Film cameras
MICROSIX - L User manual
User manual for MICROSIX - L. 13 pages in English. Read the original PDF, download or print a copy without registration.
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Document details
- Brand
- Microsix
- Model / document
- MICROSIX - L
- Document type
- User manual
- Language
- English
- Pages
- 13
- File size
- 1.5 MB
- Category
- Film cameras
- Document date
- Not specified in catalog
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Page 3 · Read text
MIGROSIX-t
Exposuremeter
Fig. 1 Measuring instrument with measuring head
@ : Registered
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The MICROSI4-Lis an extremelysensitiveexposuremeasuringdevicefor photo-Description micrographyahO can be used with any photomicrographicinstrument.lts large
MICROSIXcoveringB additionalexposuretime steps - reliablyaccommodatesalland measuringrange-the new exposuremeter is 250 times as sensitiveas the former
exposuretimes likely to be met with in photomicrographyfrom instantaneousex-
posuresof living specimensto the long time exposuresof weakly fluorescingob-Instructions jects. Even with extremeexposuretimes the microscopistwill hardly ever find it
necessaryto go to the upper or lower limit of the measuringrange of this in-
strument.Togetherwith our new Micro-Attachmentfor the LEICA@this exposure
meter can be used for detail measurements.The measuringfield is demarcated
by the outer test circle of the focusingtelescope.Evenwith this kind of exposure
measurementthe MICROSIX-Lcovers three more exposuretime steps than the'
MICROSIX with integrating measurement.Detail measurementscan also be
taken with our MICROSIX-Lon the groundglassscreen of the bellowscamera.
The operationof the exposuremeter could not be simpler:- The ASA speed of
commercialblack-and-whiteor colour film is first set as with any other exposure
meter; this is followed by placingthe little measuringeye over one of the mea-
suring sites, when the pointer will be deflectedtowards a certain measuringva-
lue. This measuringvalue is set on the yellow scale; the correct exposuretime
will then appearon the time scale oppositethe appropriatecalibrationvalue (see
Table).That is alll
Althoughthe MICROSIX-Lhas been speciallydesignedfor photomicrography,it
can also be used for any other photographicpurpose.The exposuretimes must
in this case be read above the stop values as usual.The viewing angle of the
measuringeye is 30o,which is roughly the same as that of the standardcamera
lenses.
Principle
TheMICROSIX-Ldiffersfrom the conventionalexposuremeters,thelight-sensitive
cell of which consistsof a seleniumphoto-element,in using a photo-resistanceas
" "measuringeye", and a battery.While the photo-elementconvertslight into elec-
trical energy,the photo-resistancemerely changesits conductivityduring expo-
sure. The electricalenergy actuatingthe measuringmechanism(pointerdeflecti-
on) is suppliedby a battery.This results in a considerablyincreasedsensitivity,
so that accuratemeasurementsare possibleeven of weakly illuminatedobjects.
*d .*id,,',,.*r:...---.-, i:,u-."*696,6View original page 4Page 5 · Read text
Construction
The exposuremeterconsistsof the measuringhead and the indicatinginstrument.
t Theinstrumentmeasuringby meanshead ofwitha cable.the photo-resistanceThe exposuremeteris connectedcan be switchedwith theon"Bright",indicating
"Dark", and "Off" througha leveron the measuringhead.
I
t -
2 a
2 b
3a
3b
2c Fig. 4
2d Fig. 3 Measuring head with switch D, B
Measuring head with measuring and OFF
Fig. 2 Measuring instrument The indicatinginstrumentcontainsthe measuringmechanismwith the pointerand
a numberof scales:
1 Scale
2a exposure times l. Indicatorscale b film speeds
c n u m b e r s1 . . . 2 1 with measuringvaluesfrom 1 to 12 and from 11 to 21. The upper part of the indi-
d light values cator scale accommodatesweak light intensities,(Darkness: D), the lower scale
3a in photomicrography: calibration strong light intensities(Brightness: B).
values in normal photography
DIN-ASA values 2. Rotatingscale
containingthe exposuretimes from 8 hrs. to r/moosec.,film speeds,a sequenceof
numbersfrom 1 to 21 visible in the yellow field, and the light values (red figures),
which are not requiredfor photomicrography.
