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W. The Columbus. Ohio ROBERT State OhioUniversity BARNARD
T h c potciit,ial and limitations of television as a means of comn~unicatinginformation to students in the classroon~for lecture demonst,rat,ions (see Fig. I), in several laborat,ories simultaneously, or in the study carrel, are now gcncr:rlly recognized. The preparation and dissemination of appropriat,c chemical information can center around simple-tooperate, inexpensive, and reliable elements: the tclcvision camera, video recorder, and receiver. The publication "Modern Teaching Aids for College Chemistry"1 identifies all the elements in a TV system suitable for the chemistry classroom or laboratory. This paper will reflect experiences which followed the publicat~ion of the report and used elements of hardware described
teaching Television for the Modern Chemistry Classroom, Part II Hardware therein. I n addition, changes in hardware nomenclat,ure dating from the AC8 publication and new prnducts will be identified. Since each of the three major elemenk in bhe TV system interrelate to produce a picture with good detail, it is important to identify cert,ain features in assembling apparatus to avoid misuse and possible unsatisfactory servicc. Cameras
Basic to obtaining a quality picture is the television camera. Generally the synchronizing source2 for a small closed circuit TV system is located within the camera. I t is possible t o obtain good quality, stable pictures suitable for transmitting, as v~deo-tapedprelaboratory. instruction on a multi-
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ceivers for lecture demonstrations, using EIA synchronized (the highest shndard), high resolution cameras such as the Sylvaiiia SC-RE. Cameras of t,his quality offer several choices of int.ernal component,s, picture tubes, lens turret,^, etc., t o meet most local requirements. A second choice of a lower priced camera with positive 2 : l interlace would he t,he General Electric TE-"A, surh
' Available from The Advisory Caruncil on Colleee Chemistrv. Slxw ford ~niversitv:701 welch 'llond. Palo Alto, ~ x l j f 8Xj0i. : a Synchrorrisation: See p. 13, "Modern Teaching Aids far Cullege Chemistry." Synrhronisaiion in belevisim~ syst,ems refers lo the el he^ the Drocess uf lockine.. toe.~ scanning beams of ihc ielevisinn eiimeraa and the televisio~lreceiver or display device. E.I.A. sync, 2: 1 Figure 1. A melting point observed by television. Two comeros were used, one focused on the thermometer, locked i,,terlxre, %,,d ,.a,rdom ilitet.. the other on the stage of the melting point apparatus. Special effects generotors (insert) con divide a TV roster into sever.1 components, or odd on orrow or circ~e.too ming the compact^^ equipment. some lace 'l" 'I' "" s).llrhl"'rvppliers of television special effects equipment include: Ampex Cmp., 2201 Lvnt Avense, Elk Grove Village, e??p'ex wavcf""m of ~ I Z I I pulses I ~ i l l the sesl~liing pallllinoir 60007; 8-11 ~ r o t h e r r~~~~~~~h carp., B O U I ~ colorodoj ~ ~ , ~ ~ ~~~~~i~~ ~ syrtemr, t CO., h475 D~~~ ~ ~ ~ of thci i n w e ~p~.od~leiug street, ~ng~ewood, N-W J~~~~~ 07631; ~ h . 1 " ~~~ ~~ ~ ~b 71 ~ so~~~ ~ ~~t td . ~, ~ ~,bo,, ~ ~ it ~ i~c h.~i ~ , tern ~ ~ ~ elerg o n~ 48103. tron beam. ~~
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positive interlace camcras sell for one-half to onet,hird the cost, of a high resolution EIA synchronized camera. Sharp stable pictures are produced by this typc of camera, but there is a noticeable diffcrcnce in t,he recorded pict,urc qua1it.y when using st,ill or st.op action. The least expensive cameras use a random interla~:c pict,ure syst,em. Cameras of this t,ype sell for one-t,enl.h the cost. of t,hc most expcnsivc closed circuit cameras. Thc Cnncnrd MTC-15 Video/RF closed circuit. t,clcvision camera is an examplc of an inexpensive camera whirh is oapahlc of producing a pioturc which can bc t,mnsmittcd directly t o a home-type receiver or a video monitor. The lower cost random iriterlace camcras might be invest,igatcd for applications where live let:t,ure demonstrations might be performed, for example, in a medium sized classroom, and where students could observe t,he demonstrat,iori on several R1' receivers as it is performed in front of a small camera. The overall ele~:tnmicquality of the signal from the lowest priced cameras generally renders them unsuitable for video tape recording, extcnsive R F , or video distribution. Television cameras use lenses of the same type as lFmm motion picture cameras, and the optical properties of good lenses will contribute significaubly to the qualit,? of the picture produced by a TV camera, regardless of camera cost. I n some cases the cost of necessary lenses may approach t,he price of the camera. Video Tope Recorders
