banding or shutter-bar on the film. This 

 condition is always present in a nonsynchro- 

 nized system but can be obviated through 

 the use of a special shutter on the motion- 

 picture camera which will synchronize its 

 frame rate with the 30 f rames-per-second 

 scanning rate of the television camera. A 

 large-capacity film magazine is desirable to 

 avoid missing important scenes. The stand- 

 ard camera is adequate for research purposes; 

 but to obtain film suitable for public show- 

 ing, a synchronized system must be used. 



A useful technique which may be used 

 in film recording is that of writing perti- 

 nent information on the protective window 

 in front of the picture tube with a glass- 

 marking pencil. The information is perma- 

 nently recorded on the film jind yet may be 

 erased easily from the glass for the entry 

 of new information. 



Single photographs are obtained with 

 any of several good-quality still cameras. 

 The low light intensity of the television 

 image requires a fast lens and fast film 

 for satisfactory photographs. Information 

 on photographing the television image is 

 available from many sources (American Cine- 

 matographer 1956, Barnes 1953, Cross 1954, 

 Eastman Kodak Compsuiy 1956, Morgan and Les- 

 ter 1955, Zworykin and Morton 1954). 



A tape recorder is a valuable addition 

 to the recording equipment for experimental 

 underwater television work. It provides a 

 ready method for recording all data on oper- 

 ational conditions and control adjustments 

 as well cis observational comments. 



DISCUSS ION 



Visibility 



Most of our work was carried out in 

 the offing of Cape Cod, Massachusetts, from 

 Pollock Rip Lightship north to Stellwagen 

 Bank, and in Cape Cod Bay at depths of 6 to 

 40 fathoms (near 42" N. latitude, 70" W. 

 longitude). The reinge of visibility under 

 natural illumination varied considerjibly, 

 depending upon amount and type of turbidity. 

 Mjiximum light penetration was ensured by 

 working on clear, sunny days from two hours 

 past sunrise until two hours before sunset. 

 Under ideal turbidity and light penetration 

 conditions it was possible to view an object 

 some 40 feet from the camera. 



Consistently good results were obtained 

 during spring and autumn with natural light 

 down to about 22 fathoms. In most instances 

 we were concentrating on haddock which we 

 were usually able to find in 18 to 22 fath- 

 oms. At these depths, visibility was usu- 

 ally limited to a maximum of about 15 feet. 

 The maximum depth in which we have been 

 able to observe fish in the net without 

 artificial light was 38 fathoms. 



Possible Improvements in Equipment 



Our field experience has brought to 

 light certain modifications and refinements 

 of the equipment which could result in even 

 greater operating efficiency. 



Camera 



The one important improvement indi- 

 cated for the caunera unit is the provision 

 of rollers on the camera carriage to permit 

 the camera to be slid in and out of the 

 housing more easily. The aluminum support- 

 ing rings of the present carriage scrape 

 against the housing, making removal diffi- 

 cult. Electrical problems may also arise 

 from the resulting aluminum scrapings. 



Camera cable 



As pointed out above, many equipment 

 failures arise from cable troubles, a good 

 mcuiy of which might be eliminated by incor- 

 porating the underwater television cable 

 into the trawl warp. Certain new problems 

 arise, of course, such as the necessity for 

 a special arrangement to provide for trans- 

 mission of circuits past the winch to the 

 control unit. Special motor driven cjible 

 reels which eliminate the necessity for 

 slip rings are available and can be used 

 for some purposes. Conductors for lighting 

 circuits can also be incorporated into the 

 towing cEible, further simplifying opera- 

 tions. 



We are developing a new connector in 

 which the stainless-steel core will be 

 anchored at the cJimera connector. This 

 connector will eliminate much of the strain 

 on the individual conductors in the cable 

 which occurs with the present type. 



Camera control unit 



The camera pickup tube occasionally 

 require electronic realignment necessitating 



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