3. Film selectordisc
showingthe ASA values,and a sequenceof numberswhich is identicalwith the
stop numbersused in normal photography.However,in photomicrographythese
numbersdo not indicatestop values;instead,they have the functionof calibration
values.Eachmeasuringsite has its own calibrationvalue determinedin the facto-
ry (see measuringsite and calibrationvalue).
www.butkus.usView original page 5Page 6 · Read text
Operation
Fig. 5 Back of the MICROSIX-L
1 Battery chamber
2 knurled disc
3 zero-setting screw
Testing the battery:
With normaluse in the MICROSIX-Lthe life of the built-inMallory batteryis app-
roximatelytwo years.During this time the voltage remainsconstant,and only de-
creasesshortly beforethe end of its useful life.
The state of the battery may be tested by movingthe knurleddisc in the back of
the housing.Duringthis operationthe pointerof the indicatorscale mustsettleon
the red mark betweenthe measuringvalues 8 and 9. lf it fails to be deflectedthe
battery must be e'xchanged.For this purposethe battery chamberis openedwith
a coin. Pleasemake sure that the batteryis of the "RM 625 R" type.
The Mallory types RM 625 and ZM 625 are liquid-proofonly up to approximately
25o C (77' F). At higher temperaturesthe electrolytemay ooze out and destroy
the instrument.Some types of mercury cells produce faulty measurementsbe-
cause of their higher voltage.A test should thereforebe carried out immediately
after the insertionof a new batteryas describedabove.
Zero point control
ln order to check the zero-settingof the pointer the battery is removed and the
MICROSIX-Lswitchedon. The choiceof rangeis immaterialduringthis operation.
The pointermust now cover the unnumbered,black line on the left of the indicator
scale. Failingthis the pointer of the measuringmechanismmust be adjustedto
this line by rotatingthe zero-settingscrew in the back of the housing.lt is im-
portantto carry out this control before taking the exposuremeter into use, since
the instrumentmay be slightlyout of adjustmenton arrival.View original page 6Page 7 · Read text
Figs. G-11 Measuring sites:
Outfit: FS Binocular Phototube, LEICA, Outfit: FS Binocular photo-tube, LEICA,
MIKAS with '/r adapter, and 10X eye- with Micro-Attachment for the LEICA,
piece in the photo-tube Outfit as before eyepiece GF 10X in the phototube
Measuring site A: in the emPty eYe- Measuring site B: directly above the Measuring site C: in the measuring
piece tube or focusing telescope of the MIKAS tube of the Micro-Attachment
1 / ' ' / ,
D
Outfit: FP Monocular tube with eye-
Outfit: Any bellows camera piece GF 10X , or other eyePieces
Measuring site D: On the groundglass with 8mm field of view, LEICA, MIKAS
screen of the bellows camera. These with % adapter and eyepiece GF 10X Measuring site E: in the empty eye-
calibration values are independent of Measuring site F: directly above the piece tube or
eyepiece and bellows extension. eyepiece GF 10X Outfit as E
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Measuringprocedure
Fig. 12 Set the ASA value of the exposure material,e. g.
25 ASA
Fig. 13 Place the measuringeye over the site, switch on range,
and read off the measuringvalue on the MICROSIX-L,
e . g . 1 8
F i g . 14 Set the measuringvalue on the yellow scale: l8
F i g . 15 Read off the exposure time opposite the calibration
value; e. g. with value 5.6 exposure time : r/5esec.
F i g . 16 Switch off the instrumentimmediatelyafter every mea-
surement.
F i g . 1 4
F i g . 1 2
5 6 11
19
\
F i g .1 3 F i g .1 6
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The calibration
Calibrationof the exposuremeter may be necessaryif the highestpossiblequali-
ty in the photomicrographsis aimed at. Calibrationis also requiredif the manu-
facturershave changedtheir emulsionsor introducednew products.With certain
methods of development,too, calibrationmay under some conditionsbe advis-
able. The values thus determinedby the user can be entered in the empty fields
of the table.
It is basicallyimmaterialwhere the exposure meter is calibrated.However,it is
preferableto use the same site for calibrationand subsequentmeasurement.In
the case of bellowscamerasthe calibrationshould be carriedout on the ground-
glass screenof tire mirror reflex attachment.
Determinationof the calibrationvalue
Set the film speed (ASA) by rotatingthe film dial. Inserta specimenof weak con-
trast range in the photomicrographicapparatusreadyfor the exposure.
Placemeasuringeye over meaburingsite and switch on range.
Read off the measuringvalue on the indicatorscale. Set the measuringvalue on
the yellow scale by rotatingthe outer knurled ring.
