The motion picture projectionist (Oct 1928-Oct 1929)

24 The Motion Picture Projectionist November, 1 928 §3L N ■ ota PlicKer ■^O dimming or wavering, but a strong, clean-cut x^ picture, and perfectly steady projection at all times, even during change-overs or when several arcs must be carried — such are the results when the Roth Actodector supplies the arcs. There is nothing about it to adjust — requires no watching. Let us tell you all about our varied types of Actodectors for every voltage and amperage requirement ROTH BROTHERS & CO. "The Leader of the World" 1400 W. Adams St. CHICAGO, ILL. New York Office, 52 Vesey Street Export Department, 44 Whitehall St., Nezv York, N. Y. ACTODECTORS .'■■-' ....■••:•'■-•:"; ;--V.i Keep your Simplex •t; :.%.«fa.j. ..... i — ^ 1 T ~ B £ cool with a "BEST" |P./;jii; "Cn\\ HEAT Shield #, 10 Your dealer has them. Price $3. ' BEST DEVICES CO. Film Bldg. Cleveland, Ohio Less Heat Insures Better Sound Reproduction (Continued from page 21) sets up a condition equivalent to a lengthwise movement of the sound projection optical unit from its correct position, with a like effect on the pureness of the projected sound. Warping of the film is usually a condition which occurs when the heat causing it is not quite sufficient to create a distinct buckle. However, warping causes the film to wave or to take other forms in passing through the projector which set up various disturbances. Its effect on sound projection is difficult to analyze, since it might cause any of the aforementioned disturbances. It is a quite well understood fact that for perfect projection it is essential that the film pass through the projector in a true, flat focal plane, as under such circumstances the objective lens is able to transmit to the screen a projected image of the film in perfect focus and with all of the high corrections of the objective lens utilized. In sound projection it is evident that for true tone values and to obtain a maximum of perfection, it is equally important to pass the film through the projector in a flat focal plane since the perfect functioning of the sound projecting equipment depends upon it. One can easily appreciate the fact that the engineers who developed sound projection accepted as a fact that the film would pass through the projector in a flat focal plane which is as it should, since buckled or warped film is an unnatural condition to projection. Less Heat Only Solution However, we still have heat on the film and film still continues to buckle; so what are we going to do about it to secure perfect results, both in projection and sound projection? Until recently nothing much could be done except to either reduce the amperage and be satisfied with poor illumination or let the film buckle and make the best of it. With the advent, however, of the new Model "H" Motiograph DeLuxe projector which was described in these columns in a recent issue, a remedy has been found. It is evident from the thorough and practical way in which the engineers have worked out the heat eliminating feature of this new projector by means of the new type cylindrical, horizontal shutter, that they must have been a step in advance of others in realizing the importance of this heat-onthe-film problem. In addition to its heat eliminating feature, the new shutter also serves two other purposes, both of which may be considered as a help to better sound projection as well as better screen projection. These are accomplished by the peculiar formation of the shutter designed to promote forced air circulation of such a character as_ to cool the aperture and the metal surrounding it and to tend to draw free dust from the film before the film passes through the sound pick-up aperture. A point in sound projection not readily thought of is the fact that dust on the film if it lodges in the