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he comments on precision and quality of standards given in item (a), bove, also apply here.

(c) and (d) The determination of the residual sodium thiosulfate ontent of processed photographic film is made according to USA Standard ethod PH4.8-1958 or the latest revision thereof.

Hypo concentrations less than 1 microgram per square centimeter re reported as "nil." When hypo concentration is 0.005 mg per square inch r over, it is reported to one significant figure.

Each sample

submitted should be identified properly, contain no mage (slight fog permissible), and must be submitted immediately after rocessing. Each sample submitted should be 6 to 8 inches in length and hould be attached securely to request letter by stapling.

Samples are not returned since they are destroyed during tests.

(e) and (f) The determination of residual sodium thiosulfate oncentration of processed photographic paper is made according to USA tandard Method PH4.30-1962 or the latest revision thereof.

Each sample submitted should be identified properly, contain no (slight fog permissible), and be of such dimensions that two strips, x 4 inches, can be cut for test.

mage

Item

12.135a

12.135b

12.135c

12.135d

12.135e

Description

Calibration of photographic step tablets for printing density, one sample.

Calibration of photographic step tablets for visual density,
sample.

one

Residual sodium thiosulfate concentration of processed film, one sample.

Each additional sample for the determination of residual
thiosulfate concentration of processed photographic paper.

Residual sodium thiosulfate concentration of
photographic paper, one sample.

processed

12.135f Each additional sample for the determination of residual

thiosulfate concentration of
submitted at the same time.

processed photographic paper

schedule, such as

12.135z Special measurements not covered by this

precise determination of optical density and measurements of resolving power of photographic materials.

212.140 General.

for

the attention of: A310, National Bureau of

Direct inquiries to, and mark shipments
Colorimetry and Spectrophotometry Section, MET
Standards, Washington, DC 20234. Telephone: 301-921-2761.

has

212.141 Spectrophotometric standards.

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(a) 212.141a: Transmittance of these standards at wavelengths from 365 to 390 nm (nanometer, 10-9 meter) and from 750 to 1,000 nm will also be determined on request in accordance with 212.141c. Values will be obtained for a temperature of 25 °C. The effect of a change in temperature been determined for these glasses outside the range of 390 to 750 nm. It is known, however, that for all four types of glass the temperature effects are very small from 750 to 1,000 nm, probably negligible for the usual room-temperature variations. On the other hand, temperature effects are always large for these kinds of glass when the transmittance as a function of wavelength is decreasing rapidly toward shorter wavelengths, so that increasingly large temperature effects may be expected for these filters in the ultraviolet.

(b) 212.141j and k: In the General Electric recording spectrophotometer the design is such that the radiant energy is incident in a slightly diverging beam whose axis is at 6° to the perpendicular to the surface. The specular component of the reflected energy is diverted from the entrance aperture toward a port on the side of the sphere. This port may be filled with MgO or with a black material so that the specular component may be respectively "included" or (for plane surfaces) "excluded" from the measurements.

to

the

(c) Only one Vitrolite working standard is needed for measurement of spectral reflectance factor on the General Electric recording spectrophotometer. This calibrated Vitrolite standard and the samples tested are in turn placed at the sample aperture of the integrating sphere and any highly reflecting substance such as MgO or MgCO, may be used at the comparison aperture provided the material to be tested does not reflect more than the comparison material. The reflectance factors of the test samples relative to a perfect diffuser are then obtained by multiplying (at the respective corrected wavelength) the values for these samples, read from the curve sheet, by the ratios of (a) the standard Vitrolite values reported to (b) the values for the Vitrolite, read from the curve sheet.

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Standards of spectral transmittance for checking the photometric scale of spectrophotometers. These are either 30 mm polished glass disks or 51 mm polished glass squares, 2 to 3 mm thick, designated as cobalt blue, copper green, carbon yellow, and selenium orange (disks will be supplied unless otherwise specified). Report includes: (1) values of transmittance at 25 °C at certain wavelengths from 390 to 750 nm, (2) estimated uncertainty of each value, (3) effect of temperature change on transmittance at each wavelength:

2.141a Each standard or square.

nm,

for standardization purposes.
good optical
optical condition.

Transmittance, 365 to 1,000
Samples submitted must be in
Measurements at room temperature.

(If the

sample is a disk

29.7 +0.2 mm in diameter, the measurements can be made at a special specified temperature.):

2.141b

One sample at one wavelength.