Obtaln a few trial exposureswith various exposure times. Note the exposure
times and the measuringvalue given by the MICROSIX-L(which,of course, re-
mainsconstant).
Example:
Measuringvalue 1 5
I l^ 24 sec. Exposure time: t lso 1lts ,le l l t
Film speed: 12 ASA
The trial exposurewith the best exposure time is selected, for instance with the
exposure data
Measuringvalue: 1 5
Exposuretime: r/s sec.
Film speed: 12 ASA
F i g . 1 7
On the rotating scale the stop values, which function as calibration values, faceAssumed correct exposure time of the trial
negative l/s sec, at a film speed of 12 the exposure times. ln the case of the exposure time l/s sec. it is the value 4. This
ASA, and a measuring value of 15, results value is now the calibration value as long as the type of film and development
in the calibration value 4 after the setting are not changed. Hence, the correct exposure time will be found above the cali-
of the above values on the MICROSIX-L. bration value 4 with all future measurements.View original page 10Page 11 · Read text
Micro-flashand exposure meter
The determinationof the correct light intensityfor flash photographywith the aid
of an exposuremeter is obviouslypossibleby indirectmeansonly. Basicallythis
is done by measuringthe image brightnessof the preparationin incandescent
light after the exposuremeter has been calibrated.The measuringvalue obtained,
in connectionwith the additionalscale of the exposuremeter, directly produces
the correct filter value (see also List 54-14).
Calibrationfor flash exposures
Apart from the possibilityof choosingbetweenfull and half power by changing
the dischargeenergy the light intensityof every flash is constant.However,for
the correct exposure of preparationswidely differing in practice it is necessary
to reduce the light intensityas accuratelyas possible.For this - light intensity
can be reducedby uniformsteps.Also, the filters are sufficientlyneutral,so that
colour casts are avoidedin colour photomicrographs.
The MICROSIX-Lis calibratedas follows:
1 . Placespecimenin position.
2. Switch on microscopelamp and regulate at a certain current strength,e. g. 6v
15W lamp at 2.5A; 6v 30W lamp at 5A (see also the colour temperaturecur-
ves below).
T'rKt T'rKl
5962-5t3
Ampere
Fig. 18 Golour temperaturecurve of Flg. 19 6'v 30W low-voltage lamp Fig. 20 12v 60W low-voltagelamp
the 6v 15W low-voltagelamp
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-1
3. Set film speed /onthe MICROSIX-L,e. g. 200 ASA.
4. Determinethe valuewith the MICROSIX-L,e. g. 6, and record it. feasuring
5. Take a series r/rfexposureswith one grey filter, or a combination of grey tr\ters,
accordingto t'ie followingtable: (Dischargeenergy half/full power as desired)
Measuring value
Light quantity o/s 100 50 25 12.5 6.25 1 . 5 0.75 0.4 0.2
FilterNo. 2 + 1 3 + 1 3 + 2 3 + 2 + 1 4 4 + 1
6. Select the correctly exposed picture and note the filter value, e. g. filter com-
bination2+3.
7 . Placethe filter scalesuppliedon the MICROSIX-L.
8. Set the measuringvalue on the yellow scale,in our case 6, when the exposure
time 15 will face f on the filter disc. This is our future calibrationvalue.Hence,
the calibrationvalue for the flash will be found on the time scale.lt can be em-
ployedas long as type of film and developmentare not changed.
With this calibrationit is now possibleto find the appropriatefilter value for
any preparation.lf, for instance,the exposuremeter shows the measuringvalue
8 (currentstrengthconstantat2.5 A or 5 A respectively),Filter4 must be used.
Fig. 21 MICROSIX-L with filter scale
for flash photographyin position
Spectral sensitivityof the photo-resistance
and the use of filters
The photo-resistcnceof the MICROSIX-Ldiffers from the selenium photo-ele-
ment in its reducedsensitivityin the blue and its increasedsensitivityin the red
range of the spectrum.The followingfilter factors should be used with the normal
filters for photomicrography:
Filter Filterfactor F
without filter, with yellow-green,or with yellow filter 1 x
with green filter 1.5mmVG I 0.5x
with strong red filter 2mm RG 1 4 x
with strongblue filter3mm BG 12 0.03x
The correct exposuretime is determinedas follows:
Exposuretime : F x time measured(with filter)
The spectral sensitivitydistributionof the photo-resistancealso displacesthe
calibrationvalue one step towards shorter exposuretimes if xenon or mercury
vapour lampsare used insteadof incandescentlamps.
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