Film cameras
OPTIX Camera - Pt. 1 User manual
User manual for OPTIX Camera - Pt. 1. 58 pages in English. Read the original PDF, download or print a copy without registration.
58 pagesEnglish4.8 MB PDF
Loading your manual…Open PDF directly
Document details
- Brand
- Optix
- Model / document
- OPTIX Camera - Pt. 1
- Document type
- User manual
- Language
- English
- Pages
- 58
- File size
- 4.8 MB
- Category
- Film cameras
- Document date
- Not specified in catalog
Search available document text
Find a term, then jump to its page in the original PDF. Image-only pages may not be searchable; check the PDF for exact wording and diagrams.
Page 1 · Read text
www.butkus.us
OPTIX
INSTRUCTION AND
EXPERIMENT MANUAL
BY PETER SCHONE, ENGINEER
loBix-kosmosView original page 1Page 2 · Read text
'(.1
165 66 67 68 69 72 73 74 7s77 78 76l|
52 @
ffiffi# @@
1. Objective Holding Ring. 28. Mirror Support. 56. Laree Obturator I
Z. Glass Mirrors (Zl . 29. Picture -Counting Dial. ( 387, Hole tz/1l
3. Glas s Sheet. 30. Dial S uppo rt. 57. Large Obturator II
4. Converging Lenses (5) . 31. Half Shells (8) ( 387, Hote t6. 4/l .
( Planar-Convex Igfi . 32. Daylight Obturator. 58. Srnall Obturator I
5. Divergent Lehses (Zl 33. Red Filter. ( IBd, Hote 7 . 5/l .
( Planar -Concave L86l 34. Green Filte r. 59. Srnall Obturator II
6. Srnall Converging r,€os. 35. Yellow Filter. ( rs/, Hote Lodl ( zl .. ( Planar Convex I0/) . 36. Blue Filter. 60. Slit Diaphragrn F ( l8l) .
7 . Large Converging Lens. 37, Transparent Mat Screen. 61. Converging Lensesl
( Bi-eonvex 37 .961 . 38. Articulation Axis (Z) . Support Rings ( 4l .
8. Lar ge Dive rgent Len s. 39. Plastic Bolt. 62. Elastic Rubber Band.
( Convex-Concave Zl .9ll 40. Filrn Advancernent Pe g. 63. Felt Band.
9, Mat Piece of Glass. 4L. Irriage Guide, 64. Bag with Cornponents
10. Lurninous Screen. 42. Support Bracket. 65 - 78.
I l. Flexible Mirror. 43. Nut. 65. Obturation Ratchet.
LZ. Universal Adjusting 44. Filrn Advance rnent Wheel, 66. Large Traction Spring.
C ornponent. 45. Vis ion F rarne. 67. Srnall Traction Springs ( Zl
13a. Microrneter. 46. Pedestal. 59. B olting Le ve r .
13b. Photornete r. 47. Square Conver ging Lens. 69. Expos ure Leve r.
L4. Front Lens Support. ( Planar-Convex ZZ. 8 ) . 7 0. Wheel Catch.
I 5. Diaphragrn Suppo rt Ar c s . 48. Obje ctive Half- Shells ( Z) 71. Picture C ounting Catch.
16. Strap, 49. Red Potas s ium Fe r ric 72. Mounting Screws ( 8) .
17. Ey" Lens Support. Cyanide (III) K3 (Fe (CN)O ). 73. Strap Buttons ( Zl .
18. Field Lens Support. 50. Fe(III) -Arnrnoniurn 74. Shutter Base.
19. Deflecting Prisrn. Citrate. 75. Pres sure Spring.
ZZ. Carnera Casitrg. 51. Pre s sure Sensitive 76. Shutte r Spring Support.
23. rrRapidrr Filrn Cassette. Sheets ( Zl . 77" Shutte r Button.
24. Tele scopic Tube. 52. Camera Back Panel. 78. Shutte r Button Support.
25, Diaphragm Adjustrnent 53. Sliding Tubes ( 3) . 79. Pierced Disk I(1 8y'Ho1e .8y'.1 .
Ring. 54. B"g with Cornponents 80. Pierced Disk II(18/HoIe 361 .26. Diaphragrn Ring. 55-63 and ?9-80. Adh esive Strip. Cut-Out Sheet.Z7 . Obturato r. 55. Obturation Arcs ( 4l , Ins t ruction Manual.View original page 2Page 5 · Read text
I. HANDLING YOUR LENSES
It is impossible to damage one of the parts throush lack of experience, if yo-u carefully iii.r-rrrJ"-ri?"""t.
From the start, you learn-the appropriate way of hand- ling all the parts. The,,follow!ng'parts are especially
delicate: rnat rnirror #9, .and instrurnents #l3a and l3b. Their surfaces ,.ro"t ,r..."" b" ;;";h;;";i;;;""
hands, as grease stains- or finger rnarks a." i.rpJs"iUt" to rernove. As fo.r the le-nses, yoo rnust only hoid them by their edges. Be carefut ,roi io touch their surface!
I_f you e-ver^drop a lens, consult the nCleaning Lenses
f::"1 the Optix Kitil chapter at the end. of this manual.
This last chapter also d6scribes how ro prepare an or- smSt] paint brush ( you rnust cerLiniy have one l_t"1"trn your paint box) to clean your lenses.
You rnust under no circurnstances wipe or rub any lens with a cloth, with- your fingers, o" *ith the palm,oi your hand. The dust.you were trying to get would scratch the polish of the surfa-... "a "fJ "i,-
of grease that would be invisible at first, "figni-i.y",*itt time, tarnish the lensr surface. "oofE,
Cleanliness in optics must truly be the first cornmand_ rnent! It is with good reason tiat the big optical lab_ oratories have cleansing'units at their J"t"L""u". --
In these laboratories, the operators are dressed in special_overalls, their shoes, 1.d rnust ihange street dust is not introduced into- the working area."o-ifr", During particularly delicate experirnent", put on fine white gloves, and wear *t lt. "Ei"rrii"is ""p".
