acceptable, or any emulsion which gives equivalent results. 
2.9.2. For cameras in which the intended shape of the emulsion surface is a plane, the emulsion 
shall be supported on a glass plate. Flatness of the plate at the time of exposure shall at . i 
least meet the tolerance for the flatness of the film plane in the camera under test. 
Preferably it should meet one-tenth of this tolerance. Alternatively the plate should be 
adequately stable, its unflatness should be measured and computational corrections applied. 
NOTE: For present (1960) accurate calibration it is desirable that the plate be flat, or its 
errors known, to tl micron (see section 2.13.2). 
2.9.3. For cameras in which the intended shape of the emulsion surface is not a plane, a plate of 
the intended shape shall be used, or a flat plate may be used and corrections applied if it is 
established that the corrections lead to results equivalent to measurements made in the 
intended surface. 
Discussion 
In the discussion to section 2.1 we already pointed out the desirability to also check the | 
operation of the entire camera system, including the magazine, by taking exposures of the collimator | 
images on film. The film used should be the same kind as that used with the camera in photographic 
missions. For evaluation, contact diapositives on (microflat) glassplates should be used. 
If the operation of the magazine were to be tested in operational conditions excluding the lens 
cone by a suitable procedure, the same kind of film as used with the camera for photographic 
missions should also be used. 
2.10 Exposure 
The exposure level shall correspond sufficiently closely to that used ín practice to ensure 
that no significant errors in image position are introduced. 
NOTE: When the energy distribution in the spatial image is not symmetrical, the apparent 
centre of gravity of the photographic image may be displaced by underexposure or by 
overexposure. 
Discussion 
It is important to image on the straight-line section of the D-LogE curve, as already pointed out 
in the discussion to section 2.4. (Target). 
2.11 Processing 
Processing of the service emulsion shall be equivalent to that used in practice. An 
alternative emulsion permitted under section 2.9.1 shall be processed .to give the equivalent - — : M 
results required there. Care should be taken to avoid conditions which would produce strains 
in the emulsion. 
No comment. i 
2.12 Measurements 
Measurements shall be made in a way which permits all tangential measured distortions to P | 
be based on a single reference system. 
Discussion 
The measurements should be carried out in such a way that the overall lens distortion can be 
determined and reported in tabular form as corrections to x- and y-coordinate readings. 
2.13 Shape and Locating Surfaces for Films and Plates 
2.13.1 The departure of the film or plate locating surfaces from flatness, or from some other 
intended shape, shall be determined. 
2.13.2 These departures shall be computed with reference to an ideal plane-{or-other intended - - 
surface) so positioned as to fit the real surface well and to make the maximum value of 
absolute departure as small as possible by making the numerically largest positive and negative 
departures equal in absolute value. The positive direction shall be away from the lens. 
2.13.3 When a locating surface is in the magazine, all magazines to be used with the camera shall 
be tested. 
Discussion 
In the discussion to section 2.2 (Definitions) the distinction between reference plane and image 
plane was introduced. This distinction proves also useful when considering cameras where the film 
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