the optic camera

8/13/2019 The Optic Camera

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The optic camera

-Historical facts-

The word photograph, spoken or written, can be understood everywhere in the world, as it

represents a universal mode of communication. Its very first applied research was the study of solar

eclipses, and the first mention about the so-called obscure chamber can be found in the studies of ascholar named Ibn Al aitan !"#$ -%&'().

*ubse+uently, the physician and mathematician

irolamo ardano !%#&% -%#$) proposed the use of a

conve/ lens in the obscure chamber, thus getting a

clearer and a brighter light.

It followed other improvements as 0aniel 1arbaro2s

suggestion in %#$( to cover the borders of the lens,

keeping 3ust a narrow orifice in centre 4nowadays

stopping down procedure- in order to obtain clearer

pictures.

The obscure chamber was a very dark space and the

image could have been seen only by the people inside the room. In the long run, the obscure

chamber became smaller and smaller, particularly in order to e/ecute topographical works, and

turned into a portable camera, liable to be installed into a tent. *ir enry 5attson described the tent

that the famous erman astronomer 6ohn 7epler !%#% -%$'&) used to utili8e in order to create an

accurate and detailed panoramic

landscape. elped by a telescope, the

image was blueprinted on the paper

and 7epler reproduced it by drawing

all the forms. Afterward the tent was

rolled around its a/le and the operationcontinued until the hori8ontal tour was

completed.

owever, the process of reduction and

portability of the optic chamber was

going further. 7aspar *cott !%$&(

-%$$$) published 4in its book

9agical optic !%$#()- the first

description of a small obscure chamber

composed of two bo/es, a smaller one

introduced into a larger one in order to

obtain the e/pected clarity. 9ore, itwas ad3usted with a pipe consisting on two conve/ lenses, which served at seeing the image inside

without entering the obscure chamber.

:bscure chambers of all forms and dimensions turned out to be widespread and used in topography

for both civil and military purposes, for precise reproduction of drawings, maps and engravings at

different scales, and also in medicine in order to reproduce anatomical sketches as accurate as

possible. 0escriptions of real application of the obscure chamber in optical studies, encyclopedias,

painting treaties and books for high society games, were fre+uently published.

In the middle ;# degrees for refle/, the option for setting the clarity and frosted and fine glass for a

perfect picture. A single element was missing= the perpetuation of the image, the possibility of


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making it permanent with the help of some chemical processes. ?ntil the day there were discovered

completely new principles, the cameras had been made of ' essential parts=

The opening space through which the rays of lights enter into the camera@

A dark cavity 4the proper obscure chamber@

A plane surface -on which the image is pro3ected - or other system which makes the image

visible.

rom the point of view of the material the obscure camera is made of, it is created by black plasticand it forms a common body with the whole machine. In order to diminish the inner refle/es, the

obscure camera has some striations arranged perpendicular on the optic a/le. The striations are

chosen taking into consideration the material used.

The e/pose window - the

rectangular frame in which the

film is settled- ensure a standard

dimension for the picture, namely

B>;'$.

Cven if the obscure chamber is

very well protected from the

e/ternal agents is recommended to

be carefully dialed with as it is

very sensible at dust and film

pieces that could come off the film

and could sometime make useless

important pictures. 9ore, these

pieces of dust could deposit on the

lens diminishing the +uality of the

image.

The fundamental working principle for the camera was discovered even from the times of the

inventor and the architect Deonardo da


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The dimension of the negative image the camera is taking@

The fi/ing-distance system@

The shutter, with the help of which is achieved the the e/posing time.

onsidering the first element 4the dimension of the negative image formed on the sensible surface

of the film, plan-film or record -the cameras are mainly part of one of the following four groups=

ameras which take largenegative images 4over $;" cm- as *inar, Toyo, Dinhof.

ameras able to make medium negative images 4 $;" cm, $; cm, $;$ cm, $;>,# cm asGolleifle/, le/aret, Diubitel-B.

ameras capable of making smallnegative images -B>;'$ mm, B>;B> mm, B>; %,# mm- the

most important names from this category being :ri8ont, Horky, ed, Eraktica, Fikon, :lympus.

ameras able to make very smallnegative images, of mino/ type -%$;( mm, (/( mm, >;(

mm- as Agfamatic $&&(.