You donr t have to attire yourself s-o ceremoniously; how_ ever, when you are working with glue or when your'hands
are greasy, it would be a good idea to wash your hands continuing with. youi experiments. d;;;;i= *l:::,sclentlst, experimenting with prisrns, lenses, reflectors and rnirrors, as you are now ibout to do, finds his re_ y?.rd in clear pictures which he can view through-;.;"_ fully cleaned lenses and apparati.
Z. IMAGES REFLECTED BY A MIRROR
If you place a mirror between two lines of a book text, you will notice that the lines are reversed in the mirror, In reality, a rnirror reverses irnages in the following
way: objects which are situated in front are placed tehind,
and are thus upside down in appearance, as in the lineunder the word OVER.
{Can we see the lines back in their proper position if weplace the rnirror between lines whi.'ch are already opsia.down? If you try this by turning the book upside'd";;, :i
it is seen that this works. Howlver, because we have
reversed the book, the line rnust be read from righi toleft rather than in the usual way.
i
"n'{View original page 5Page 6 · Read text
www.butkus.us
Not only the words, but the letters too are written f rorn
right to left.
You will also get ieversed writing if you place the rnirror
Iaterally along the edge of the text. Then, and if the
rnirror is placed on the right end of the text, letters sit-
uated far from the mirror - on the left - aPpear to the
rear, or on the extrerne right in the rnirror irnage.
Since the rnirror is placed laterally, there is a back to
front permutation, and a left to right permutation: we
thus obtain rrreversed writingrr.
If you want to see how a rnirror perrnutes or changes
back to f ront, simply place the rnirror in front of you,
and draw a line with a pencil - a line drawn away frorn
you and towards the rnirror; now, in the rnirror you see
a pencil which is corning frorn the back and towards you.
If you draw a V in front of the rnirror, it is seen as an
incornplete A in the rnirror. T"y to write the word OVER
so that it can be read norrnally in the rnirror: you will
notice that you rnust write your original word in reverse.
3. SECRET WRITING
If you place the rnirror between the lines of a book, which
is upside down, you will no longer be able to read the
writing in the rnirror, even if you are aware that it is
reversed writing, This fact has been known since the
tirne of Leonardo Da Vinci ( the farned physicist and
painter) and exploited by scientists, who wished to write
their results of their research in a writing which only
they could understand.
You too can cornrrrunicate in a similar secret writing.
You rnight argue that it would be too difficult, to write
letters in reverse. Well , not if you know a little trickl
Take an ordinary piece of carbon PaPer ( with the carbon
side up) , and place two thin sheets of paper on top of
this carbon paper. On the top sheet, write norrnally
with a pen or pencil, and on the back of the bottom sheet
you will find that your writing has been reversed.
When you wish to read the letter, you only have to place
it in front of a rnirror in order to read it norrnally.
4. SELF-PORTRAIT OR NOT?
If you stand in front of a rnirror and rub your right eye
with your right hand, what is your irnage doing in the
rnirror? It is obviously rubbing the eye which is located
exactly in front of your right eye. If this were not a
rnirror irnage, but a real person standing behind a pane
of glass, then that person would have to be rubbing his
left eye in order to irnitate exactly your rnirror irnage.
In a later experirnent, you will see what rnust be done
for the rnirror irnage not to be reversed. For the mom-
ent you can hardly imagine this, but on the other hand,
you will certainly be able to tell which of the three rnen
in the sketch painted his own portrait and which had his
done by another artist.
5View original page 6Page 7 · Read text
Generally, a painter holds his brush in his right hano.
But what happens when the painter is left-handed? This
is very simple: if we can spot any buttons or button
holes on a shirt, a jacket, or a coat' we can decipher
whether we are dealing with a rnirror irnage or not -
sirnply by observing the position of these objects.
5. OBSERVING WITI{OUT BEING NOTICED
A detective who has been inforrned of a planned robbery
in a seashore hotell s garage, wanting to capture the
criminals, would not place himself in front of the garage
and overtly observe the door. If he did this, the robbers
would certainly be suspicious and postpone their plans
for another day. But, if sorrleone at a certain distance
from the garage was looking out over the open sea with
a telescope, aPParently viewing sail boats, then the
robbers would believe thernselves to be totally unobserved.
They would not know ( thanks to a reflecting rnirror
placed in f ront of the telescope), that the image of the
garage door was reflected to the detectiver s eye.
You can build such a device if you ir-rsert the three sliding
tubes #53 into each other, and then place thern in front of vision frarne #45, which would serve as an trairning frarnerr'
On this rraiming frametr you pLace glass reflector #2
attached with three pieces of adhesive tape, as seen in
the diagrarn to the left.
6. INVERSING THE IMAGE A SECOND TIME
In the event that sorneone were to place a sign on the door
of the garage which the detective frorn the previous chap-
ter was observing with his rrdeflectionrr instrurnent, the
Digitally signed by Mike Butkus detective would find hirnself in difficulty' His rnirror DN: cn=Mike Butkus, o=Butkus But a only. reversed writing sign in camera manuals, ou=butkus.org, show the wouldMike Butkus email=mike@butkus.org, c=US problerns. these how knows to overcorrre real detective Date: 2021.08.01 23:06:59 -04'00'
He would simply take a second reflector, through which
he would be able to perceive the reflected irnage of the
first reflector. Because the objects which are inversed
by the first reflection are inversed again by the second
reflection, the image therefore aPPears in its norrnal
position.
Our detective consequently, would place a second re-
flector at the opening of his instrurnent, as shown in the
diagrarn. This rrdouble reflectorrrtelescope has the
advantage that our detective could now turn his back on
tJre object he is observing.
7. A SURPRISE RESULT
This is sornething that we do not see daily, and that does
not go by unnoticed! Irnagine sorneone looking through
an instrurnent placed at an angle in front of his face!
This is why our detective would think that he should hold
the instrurnent verticallv and above his head, and lookView original page 7Page 8 · Read text
www.butkus.us
through the lower reflector, thus seeing the area behind
hirn a-nd over his head. Holding his instrurnent this way,
the detective would be able to stand behind a wall and
remain unseen.
