Camcorders of Grass Valley a Thomson Brand company

By Theodor Samoylov

The professionals of TV broadcasting know that European companies Thomson and Philips were traditionally considered as main world producers of the shooting cameras, having high quality and reliability. Nearly 2-3 years ago the process of the joining up these two companies in one is began, which was named Thomson Multimedia Broadcast Solutions, but one year after hereto alliance has verged the American company Grass Valley widely known to specialists as well. At June of this year the official Thomson representatives have declared that hereafter this “three-headed dragon” will nevertheless carry the name Grass Valley.

The line of TV-cameras and camcorders of this company is broad and comprises ensemble of the different models. The main topics of this article are the most interesting and popular models, have been spreading in many countries.

We shall begin with digital camcorders LDK 100 series. Previously, than proceed with their production in series, Thomson has interviewed the wide group the most respected specialists from broadcasting television area, which have expressed their own wishes and requirements, taken into account in process of the development. When making the camcorders of this series the algorithms for 12-bit analog-to-digital conversion and 22-bit internal processing of signal were used. The camcorders are released with three CCD-types: with line (IT), with line-frame (FIT) transfer of charge, as well as with dynamic processing of pixels (DPM). Also, there are camcorders for picture forming with standard (4:3) and wide-frame (16:9) ratio of the raster sides. By means of special set adapter to camera head it is possible to connect the video recorder of the required recording format such as DVCPRO, DVCPRO50, Betacam SP and others, as well as triaxial adapter for using of camcorder in studio conditions. The small dimensions and low weight allow to use the camcorder for field conditions of the shooting and in OBV complex.

LDK 100 have a broad set of handy automatic functions, including, for instance, constant support of black level, possibility to color correction even under florescent illumination of the shooting object. Two powerful built-in processors provide the high-quality digital processing of sound and videosignals, as well as calibration and diagnostics of the separate functional units. By many functions and adjustments of working state of camcorders it is possible to control by means of personal computer and standard interface RS-232. Smart-card capable to keep four scenic and two camera files that is considerably simplifies and accelerates an adjusting of camcorder and shooting process. Camera files contains all working settings of the camcorder, including, for instance, information about working state of viewfinder, signalizing, tables of the “zebra” type etc. Powering of the camcorder is realized either through triaxial or multiple-strand cable (studio variant), or from the source of the direct current with voltage 12V. Weight of the camcorder with viewfinder and triaxial adapter is 4.9 kg. Sensitivity is 2000 lux under relative aperture F11. Minimum sensitivity is 0.5 lux at iris F1.4 and gain is +36 dB (the range of the gain regulation is between -6 and +36 dB). The resolution ability is not less than 600 TVL. The full assortment of accessories, including base stations, blocks of the remote controls, 5" or 7" viewfinder, tripod plate, cables and even identification number for functioning in multi-camera studio mode is proposed.

Also, in the line of camcorders are entered the following models: LDK 140 (DVCPRO50), LDK 150 (DVCPRO50), LDK 120 (DVCPRO), LDK 110 (DVCPRO).

TV-camcorders released for studio application are possessed by higher qualitative features. There are LDK 200, LDK 20, LDK 4482, TTV 1657 and TTV/LDK 1707 models. On the base of last model another two models are designed: 1707 Microcam, in which body and camera head are unified by standard 26-wire cable by length up to 100m with block of the compensations of the cable losses, as well as model 1707 Sportcam, which is characterized by possibility of the quick lens change (the lens can be from studio to the simplest model) to account of the special frontal adapter. This, for instance, allows the operator to use the different rented lenses depending on the current tasks. One more particularity of the camcorder is concluded in presence of the circuit for double aperture correction that is particularly effective under portrait shooting in studio conditions. This correction allows to change the amplitude of the aperture of the signal of the picture as function of the color and, hereupon, to change the amount of the details on person leading or guest in studio outside of dependencies from remaining portions of the frame and to realize separate color correction in any part of the color spectrum. There is also a system for the dynamic range change, allowing to reproduce too bright and over-lighting areas on objects correctly, as well as to restore the signals of brightness and chrominance by the same way as contour signals at overexposed areas.

One more interesting model is LDK 23 High-Speed mkII. This is specially designed transmission camcorder for high speed shooting. It can be successfully applied for transmission of sport events, when reproducing the repetitions of separate fragments is required. In camcorder some special innovative technical methods are used, which allow complete avoiding of vertical smearing of picture that it is important particularly on shooting of processes with high-speed change. For instance, translations from ski world championship in Hanty-Mansiysk were realized by such camcorders.

There are many items for HD TV, getting all broader spreading in the world. This has found its reflection in studio camcorder for HD TV of LDK 6000HD model. This camcorder was named “work of art”, and for it special CCD HD TV were designed, which forming of 9.2 milions picture elements (1920 pixels in horizontal and 4320 pixels in vertical direction) are provided. However, this camcorder is capable to function as well in standard mode of line scanning. The working modes are: 1080i, 720p and HD-DPM. Herewith there are the small dimensions and low weight of the camcorder (5 kg together with viewfinder). It can work from the power source of the direct current by voltage 12V.

Viper FilmStream

Now it is necessary to say several words about TV-camcorder for electronic cinema. This model has got the name Viper FilmStream. As in all model of the above examined camcorders, 12-bit analog-to-digital signal transformation is used. The progressive raster scanning at resolution 1920×1080 pixels for each of forming color signals is applied. Such technology, patent pending by developer, is based on logarithmic calculation of data in each of the primary colors of RGB-signal. For transformation of data with 10-bit sampling (for signal of chrominance) and the following recording on HD recorder as transferring two-set HD-SDI line is used. Due to application of such method, the resolution ability does not get lost, over-sampling of dataflow is not required and there is no need to compress the signals. Besides, such technology allows to perfect the color rendition of green and blue components of chrominance signal. The technical methods using in new camcorder, allow to convert the videosignal in picture, which is maximum nearly to cinematographic by many factors. Besides, special CCD enable greatly to raise the factor of picture brightness, which value in standard matrix usually does not exceed 70% of general stream. This, in turn, allows much deeply study the details of a scene during shooting that earlier was possible only when use the movie film. Viper can work in the following formats: 1080i, 24/25/30 frames/sec or 720p, 24/25/30/60 frames/sec. The graphic presentation of the logarithmic transformation of chrominance signals is drawn near to feature of the human eye, which also fixes and processes the colors accordingly to logarithmic law. This has been proven by medical experiments. All features of color rendition are carefully calibrated for achievement of the maximum cinematographic effect.

Material provided by Sankom-Pro Company