The destinations of the first category cameras are considered special destinations because they

are professional. Actually these domains, in which the cameras with possibility of taking very

large photographs are used, are multiple and very strict= works of photographic art, scientific

researches, commercial publicity, fine +uality replicas. This kind of cameras can be met in the very

large studios, where the negative images are usually transformed into e/tremely enlarged

photographs. 1ecause of the comple/ity these photos imply in their manipulation and because of

their weight, they are totally uncomfortable to deal currently with.

Cven their law price is not a stimulus for the amateur photographer.

The cameras that achieve negative image of medium format are using the roll film of the $;" cm

type for the amateurs too. These images of a medium format offer the possibility of magnifying the

image !%&&;%&& cm) at a good +uality. 9ore, all these cameras en3oy of an e+uilibrate weight, some

accessories that enlarge the activity area and also a very good system for fi/ing the distance. Thus,

the medium cameras are recommended for portraits, reportages and also for the pretentious amateur

photographers.

inally, the cameras achieving negative images of small type, often called cinematographic

images, are using the film with peripheral perforations, the so-called Deica films. ?ndoubtedly,this type of camera is the most widespread category at the moment, the number of marks and the

films in circulation being remarkable. Actually, these cameras are so convenient and handy as they

could satisfy all contemporary world pretensions. They posses an e/cellent optics, reduced

dimensions and a lot of accessories, in other words they are perfect and comfortable.

The negative images with e/tremely small dimensions, which use the special compartmented film,

offer obviously the advantage of an e/ceptionally dimensions and weights,

and they are also discrete and simple to manage with. Fevertheless, the accessories 4very useful

nowadays- are almost ine/istent, the +uality cameras are very rare and the processing of the film is

made in special laboratories.

As it was mentioned above, the second element

taken into consideration for camerasclassification was the system for measuring the

distance, because of its importance in

achievement of a high +uality photograph. The

producers lasting concern for a permanent

improvement of cameras technical performance

was obvious this time too. Fowadays we have

mechanisms and systems capable of ensuring

e/cellent conditions for the sub3ect observation

and for the establishment of proper parameters in

order to create very good photographs. There are

four categories of cameras, regarding the systemfor fi/ing the distance=

'


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-cameras having a direct system of visuali8ation, giving an e/act distance or not@

-cameras embedding a system for visuali8ation with a mirror or a frosted glass@

-cameras enclosing the direct visuali8ation system through the ob3ect lens, having a mobile mirror

and prism with a frosted glass@

The direct visuali8ation system is the most widespread mechanism, and it could be seen almost to all

cheap cameras. This system lacks the possibility of measuring and fi/ing the distance between the

camera and its sub3ect. The fact that this type of cameras is usually marketed at low prices does not

constitute a stimulus for the people to by them@ even they have the advantage of a very good

luminosity. et the cameras of this type are still produced by prestigious firms, they are e+uipped

with an improved sight, a very precise mechanism for the direct sight, named telemeter. 9ore,

for modern cameras was solved the problem with the paralla/ occurring in the cases of the different

distances photographs, and also the measurement 4direct through the ob3ect lens- of the +uantity of

light which touch the film, became possible too.

The process of eyesight is limited to a successive e/amination of the ob3ects around, which is a very

important physiological phenomenon. 0ue to this fact, we can orient in the space and we can

e/amine an ob3ect without taken into consideration too many details. enerally the eyesight process

is very complicated one because of the memory, which interferes with. The crystalline lens and the

cornea set up an image pro3ected on the retina and than this image is interpreted by the brain through

the optic nerve. In order to have clear images is necessary for them to be created on the retina, no

matter the distance between the eye and the ob3ect would be. onse+uently the eye must become

habituated with the environment.Eractically we can see the ob3ects in front of us because they are sending the ray lights towards us.