But whatr s happening? Now everything is once again
upside down!
8. HOW ARE RAYS DEFLECTED?
The detective draws hirnself a diagram which shows
him how the rays are deviated by the reflectors'
First of all, he draws a diagram shwoing how light from
an image is deflected by a single rnirror towards the
right. The light corning frorn the sign with the letter.s
L?nd R is dellected onio a screen' which shows what
the eye would see if it were the screen'
Here, we can clearly see how the rays comingJrom L
and Ii cross each other and change sides after being
deflected by the rnirror, A second perrnutatigl ( or
change) is produced with two rnirrors - the sides are
again exchanged bY the new mirror.
Next, our detective rnakes a second diagrarn showing
how the rays are deviated to different heights by two
mirrors. We easily notice how the instrument used by
the detective ( chapter ?) gives reversed irnages if it
is held in a verticil position. We realize that what'the
detective had in rnind to improve his instrurnent was to
deflect the light as in a subrnarine periscope' Now, 'after having turned the bottorn rnirror, the detective
really can rnake observations over a wall without
being noticed. He can also, look at the spectators
behind hirn while in the midst of a crowd watching a
football game. This type of periscope shows norrnal
pictures even if it is held in a lateral position.
g. ANGULAR MIRRORS
Two rnirrors, whose edges touch, while they are oblique
to one another, are termed Angular Mirrors. In each
of these rnirrors you see the reflected irnage of the
other, and naturally, the inversed image of anything
that is reflected in the other mirror.
Place the Angular Mirror behind the word OVER, printed
upside down. Having done this, you first see the word
ABER on the left and right, in reversed letters. On
the right mirror, the beginning of the word is at the
lowest point; and on the left one, the beginning of the
word is at the top-most point. At the center, you see
the rnirrors reflecting one another, as well as the in-
versed images of the word. If you have adjusted the
rnirrors correctly, it is astonishing that these inverted,
reflected images end up as one word - OVER - normally
written and in the correct posttion.
ltView original page 8Page 9 · Read text
10. THE IMAGE PRODUCED BY THE INVERTING
MIRROR
If you have a dresser or washroorn rnirror at horne on
which there is a triple mirror with adjustable sides, you
can then place one of the side rnirrors.on a slant re-
lative to the central rnirror. If you do not own one of
these, all you need is another mirror (as large as
possible), which you can hold next to any wall rnirror.
By looking into the corner of the rnirror, you will see
a reflected irnage, cornposed of two images which are
inverted, reflectbd, and re-united, co.tslqoently dis-
playing a normal image.
If yo.u now lift your right hand while holding a comb, the rrinverted reflected irnagerr will not lift the hand
which is irnrnediately in {ront of your right hand., but
the one which faces your left hand - just as if you were
not facing a rnirror irnage, but rather a living person
who is also lifting the right hand as you are doing....
You are now seeing yourself as others see you. An
Angular Mirror then solves the problern we encount-
ered in chapter 4.
II. AN EYE THAT CONSTANTLY WATCHES YOU
AIl angular mirrors, includin-g the one you can assernble
with two glass reflectors #2, possess one peculiarity:
if with one eye you watch the point of contatt of the two
rnirrors, the reflection will always be such that the eye
will be watching you - whether you are gazing into the
Angular Mirror, or either of the side rnirrors.
Of cour-se, for you to observe this characteristic, you
rnust adjust the rnirrors at a very precise oblique
angle to one another. However, this is not very difficult!
Sirnply hold thern so that the contacting edge passes
exactly through the reflected irnage of the pupll of the
eye, and each rnirror contains half the eye. This way,
you can see the whole eye between the tw-o of them. If
you then liold the rnirrors firrnly in place, foo will beable to move your head in eitherra lateral or horizontal
direction; the eye will always remain behind the con-
tacting edges of the two rnirrors. Do you want to know
how this is possible? Very simply: an Angular Mirror
sends back each bearn of light that strikes it ( and pre-
cisely in the direction frorn which it arrives) , as iongas it cornes frorn a horizontal direction and not on a
slant, The next two chapters will show you exactly
why this is so.
IZ, HOW IS LIGHT REFLECTED BY A MIRROR?
_We already know that a mirror reflects light r3ys.
Now we wish to know in what manner, or in wfrilfr ai-
rection this occurs. If you draw a line with a ruler,
the rnirror irnage of this line seems to run backwards_
As soon as you turn the rnirror slightly sideways, theView original page 9Page 10 · Read text
www.butkus.us line appears to break when it reaches the plane of the
mirror and pursues a different direction.
Place a mirror on the thick black line in the drawing
on the left. It is rernarkable that lines oblique to one
another extend thernselves without breaks in their re-
flected irnage s !
Starting near the mirror, go over the line ending in an
arrowhead, and go right up to the arrowhead,
If, while doing this you can look sideways in the rnirtor,
you will see how the pencilr s rnovernent is reflected in
the rnir-ror. The actual direction in which you are
rnoving your pencil , shows the actual rnovernent of the
entering light ray, once it has been obliquely deflected
by the rnirror.
You see then, that a line directed towards the rnirror
always continues in a straight line in the reflected irnage
( single arrow) , which is equal to the angle forrned by
the arrowed line that leaves the surface of the rnirror
( double arrow) A ball, kicked at an angle against a
wall, also bounces in the opposite direction and at the
sarne angle with which it originally hit the wal1.w The law that states that these two angles (the one de-
noted by a single arrow in the diagrarn, and the one
denoted by a double arrow) are equal, is outlined for
you in greater detail in chapter 33. It holds true for
any light ray hitting a reflecting surface ( scientists
say th;t this ray is reflected) , no rnatter if the ray
hits the surface at a srnall angle ( a) or at a greater
one ( b) . If it hits the rnirror directly frorn the front
it is thrown back along its own path.
