Exakta 35mm Guide

888@ ##Above: Completc cassette (left)rnd its component parts.(8elow: Handle thc film by itssdtes.
HANDLING, trVINDING, TRIMMING 35 mm. FILMshould be perfectly dry, clean and dust free. Only a spotless,clean negative will produce the desired result! -
Whgn using bulk film in loading cassettes, the edge of thervork-bench can be marked with notches or drawing-pins toindicate various distances, let us say for 12,24,36 eiposuresof film. This considerably sirnplifies the measuring-of filmlengths in the...

m_4ke sure, while winding on, to hold the film only by itsedges.When winding the film on and off, care must be taken thatno great pressure is put on the film, and that the film-endsare not squeezed when drawing through the hand. Failureto take the first precaution may result in fogging, while
leglect of the latter precaution may give rise to peculiarkinds of exposure effects known as lightning flashes.These are due to electrical discharges, and appear as dark,zigzag lines running from the edge of the...

COPYING FILM. For -copying black-and-white objecrs (books,ledgers, etc.), a micro+opyingfilm can be recommendeil. It lias fin6grain, high resolution and contrast. For coloured originals there is apanchromatic type.
SPEED. The sensitivity of film materials to light in generalis expressed as a number of degrees, or as juit a nimber,according to the system used. The principal iystems are theAmerican standard (ASA) and the German standard (DIN).
Fpeed is._an asset, but it is a quality which must be piid...

CONYERSON OF FILM SPEED SYSIEMS
A5A & 85Arith.(New) +
*Also Weston Master lll and later meters.
In this table each value represents twice as fast a film speed as theone immediately above it.In some systems this doubling of film speed means increasing thespeed number by 3 each time (B.S. Log. DIN), while in others thefilm speed itself is proportional to the exposure required (ASA).GRAIN. Silver grains themselves form the picture in the emulsion.To the naked eye they form a cornpact, dark mass; but under...

35 mm. COLOUR FlU,tlSDISPLAYING THE COLOUR PICTURE. The colourtransparency can be viewed in a variety of transparencyviewers. The simplest consist of a magnifying glass set in aframe into which the picture can be inserted. If the vieweris held against a lighied background, the picture appearsenlarged and well illuminated. More elaborate viewers havean artificial light source of their own.The most satisfactory way is to project the transparencyin a slide projector which will throw a large picture on to...

EXAKTA LENSES
A wide range of lenses has been mounted for the 35 mm.Exakta cameras. The standard lenses arc 2 in. (5 cm.) or2l in. (5.8 crn.).Some of these lenses weie, or are, marketed by the manu-facturers of the camera, some quite independently of them.For that reason one mav find Exaktas r.vith lenses not listedin this book.Lenses of any focal length from 20 mm. to 1000 mm. andof apertures up to .f1.5 can be interchanged with thestandard lens in any of the 35 mm. Exakta cameras.A most important...

Ienses may tempt the owner to use them more frequentlythan necessary. It must be remembered that focusing a leniof long_ focal length has to be done more accuratEly, as,agaln, the depth of focus is considerably more limited thanwith lenses of shorter focal length. At the same time, owingto thelonger axis, slow exposure speeds of l/50 or l/25 wit[these lenses tend more easily to camera shake-if a rigidtripod is not used-than with lenses of normal focal lenpfih.
All Exakta lenses may be used in enlargers...