Thus, the images are temporary -fleeting - and they evaporate ones their cause disappeared.

*crutini8ing carefully nature2s way of resolving such a problem, the people created the camera. If we

are e/amining vigilantly one camera we will discover that it is similar with the human eye. In front

side, the camera has an open area e+ual with the crystalline, in which are fi/ed the optical lens,

namely the ob3ect lens of the camera. This ob3ect lens is responsible for the creation of the images

inside the camera. In order to normali8e the light entering inside the camera, the machine is provided

with a stop !diaphragm) which enlarges or diminishes the open area in front of the camera 4which is

the ob3ect lens- e/actly as the human iris does.

The telemeter is not actually a simple device, and the possible flaws are not very easy to fi/.

Eractically it is not a very fragile piece@ it rather re+uests a careful handling. The result of a measuremade by the telemeter it is the shown in the yellow spot. Thus, if the distance is correctly settled

the image will appear clear in the yellow spot .:n the contrary, the errors are registered when the

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distance is not an appropriate one. These kinds of errors, which can take a cut or a doubled form

usually, appear as a vertical, hori8ontal or sometimes diagonal cut.

The visuali8ation system with a mirror and a frosted glass could be found at the ma3ority of the

cameras of a medium si8e. This system offers the photographer a lot of advantages, for e/ample the

surface of visuali8ation, which is very bright.

The system with a mobile mirror and a prism used to be the most utili8ed camera as it offered a

broad range of accessories that could have been changed and adapted easily. The only limits of thistype of cameras were the possibility of loosing control of the sub3ect in front of the ob3ect lens.

As long as regards the

shutters, we could easily say

that they represent the most

mobile and dynamic part of

the machine and they move

3ust for an operation, a

multitude of pieces.

As in the ma3ority of the

domains, the electronics

penetrated the area of hephotographs too. There were

created a lot of completely

electronic mechanisms and

systems, capable of opening

automatically the stop

depending on the light value,

to fi/ the e/posit time, to e/ecute the e/act measurement of the distance.

The development of the photograph in the electronic direction, determined a new element of

classification=

completely automatic cameras, where is not necessary to fi/ the time, the distance and the opening of the stop@

semiautomatic cameras, where 3ust one system is electronic !for e/ample he stop)@

non automatic cameras, which have some electronic elements but with very restricted actions.

0espite of the technical advance of the photograph, the cameras still have the same base elements=

a. The body of the camera 4the obscure chamber@

b. The ob3ective !ob3ect lens)@

c. The diaphragm@

d. The shutter@

e. The sight@

f. The transportation system.

a) The body of the camera

It is very important for the :bscure chamber to be isolated, in order

the light can not enter the camera, e/cepting the light designated to

enter the ob3ective !ob3ect lens) to blueprint the film. The body is

usually pro3ected in accord with some ergonomic principles, so as to

permit an easy and fast access to the camera2s services.

b. The Objective (object lens)

The ob3ective allows the access of the light into the camera andfocuses the image on the film. It is the element that determines in a

large measure the clarity and the +uality of the final image. The main

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characteristics of the ob3ectives are the focal distance and the luminosity. The focal distance of an

ob3ective is measured in millimeters and determines the champ angle. After the focal distance, the

ob3ectives are divided in=

*uperangulars, with the focal distance till >& mm.

Formal ob3ectives, with the focal distance around #& mm.

Teleob3ectives, with the focal distance over & mm.

Those values are valid for a '#mm film and they are increasing once with the dimensions ofthe film used, thus, for e/ample, for a camera with $;$-cm film an (#mm ob3ective is normal. The

luminosity represents the ma/imum opening of the ob3ective diaphragm.