If you place a rnirror on the thick black line on the
drawirlg on the left, you will see how each line is re-
flected as a straight line in the rnirror. You can tell
which line is which by running your pencil along thern
and, at the sarne time, watching the mirror'abt\ You will then notice that the trajectory of the ray is
reversible. You see the li'ne drawn as an incident ray
( the angle rnarked by a single arrow in the diagrarn
above) f just as clearly as the extension of the -refl'ec -
tion angle ( the one denoted by a double arrow in the
sarne diagrarn in the reflected irnage) , if you look
trbehindrr in the rnirror along the angle of reflection'
13. 14/HEN LIGHT FALLS INTO THE ANGULAR MIRROR
In this diagrarn you can see how the light rays falling
into an Angular Mirror, leave in exactly the sarne
direction by which they carne' When the rays fall
obliquely, the angle they forrn with the first surface
of thl rnirror is small , and the one they lorrn with tle
second surface is greater. As the bearn straightens
out and hits the mirror rrlore directly, the angle on the
first rnirror becornes greater, and the one in the secondView original page 10Page 11 · Read text
bepornes srnaller, The bold lines show the beams
hiitting the rnirror straight on. When this happens, all four angles are equal.
14, A THREE MIRROR REFLECTOR
A reflector rnust send back light received in the sarne
direction frorn which it carne; a driver of a car, seated
directly behind the headlights, is therefore reached by
the light reflected by the reflector of the car ahead.
This is the desired effect.
'Would the Angular Mirror of chapter ll rnake a good.
reflector? After all, it does return rays in the direc-
tion frorn which they corne ( as you saw in chapter 13) .
If you point the Angular Mirror in your friendis direction
( who is rneanwhile pointing a flashlight at it) , you will soon realise that the rnirror works, only if it is held
exactly at your friendr s height.
If you turn the rnirror so that the two side rnirrors are
pointed at each other, a difference in the height and
position of your friend would not rnatter; butLn the
other hand, he wou_ld not see the light bearns being
reflected - unless hisposition was exactly adjustJd to
the rnirror.
fhe best idea is to transform the Angular Mirror, so
that it possesses the characteristics of this type of
rnirror and also those of rnirrors set side by Jide and
on top of each other. This is achieved by providing
it with a reflecting surface. To do this, simply place
it on flexible mirror #11.
This cornbination of 'rnirrors ( cornposed of three
mirrors placed vertically on top of each other ), is called a triple mirror. You rnay prove that this triple
rnirror throws back all the light which hits it obliquely,
with a visual test: if you glance into the triple rnirror,
so that the pupil of your eye appears to be piaced be-
hind the corner where the three rnirrors rneet, you
can rnove your head in any direction without this eye
ever changing place. Once again, you can use this
phenornenon in adjusting the mirrors. Just before the
rnirrors are perfectly in place, you notice six eyes
forming a crown set about the central point; after a
slight re-adjustrnent of the rnirrors, the crown will
becorne one single eye.
If you cornpare this irnage with the one we previously
obtained in the Angular Mirror, you will rrotic" that in
this case the eyebrow is below the eye. Top and bottom
are thus perrnuted in the triple rnirror. If you observe
the irnage reversed, the top and bottorn then appear
in the correct position, but the sides are then dis-
placed, In any case, you cannot rnake this observation
with the eye, for, when you perforrn the experirnent
in which you view the image reversed, youi eye is also
then reversed. This experirnent can only be done wittr
a sheet of paper on the corner of which you inscribe,
t0
II
JView original page 11Page 12 · Read text
www.butkus.us
for instance, the word OVEFL If you hold this PaPer
upside down near your eye, you will see the word
OVER in the mirror inverted'
Seeing that one mirror grye: an inverted image and
two rriirrors give a normal irnage, it is not too surp-
rising that three rnirrors produce an inverted irnage'
For use as a reflector, it is unirnportant that the rays
are sent back inverted. aw
If you observe a reflector carefully, Yotr will-notice.
iijiit .o""i"t" of small shining triangular cells' Each
of these cells is nothing rnore than a triple rnirror.
consisting of three triangular sides of cornbined'mirrors
Most oftei however, the rnirrorsr surfaces cannot be touched for they are located behind a smooth and trans-
;;;;;i;";face'made of glass or of svnthetic matter'
On July Zl' 1969, the Arnerican astronauts who landed on
the moon left behind a laser reflector. The reflector,
very rnuch like the reflector we have discussed in this
chaptet, is being used by scientists to bounce laser light
beahs frorn the surface of the mrron back to earth' Even
if the reflector is not pointed directly at the earth, it
will reflect the light to its source.
15. A KALEIDOSCOPE
If you once again combine the two glass mirrors'
."i[i"g a si.tt--ple Angular Mirror, ( as you learned to
do in Jhapter 9) , yoo can then pl1,c-e a mounting screw
#tZ U"*rien them, This screw will be reflected three iirrr"". We will then see four adjoining screws arranged the 'A,'A ir, ."o*n shape. If you enlarge the angle which
two" rnirrors forrn, you will see only three screws - IAN [Kil the screw itself and twoof its reflections'
If, however, you reduce the angle, more inverted
screws will appear, and a rnagnificent drawing will -
result. When yoo at. finished this experirnent' donr t
throw the screw aw?f r as you will need it later'
The instrument with which reflected irnages are assernbled
to form drawi.ngs is called attkaleidoscoperr' If you
place a nurnber of rnulti-coloured PaPers, in randorn,
itJu., between the mirrors, a geornetric drawing which
can co.tstantly be rnodified ( if you ruffle the bits of
pape r) wiII aPPear.
il 16. A DRAWING INSTRUMENT
If you stand in front of the window looking down on-glass
strl.t #3, (which you should lean towards the wi'ndow) ' you will be able to see everything that is going on in
iront of the window, just as if you were using a mirror'
This segrnent of glass has a polished surface, and is
th,refoie smooth, so that it reflects aII the light rays'rl Furtherrnore, it is also transParent, so that the light
iay" fto.rr a sheet of paper, (which you shoul-d P1":"
o.ri.. it) , can also rlach yorrr eyes' If you hold the
llView original page 12Page 13 · Read text
glass sheet very near your eyer fou should be able to
reproduce on the paper, outlines of objects reflected
in the glass sheet. However, you will soon realize
that this procedure cannot succeed for three reasons:
Firstly, the reflected images shift relative to the tip
of a pencil held near the paper. This occurs even ii
you modify the inclination of the mirror only slightly.