About 20 models of vidco tape recorders are available in the United St,at,es, priced from approximat,ely $700 t o $4700. Generally speaking, as with TVcamcras, the higher the price, the more flexible t,he recorder, and the natc t,he educational field, because so many models have been sold, and thc performance of equipment in t,his format has been highly satisfact,ory. Features which will be of interest t,o teachers planning t o use video recorders include
planning t,o use the recorder in the clnssroom to play tapes nf demonstrat.ion experiments. (2) Ararraliuentrdio track. Sound rat, he added to a video tspo in t.w, fashions, eit,her a t the t,ime of initial recording, s y w rhronising aet,ion and lip movements wit,h the sound, ov later, as n. narrative. Adding sonnd later relieves presswe on the tearher dnring the pictwe recording, allowing him to coneentrate on the pirtnru prodoetian, and facilitates a caroful analysis of t,he pictorial cont,ent hefore cornmenling. Since (,he narrative (somet,imes referred t,o as a 2nd audio) track can be erased and re-recorded without interfering with the picture portion of t,he tape, considerable flexihility in prodming x eomplet,e tape is possible. (3) Color capnhililg. Sony I-in. video recorders provide for colov recording wit,h the addition of an ext,ernal (CrrlocAdapter Model CLP-1A) electronics package which is s slave unit to the basic recorder, coding or decoding video information so it can be processed by t,he recorder's electronics. This accessory is availahle for the new Model 210 recorder. Presently it does rml, appear to he economical to convert earlier model recordem for color recording or playhack. Tapes recorded on I& model recorders arc int.erchangeable with the early onits. Ampex recorders require int,ernal modification in earlier models (VR-7000) to play hack or record color pict,ures. A wide prodnrl. line of I-in. color or B/W recorders has heen introdwed by Ampex, and new models guarantee complete inte~.cha~,gexbility of tape rerorded on either B/W or colar models.
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Figure 2. The Bell a n d Howell color video tape recorder model 2920 user 1-in. tape operating at 6.9 in. per let, hos electrical push bunon controls for remote operotion, $top motion, second audio lrock, 90-rec, fast forword or revene, ond weighs 67 lb. For further informotion, contact the Tope Pmductr Div.. 71 00 McCormick Blvd., Chicogo, Illinois 60645.
The Bell and ITowell rerorde~model 2020 (IVC format), t,he latest entry into the I-in. video rceo~.derfield, h a an inherent color recording capahilit,y, and requires only the insertion of an addit,ional circnil, hoard to play baek color (sec Fig. 2). (4) Tape intcrchangeabilil~,. Basic design dilferences still prevent. t,he interchange of t,apes het,weeu 1-in. video recorders of diRerent mannfect,ure. Tapes made on some '/2-in. recorders cannot be played baek on similar makes and models; others ofi'er tape it~t,ercherrgcabilit,y only on units specially set, up a t t,he faetory; some, eomplet.e int,erchangeithilit,y. Specific statemenls or guarant,ees concerning interrhangeahility can be fomd in the factory specifications. Tape tension ndjrst,ment,s on t,he recorder and the general quality of the recorded ~ignhlare factom which cmnot always be complet,ely controlled and also cantribnte t,o t,he qnditityof the pict,nre when tapes are int,erchanged. ( 5 ) Local service. Viden tape recorders require periodic adjustment and service bvskilled technicians: in addition.. redacement parts are highly speeinliaed. Schools wifh s eommitlment for unint,en.npted recording or playhsek, e.g., weekly video-taped laboret,ory pre-labs, mighl well consider t,he availability of immediate service a s prime consideration in purchasing equipment,.
