THE CALIBRATION OF PHOTOGRAPHIC AND SPECTROSCOPIC FILMS

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Film Batch Variat ions of Reciprocity Fai lure in l l aO film

Thermal a n d Ag ing Effects in Relationship to Reciprocity Fa ilu r e

SEMI-ANNUAL REPORT

December, 1986

(SASA-CB-179833) TEE CALXEIiATICN OF F H O ? O G R A P H I C B P C S E C I E C S C C F I C EiIpIS, 1 : FILM BATCH VAEIATICNS CP B E C I € E C C I T Y FAILURE It4 IIaO E I L f l , 2: THERMAL A N D A G I N G EFFECTS IN R E I A T I G N S B I F TC EiECI€ROCI?P [florgan S t a t e 63/35

B Y

M87-11142

U n c l a s 43785

Kev in A. Peters, Pamela F. Atkinson, Ernest C. Hammond J r .

MORGAN STATE UNIVERSITY BALTIMORE, MARY LAND 2 1239

Submitted to NASA, Laboratory for Astronomy and Solar Physics, Goddard Space F l i gh t Center, Greenbelt, Maryland 20770

https://ntrs.nasa.gov/search.jsp?R=19870001709 2020-07-30T05:49:06+00:00Z

ABSTRACT

Reciprocity failure was examined for I la0 spectrocopic film. Three

separate experiments were performed in order 30 study film batch variations, thermal and aging effects in relationship to reciprocity failure, and shifting of reciprocity failure points a s a function of thermal and aging effects. The failure was examined over ranges of time between 5 and 60

seconds. The variation to illuminance was obtained by using thirty neutral density filters. A standard sensitometer device imprinted the wedge pattern on the film a s exposure time was subjected to variation. Our

results indicate that film batch differences, temperature and aging play an important role in reciprocity failure of I la0 spectroscopic film. A shifting of the failure points was also observed in various batches of film.

INTRODUCTION

A n examination of rec iproc i ty failure us ing l laO f i lm is necessary

because o f the ut i l izat ion of tha t medium f o r experiments performed when

NASA's Ul t raviolet Imaging Telescope, ( U I T ) , i s in orb i t , and including

o ther u l t rav io le t experiments tha t may be conducted by the Un ivers i ty o f

Wisconsin and others. Three seperate experiments were performed in o rde r

t o examine rec iproc i ty fa i lure. They were:

( A ) Film Batch Var iat ions of Reciprocity Fai lure in l laO f i lm

( B ) Thermal and Ag ing Effects in Relat ionship to Reciproci ty

Fai lure

Sh i f t ing o f Reciproci ty Fai lure Points as a Funct ion of

Thermal and Ag ing Effects. (C)

MATERIALS AND METHODS

The standardized wedge patterns were placed on I l a 0 Spectroscopic

f i lm in total darkness us ing a sensitometer w i th a 24 hou r burn in time f o r

the bulb. Each fi lm section was exposed to the light source for a specif ic

per iod o f time. Time exposures were in in terva ls o f 5 seconds f rom 5 - 60

seconds.

The development process included 4 minutes in Kodak D-19 developer,

4 minutes in Kodak rap id f ixer , followed by th ree minutes in Hypo

Clear ing Agent and one minute in Photo Flo. T h e film was washed for 30

seconds between developer and f i xer . A f te r the f i x e r process, the f i lm was

washed and the ant i - ref lect ion coating was removed w i t h a soft sponge.

T h e agi ta t ion o f the film, in the developer and f ixer, included a 30 second

agi tat ion followed by a 30 second soak, then a 10 second agi ta t ion - 20

second soak sequence up t o 4 minutes. A l l chemicals were in a water ba th

a t a standard temperature o f 2OOC.

Next, the f i lm was d r ied for a period of approximately 24 hours, and

the opt ical densities were read us ing a MacBeth Densitometer. The densi ty

readings were then recorded and graphed. The g raph coordinates were

opt ical densi ty vs. exposure time.