Secondly, the reflected irnage is usually so brigfit
that the pencil tip becornes invisible. Thirdly, since
the irnages are reversed when they come into view.
they present an inverted drawing when it is turned
around.
Why abandon our experirnents already, just because
of a drawing instrument? Actually, it ii possible to
remedy these three unfavourable characteristics bv
making use of a few rrrore trtricks of the tra6"rr. '
I7. IMPROVING THE DRAWING INSTRUMENT
'jl To irnprove the drawing instrurnent, you must deviate
light frorn the window by using rnirror #2, before the
light goes through glass sheet #3. In other words,
send it onto the glass sheet via a detour - by having.it
hit the rnirror first. To accornplish this, yoo hold the mirror with its reflecting side towards-o"ithe
window, so that the light beams are repelled towards
the floor with only srnall angles of incidence and re-
flection. You then direct these beams towards vour
eye with the help of the glass sheet, which is held at
an oblique angle in front of the mirror. It does not
rnatter if the bearns of light pass through the glass
during their trajectory from the window to thJ mirror.
: So that you can easily rnaintain the glass sheet and the
,j mirror at the correct angles, we have drawn a mirror
support on the cut-out sheet.
A,{ter having cut out this support, you put a thin layer
of glue on one side of the contour"-opor which the edges
of the glass sheet and the mirror must be stuck. piess
these firrnly into place, ( the rnirror, with the reflec-
www.butkus.us ting surface turned towards the glass .sheet) Then,
wait until they are dry. Finally, apply sorne glue to
the- o-ppgsite edges of the mirror arrd tir. glass sheet,
and fold the other side of the support whiih is still
free. Press until this section ii al so dry.
The diagrarn on the left shows you the completed draw-
ing instrurnent ready for use. you can recbgnize the
gpper part of the new instrument by the turned down
flap of the central piece. you must observe the gtass
sheet from above.
Are you asking yourself how this new instrurnent
eliminates the disadvantages, encountered in the pre-
ceding chapter? The first disadvantage is now co-rrected
by the double reflection; therefore, a rnodification of
the inclination, in which the instrument is held, can no
l2View original page 13Page 14 · Read text
www.butkus.us
longer have any effect on the examined image. As long
as the angle between the glass sheet and the rnirror
rernains unchanged ( and these two have now been glued) ,
the bearn of incident light forms relatively to the beam
of reflecting light. This provides an angle which is
invariable, and upon which the inclination of the drawing
apparatus has no influence. Only a horizontal ( or
lateral) rnotion would cause the irnage to shift.
The over-bright quality of the irnages viewed through
the drawing apparatus is now irnproved by the glass
sheet - which deflects certain bearns so that they
neve r ente r the ins trument. It a1s o abs orbs othe r
bearns, with the same result.
Finally, the images are in their normal position and
level, due to this double reflection phenornenon.t
18. A MIRRORIS THICKNESS
You now know that polished, shiny, surfaces reflect
light. However, sornetirnesr fou may not be sure
whether a certain object reflects because its surface
is naturally shiny, or because it consists of a glass with
a layer of foil on its back surface. You rnight also want
to know the thickness of a certain frarned mirror
without having to rernove the frame. This can be done
easily. Just touch the glistening surface with the tip
of your pencil. You can easily notice whether the tip
is in contact with its reflected irnage or not. If it is
not in contact, this is because the shiny surface is
behind a transparent coating, such as a pane of g1ass.
Try this out with glass reflector #2.
Flexible mirror #11, on the other hand, has a polished
rnetallic surface. Here the object and its reflection,
touch when the object is brought up to the mirror.
This I touchingr is a valid criterion for all reflecting
s urface s.
You might think that the space between the tip of your
pencil and the reflected image in a pane of glass with
a layer of foil behind it, is equal to twice the thickness
of the pane of glass ( ie: the thickness of the glass
added to the thickness of its reflected image) . This
is not so. A pane of glass always seerns thinner when
we look through it. We will later exarnine the meaning
behind this optical illusion. A11 wetll say for now, is
that the distance between the tip of the pencil and its
reflection is only slightly greater than the thickness
of the pane of glass, measured when the tip touches
the pane of glass.
19. A CURVED MIRROR
Place flexible mirror #tt, 1 with its polished, glisten-
ing, surface face up) on sliding tube #53 and press its
edges down. You then have a curved mirror. lf you take
a look at yourself in it, your face will seern stretched
l3View original page 14Page 15 · Read text
and narrow. In this type of rnirror, all objects appear
narrower than they really are. Its advantage is that
more objects can be seen in it at once than in a flat
rnirror. A curved rnirror directs light rays ( captured uffi frorn the sides) towards the viewer standing in f ront
----N<4L* Iiquely,of it. In relativethis typetoofthernirror,axis aboutall objectswhich theappearrnirrorob- is curved. They also appear rnore cornpressed. '
The rnirror rnust be curved evenly for objects to be
narrowed proportionately. Its bent edges are in fact,
the arcs of a circle. Such rrreduction rnirrorsrr are
used on cars as rear-view rnirrors. Their field of
vj.sion is rnuch greater than that of flat rnirrors.
www.butkus.us
ZO. A CONCAVE MIRROR
Now take fl.exible rnirror #11 again and place it over l/1l\lW sliding tube #53, Bend it so that the shiny surface is
I on the interior. If you place any object near enough I nn to this arched rnirror, the object will seern larger
than it really is. If you hold the tip of your pencil
close to the rnirror, it will appear laterally stretched ryN out,
How is this effect in the reflected irnage produced?
The diagram on the left shows how the rays leaving
b frorn points A and B rneet at a relatively narrow angle
These rays are drawn with dashes. The rays which
leave frorn points A and B ( indicated by a solid line)
rneet at a wider angle, since the mirror is curved.
Therefore, the distance between A and B will seerrr
rnuch greater in the latter case, than in direct ob-
servation, A real concave rnirror - for exarnple a
circular shaving rnirror - is evenly curved on all
sides. Thus it is a fraction of the interior of a re-
flecting sphere.