2.141c Each additional wavelength on the same sample.

calibration

Didymium glass standards for checking the wavelength
of General Electric recording spectrophotometers. These
consist of Corning 5120 glass, 51 X 51 mm,
polished. Report includes table of wavelengths of minimum
transmittance:

2.141d 400 to 750 nm, 10-nm slits, each standard.

2.141e 730 to 1,080 nm, 20-nm slits, each standard.

2.141f

2.141g

2.141h

2.141i

2.141j

2.141k

2.141e

3.0 mm thick,

For two calibrations on the same glass (items 212.141d and e),

each standard.

3130

Holmium oxide glass standards for checking the ultra-violet and
visible wavelength calibrations of recording spectrophotometers
with slit width less than 2 nm. These consist of Corning
glass, 51 x 51 mm, 2.5 mm thick, polished. Report includes
table of wavelengths of minimum transmittance:

240 to 370 nm, each standard.

360 to 650 nm, each standard.

For two calibrations on the same glass (items 212.141g and h), each standard.

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Working standards of spectral reflectance factor for use on General Electric recording spectrophotometers with perpendicular irradiation and diffuse reception. Standards consist of white structural Vitrolite glass, 102 x 102 mm, 8 mm thick. Report includes table of spectral reflectance factors relative to perfect diffuser at every 10 nm:

400 to 750 nm, specular component both included and excluded (on same glass), 10-nm slits, each standard.

730 to 1,080 nm specular component both included and excluded (on same glass), 20-nm slits, each standard.

For two calibrations on the same glass (items 212.141j and k),

each standard.

Working standards of spectral reflectance factor for use on the
Beckman Model DU quartz spectrophotometer with nearly
perpendicular irradiation and approximately 45° circular
reception. Standards consist of
of white structural Vitrolite
glass 38 X 51 mm,
11 mm thick. Report includes table of

spectral reflectance factors relative to freshly prepared MgO
at every 10 nm:

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The tests described in this section are made primarily for informational purposes and samples SO tested should not be accepted as "standards". All measurements are made at room temperature. For various types of spectrophotometric standards, see section 212.141.

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Spectral reflectance factor relative to MgO, normal irradiation and 45° circular reception, as obtained with the Beckman Model DU spectrophotometer, 254 to 1,000 nm:

212.142d One sample at one wavelength.

212.142e Each additional wavelength on the same sample.

212.142f Each additional sample, each wavelength.

obtained

on

including 100

Spectral transmittance or transmittancy curves
General Electric recording spectrophotometer,
percent and zero calibration curves and didymium glass curve
for checking the wavelength calibration. Report includes
Ozalids of tracings:

nm, with

212.142g Testing a single sample, 400 to 750 nm or 730 to 1,080 slits approximately 10 nm or 20 nm, respectively, of spectrum, either spectral range.

12.142h Each additional curve or each additional sample.

12.142i Same as 212.142g, but with both spectral ranges, 400 to 1,080 nm. 2.142j Each additional pair of curves or each additional sample.

2.142k

Spectral reflectance-factor curves obtained on General Electric recording spectrophotometer, including (1) Vitrolite calibration curve for correcting values relative to fresh Mg0 as 100 percent, (2) zero curve for checking the wavelength calibration. Report includes Ozalids of tracings:

One sample, 400 to 750 nm,
or 730 to 1,080 nm, with slits
approximately 10 nm or 20 nm, respectively, of spectrum, with
specular component of reflected flux included or excluded,
either spectral range, and either
of specular

reflection.

condition

2.142& Each additional curve or each additional sample.

_2.142m Same as 212.142k, except both spectral ranges, 400 to 1,080 nm. .2.142n Each additional pair of curves or each additional sample.

.2.1420

.2.142p

of

Reduction of data obtained as in 212.142g to n, giving table values of transmittance, transmittancy, or directional reflectance relative to MgO for every 10 nm, for each curve.

on the

Relative spectral sensitivity of photodetectors obtained
NBS Detector Spectrum Recorder over the spectral range 400 to
800 nm. Report includes a photocopy of the relative spectral
response curve:

Each photodetector sensitivity curve.

2.142z Special measurements not covered by this schedule.

212.143 Colorimetry.

Item

2.143a

2.143b

2.143c

Computing

Description

chromaticity coordinates and luminous reflectance factor or transmittance from spectrophoto-metric data for certain specified light sources, per source per sample.

Computing luminous reflectance factor or transmittance from spectrophotometric data for certain specified light sources, per source per sample.

Determination of the Munsell renotation or book notation of a specimen from its daylight reflectance and chromaticity coordinates, each specimen.

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