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Television Receivers
The most important link in t,he communication chain between the tclcvision source and the viewer is the television display; present,ly it is also the weakest link. TV displays arc divided into t,hrce types: receivers, monitors, and projectors. The television receiver essentially is a dcvicc which is intcnded for home use, and is equipped with a radio frequency (RF) tuner designed to receive a broadcast typc TV signal which can be separated into picture and sound components, and amplified t.hn)ugh the appropriat,~electronics to form t,he composite picture wc arc so familiar with at home. Resolut,ion3 from t,his t,ype of viewer is approximatcly 300 lines. Vestdotion (operntimal definition): the nrlmher of v e r l i d lines on x standard test pattern which can bo dist.inguished 01, n horisontslly scanned line i n (,he l,elevisiou raster. The inlmher of horimntnl scanlling lines is fixed a t 323; reah~t,ir>n is n f w r t,ion of bandwidth and may run 11.0m 200 1-0 1200 lines i n video systems hut is limikd 1.0 :$XI lines i n R F systoms.
Educational television receivers many times are "dressed up" domestic models and seem to lack features found in video monitors or commercial receivers which contribute to extended life and reliable operation. Additional controls and features found on the "educational" receivers can be confusing to students and teachers and make routine adjustments and servicing timeconsuming and expensive. The need for features such as non-standard video-inputs, extensive audio input-output jacks, switches, etc., should be evaluated for specific applications. The television monitor (so-called because of itsoriginal use for monitoring pictures in TV studios) is superior in design and performance to the home receiver. Monitors are manufactured in smaller quantities and generally use heavy duty components, which contributes to their increased cost, weight, and size. TV monitors are designed to receive the TV signal before it is modulated (video), and therefore have no radio frequency tuners, circuits, or internal sound components. Since video monitors are not limited by R F hand widths, resolution in excess of 1000 lines is possible. An example of a high-quality video monitor is the Conrac model CVA-23. Television projectors use small and intensely bright cathode-ray tubes which project an image onto an enlarging mirror, then through a corrector lens to focus the enlarged secondary image onto a projection screen similar to a motion picture screen. TV projectors have video inputs with R F tuners available as an accessory. Resolution can approach that of a video monitor. One source of TV projectors is Amphiron Systems, Inc., 1 Graphic Place, Moonachie, N. ,I. The advantages of R F vs. video installations in classrooms or laboratories is discussed in the publication "Modern Teaching Aids for College Chemistry,"' p. 11, and the elements in video or R F distribution systems, e.g., line amplifiers, tuners, modulators, etc., will not be discussed here, hut the table lists some manufacturers supplying these elements and excellent technical support.
offer kinescoping services. In addition, Palmer Films markets a special 8mm camera and monitor combination designed to make direct transfers of closed-circuit or video taped material to 8mm or S-8mm film. Limited tests here a t The Ohio State University, kinescoping from videotape recordings made on the Sony 1-in. video tape recorder to 16mm B/W film, demonstrated that it is possible to obtain resolution and detail on the film print suitable for projection up to a 6-ft wide screen size. Tmnsfering Images
I n addition to the kinescoping process it is possible to convert film to tape, or copy tapes from one recorder to another. For multiple copies this work requires supporting electronics and the Ampex duplicating center, 2201 Lunt Avenue, Elk Grove Village, Illinois, 60007, or Videoflight, Inc. (Sony), 147-05 New York Boulevard, Jamica, N.Y., 11434 can be contacted concerning these services. Special 16mm motion picture projectors such as the Graflex Model 930 are available which can play a motion picture directly into a television camera for "live" distribution or conversion t,o video tape. The equipment is as simple to operate as a classroom projector. S-8mm projectors compatible with the TV scanning systems are not yet commercially available; however, existing projeotors can be modified in a department shop and a suitable design, "Adaption of an 8mm Projector for Telecine Use," was published in the June, 1967 Journal of the S M P T E (9 E. 41st St., N.Y. 10017) Vol. 76, No. 6. If the needs of the chemistry community concerning the converting of video tape to film, film to tape, and the duplication of tapes are made known to the manufacturers of appropriate equipment at this time, it is possible that additional items of equipment to simplify these processes could be made available. Color