*tarting with the first ob3ective, the glass roundness that irolamo ardano had

introduced in %##& in the obscure chamber hole till the big variety of nowadays high +uality

ob3ectives, hundreds of skilful inventors tried to improve, step by step camera2s performances.

5e can see how ancient is the optic knowledge from the ne/t te/t of the hin dynasty,

dating B milleniums ago= cut an ice ball, lift it to the sun and put some dry grass in the shadow@ fire

will be born. It is the description of what we call now the focali8ation of the rays through a conve/

lens.

The focal distance is the first and the most important information that we need to have

about an ob3ective. It determines=a) the si8e of the sub3ect image that is formed on the film

b) the involved angle of the ob3ective

c) the format and the kind of camera that can fit

d) the depth2s clarity

e) the kind of deformation in perspective that are obtained

f) the applicability domain

g) the artistic effect that it promote

The photo cameras with visuali8ation through the ob3ective uses a mirror, a mat glass and a

pent prism in order to create the image in the sight of the camera, in accordance with the scheme

below=

%-the sub3ect to be photographed $-pentaprism

B-the camera ob3ective -the sight lens

'-the mirror inclined to >#degrees

>-the image on the film

#-the image on the mat glass

The focal distance of the otociar ob3ectives is of >&mm. Det2s try to clear the meaning of that

value. The more comple/ cameras have the possibility of the interchangeable ob3ectives, because= a

solid ob3ective usually has a focal distance like the diagonal of the format or bigger and being called

the normal focal. This kind of ob3ective is capable to gather a certain champ in front of it. Det2s

say we want to take a picture of a building= we must go away from the chosen building on the other

side-walk and when we try to hint we2ll see that only a part of that building ca be framed. 5e haveno other place to go. or that kind of situations, the modern cameras have the possibility to replace

the ob3ective with another that can contain more. This kind of ob3ective has a smaller focal distance

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and it2s called superangular. or the '# mm

cameras, named after the breadth of the film

they use, it was decided that the normal focal

distance to be around #& mm for the B>;'$

mm e/posure format.

a) The biggest the focal distance the bigger the

sub3ect2s image and vs.b),c) To the normal +ualitative camera, the aria

of the circle with ma/imum luminosity and

clarity has a diameter e+ual!or bigger) with the

focal distance. In the circle with the best

+uality it can place a rectangle or s+uare, the

diagonal to whom is e+ual with the diameter of

the circle so with the focal distance. This is the

way it is obtained the dates about the opening angle of the ob3ective and about the proper format of

the negative.

d) The depth clarity is conversely proportionally with the focal distance

e) The perspective modifies only concerning the camera sub3ect distance. The one modifying theperspective is the distance itself not the focal distance.

c) The Diaphragm

The diaphragm controls the

opening of the ob3ective and

determines the +uantity of light that

enters the film. It is measured with

the f-number that is a report

between the physical diameter of

the opening and the focal distance of the ob3ective, so no matter the ob3ective a certain value of the

diaphragm is e+ual to the same +uantity of light entered into the camera. ?sually it is controlled with

the help of a ring on the ob3ective. The diaphragm takes from the scale %@ %,>@ B@ B,(@ >@ #,$@ (@ %%@

%$@ BB@ 'B@ $> etc every value representing half of the +uantity of light admitted of the previous

value. or e/ample a fJ%,> diaphragm

admits twice luminosity than fJB.

The luminosity of the ob3ective

or his capacity of lightening the

photographic plate is usually

e/pressed through the fJnumber report,

which is determined by the focaldistance of the lens and of its diameter

or the diaphragm2s diameter that is

determining the lens aria. *o the fJ>,#

sign means that the focal distance of

the lens is >,# times bigger than her

initial diameter. The smaller fJnumber

report, the bigger the diameter for a focal distance and the luminosity on the speed of the lens is

higher. The time of the e/posure grows with the +uarter of the fJnumber report.