ZL, A CONCAVE MIRROR AS A LAMP REFLECTOR
If you want the light from a larnp to shine in only one
direction, you can obviously place a rnirror behind the
larnp. In this way, the light rays, which are otherwise
lost in every direction, are projected in the desired
direction.
If the larnp is placed in front of a flat rnirror, ( as in
the diagrarn on the left) , the rays are still scattered.
If, on the other hand, the lamp is placed in front of aZfiMM concave mirror, the rays cluster together. If the curve of the rnirror is circular, the best concentration
of rays is obtained when the larnp,is placed at a dis-
tance from the surface equal to l/2 radius of the sphere
of this surface. The rays do not leave the surface of
the rnirror in parallel lines. Rays which aie directed
farther out and into the rnirror, cluster together, so
that the group becornes narrower. The further out
the rays are projected frorn their source onto the sur-
l4View original page 15Page 16 · Read text
www.butkus.us
face of the mirror, the closer their meeting point
will be to the rnirror. After the rays have rnet, they
disperse again.
If a projector has to throw light at a great distance,
the rays involved should be as parallel as possible.
The way to achieve this, is to use a concave rnirror,
the edge of which is not as curved as the central part.
This is called a parabolical rnirror, and is used in
car headlights.
22. MIRRORS WHICH MELT METAL
This seems unbelievable, but itr s true! Unfortun-
ately we cannot dernonstrate it with the three mirfors
that we have in our Optix kit, If we listen to stories
of olden tirnes, we find that rnirrors were once used
in battle to burn the sails of enerny ships. No doubt
you wonder how this was possible!
Take flexible rnirror #11 ( which has been curved into
a concave shape) and direct its shiny side towards the
window or a lamp. You will be able to see a bright
spot forrned, after which the rays disperse. The rays
merge when they fall parallel to one another onto a
concave rnirror. If the rays enter a parabolical rnirror
directly by the front, they unite at a single point.
In aiming this type of rnirror at the sun, all the rays
which hit the rnirror, unite at a eertain point. This
one point is very hot, because solar heat rays also
corne together at this point. We can easily light rnat-
ches with srnall parabolical rnirrors if we hold the
inflarnmable end at the raysr point of convergence.
If the surface size of a mirror directed towards the
sun is 1,000 tirnes that of the spot of light produced,
that spot then receives I,000 tirnes the arnount of heat
it would norrnally receive. We would obtain intense
heat if a concave rnirror several rneters in diarneter
were used.
Try to irnagine thousands of people seated at a football
game. If each of these spectators had a large wall
mirror, and all of thern directed their rnirrors at the
sarrre spot, the grass at that spot would gertainly burn
irnrne diately !
In the Mediterranean area, where the sun is very hot,
such a mirror actually exists! It consists of a great
nurnber of srnall rnirrors which can be turned towards
the sun. Even though the diarneter of this mirror is
not as great as that of a football field, rnetal bars rnelt
instantly if they are held at the point where the rays
conve rge.
23. CHECKING THE MIRROR
You already know how the images reflected frorn a
I5View original page 16Page 17 · Read text
curved rnirror differ from those produced by a flat
rnirror. Now you are about to find out how undulated
mirrors ( rnirrors with uneven shiny surfaces) , give
distorted reflected images, We say that such rnirrors ttlierr. Do our glass reflectors tell the tltruthrt? If
you look carefully at glass rnirrors #2, you will not
spot any defects, for they give perfectly good irnages.
However, in reality, there are very few perfectly
shaped glass pa-nes - whether they be window panes
or panes used to'cover mirrors. However, usually theee
defects are so insignificant that we must take a very close
look to be able to discern thern at all. How can we check 'our glass reflectors for whatever defects they rnight
have ?
Take one of these reflectors and simply place it flat in
front of you at a footts distance.
Then, extend your arm while holding a pencil before
the mirror, so that you can see the pencilt s reflected
irnage when you look flat along the mirror. If there
is an undulation ( or wavy motion) then the straight
pencil will seerrr warped, and will appear to be rnoving
if you change the position of either the pencil or the @N mirror. To spot other undulations (those running in
different directions along the surface of the rnirror) ,
sirnply check the mirror frorn different sides.
24, THE REFLECTOR TUNNEL
When you are not using your drawing instrurnent,
rernove the reflector frorn it. Check it as we have
outlined in the previous chapter. If the two rnirrors
are of different quality, keep the best one ( the one in
which the central part is better) You will need it
later for the photographic apparatus, so be careful 'ri1i
with it! On the other, draw two lines f rorn its corners, Yt! so that they intersect at the center. Do this on the back I
of the mirror and scratch the foil-coating away at the 'l
intersection point of the two lines. Use a sharp point { to obtain a hole with a Z rnm. diarneter. Place both #Z
reflectors facing one another, and to help you keep
thern in the correct position, place the half-shell #31
between thern. You can tie this part on with rubber
bpnd #52 wrapped around twice. Each surface alter-
nately reflects that which is present in the other sur-
face. This happens an infinite nurnber of times, and
I tW through the hole you have rnade, you can observe this. I.i
J
25. THE HIDDEN COIN
Very little light can penetrate a tall, dark, and narrow
tube, This is why your friend would not be able to
distinguish which coin has been placed on the table,
if you have covered it with a long tube consisting of
three sliding tubes #53 and vision f.rarne #45. The
more he bends over the tube, the less he can see the
coin. This is because his shadows are also penetra-
. ting the tube. Bring the tube nearer to the window,
r6View original page 17Page 18 · Read text
www.butkus.us
so that the light which is reflected frorn your friendr s
face, can light up the tubet s interior. If he wishes
to let the light penetrate the tube, heril think that he
must remove his head frorn the opening. Then, of
course, he will no longer be able to look inside!
You, on the other hand, knowing how to use mirrors,
know what to do. The rnirror with the hole laterally
directs light into the tube. However, tour eys, peer- ing through the hole, can follow the light down to the
coin. If the hole is a little srnall ( seeing -over'theas you must hold this mirror at an angle) , then look upper
edge of the rnirror and shift it a little to the side, yoo
will then notice the coin, brilliantly flooded with light.
