside.
- We know all about the camera now, my uncle, said Taquinet, quickly let take a cliché to me.
The uncle Fémur smiles: - Oh! You have again many things to learn! You undoubtedly believe, like a lot, that to photograph consists in pressing on the click of the camera. The thing is not so, if you want to obtain a suitable photograph.
Do you know initially what it is that the exposure time?


Taquinet rather than to say a stupidity prefers not to answer.
The old scientist explains then:
- To impress our sensitive plate and to obtain a correct photograph, we let penetrate in the camera through the lens and the diaphragm, the light sent by the subject and that during a certain time.

The time necessary of opening of the lens is “exposure time”. For a well understanding, I will make a comparison:
“Let us suppose that at the time of a drive with bicycle, a tire comes to deflate…
- I take the pump and I reinflat, it is not complicated, said Taquinet.
- You then have three factors which come into play.
Initially the diameter of the tire tube… Then the size of the connection of the pump and, lastly, the air flow of the pump in compressed air. The inflation of the tire will take a certain time that we will call “duration of inflation”.
This duration of inflation depends on the size of the pump.
- If I take a pump of car, that will go faster! Answers Taquinet.
- Yes, but if instead of your tire of bicycle, you have a tire of my old 6 CV to inflate, you will be able to take off your jacket, because the duration of inflation will be increased considerably!
But let us return to our exposure time. If I substitute the tire tube by the sensitive emulsion, the opening of the connection of the pump by the diaphragm, the compressed air by the light intensity and the size of the tire by the sensitivity of the emulsion, you will easily understand what it is that the exposure time!
- Me, I understood, hazards Finette which, up to now did not say anything: the exposure time, it is the duration of inflation! The uncle Fémur taps the cheek of the little girl.
- Very well Finette, you understood! And if our emulsion is not very sensitive, it will take more exposure time to produce a suitable image, just as Taquinet will take more time to inflate a tire of car than a tire of bicycle!
In other words, less the emulsion is fast, longer is the exposure time! …
When the subject is slightly lightened, you will have to prolong the exposure time whereas you can allow yourself to make instantaneous, if lighting is favourable.
- With the instantaneous one, I photograph the subjects moving, isn't it, my uncle? Ask Taquinet.
- Provided that the movement is not too fast. Don’t forget that the shutter of your camera operates only to the 1/25 of second. If you had an camera of a higher class, of which the shutter speed reaches the 1/250 and even the 1/500 of second, you could take subjects moving extremely fast. Be thus satisfied with what you have and does not try to execute amazing feats, your camera cannot follow you. When you want to photograph a subject moving, take care not to move yourself. Retain your breath and presses softly on the shutter release.
“You will thus avoid having some “blur of moving” cliché, without sharpness. When you want to make use of the pose, put your camera on an unspecified fixed support: table, chair, or, better even, screws it on a photographic foot.
“You will have, moreover, few opportunities to take posed photographs ”



Admittedly, I do not respect the royalties, but I do not know if there have-rights of the Prisma editions.