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The diaphragmatic effect The closing of the diaphragm diminishes the diameter of the diffusion spot,

like in the picture below. The diaphragm has two important functions= regulates the +uantity of light

that enters to the emulsion and modifies the depth clarity of the ob3ective. Fowadays the diaphragm

is installed between the groups of lens that are forming the ob3ective. ?sually it is used the Kiris

diaphragms, formed by a set of gliding lamellae, that are assembling concentrically, diminishing

progressively the diameter of the entering circle of the sun-beams. A pointing arrow shows the value

of the diaphragm into the sight, so the photographer can appro/imate the depth that he can use.

d)The hutter

The shutter is the mechanism that controls the time e/posure of the film to light. *imilar to

the diaphragms the control of time e/posure is made in steps, every one of them doubling or

diminishing the e/posure time%JB&&&@ %J%&&&@ %J#&&@ %JB#&@ %J%B#@ %J$&@ %J'&@ %J%#@ %J(@ % etc. or

e/ample a

%J%&&&-e/posure

time allows

passing half of

the admitted lightin a %J#&& time.

The shutter cam is of two types= leaf shutter and focal plane shutter. The number of the lamellae

composing that kind of shutter is between ' and $. The simple comple/ shutters have only ' lamellae

but their efficiency is low and those with more than ' lamellae have a better efficiency but they are

more complicated, harder to reali8e and more e/pensive. To the usual cameras has been developed a

single shutter that had the function of a diaphragm.

e) The *ight

It allows the visuali8ation of the image before being

recorded on the film, allowing also controlling the composition

and, depending on the type of camera, of clarity. or the ma3ority

of the photos we need something else besides the camera and the

ob3ectives. All these things are called accessories. The most

important are=

The C/posure 9eter

There are two types of e/posure meters= sure and unsure. 5ith the e/posure meter2s help

there can be made appro/imate measurements,

e/posure calculus for choosing with discrimination

and precision to those times that will give a

personal note to its own images. aving thepossibility to change the batteries when they are

finished, the photoelectrical shutters maintain their

+uality to a high level. It is better if the including

angle to be smaller than the normal ob3ective angle

and to offer a possibility of measuring the reflected

light and the incidental one too.

The Tripod and other Erops

The most important thing to a tripod is its head, meaning the part that takes contact with the

camera. The entire camera, have in a proper position that assures to e+uilibrate a place where they

screwed on the tripod2s head. The best tripod is the one called nut2s 3oint. In case the tripod did not

have such 3oint it must be bought. The 3oint usually must allow multiple positions of the camera,even the perpendicular up side down photograph.

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The


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"ny photo sensible negative material having as a prop a thin material li#e the celluloid or

the cellulose acetate$

The photographic filmis a plastic one, covered with microscopic granulates stratum on which the

light create a chemical reaction. In order to make the image to appear the film must suffer a chemical

treatment called development.

0epending on the film used it can be obtained slides or negatives= after that it can be made photos on

a photographic paper. Dike the eye, the camera records the image of some ob3ects. The film can beformed in different formats! plan film, film pack) in length! '# mm film) or in reel! roll film)=

plan film= semi rigid transparentprop, made by synthetic

uninflammable material, on which

there is a photo sensible emulsion

film pack= the package formed by%B negatives cut to a standard

distance, that also allows the using of

a desired numbers of negatives

without the obligation to develop the

entire package.

roll film= a band of photo-sensiblefilm wrap up on a wooden ,metal or

dplastic spool. In orer to be protected

by the light the film is covered with a banderole of opa+ue paper, black on the inside part, that also

allows the handling of the material in the full light.

The rally and the positioning system of the film

An advanced camera permits the control of the system, offering the continuous possibility of

rallying frame by frame !the camera made several frames per second as long as the release button ispushed) and a multi e/posure !the shutter is armed, but the film is mentioned on position for the

e/posure of a supplementary image).

%&

the optic camera

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