(A ) Film Batch Variations of Reciprocity Failure in Ita0 film

Four different film samples were used in order to s tudy reciprocity failure in llaO f i lm . These four samples of f i l m were exposed for various t i m e periods in order to detect reciprocity failure. Earlier experiments have shown that reciprocity failure in llaO f i lm can occur around 30 seconds of light exposure. The four f i lm samples were initially exposed to

light from a sensitometer for periods of 10,15,20,25,27,30,33,35 anti 40

seconds. In order to verify that reciprocity failure occurs a t 30 seconds, a second experiment was designed to focus on exposure times of approximately 30 seconds. For this study, exposure t i m e s of 25,27,30,33,35

and 38 seconds were chosen.

Each f i lm sample was developed and the densities were measured by a MacBeth Densitometer. The densities were then graphed by an IBM personal computer. The film samples were number coded for proper identification. The nurrbcred samples a r e a s follows:

1 - aged f i l m sample 0608-004-111 (-!-) 2 - new film sample 0608-003-111 (A) 3 - Ernie f i l m sample 5bc0608-007(0) 4 - aged film sample d0608-007-111 (0)

Each individual wedge for each f i l m sample was graphed a s a function of optical density vs . exposure t ime .

RESULTS The results seem to indicate that there was minimal reciprocity failure

of all samples a t the lighter density wedges ranging from wedge 1 to wedge 6. (see graphs 1 - 6 ) . However, a s the densities increased, each film sample began to show reciprocity failure a t different exposure times. This phenomena is illustrated in graphs 7 - 30. The results also indicate that there is a shifting of the failure points which could be due to

thermal, aging and batch differences between various f i lm samples. It

should be noted that this experiment included four different batches of

f i l m . The results clearly indicate that batch to batch variations play a substantial role in the phenomenon reciprocity failure.

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( B ) Thermal and Aging Effects in Relationship to Reciprocity Failure Three different film samples were used to observe the possible

relationship between reciprocity failure and temperature. '

Temperatures of 31OC and 39OC were chosen for this initial s tudy. The three different samples were taken from three different batches.

The three different f i l m samples were identified a s samples one, two and three. Fi lm samples two and three were aged samples of film , whereas film sample one was relatively new compared with the other

two samples. For this study, exposure times of 25,27,30,33,35 and 38 were chosen to detect reciprocity failure. Fi lm samples one and two were incubated for a period o f one hour a t 39OC and f i lm sample three was incubated a t 31OC for a period of one hour.

Each film sample was develnped a n d the notical densities were

measured by a h4acBeth Densitometer. The densities were then graphed by an IBM personal computer. Each individual wedge for

each film sample was graphed a s optical density vs. time.

' RESULTS

The results of th i s experiment indicate that the oldest aged film

batch incubated a t 31OC displayed higher densities and more dramatic reciprocity failure than t h e newer batches that had been exposed to 39OC for a one hour incubating period. (see graphs 1 - 5) . This indicates that reciprocity failure is effected more by aging of film

than small temperature variations. The age differences in the f i lm

was approximately four months and the temperature differences of

the f i lm batches was 8OC.

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(C) Shifting of Reciprocity Failure Points a s a Function of Thermal

and Aging Effects Two identical experiments were set up to detect reciprocity failure of

llaO f i lm between 5 and 60 seconds. This was done for verification of reciprocity failure of llaO film during these exposure times.

RESULTS

The data suggests that there is a shifting of the reciprocity failure

points from film batch to batch. Set one, which was developed first, indicates that reciprocity failure is occuring a t 15 and 35 seconds. (see graphs 1 - 3). Set two, which was developed last, indicates that reciprsciiy failiir-e i s occuring a t 20, 35 and 40 seconds. (see g raphs 4 - 6 ) . Since t h i s f i l m was developed from the same batch there appears to be a shifting of t h e reciprocity failure points. This could also be due to

thermal and aging of the film.

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