26. THE BENT SPOON
Surely you have noticed how a spoon or a straw appears
broken or bent when you place il in a glass filled;ith
wate r.
You can continue these observations with a large bowl
filled with water. An object placed at the bottolm of
the bowl appears to rise from the bottom of the bowl,
your eyes approach the edges of the bowl and as you -aslook flatly along the surface of the warer,
If you go swirnrning you are aware that in order to pick
up a stone from the bottom of the lake, you must al-ways
probe more deeply with your hand than you had origin-
ally expected. When you look into water, stones app"a"
remarkably flat and at a very shallow depth.
As you can see from the diagram, each ray of light
that enters the water, bends ( or is refracied) , -and
enters into a steeper slope below the surface. If your
glance is centered, for example, on ray t ar , you willsee that it bends as it enters the water at point I and
that it is directed towards stone S which liLs at the
bottom of the bowl. Of course, you dont t notice this
deviation in norrnal observation, and usually you would
think this stone lies at the extension of your trajectory
of vision I ar ( at point A) .
You will no doubt be surprised to know that the distance
cover.ed by the light frorn point l to stone S is longer on
our diagram than the extension predicted from e.rt"y
point 1 up to the virtual position of the stone at poini A.
This is true however, becau.se in water all objects seem
closer to the observer by I/a of their real disiance.
Therefore, if you take 3/4 of the d.istance f rom point
l to stone S and compare this to the extension of the
trajectory of vision a, you then reach the apparent
position of the Stone at point A. This is due to the
fact that A is perpendicularly above S.
If you follow trajectory b, you then reach position B
where stone S is apparently situated. B is also located
perpendicularly above S and is 3/a of the distance be-
tween 2 and S, frorn point 2. You then will notice that
t7View original page 18Page 19 · Read text
the apparent position of the stone always becomes
deeper as your trajectory of vision becornes steeper.
27. AT WHAT DEPTH IS THE bTONET
If you look vertically into the water, the actual distahce
towards the stone and the virtual one ( caused by the
trajectory of, vision) , become one. you see the stone
resting at 3/4 of its actual depth. Therefore, a stone
resting at a depth of I meter under the surface of the
water seems to be at a depth of only Z5 cm.
1A.n-d. n9w let us pose ?- problem. place yourself on a bridge and photograph with the rtRefle* it carrre"a vou
will build from the eeparate parts of your kit, frorn
above and vertically, a stone resting at the bottom of
a lake. Hold the instrument 80 cm. above the surface
of the water. If, for inetance, the distance finder on
the carnera indicates 2, at what depth is the stone under
the surface of the water? Here is a little clue to help
you figure this out for yourself. When a known dis-
tance ( for exarnple, 75 cm. ) is t/+ less than the
distance we are looking for, it is 3/4 of the distance. 'W'e find the desired,distance by increasing the known
distance by l/3. t/l ot ?5 crn. is 25 crn.l and Z5 crn.
plus 25 crn. is equal to 100 cm.
Now for the solution! you hold the instrument g0 cm.
above the surface of the water. As the instrument is
regulated for a dislance of 2 rneters, there are Z rrreters
minus .8 rneters, ( or l. Z0 rneters left for the traiec_
tory in the water) This is the apparent or virtuai
distance frorn the surface of the *"t., to the stone,
and it represents 3/a of the actual distance. The actual
drstance is l/3 greater than the apparent distance, and
this thergfgre, gives l. Z0 rnete"" pto" 40 crn., *hi.h i"
equal to 1. 60 rneters. The stone co.rseque.rtly rests at 1. 60 meters, under the surface of the wit... Inciden_
tally, if an instrurnent with reflecting rhirrors has a
distance finder, you can easily measure the distance
of the instrurnent from the surface of the water. For
example, by placing a sheet of paper on the surface of the water ( -so that this sheet passes vertically Uru
lens of ihe ca.nera) , youihen only have to focus""a"i the
distance finder precisLly onto the street of paper,
and you are able to read the distance.
28. THE DIVERIS WORLD
You already know that light rays striking the surface
of a lake frorn above are reflected by thJ water. B;
c-an light rays also be reflected. under the surface of
the water? You donrt have to be a diver to find out
the answer! Now, just place a mirror in a bathtub filled with water. you ian look vertically down onto
the rnirror held in the water, since light rays faif ing
vertically into the water do not break. Then hold thZ
rnirror sufficiently sideways, so you can then see in it part of the bottorn of the bathtub. This is possible
l8View original page 19Page 20 · Read text
www.butkus.us
because the light rays are sent back by the water on
the surface, If you now slowly turn the mirror in
a rrrore horizontal position, you at first see only a
greater part of the bottorn at the center of the bath-
tub. Objects which are situated near the edges of
the bathtub but ouside of the water, suddenly appear.
You rnust then remember that light rays entering
water break upon penetration. Since all light rays
trajectories are reversible, a diver who is in the water,
looking up obliquely has the consequent possibility of
seeing the sides above the water. He can therefore
see the bushes on the shore above hirn. On a greater
angle above hirn, he can see the sky and the other
side the opposite shore. But, if he looks rnore ob-
liquely upwards, he will see the reflection of the bottorn
which is extended frorn the shores. A diver, therefore,
has above hinn (on the surface of the water) an entire
zone in which he can see all that goes on either on the
surface, or in the neighborhood of the stretch of water
in he which is diving. This zone acts as a circular---- opening in which reflected the entire irnage of the \ _-r bottorn of this stretch of water is incorporated. At
the crest of this zone, the bottorn of the reflected
stretch of water confuses itself with the image of the
shores in an incredibly cornpact and hazy rrranner,
At this point, the outline of objects appear colored,
29. A FINGERTIP WITHOUT THE FINGER
If you once again place a mirror obliquely in the water
and look down upon it, you will notice a very special
optical illusion. For best resultsr a' tr4nsparent con-
tainer should be used. Let your friend look into the
rnirror. He will not notice that what he sees in the
'mirror is the bottom of the tank. He will, on the
contrary, think that he is seeing part of the ceiling
above him being reflecr"ed on the mirror. Now, stick
your index finger in the water and find the area where
you can spot your finger in the rnirror. In the rnirror,
it now seerrrs that the tip of your finger is floating
f reely in the water. What you are really seeing in
the rnirror is the bottorn of the tank being reflected
by the rrrass o{ water situated under the surface, The
tip of your finger breaks into this image projected by
the lower mass of water, so that you can only see the
tip of your finger in the rnirror. You cannot see the
hand to which this finger belongs, for this hand is
outside the reflected rnass oI water. The rays tiat
your eyes are following to the surface of the water
( where this finger tip is located) , cannot leave the
water. This is because they are travelling at such
an oblique angle that they are once again reflected
into the tank.