Some Suppliers of Television Distribution and Switching- Equipment .~ Blander-Tongue Carp., 9 Alling Sbreet, Newark N. J. 07102 Dvnair Electmnim. 6360 Federal Bouleverd. San Iliego, Calif. " 92114 Jerrold Electronics Corp., 15th and LeHigh Avenue, Philadelphia, Pa. 19132 ~
A list of specifications which can be used as a guide when purchasing television receivers or monitors for the classroom or laboratory has been prepared by the engineering staff of WOSU-TV, Columbus, Ohio, and copies are available from the author. Kinescoping
The conversion of a television image to a 16mm motion picture film (kinescope), as an art, has largely been de-emphasized by the broadcast industry, with the interest presently directed towards videotape recording. Videotronics, Inc. (a division of Technicolor), 1300 Frowley Drive, Costa Mesa, Calif. 92627; Palmer Films, Inc., 611 Howard Street, San Francisco, Calif.; and Advanced Film Reproductions, New York City,
Advancements in the design of color television cameras, recorders, and receivers have been encouraging in terms of the direction towards lower cost and improved quality. The lowest priced television cameras now have a list price of $12,000 (Bell and Howell, model 2970), color broadcast (RF) systems and receivers, however, still cannot provide assured color information of sufficient resolution and fidelity to guarantee the chemist, for example, that theV" solution viewed over color TV will consistently be the characteristic blue. Color video monitors (priced about $2500, for a 21-in. model) overcome many of the problems encountered in R F color transmission and are being used successfully in hospital teaching programs, with the 1-in. video recorders. Combination RF-video monitors have been introduced, priced in the $600 range, and an evaluation of these units will appear later in this series. Elements in camera design, competing systems to process the electronic color information within videotape recorders, resolution restrictions within the broadcast standards for color, and the number of combinations of color that can be obtained with the receiver controls should be considered in designing closed circuit systems with an eye towards effective use of color. Volume 45, Number 10, October 1968
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The Future
Experience in the last two years has demonstrated that inexpensive, instructor-operated television cameras and recorders offer reliable operation with picture quality equal to or better than home reception. Advancements in the state of the art will probably bring inexpensive color cameras and improved receivers and TV projectors on the market within the next two years. Basic elements in a system acquired now will remain compatible with future equipment components. The outlook is good for increased support from the television industry in designing inst.ructor-operated t,elevision systems which are economical to purchase and maintain. This is the time for the needs of the chemistry community to bc cxpressed to the appropriate manufacturers of television equipment. I wish to thank Mr. William Justus and Bourke Varquhar of WOSU-TV, Columbus, Ohio, for their helpful suggestions and editing of this report. Bibliography
The manufacturers of television cameras and recorders, as well as TV projects, have published a number of
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reports which furnish excellent guidelines for t,he school or department planning an installation. Some specific examples are Video Talk, Vol. 1, No. 2, 1968, "The Handling and St,orxge of Video Tape." Avrtilable fmm: Technical Service Magnotics Products Division, 3M Co., 3M Center Street,, St,. Paul, Minn. 5.5101. "Television Tape Recording System: A Guide for School Administralors." Available from Ampex Corp., Video 1nstl.umentdion IXv., 401 Broadwhy, Redwood Cit,y, Calif. 94063. " A View of Eduealional Television!' Available from General Precision Systems, Inc., GPI. v . Pleasantville, N.Y. 10770. "Questions and Answers Concerning the Purchase of Video Tape Recording Equipment." Availahle from Ampex Corp., Consumer and Educational Producta lliv., 2001 Lunl Avenne, Elk Grove Village, Illinois 60007. "Equipment Guide for Classr.oom Television." Available from Sylvmia Corp., 730 Third Avenue, New York, N.Y. "Video Tape Recorders-A Comparative Study." Available from State of California, Department of Education, 721 Capitol Mall, Sacramento, Calif. 95814, Attention: Guy M. IIelmke, Consultant. "Mulliple Generations on Video Tape Recorders." Available from California. State Department of Education, 721 Capitol Mall, Sacramento, Calif. 95814, Attention: Max Raflerty.