30. OBSERVING OBLIQUELY THROUGH A GLASS
SHEET
You now know that you can only obgeive obliquely
through a conrpact substance ( optically speaking) ,
I9View original page 20Page 21 · Read text
such as water and glass, if the angle formed by the
light rays and the surface is sufficiently open. There-
fore, you rnight be surprised to learn that in spite of
this fact we can obderve obliquely through a sheet
of glass, without the intervention of a total reflection
back into the glass! How is it that light rays, which
have penetrated obliquely through the side of a sheet
of glass, always corne out on the other side? The
answer is sirnple! In a glass sheet, we cannot see
in a rnore oblique direction than that represented by
the light beams sliding through it. In each case, after
the bend following the penetration into the interior of
the glass sheet, the light rays develop steeper trajec-
tories relative to the exterior surfaces. As a result
of this, they are not reflected, If they exit f rom the
glass sheet on the other side, they are broken and
return to their forrner direction. A light ray always
leaves on the other side of the glass sheet at the sarne
angle by which it entered. It exists at a sPot which has
shifted sideways relative to the extension of the enter-
ing light ray. This shifting depends on the thickness
oflhe-glass and the angle of incidence. However, all
this is valid only when the two surfaces of the glass
sheet are parallel to one another. Lf you have a block
of glass whose surfaces are oblique to one another,
the result is alrnost certainly a total reflection. These
blocks ( made of glass or synthetic substances) are
called prisrns, when a rninimurn of three surfaces are
parallel to one another.
31. THE PASSAGE OF LIGHT THROUGH TRANSPARENT
BLOCKS
Transparent blocks do not allow iight to pass .hrough,
at least in one direction. Deflecting prism #19 acts as
a reflector entirely covered with foil (thus reflecting
all light) , for rays which stri'<e sorrre of its outlined II
surfaces. To see this, take a deflecting prisrn by its I
handle. If you look onto the deflecting prisrn in the
way shown on the diagrarn, you seerrr to be looking
onto a rnetallic surface, no rnatter what is on the other
side of the deflecting prisrn. The cause of this pheno-
menon is a total refleition, and to be exact, two total
reflections. You will get a clearer understanding of
this in the following experirnent.
-/4 32, OUR PRISM INVERSES RAYS IIi
You rnust certainl.y want to know why our prisrn is
called a deflecting prisrn, and if it can inverse an {:I
irnage. To test this out, place the border of the red
filter #33 on the srnall step of the deflecting prisrn.
Now, look down onto the slightly inclined surface at
the upper part of the prisrn. This surface is now also
red. When you rrrove the filter towards the right, you
notice that the reflected irnage of the red filter dis-
appears towards the left. As you have already-learned
in-chapter 10, this can only happen when there has been
a double reflection. The following experirnent will
z0View original page 21Page 22 · Read text
www.butkus.us
confirrn this, W'rite a very srnall nurnber ( say a 5)
on the edge of a piece of paper. Place this #5 on the
step on the deflecting prism. As in the case of the red
filter, if you have written the 5 correctly, it is now
reflected and inversed, on the same surface which has
previously reflected the red filter. The diagrarn on
the left shows how the light rays are inversed at the
two neighboring surfaces at the bottom of the prism.
At each step, there is total reflection.' Cbrefully
replace the deflecting prisrn and the red filter. you
will need thern again later!
33. THE SHORTEST DISTANCE
In observing the trajectory of the rays in the deflecting
prism, you notice that the rays of deflection proceed
along oblique angles relative to the incident rays.
Actually the two reflecting surfaces at the extrernity of
the deflecting prism, do not {orrn a right angle. The
angle which they form is greater than a right angle
( exactly 94ol . This is why, in the diagram, tf,e in-
cident rays falling vertically onto the first surfaceI (from which they had been repelled_) , do not forrn an
angle of 45" - but rather, one of.47". In chapter 12we
prornised to explain the fact that a reflected light ray
when leaving the reflecting surface, always forrns an
angle which is equal to that of the incident ray. On the
opposite diagrarh, you can see the different traiectories
which the reflected rays take from A to B. If you then
rneasure the length of the different trajectories, which
the light should cover frorn A to the mirror and.frorn
there to B, you will discover that the trajectories which
we have drawn in broken lines are longer than those
which are indicated by a solid line. In this latter case,
the two angles that we have drawn in, are equal,
Light always finds the quickest trajectory, which in
this case, is also the shortest one,
34. THE QUICKEST WAY
If you have read the last sentence of the preceding
chapter carefully, you will presume that the quickest
way for light to travel does not always have to be the
shortest. This is true!
You had an example of this in chapter 26: the breaking
of the light ray which we called refraction. The oppo-
site diagrarn will again describe this case.
Here a light ray travels frorn A to C. point A is in
the air, and point C rests in the water. We know now
that light travels quicker in air than in water. The
light going from A does not choose the shortest path
from A to C via B but rather the quickest trajeclory.
Thus, the path goes through D, because this rneans
that the light can stay longer in air. Therefore, the
trajectory through the denser water is shortened.
Even though this adds distance to the trajectory as
well as a detour, the light 3rrives rrrore quickly at
ztView original page 22Related documents and language editions
From the M. Butkus archive. Original publisher and archive notices are retained.
Check the model and edition against your equipment.
PDF verified 2026-10-10.